JP2018032743A - Memory cell, and nonvolatile semiconductor memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a memory cell capable of suppressing the occurrence of a disturb and a non-volatile semiconductor storage device while achieving miniaturization. SOLUTION: In a memory cell MC, even if the impurity concentration in the fin portion S2 is increased and the drain region 12a and the source region 12b are brought close to each other on the surface of the fin portion S2 to reduce the size, the shape of the fin portion S2. By selecting, the potential difference between the memory gate electrode DG and the fin portion S2 can be reduced to suppress the occurrence of disturb. Thus, the memory cell MC can suppress the occurrence of the disturb while achieving miniaturization. [Selection diagram] FIG.

Description

  The present invention relates to a memory cell and a nonvolatile semiconductor memory device.

  Conventionally, Japanese Unexamined Patent Application Publication No. 2011-129816 (Patent Document 1) discloses a memory cell in which a memory gate structure is disposed between two select gate structures (see Patent Document 1 and FIG. 15). . In practice, this memory cell comprises a drain region to which a bit line is connected and a source region to which a source line is connected, and a first select gate structure on a semiconductor substrate between the drain region and the source region, A memory gate structure and a second selection gate structure are arranged and formed in order. In a memory cell having such a structure, a charge storage layer surrounded by an insulating material is provided in the memory gate structure, and data is written by injecting charges into the charge storage layer, or charge storage is performed. Data can be erased by extracting charges in the layer.

  In practice, in such a memory cell, when a charge is injected into the charge storage layer, the low voltage bit voltage from the bit line is reduced while the voltage is cut off by the second selection gate structure connected to the source line. The voltage is applied to the channel layer of the memory gate structure via the first select gate structure. At this time, in the memory gate structure, a high memory gate voltage is applied to the memory gate electrode, and charge can be injected into the charge storage layer by a quantum tunnel effect caused by a large voltage difference between the bit voltage and the memory gate voltage. .

  In the nonvolatile semiconductor memory device in which a plurality of memory cells having such a configuration are arranged in a matrix, a memory gate line for applying a voltage to each memory gate electrode is shared by the plurality of memory cells. When a high voltage charge storage gate voltage is applied to a memory gate line in order to inject charge into the charge storage layer of a given memory cell, the high voltage is also applied to the memory gate electrode of another memory cell sharing the memory gate line. The charge storage gate voltage is applied.

  Therefore, in a memory cell in which no charge is injected into the charge storage layer, for example, a high bit voltage is applied to the channel layer of the memory gate structure to reduce the voltage difference between the memory gate electrode and the channel layer. Even when a charge storage gate voltage is applied to the memory gate line, injection of charges into the charge storage layer is prevented.

JP 2011-129816 JP

  However, in a memory cell that does not inject charge into the charge storage layer, when a high voltage charge storage gate voltage is applied to the memory gate line, it does not simply block the injection of charge into the charge storage layer, It is desirable to take measures to prevent a phenomenon (hereinafter referred to as “disturb”) in which an unintended charge is injected into the charge storage layer and the charge storage state of the charge storage layer changes.

  Further, in such a nonvolatile semiconductor memory device, since a plurality of memory cells are arranged in a matrix, more memory cells can be arranged within a limited area even when taking measures against defects due to disturbance. Thus, it is important to reduce the size of the memory cell.

  Accordingly, the present invention has been made in view of the above points, and an object thereof is to propose a memory cell and a nonvolatile semiconductor memory device capable of suppressing the occurrence of disturbance while reducing the size.

  In order to solve such problems, a memory cell of the present invention includes a semiconductor substrate covered with an insulating layer, a fin portion formed on the semiconductor substrate so as to protrude from the insulating layer, a lower memory gate insulating film, and a charge storage A memory gate structure formed on the insulating layer so as to straddle the fin portion, and a first selection gate electrode on the first selection gate insulating film A first select gate structure formed on the insulating layer so as to straddle the fin portion along one side wall spacer formed on one side wall of the memory gate structure. A second selection gate electrode is provided on the selection gate insulating film, and is formed on the insulating layer so as to straddle the fin portion along another side wall spacer formed on the other side wall of the memory gate structure. A second selection gate structure, and a drain provided on the surface of the fin portion adjacent to the first selection gate structure to be insulated from the first selection gate electrode and to which a bit line is electrically connected A source region that is provided on the surface of the fin portion adjacent to the second select gate structure so as to be insulated from the second select gate electrode, and to which a source line is electrically connected. The one selection gate structure, the memory gate structure, and the second selection gate structure are provided between the drain region and the source region, and the insulating layer is insulated from the semiconductor substrate from the lower memory gate. The distance to the lower surface of the film is formed larger than the distance from the semiconductor substrate to each lower surface of the first selection gate insulating film and the second selection gate insulating film, the first selection gate electrode Preliminary Each lower surface position of the second selection gate electrode, wherein said has a lower surface position of the memory gate electrode is disposed at a position closer to the semiconductor substrate.

  The memory cell according to the present invention includes a semiconductor substrate covered with an insulating layer, a fin portion formed on the insulating layer, a lower memory gate insulating film, a charge storage layer, an upper memory gate insulating film, and a memory gate. An electrode is stacked, and a memory gate structure formed on the insulating layer so as to straddle the fin portion, and a first selection gate electrode is provided on the first selection gate insulating film, and one of the memory gate structures A first select gate structure formed on the insulating layer so as to straddle the fin portion along one side wall spacer formed on the side wall of the first select gate electrode, and a second select gate electrode on the second select gate insulating film A second select gate structure formed on the insulating layer so as to straddle the fin portion along another side wall spacer formed on the other side wall of the memory gate structure, and 1 Select gate structure A drain region that is provided on a surface of the fin portion adjacent to the body so as to be insulated from the first selection gate electrode, and to which a bit line is electrically connected; and the fin portion adjacent to the second selection gate structure A source region electrically insulated from the second select gate electrode and electrically connected to a source line, the first select gate structure, the memory gate structure, and the second The selection gate structure is provided between the drain region and the source region, and an upper insulating layer is provided on the upper surface of the fin portion.

  The non-volatile semiconductor memory device of the present invention is a non-volatile semiconductor memory device in which memory cells each having a memory gate line connected to a memory gate electrode are arranged in a matrix, wherein the memory cells are defined in claims 1 to 7. The memory cell according to any one of the above, wherein a plurality of the memory cells arranged in a matrix share the memory gate line.

  In the memory cell and the nonvolatile semiconductor memory device of the present invention, when blocking the injection of charge into the charge storage layer, the first select gate structure causes the inside of the fin portion surrounded by the memory gate structure, the bit line, The depletion layer is formed on the surface of the fin portion by blocking the electrical connection between the source line and the inside of the fin portion surrounded by the memory gate structure by the second selection gate structure. And a memory cell that can reduce the potential difference between the memory gate electrode and the fin portion by the depletion layer.

  As a result, in the present invention, even if the impurity concentration in the fin portion is increased and the drain region and the source region are brought close to each other on the surface of the fin portion to reduce the size, a depletion layer is formed in the entire fin portion. By selecting the shape of the fin portion, the potential difference between the memory gate electrode and the fin portion can be reduced, and the electric field applied to the depletion layer can also be reduced to suppress the occurrence of disturbance.

  In the memory cell of the present invention, the gate width of each of the first selection gate structure, the memory gate structure, and the second selection gate structure can be replaced with the height of the fin portion. Although the height is increased, the formation area of each of the first selection gate structure, the memory gate structure, and the second selection gate structure in the direction of the gate width can be reduced, and downsizing can be realized accordingly.

  Incidentally, in the memory cell of the present invention, when blocking the injection of charges into the charge storage layer, the voltage that can cut off the electrical connection between the fin portion surrounded by the memory gate structure and the bit line (source line) May be applied to the bit line and the source line. Thus, in the memory cell of the present invention, the voltage value of the bit line and the source line can be reduced without being restricted by the charge storage gate voltage applied to the memory gate electrode, and accordingly, the first selection gate structure Each film thickness of the first selection gate insulating film and the second selection gate insulating film of the second selection gate structure can be reduced, and high-speed operation can be realized.

It is a perspective view which shows the structure (1) of a memory cell. It is the schematic which shows the planar layout of a non-volatile semiconductor memory device. 3A is a schematic diagram showing a cross-sectional configuration at the AA ′ portion in FIG. 2, and FIG. 3B is a schematic diagram showing a cross-sectional configuration at the BB ′ portion in FIG. 2. 4A is a schematic diagram illustrating a cross-sectional configuration of the memory cell in the CC ′ portion of FIG. 2, and FIG. 4B is a schematic diagram illustrating a cross-sectional configuration of the memory cell in the DD ′ portion of FIG. 2. 1 is a schematic diagram showing a circuit configuration of a nonvolatile semiconductor memory device in which a plurality of memory cells are arranged in a matrix. 6 is a table showing an example of voltage values at each portion during a data write operation, a data read operation, and a data erase operation. It is the schematic where it uses for description of the electric potential in a write non-selection memory cell. It is the schematic which shows the manufacturing process (1) of a non-volatile semiconductor memory device. FIG. 9A is a schematic diagram showing a manufacturing process (2) of the nonvolatile semiconductor memory device, FIG. 9B is a schematic diagram showing a cross-sectional configuration at a portion EE ′ in FIG. 9A, and FIG. 9C is a nonvolatile diagram. FIG. 9D is a schematic diagram showing a manufacturing step (3) of the semiconductor memory device, and FIG. 9D is a schematic diagram showing a cross-sectional configuration at a portion EE ′ in FIG. 9C. 10A is a schematic diagram illustrating a manufacturing process (1) of the nonvolatile semiconductor memory device at the position illustrated in FIG. 9D, and FIG. 10B illustrates a manufacturing process of the nonvolatile semiconductor memory device at the position illustrated in FIG. 9D. FIG. 10C is a schematic diagram illustrating a manufacturing process (3) of the nonvolatile semiconductor memory device at the position illustrated in FIG. 9D. FIG. 11A is a schematic diagram illustrating a manufacturing process (4) of the nonvolatile semiconductor memory device, and FIG. 11B is a schematic diagram illustrating a cross-sectional configuration at a portion EE ′ in FIG. 11A. 12A is a schematic diagram illustrating a cross-sectional configuration of a memory cell according to another embodiment in the AA ′ portion of FIG. 2, and FIG. 12B is according to another embodiment of the BB ′ portion of FIG. It is the schematic which shows the cross-sectional structure of a memory cell. It is a perspective view which shows the structure (2) of a memory cell. 14A is a schematic diagram illustrating a cross-sectional configuration in the AA ′ portion of FIG. 13, and FIG. 14B is a schematic diagram illustrating a cross-sectional configuration in the BB ′ portion of FIG. 13. 15A is a schematic diagram illustrating a cross-sectional configuration of the memory cell in the CC ′ portion of FIG. 13, and FIG. 15B is a schematic diagram illustrating a cross-sectional configuration of the memory cell in the DD ′ portion of FIG. 13. It is a perspective view which shows the structure (3) of a memory cell. 17A is a schematic diagram showing a cross-sectional configuration at the AA ′ portion in FIG. 16, and FIG. 17B is a schematic diagram showing a cross-sectional configuration at the BB ′ portion in FIG. 16. 18A is a schematic diagram showing a cross-sectional configuration of the memory cell in the CC ′ portion of FIG. 16, and FIG. 18B is a schematic diagram showing a cross-sectional configuration of the memory cell in the DD ′ portion of FIG. It is a perspective view which shows the structure (4) of a memory cell. 20A is a schematic diagram illustrating a cross-sectional configuration in the AA ′ portion of FIG. 19, and FIG. 20B is a schematic diagram illustrating a cross-sectional configuration in the BB ′ portion of FIG. 19. 21A is a schematic diagram showing a cross-sectional configuration of the memory cell in the CC ′ portion of FIG. 19, and FIG. 21B is a schematic diagram showing a cross-sectional configuration of the memory cell in the DD ′ portion of FIG. 19.

Hereinafter, modes for carrying out the present invention will be described. The description will be in the following order.
<1. Outline of memory cell having fin structure>
<2. Detailed configuration of memory cell>
<3. Circuit Configuration of Nonvolatile Semiconductor Memory Device>
<4. Regarding Voltages During Various Operations in Nonvolatile Semiconductor Memory Device>
4-1. Data writing operation 4-2. Data non-write operation 4-3. Data read operation 4-4. Data erasing operation <5. Regarding the potential in a write unselected memory cell in which a high voltage charge storage gate voltage is applied to the memory gate electrode>
<6. Manufacturing Method of Nonvolatile Semiconductor Memory Device>
<7. Action and Effect>
<8. Other embodiments>
8-1. Configuration of memory cell when memory gate electrode, first selection gate electrode, and second selection gate electrode are formed of a conductive material other than a metal material 8-2. Configuration of memory cell in which cap insulating film is provided on upper surface of fin portion 8-3. Others <9. Memory cell with reduced thickness of insulating layer in region where first select gate structure and second select gate structure are provided>
9-1. Configuration of memory cell 9-2. Action and effect <10. Memory cell in which fin portion is provided on insulating layer>
10-1. Configuration of memory cell 10-2. Action and Effect 10-3. Fins according to other embodiments

(1) Outline of Memory Cell Having Fin Structure FIG. 1 is a perspective view schematically showing a fin structure of a memory cell MC provided in the nonvolatile semiconductor memory device 1. Here, first, the point that the memory cell MC has the configuration of a fin-type FET (Field Effect Transistor) will be briefly described with reference to the perspective view shown in FIG. In this case, the memory cell MC has, for example, a semiconductor substrate S1 formed of a semiconductor material such as silicon, and a fin portion S2 formed integrally with the semiconductor substrate S1 and formed of the same semiconductor material as the semiconductor substrate S1. The fin portion S2 is formed to protrude from the semiconductor substrate S1.

  Actually, in the memory cell MC, the surface of the semiconductor substrate S1 formed in a plate shape is covered with an insulating layer IS made of an insulating material, and the semiconductor substrate S1 has a fin portion S2 extending in the vertical direction z. The fin portion S2 is formed so as to protrude from the surface of the insulating layer IS. The fin portion S2 is formed in a rectangular parallelepiped shape, for example, and the longitudinal direction extends in the y direction along the surface of the semiconductor substrate S1. In the case of this embodiment, it is assumed that, for example, a P-type impurity is implanted into the semiconductor substrate S1 and the fin portion S2.

  In addition, in this embodiment, the memory cell MC includes a memory gate structure 2 in which an N-type memory transistor MT is formed in the fin portion S2, and an N-type MOS first select transistor T1 in the fin portion. The first select gate structure 3 formed in S2 and the second select gate structure 4 that similarly forms the second select transistor T2 of the N-type MOS in the fin portion S2 so as to straddle the fin portion S2. Formed on the IS.

  The detailed configuration of the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 will be described later with reference to FIGS. The description will be given focusing on the configuration in which the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 straddle the fin portion S2.

  In this case, the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 are formed on the insulating layer IS so that the longitudinal direction intersects the y direction in which the fin portion S2 extends. The fin portion S2 is provided so as to cover the surface of the fin portion S2 in a U-shape. As a result, the exposed surface (opposite side surface and upper surface) of the fin portion S2 on the surface of the insulating layer IS is covered with the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4. It becomes the composition.

  In the case of this embodiment, the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 are extended so as to run in parallel, and the fin portions S2 are respectively connected. The straddling x direction is arranged so as to be orthogonal to the y direction in which the fin portion S2 is extended and the vertical z direction. The memory gate structure 2 is insulated from the first selection gate structure 3 by one side wall spacer 6 formed along one side wall, and another side wall formed along the other side wall. The spacer 7 is insulated from the second select gate structure 4.

  In the fin portion S2, a drain region 12a is formed on the surface adjacent to the first selection gate structure 3 so as to be insulated from the first selection gate electrode DG of the first selection gate structure 3. A bit line (not shown) is connected to the region 12a. In the fin portion S2, a source region 12b is formed on the surface adjacent to the second selection gate structure 4 so as to be insulated from the second selection gate electrode SG of the second selection gate structure 4. A source line (not shown) is connected to the source region 12b.

(2) Detailed Configuration of Memory Cell Next, FIG. 2 showing a planar layout of the nonvolatile semiconductor memory device 1 in which, for example, four memory cells MC are arranged in the x direction, and AA in FIG. 1 and FIG. 3A showing a cross-sectional configuration in the 'portion, FIG. 3B showing a cross-sectional configuration in the BB ′ portion in FIGS. 1 and 2, and FIG. 4A showing a cross-sectional configuration in the CC ′ portion in FIGS. A detailed configuration of the memory cell MC will be described with reference to FIG. 4B showing a cross-sectional configuration in the DD ′ portion of FIGS. 1 and 2.

  2 mainly shows the fin portion S2, the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4, and is shown in FIG. The configuration of the side wall spacer 6 between the memory gate structure 2 and the first selection gate structure 3 and the side wall spacer 7 between the memory gate structure 2 and the second selection gate structure 4 is omitted. ing.

  In this case, as shown in FIG. 2, the nonvolatile semiconductor memory device 1 is arranged such that a plurality of fin portions S2 run in parallel in the y direction, and a memory cell MC is formed in each fin portion S2. In the nonvolatile semiconductor memory device 1, the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 are arranged in parallel so as to intersect with the extending y direction of each fin portion S2. The memory gate MT, the first selection gate structure 3 and the second selection gate structure 4 are extended in a region extending across the fin portions S2, and the memory transistor MT and the first selection transistor A memory cell MC having T1 and a second selection transistor T2 is formed.

  The nonvolatile semiconductor memory device 1 is provided with a memory gate contact MGC to which a memory gate line (not shown) is connected at a predetermined position on the upper surface of the memory gate electrode MG of the memory gate structure 2, and a plurality of memories The memory gate voltage applied to the memory gate line can be applied to the memory gate electrode MG shared by the cells MC via the memory gate contact MGC.

  Further, in the nonvolatile semiconductor memory device 1, a first selection gate contact in which a first selection gate line (not shown) is connected to a predetermined position on the upper surface of the first selection gate electrode DG of the first selection gate structure 3 The DGC is provided, and the voltage applied to the first selection gate line can be applied to the first selection gate electrode DG shared by the plurality of memory cells MC via the first selection gate contact DGC.

  Further, the nonvolatile semiconductor memory device 1 includes a second selection gate contact in which a second selection gate line (not shown) is connected to a predetermined position on the upper surface of the second selection gate electrode SG of the second selection gate structure 4. The SGC is provided, and the voltage applied to the second selection gate line can be applied to the second selection gate electrode SG shared by the plurality of memory cells MC via the second selection gate contact SGC.

  A drain region 12a is formed on the surface of the fin portion S2 adjacent to the first selection gate structure 3, and a bit contact BC connected to a bit line (not shown) is provided in the drain region 12a. . Thus, the bit voltage applied to the bit line can be applied to the drain region 12a via the bit contact BC in the memory cell MC.

  On the other hand, a source region 12b is formed on the surface of the fin portion S2 adjacent to the second selection gate structure 4, and a source contact SC connected to a source line (not shown) is provided in the source region 12b. ing. As a result, the source voltage applied to the source line can be applied to the memory cell MC via the source contact SC to the source region 12b.

In practice, the memory cell MC includes silicon oxide (SiO, SiO) along the side wall of the first select gate structure 3 as shown in FIG. 3A showing a cross-sectional configuration in the AA ′ portion of FIGS. ₂ ) A sidewall portion 22a made of an insulating material is formed, and a drain region 12a is formed on the surface of the fin portion S2 adjacent to the sidewall portion 22a. The drain region 12a is insulated from the first selection gate electrode DG of the first selection gate structure 3 by a sidewall portion 22a formed between the first selection gate structure 3 and the drain region 12a.

In the memory cell MC, a sidewall portion 22b made of an insulating material such as silicon oxide (SiO, SiO ₂ ) is formed along the sidewall of the second selection gate structure 4, and the sidewall portion 22b A source region 12b is formed on the surface of the adjacent fin portion S2. The source region 12b is insulated from the second selection gate electrode SG of the second selection gate structure 4 by a sidewall portion 22b formed between the second selection gate structure 4 and the source region 12b.

  In this embodiment, the drain region 12a and the source region 12b formed on the surface of the fin portion S2 with a predetermined interval are made of a semiconductor material such as SiGe, and are formed on the surface of the fin portion S2 by an epitaxial growth method. It is selectively formed and has a predetermined film thickness.

The memory gate structure 2 is formed on the fin portion S2 between the drain region 12a and the source region 12b via a lower memory gate insulating film 13 made of an insulating material such as silicon oxide (SiO, SiO ₂ ), for example, silicon nitride ( Si ₃ N ₄ ), silicon oxynitride (SiON), alumina (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), etc., and has a charge storage layer EC. The memory gate electrode MG is interposed through the upper memory gate insulating film 14 made of an insulating material different from the lower memory gate insulating film 13 (for example, a high-k material such as hafnium oxide (HfO ₂ ) or hafnium nitride silicate (HfSiON)). have. As described above, the memory gate structure 2 has a configuration in which the charge storage layer EC is insulated from the fin portion S2 and the memory gate electrode MG by the lower memory gate insulating film 13 and the upper memory gate insulating film.

  The memory gate electrode MG is made of, for example, a metal material such as aluminum (Al), titanium aluminum (TiAl), tantalum carbide (TaC), or silicon tantalum nitride (TaSiN). The upper surface is flattened by the flattening process. Further, the memory gate line ML is connected to the memory gate electrode MG, and a predetermined voltage can be applied from the memory gate line ML.

  In the memory gate structure 2, a wall-shaped side wall spacer 6 made of an insulating material is formed along one side wall, and the first selection gate structure 3 is adjacent to the memory gate structure 2 with the side wall spacer 6 interposed therebetween. In this embodiment, the memory gate structure 2 is provided with a wall-like memory gate sidewall insulating film 15a integrally formed with one end of the upper memory gate insulating film 14 along one sidewall of the memory gate electrode MG. In addition, sidewall spacers 6 are formed along the sidewalls of the memory gate sidewall insulating film 15a, the upper memory gate insulating film 14, the charge storage layer EC, and the lower memory gate insulating film 13. The memory gate sidewall insulating film 15a formed in the memory gate structure 2 is formed of the same insulating material (for example, a high-k material) as the upper memory gate insulating film 14, and the upper memory gate insulating film 14 can be formed in the same manufacturing process.

  The side wall spacer 6 formed between the memory gate structure 2 and the first selection gate structure 3 is formed with a predetermined film thickness, the memory gate side wall insulating film 15a in the memory gate structure 2, The memory gate electrode MG and the first select gate electrode DG can be insulated together with the first select gate sidewall insulating film 19a in the first select gate structure 3 to be described later.

In this case, the side wall spacer 6 is an insulating material (for example, a high-k material) of the memory gate side wall insulating film 15a in the memory gate structure 2 or the first selection gate side wall insulating film 19a in the first selection gate structure 3. ) And an insulating material such as silicon oxide (SiO, SiO ₂ ), and the upper surface is flattened by a flattening process such as CMP performed in the manufacturing process.

  Here, when the distance between the memory gate electrode MG and the first selection gate electrode DG is less than 5 [nm], when a predetermined voltage is applied to the memory gate electrode MG or the first selection gate electrode DG, the memory gate There is a risk that a breakdown voltage failure may occur in the sidewall insulating film 15a, the sidewall spacer 6, and the first selection gate sidewall insulating film 19a.

  On the other hand, when the distance between the memory gate electrode MG and the first selection gate electrode DG exceeds 40 [nm], the fin portion S2 (for example, 50 [nm from the surface) is formed between the memory gate electrode MG and the first selection gate electrode DG. ] (Region (surface region)) until the data is read, it becomes difficult for the read current to flow between the memory gate structure 2 and the first select gate structure 3.

  Therefore, in the case of this embodiment, the distance between the memory gate electrode MG and the first selection gate electrode DG is preferably selected from 5 [nm] to 40 [nm]. The total thickness of the film 15a, the side wall spacer 6, and the first selection gate side wall insulating film 19a is also preferably selected from 5 nm to 40 nm.

  Furthermore, the sidewall spacer 6 is preferably formed of an insulating material having a relative dielectric constant smaller than that of the memory gate sidewall insulating film 15a and the first selection gate sidewall insulating film 19a. In this case, the capacity between the first selection gate structure 3 and the memory gate structure 2 is reduced, and the access speed can be increased.

In the first select gate structure 3, a lower first select gate insulating film 17a made of an insulating material such as silicon oxide (SiO, SiO ₂ ) is formed on the fin portion S2 between the side wall spacer 6 and the side wall portion 22a. An upper first selection gate insulating film 18a made of an insulating member (for example, a high-k material) different from the first selection gate insulating film 17a is formed on the lower first selection gate insulating film 17a. ing.

  The first selection gate structure 3 includes a first selection gate sidewall insulating film 19a formed in a wall shape along the sidewall spacer 6, and a side wall formed in a wall shape along the sidewall of the sidewall portion 22a. The wall sidewall insulating film 20a is integrally formed with the upper first select gate insulating film 18a. The first select gate sidewall insulating film 19a and the sidewall sidewall insulating film 20a are also formed of the insulating material of the lower first select gate insulating film 17a and the sidewall spacer 6 in the same manner as the upper first select gate insulating film 18a. Are made of different insulating materials (for example, high-k materials), and can be formed together with the upper first selection gate insulating film 18a in the same manufacturing process. Here, the total thickness of the lower first selection gate insulating film 17a and the upper first selection gate insulating film 18a is 9 [nm] or less, preferably 3 [nm] or less.

  In addition, the first select gate structure 3 includes a first select gate electrode DG formed on the upper first select gate insulating film 18a, and the first select gate sidewall insulating film 19a and the sidewall sidewalls. The insulating film 20a is formed along the side wall of the first selection gate electrode DG.

  The first selection gate electrode DG is formed of the same metal material as the memory gate electrode MG (for example, aluminum (Al), titanium aluminum (TiAl), tantalum carbide (TaC), silicon tantalum nitride (TaSiN), etc.). The upper surface is flattened by a flattening process such as CMP performed in the manufacturing process. The first selection gate electrode DG is connected to the first selection gate line DL, and a predetermined voltage can be applied from the first selection gate line DL.

  On the other hand, a wall-like side wall spacer 7 made of an insulating material is also formed on the other side wall of the memory gate structure 2, and the second selection gate structure 4 is adjacent to the other side wall spacer 7. In the case of this embodiment, the memory gate structure 2 has a wall-like memory gate side wall insulating film 15b integrally formed with the other end of the upper memory gate insulating film 14 on the other side wall of the memory gate electrode MG. Other side wall spacers 7 are formed along the respective side walls of the memory gate side wall insulating film 15b, the upper memory gate insulating film 14, the charge storage layer EC, and the lower memory gate insulating film 13. The other memory gate sidewall insulating film 15b formed in the memory gate structure 2 is made of the same insulating material (for example, a high-k material) as the upper memory gate insulating film 14 and the one memory gate sidewall insulating film 15a. The upper memory gate insulating film 14 and the one memory gate sidewall insulating film 15a can be formed in the same manufacturing process.

  The side wall spacer 7 formed between the memory gate structure 2 and the second select gate structure 4 is formed to have the same film thickness as the one side wall spacer 6, and the memory gate side wall in the memory gate structure 2 is formed. The memory gate electrode MG and the second select gate electrode SG can be insulated together with the insulating film 15b and the second select gate sidewall insulating film 19b in the second select gate structure 4 described later.

In this case, the side wall spacer 7 is formed of the same insulating material such as silicon oxide (SiO, SiO ₂ ) as the one side wall spacer 6, and the upper surface is flattened by the flattening process such as CMP performed in the manufacturing process. Has been.

  Here, between the memory gate electrode MG and the second select gate electrode SG, similarly to the memory gate electrode MG and the first select gate electrode DG described above, the memory gate sidewall insulating film 15b, the sidewall spacer 7, and the second select gate electrode DG. 5 [nm] or more and 40 [nm] or less because there is a risk of a breakdown voltage failure in the gate sidewall insulating film 19b or a problem of a decrease in read current between the memory gate structure 2 and the second selection gate structure 4. It is desirable that the distance is selected.

  Therefore, also in this case, it is desirable that the total thickness of the memory gate side wall insulating film 15b, the side wall spacer 7, and the second selection gate side wall insulating film 19b is selected to be 5 [nm] or more and 40 [nm] or less. The other side wall spacers 7 are also preferably formed of an insulating material having a relative dielectric constant smaller than that of the memory gate side wall insulating film 15b and the second selection gate side wall insulating film 19b. In this case, the capacity between the second selection gate structure 4 and the memory gate structure 2 is reduced, and the access speed can be increased.

In the second select gate structure 4, a lower second select gate insulating film 17b made of an insulating material such as silicon oxide (SiO, SiO ₂ ) is provided on the fin portion S2 between the side wall spacer 7 and the side wall portion 22b. An upper second selection gate insulating film 18b made of an insulating member (for example, a high-k material) different from the second selection gate insulating film 17b is formed on the lower second selection gate insulating film 17b. ing.

  The second selection gate structure 4 includes a second selection gate sidewall insulating film 19b formed in a wall shape along the sidewall spacer 7, and a side wall formed in a wall shape along the sidewall of the sidewall portion 22b. The wall sidewall insulating film 20b is integrally formed with the upper second select gate insulating film 18b. Note that the second select gate sidewall insulating film 19b and the sidewall sidewall insulating film 20b are also formed of the insulating material of the lower second select gate insulating film 17b and the sidewall spacer 7 in the same manner as the upper second select gate insulating film 18b. Are made of different insulating materials (for example, high-k material) and can be formed together with the upper second selection gate insulating film 18b in the same manufacturing process. Here, the total thickness of the lower second selection gate insulating film 17b and the upper second selection gate insulating film 18b is 9 [nm] or less, preferably 3 [nm] or less.

  In addition, the second selection gate structure 4 includes a second selection gate electrode SG formed on the upper second selection gate insulating film 18b, and the second selection gate sidewall insulating film 19b and sidewall sidewalls. The insulating film 20b is formed along the side wall of the second selection gate electrode SG.

  The second selection gate electrode SG is made of the same metal material as the memory gate electrode MG (for example, aluminum (Al), titanium aluminum (TiAl), tantalum carbide (TaC), silicon tantalum nitride (TaSiN), etc.). The upper surface is flattened by a flattening process such as CMP performed in the manufacturing process. Further, the second selection gate line SG is connected to the second selection gate line SGL, and a predetermined voltage can be applied from the second selection gate line SGL.

  Here, in the memory cell MC, the upper surfaces of the memory gate structure 2, the first selection gate structure 3, the second selection gate structure 4, and the sidewall spacers 6 and 7 are flattened, and all have the same height. Since they are aligned, the upper layer can be easily processed as long as the protruding region is not formed.

  Incidentally, in the memory cell MC, since the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are formed of a predetermined metal material, the memory gate electrode MG, the first selection gate electrode DG, It can also be prevented that the selection gate electrode DG and the second selection gate electrode SG are depleted.

In this nonvolatile semiconductor memory device 1, the periphery and upper surface of the memory cell MC, the insulating layer IS on the semiconductor substrate S1, the fin portion S2 protruding from the insulating layer IS, and the like are formed of silicon oxide (SiO, SiO ₂ ). It is covered with an interlayer insulating layer 25 made of an insulating material such as an upper interlayer insulating layer (not shown).

  Next, FIG. 3B which shows the cross-sectional structure in the BB 'part of FIG. 1 and FIG. 2 is demonstrated. As shown in FIG. 3B, at the position where the fin portion S2 is not formed, the memory gate structure 2, the first selection gate structure 3, the second selection gate structure 4, the sidewall spacers 6, 7 shown in FIG. 3A. The sidewall portions 22a and 22b are formed on the insulating layer IS covering the semiconductor substrate S1. The first selection gate structure 3, the memory gate structure 2, and the second selection gate structure 4 on the insulating layer IS are the first selection gate structure 3 and the memory gate on the fin portion S2 shown in FIG. 3A. The upper surface is flattened at the same height as the structure 2 and the second selection gate structure 4.

  Here, at the position where the fin portion S2 is not formed, the surface of the insulating layer IS is at a position lower than the surface of the fin portion S2, and accordingly, the first selection gate structure 3 and the memory gate structure 2 The second selection gate structure 4, the side wall spacers 6 and 7, and the side wall portions 22a and 22b are formed to be vertically longer than the position where the fin portion S2 is located, whereby the first selection gate structure 3 and the memory gate structure 2. The second selection gate structure 4, the side wall spacers 6 and 7, and the side wall portions 22a and 22b are at the same height as the position where the fin portion S2 is located.

  In the memory cell MC, the distance H1 from the surface of the semiconductor substrate S1 to the lower surface of the memory gate electrode MG is the distance from the surface of the semiconductor substrate S1 to the lower surfaces of the first selection gate electrode DG and the second selection gate electrode SG. For example, the thickness of the charge storage layer EC is larger than the thickness of the H2, and each lower surface position of the first selection gate electrode DG and the second selection gate electrode SG is disposed at a position lower than the lower surface position of the memory gate electrode MG. Has been.

  As a result, in the memory cell MC, the first selection transistor T1 and the second selection transistor T2 are turned on and off in the region of the side surface of the fin portion S2 so that the lower surface position is lower than the lower surface position of the memory gate electrode MG. The first selection gate electrode DG and the second selection gate electrode SG can be sufficiently controlled. Therefore, in memory cell MC, malfunction during data write operation and data read operation can be prevented.

  Here, as a comparison explanation with the memory cell MC, unlike the memory cell MC, the distance H1 from the surface of the semiconductor substrate S1 to the lower surface of the memory gate electrode MG is different from the memory cell MC at the position where the fin portion S2 is not formed. The position of each lower surface of the first selection gate electrode DG and the second selection gate electrode SG is smaller than the distance H2 from the surface of S1 to the lower surfaces of the first selection gate electrode DG and the second selection gate electrode SG. A memory cell (hereinafter referred to as a comparative example) arranged at a position higher than the lower surface position of the MG will be described below.

  In the comparative example, each lower surface position of the first selection gate electrode DG and the second selection gate electrode SG is arranged at a position higher than the lower surface position of the memory gate electrode MG, so in the region of the side surface of the fin portion S2 On / off of the first selection transistor T1 and the second selection transistor T2 cannot be sufficiently controlled by the first selection gate electrode DG and the second selection gate electrode SG. In particular, in this comparative example, even if a gate-off voltage is applied to the first selection gate electrode DG and the second selection gate electrode SG, the fin portion S2 that is not covered with the first selection gate electrode DG and the second selection gate electrode SG When the information written in the memory transistor MT has a low threshold voltage Vth, the side region of the drain region 12a and the source region 12b are located along the side surface region of the fin portion S2. Leakage current flows, and a malfunction may occur.

  Here, as shown in FIG. 4A showing a cross-sectional configuration in the CC ′ portion of FIGS. 1 and 2, the memory gate structure 2 is formed on the insulating layer IS so as to straddle the fin portion S2. Therefore, the lower memory gate insulating film 13, the charge storage layer EC, the upper memory gate insulating film 14, and the memory gate electrode MG can be provided so as to surround the surface of the fin portion S2. Thereby, the memory gate structure 2 can form a channel layer of the memory transistor MT along the surface of the fin portion S2 surrounded by the memory gate structure 2.

  As described above, in the memory gate structure 2, the gate width of the memory transistor MT is a distance along the surface of the fin portion S2 surrounded by the memory gate structure 2, so that a part of the gate width is By replacing the height along the side surface of the portion S2, the formation area of the memory transistor MT can be reduced accordingly.

  Further, as shown in FIG. 4B showing a cross-sectional configuration in the DD ′ portion of FIGS. 1 and 2, the first selection gate structure 3 is also formed on the insulating layer IS so as to straddle the fin portion S2. Therefore, the lower first selection gate insulating film 17a, the upper selection gate insulating film 18a, and the first selection gate electrode DG can be provided so as to surround the surface of the fin portion S2. Thereby, even in the first selection gate structure 3, the channel layer of the first selection transistor T1 can be formed along the surface of the fin portion S2 surrounded by the first selection gate structure 3.

  Thus, even in the first selection gate structure 3, since the gate width of the first selection transistor T1 is a distance along the surface of the fin portion S2 surrounded by the first selection gate structure 3, the gate width Can be replaced with a height along the side surface of the fin portion S2, and the formation area of the first selection transistor T1 can be reduced accordingly. The second selection gate structure 4 also has the same configuration as the first selection gate structure 3 shown in FIG. 4B because the configuration straddling the fin portion S2 is omitted.

  In this embodiment, as shown in FIGS. 4A and 4B, the memory cell MC has a distance (fin portion) from the top surface of the fin portion S2 to the bottom surface of the memory gate electrode MG on the insulating layer IS. The height of the protrusion in the electrode of S2) is Hfin, and the width of the fin portion S2 in the x direction in which the first selection gate structure 3, the memory gate structure 2, and the second selection gate structure 4 straddle the fin portion S2 is Wfin Then, the relationship of Hfin> Wfin is established.

  As shown in FIG. 3A, in the memory cell MC, the gate length of the first selection gate electrode DG in the y direction where the fin portion S2 is extended is L1, and the gate length of the second selection gate electrode SG is L2. Then, the relationship between L1 ≦ 1.5 · Wfin and L2 ≦ 1.5 · Wfin is established between the fin portion S2 and the width Wfin.

(3) Circuit Configuration of Nonvolatile Semiconductor Memory Device Next, a circuit configuration of the nonvolatile semiconductor memory device in which the memory cells MC described above are arranged in a matrix will be described. As shown in FIG. 5, the nonvolatile semiconductor memory device 1 includes a plurality of memory cells MC11, MC12,..., MC1n, MC21, MC22, ..., MC2n, MCm1, MCm2, having the same configuration as the memory cell MC described above. ..., MCmn is arranged in a matrix, and these memory cells MC11, MC12, ..., MC1n, MC21, MC22, ..., MC2n, MCm1, MCm2, ..., MCmn are on the same semiconductor substrate S1 Is formed. These memory cells MC11, MC12,..., MC1n, MC21, MC22,..., MC2n, MCm1, MCm2, ..., MCmn have a predetermined substrate by a substrate voltage application circuit (not shown) with respect to the shared semiconductor substrate S1. A voltage can be applied uniformly. Although the fin portion S2 as shown in FIG. 1 is integrally formed on the semiconductor substrate S1, the illustration of the fin portion S2 is omitted here.

  The nonvolatile semiconductor memory device 1 includes memory cells MC11, MC12,..., MC1n, MC21, MC22,..., MC2n, MCm1, MCm2,. MC11, MC21, ..., MCm1 (MC12, MC22, ..., MCm2) (MC1n, MC2n, ..., MCmn) each share one bit line BL1 (BL2) (BLn), and a bit line voltage application circuit A predetermined bit voltage can be applied uniformly to each of the bit lines BL1, BL2,..., BLn (not shown). In addition, the nonvolatile semiconductor memory device 1 includes memory cells MC11, MC12,..., MC1n (MC21, MC22,..., MC2n) (MCm1, MCm2) arranged in the other direction (in this case, the row direction) crossing one direction. ,..., MCmn) share one first selection gate line DL1 (DL2) (DLm), and the first selection gate voltage application circuit (not shown) uses the first selection gate lines DL1, DL2,. ..., a predetermined first selection gate voltage can be applied uniformly for each DLm.

  Further, in the case of this embodiment, in the nonvolatile semiconductor memory device 1, one memory gate line ML, one second selection gate line SGL, and one source line SL are combined into one semiconductor substrate. All memory cells MC11, MC12,..., MC1n, MC21, MC22,..., MC2n, MCm1, MCm2,..., MCmn on S1 are shared by the memory gate voltage application circuit (not shown). A predetermined memory gate voltage is applied to the line ML, a predetermined second selection gate voltage is applied to the second selection gate line SGL by a second selection gate voltage application circuit (not shown), and a source line voltage application circuit (FIG. A predetermined source voltage can be applied to the source line SL.

  In this embodiment, one memory gate line ML, one second selection gate line SGL, and one source line SL are connected to all the memory cells MC11, MC12,..., MC1n, MC21. , MC22,..., MC2n, MCm1, MCm2,..., MCmn will be described, but the present invention is not limited to this, and the memory cells MC11, MC12,. , MC1n (MC21, MC22,..., MC2n) (MCm1, MCm2,..., MCmn) may share the memory gate line, the second selection gate line, and the source line, respectively.

  Incidentally, in the memory cell MC11, the memory gate line ML is connected to the memory gate electrode MG of the memory gate structure 2, and the first selection gate line DL1 is connected to the first selection gate electrode DG of the first selection gate structure 3. The second selection gate line SGL is connected to the second selection gate electrode SG of the second selection gate structure 4. Further, in the memory cell MC11, the bit line BL1 is connected to one end (drain region) of the first selection transistor T1 formed by the first selection gate structure 3, and the second selection gate structure 4 forms the first cell. A source line SL is connected to one end (source region) of the 2-select transistor T2.

(4) Voltage during Various Operations in Nonvolatile Semiconductor Memory Device Next, various operations in such a nonvolatile semiconductor memory device 1 will be described. 6 shows a memory cell MCxy (where x is one of 1, 2,..., M, and y is 1, 2,..., N in the nonvolatile semiconductor memory device 1 shown in FIG. Data write operation (“Prog”) for injecting charge into the charge storage layer EC (one of them) and data read operation for detecting whether or not charge is stored in the charge storage layer EC of the memory cell MCxy ( 10 is a table showing an example of voltage values at each part in “Read”) and in a data erasing operation (“Erase”) for extracting charges in the charge storage layer EC of the memory cell MCxy.

  In the column “Prog” in FIG. 6, a column in which the memory cells MCxy that injects charges into the charge storage layer EC are arranged is referred to as a “selected column”, and the memory cells MCxy that inject charges into the charge storage layer EC are The arranged lines are represented as “selected lines”. In the column “Prog” in FIG. 6, a column in which only the memory cells MCxy that do not inject charges into the charge storage layer EC are indicated as “non-selected columns”, and a memory cell in which charges are not injected into the charge storage layer EC. A row in which only MCxy is arranged is represented as a “non-selected row”. Further, “DLx” in FIG. 6 represents the first selection gate lines DL1, DL2,..., DLm, and “BLy” represents the bit lines BL1, BL2,.

(4-1) Data Write Operation For example, when charge is injected into the charge storage layer EC of the memory cell MC11, as shown in the “selected column” column of “Prog” in FIG. A substrate of 0 [V] is applied to the semiconductor substrate S1 (indicated as “Back” in FIG. 6) on which the charge storage gate voltage of 12 [V] is applied to the memory gate electrode MG of the memory cell MC11 and the fin portion S2 is formed. A voltage can be applied.

  At this time, a gate-off voltage of 0 [V] is applied from the second selection gate line SGL to the second selection gate electrode SG of the memory cell MC11. A source off voltage of [V] can be applied. Thus, the second selection gate structure 4 forms a source-side non-conducting region in the fin portion S2, and a channel layer forming carrier region (channel) in the fin portion S2 surrounded by the source region and the memory gate structure 2 The electrical connection with the region in which carriers are induced when forming the layer is interrupted. Thus, the second select gate structure 4 can prevent voltage application from the source line SL to the channel layer forming carrier region of the memory gate structure 2.

  On the other hand, a first selection gate voltage of 1.5 [V] from the first selection gate line DL1 is applied to the first selection gate electrode DG, and the bit line BL1 to 0 [V] is applied to the drain region of the memory cell MC11. A charge storage bit voltage can be applied. Thus, the first selection gate structure 3 can form a drain-side conduction region in the fin portion S2, and can electrically connect the drain region and the channel layer forming carrier region of the memory gate structure 2.

  In the memory gate structure 2, when the channel layer forming carrier region is electrically connected to the drain region, carriers are induced in the channel layer forming carrier region, and the channel layer having 0 [V] which is the same as the charge storage bit voltage is formed. It can be formed on the surface of the fin portion S2 by the carrier. Thus, in the memory cell MC11 into which data is written (hereinafter also referred to as a write selection memory cell) MC12, a large voltage difference (12 [V]) of 12 [V] occurs between the memory gate electrode MG and the channel layer in the memory gate structure 2. Thus, charges can be injected into the charge storage layer EC by the quantum tunnel effect generated thereby, and a state in which data is written can be obtained.

(4-2) Data Non-Write Operation For example, when a charge storage gate voltage necessary for injecting charges into the charge storage layer EC is applied to the memory gate electrode MG of the memory cell MC12, the memory cell MC12 When blocking the injection of charge into the charge storage layer EC, a voltage of 1.5 [V] is applied from the first selection gate line DL1 to the first selection gate electrode DG, and a voltage of 1.5 [V] is applied from the bit line BL2 to the drain region. By applying the voltage, a drain-side non-conducting region in a non-conducting state is formed in a region straddling the first selection gate structure 3 in the fin portion S2. Accordingly, the memory cell MC12 in which data is not written (hereinafter also referred to as a write non-selected memory cell) MC12 is formed in the channel layer forming carrier in the fin portion S2 surrounded by the memory gate structure 2 by the first selection gate structure 3. The electrical connection between the region and the drain region is interrupted.

  At this time, in the write unselected memory cell MC12, a voltage of 0 [V] is applied from the second selection gate line SGL to the second selection gate electrode SG, and a voltage of 0 [V] is applied from the source line SL to the source region. Is applied to form a non-conducting source-side non-conducting region in a region straddling the second select gate structure 4 in the fin portion S2. Thereby, the write non-selected memory cell MC12 is electrically connected by the second select gate structure 4 between the source region and the channel layer forming carrier region in the fin portion S2 surrounded by the memory gate structure 2. Cut off.

  Thus, in the write unselected memory cell MC12, a depletion layer is formed in the channel layer forming carrier region in the fin portion S2 surrounded by the memory gate structure 2, and the memory gate structure is based on the charge storage gate voltage. The potential of the surface of the fin portion S2 surrounded by 2 increases, and the voltage difference between the memory gate electrode MG and the surface of the fin portion S2 becomes smaller.

  In particular, in the case of this embodiment, in the memory cell MC, as shown in FIGS. 4A and 4B, the in-electrode protruding height Hfin of the fin portion S2 and the width Wfin of the fin portion S2 satisfy Hfin> Wfin. Since the relationship is formed so that the relationship is established, when the depletion layers are formed along both side surfaces and the upper surface of the fin portion S2 surrounded by the memory gate structure 2, along the one side surface of the fin portion S2. The depletion layer with a predetermined thickness formed in one piece and the depletion layer with a predetermined thickness formed along the other side face opposed to one side surface are integrated to form a depletion layer in the entire fin portion S2. Can be done. Thus, in the write non-selected memory cell MC12, the depletion layer does not cause a voltage difference that causes a quantum tunnel effect between the memory gate electrode MG and the fin portion S2, and prevents charge injection into the charge storage layer EC. it can.

  At this time, in the write unselected memory cell MC12, the potential on the surface of the fin portion S2 immediately below the memory gate structure 2 is caused by the depletion layer D formed in the fin portion S2 surrounded by the memory gate structure 2. The first selection gate insulating films 17a and 18a (FIG. 3A) of the selection gate structure 3 and the second selection gate insulating films 17b and 18b (FIG. 3A) of the second selection gate structure 4 can be prevented from reaching. .

  Thereby, in the first selection gate structure 3, the thickness of the first selection gate insulating films 17a and 18a is reduced in accordance with the low voltage applied to the drain region 12a (FIG. 3A) from the bit line BL2. Even if it is formed, the potential of the fin portion S2 surface immediately below the memory gate structure 2 is blocked by the depletion layer, so that the dielectric breakdown of the first selection gate insulating films 17a and 18a due to the potential of the fin portion S2 surface is prevented Can do.

  Similarly, in the second select gate structure 4, the thickness of the second select gate insulating films 17a and 18b is adjusted in accordance with the low voltage source voltage applied from the source line SL to the source region 12b (FIG. 3A). Even if the thickness is reduced, the potential of the surface of the fin portion S2 immediately below the memory gate structure 2 is blocked by the depletion layer, so that the dielectric breakdown of the second selection gate insulating films 17b and 18b is caused by the potential of the surface of the fin portion S2. Can be prevented.

(4-3) Data Read Operation In the data read operation shown in the column “Read” in FIG. 6, for example, when the memory cell MC11 is a read target, the bit line BL1 connected to the memory cell MC11 is read. Is precharged to 1.5 [V], for example, and the source line SL is set to 0 [V]. As a result, when charge is stored in the charge storage layer EC of the memory cell MC11 from which data is read (when data is written), the fin portion S2 immediately below the memory gate structure 2 becomes non-conductive, The electrical connection between the drain region and the source region can be interrupted. Thereby, in the memory cell MC11 from which data is read, the read voltage of 1.5 [V] on the bit line BL1 connected to the drain region can be maintained as it is.

  On the other hand, when charge is not accumulated in the charge accumulation layer EC of the memory cell MC11 from which data is read (when data is not written), the fin portion S2 immediately below the memory gate structure 2 becomes conductive, and the drain region Are electrically connected to each other, and as a result, the source line SL of 0 [V] and the bit line BL1 of 1.5 [V] are electrically connected via the memory cell MC11. Thereby, in the nonvolatile semiconductor memory device 1, the read voltage of the bit line BL1 connected to the memory cell MC11 that reads data is applied to the bit line BL1 by being applied to the source line SL of 0 [V]. The read voltage of 1.5 [V] is reduced.

  Thus, in the nonvolatile semiconductor memory device 1, the data read operation of whether or not charges are accumulated in the charge accumulation layer EC of the memory cell MC11 by detecting whether or not the read voltage of the bit line BL1 has changed. Can be executed. Note that a non-read voltage of 0 [V] can be applied to the bit line BL2 to which only the memory cells MC12, MC22,.

(4-4) Data Erase Operation Incidentally, during the data erase operation (“Erase” in FIG. 6) for extracting the charge in the charge storage layer EC of the memory cell MC11, the memory gate electrode ML to the memory gate electrode MG In addition, when the memory gate voltage of −12 [V] is applied, the charge in the charge storage layer EC is extracted toward the fin portion S2 that is 0 [V] through the semiconductor substrate S1, and the data Can be erased.

(5) Potential in Write Unselected Memory Cell to which High Voltage Charge Storage Gate Voltage is Applied to Memory Gate Electrode Here, FIG. 7 shows a memory cell (write unselected memory cell) MC in which no data is written. FIG. 5 is a schematic diagram showing a potential state in the memory gate structure 2 and the fin portion S2 when a high voltage charge storage gate voltage Vg is applied to the memory gate electrode MG. The cross-sectional view shown in FIG. 7 is the same as FIG. 4A showing the cross-sectional configuration of the CC ′ portion of FIGS. 1 and 2, and is the position of the fin portion S2 where the memory gate structure 2 is provided. A cross-sectional structure is shown.

  A curve Vx in FIG. 7 indicates a memory cell in which a memory cell structure, a first selection gate structure, and a second selection gate structure are provided on a flat surface of a semiconductor substrate without providing a fin portion (comparative example). ) Shows the state of the potential. In the memory cell as a comparative example, when a high voltage charge storage gate voltage is applied to the memory gate electrode MG, the semiconductor substrate immediately below the first selection gate structure and the second selection gate structure just below, as described above. By making each of the semiconductor substrates non-conductive, a depletion layer D can be formed in the semiconductor substrate immediately below the memory gate structure, and as a result, the potential difference Vono1 generated between the memory gate electrode and the semiconductor substrate can be reduced to reduce the data Can prevent writing.

  Even in the memory cell of such a comparative example, the voltage drops at the three-layer component ONO of the upper memory gate insulating film, the charge storage layer, and the lower memory gate insulating film provided in the memory gate structure, and the depletion layer D In particular, the voltage value decreases as the distance from the substrate surface increases, and the substrate voltage can be 0 [V]. However, since the fin portion S2 is not formed in the memory cell of the comparative example, the voltage applied to the three constituent parts ONO of the upper memory gate insulating film, the charge storage layer, and the lower memory gate insulating film, and the depletion layer The potential change due to D is determined by the impurity concentration in the semiconductor substrate immediately below the memory gate structure.

  That is, in the memory cell of the comparative example, the lower the impurity concentration of the semiconductor substrate just below the memory gate structure, the deeper the depletion layer D is formed when the higher voltage charge storage gate voltage Vg is applied to the memory gate electrode MG. Can be formed. As a result, in the memory cell of the comparative example, the deeper the depletion layer D, the slower the potential change in the three-layer component ONO of the upper memory gate insulating film, the charge storage layer, and the lower memory gate insulating film. Therefore, the potential difference between the memory gate electrode and the semiconductor substrate surface can be reduced, and the occurrence of disturbance can be suppressed.

  However, in the memory cell of the comparative example, when the impurity concentration in the semiconductor substrate immediately below the memory gate structure is lowered, the drain region on the surface of the semiconductor substrate adjacent to the first select gate structure and the second select gate structure The short channel effect may cause a short circuit or leakage between the body and the source region on the adjacent semiconductor substrate surface. Therefore, it is necessary to increase the distance between the drain region and the source region. Cannot be refined by.

  Thus, in the memory cell of the comparative example in which the memory cell structure, the first selection gate structure, and the second selection gate structure are provided on the flat surface of the semiconductor substrate, the impurities in the semiconductor substrate immediately below the memory gate structure There is a trade-off between suppression of disturbance due to concentration reduction and downsizing by close proximity of the drain region and the source region.

  Here, for example, in the memory cell of the comparative example in which the distance between the drain region and the source region is designed to be the same as the distance between the drain region 12a and the source region 12b in the memory cell MC, as shown in FIG. When the charge storage gate voltage Vg of the voltage is applied to the memory gate electrode MG, the charge storage gate voltage Vg drops at the three-layer component ONO of the upper memory gate insulating film, the charge storage layer, and the lower memory gate insulating film. However, because the distance between the drain region and the source region is specified, the impurity concentration in the semiconductor substrate cannot be lowered below a predetermined value, so the potential difference Vono1 generated between the memory gate electrode and the semiconductor substrate is selected below the predetermined value. Difficult to do. For this reason, in the memory cell of the comparative example, when the drain region and the source region are brought close to each other and downsized, the occurrence of disturbance cannot be suppressed because the large potential difference Vono1 is generated between the memory gate electrode and the semiconductor substrate.

  On the other hand, when data is not written in the memory cell MC, as shown in FIG. 7, when a charge storage gate voltage Vg (for example, Vg = 12 [V]) is applied to the memory gate electrode MG, The voltage drops at the three-layer component ONO of the upper memory gate insulating film 14, the charge storage layer EC, and the lower memory gate insulating film 13, and a potential difference Vono is generated between the memory gate electrode MG and the upper surface of the fin portion S2. At this time, a depletion layer is formed in the entire fin portion S2 surrounded by the memory gate structure 2, and the voltage value gradually decreases even in the depletion layer, and the substrate of 0 [V] is near the lower end surface of the fin portion S2. It can be a voltage.

  In the memory cell MC to which no data is written, the potential difference Vono applied to the three constituent parts ONO of the upper memory gate insulating film 14, the charge storage layer EC, and the lower memory gate insulating film 13, and the potential due to the depletion layer The change is the height of the fin portion S2 in the region surrounded by the memory gate structure 2 (distance from the upper surface to the lower end surface of the fin portion S2) and the width of the fin portion S2 (the memory gate structure 2 is And the distance between the two side surfaces of the fin portion S2 disposed opposite to each other in the x direction across the fin portion S2.

  Specifically, when the depletion layers are formed along both side surfaces and the upper surface of the fin portion S2 surrounded by the memory gate structure 2, the predetermined thickness formed along one side surface of the fin portion S2 is formed. The fin portion S2 is integrated with the depletion layer of a predetermined thickness formed along the other side surface opposite to the one side surface, and a depletion layer is formed in the entire fin portion S2. Select the height and width.

  As a result, in the memory cell MC, even if the impurity concentration in the fin portion S2 is increased and the drain region 12a and the source region 12b are brought close to each other for miniaturization, a depletion layer is formed in the entire fin portion S2. The potential difference Vono generated between the memory gate electrode MG and the fin portion S2 can be reduced. Thus, in the memory cell MC, the drain region 12a and the source region 12b are brought close to each other for miniaturization, the potential difference Vono generated between the memory gate electrode MG and the fin portion S2 is reduced, and the electric field applied to the depletion layer is also reduced. Occurrence of disturbance can be suppressed.

(6) Manufacturing Method of Nonvolatile Semiconductor Memory Device The nonvolatile semiconductor memory device 1 having the above configuration can be manufactured according to the following manufacturing process. In this case, first, as shown in FIG. 8A, a fin-shaped substrate (not shown) made of, for example, Si is processed by using a patterned hard mask 32 to obtain a plate-like semiconductor substrate S1. The fin portion S2 is formed with a predetermined interval on the surface. Next, after forming an insulating layer made of an insulating material so as to cover the resist 32, the semiconductor substrate S1, and the fin portion S2, the insulating layer is flattened by a flattening process such as CMP (Chemical Mechanical Polishing), and the fin portion S2. An insulating layer ISa whose surface is aligned with the resist 32 on the upper surface is formed.

  Next, by processing the insulating layer ISa, as shown in FIG. 9A, after forming the insulating layer IS in which the fin portion S2 protrudes from the surface by a predetermined height, in FIG. 9A and the EE ′ portion of FIG. 9A As shown in FIG. 9B showing a cross-sectional configuration, a layered lower memory gate insulating film forming layer 13a, a layered charge storage layer forming layer ECa, and a layered first dummy electrode layer 34 are formed, and planarization such as CMP is performed. The surface of the first dummy electrode layer 34 is planarized by the treatment.

  Next, by processing the first dummy electrode layer 34, the charge storage layer forming layer ECa, and the lower memory gate insulating film forming layer 13a, FIG. 9C and FIG. 9D showing a cross-sectional configuration in the EE ′ portion of FIG. 9C. After forming the dummy memory gate electrode DM, the charge storage layer EC, and the lower memory gate insulating film 13 extending so as to straddle the fin portion S2, the layered insulating film is formed and etched back Side wall spacers 6 and 7 are formed along the side wall on which the dummy memory gate electrode DM, the charge storage layer EC, and the lower memory gate insulating film 13 are stacked (side wall spacer forming step).

  Next, a layered select gate insulating film and a layered second dummy electrode layer are sequentially formed so as to cover the insulating layer IS exposed to the outside, the fin portion S2, the dummy memory gate electrode DM, and the side wall spacers 6 and 7. Then, by performing etch back, side wall-like dummy first selection gate electrodes DD and dummy are formed along the side wall spacers 6 and 7 as shown in FIG. A second selection gate electrode DS is formed. Next, the selection gate insulating film other than the region covered with the dummy first selection gate electrode DD and the dummy second selection gate electrode DS is removed, and the dummy first selection gate electrode DD and the dummy second selection gate electrode DS are removed. The selection gate insulating film is left in each lower portion, and the first selection gate insulating film 17a and the second selection gate insulating film 17b are formed.

  Next, after forming a layered insulating film so as to cover the insulating layer IS exposed to the outside, the fin portion S2, the dummy memory gate electrode DM, the dummy first selection gate electrode DD, and the dummy second selection gate electrode DS By performing etch back, side portions along the side walls of one dummy first selection gate electrode DD and first selection gate insulating film 17a are formed as shown in FIG. The wall portion 22a is formed, and the sidewall portion 22b is formed along the side walls of the other dummy second selection gate electrode DS and the second selection gate insulating film 17b (dummy selection gate electrode forming step).

  Next, a drain region 12a and a source region 12b made of SiGe or the like with a predetermined thickness are formed on the surface of the fin portion S2 adjacent to the sidewall portions 22a and 22b by, for example, an epitaxial growth method. Next, the insulating layer IS, the fin portion S2, the dummy memory gate electrode DM, the dummy first selection gate electrode DD, the dummy second selection gate electrode DS, the drain region 12a, the source region 12b, and the like exposed to the outside are covered. After forming the layered interlayer insulating layer, the surface of the interlayer insulating layer is polished and planarized by a planarization process such as CMP.

  As a result, as shown in FIG. 10C, the parts corresponding to those in FIG. 10B are given the same reference numerals, and the surface is flattened, and the dummy memory gate electrode DM, the dummy first selection gate electrode DD, and the dummy second are formed from the surface. An interlayer insulating layer 25 in which each upper surface of the select gate electrode DS is exposed to the outside is formed (dummy electrode exposing step). Next, the dummy memory gate electrode DM, the dummy first selection gate electrode DD, and the dummy second selection gate electrode DS exposed from the surface of the interlayer insulating layer 25 are each removed by dry etching.

  As a result, a dummy electrode removal space ER1 is formed in the region where the dummy memory gate electrode DM has been formed, as shown in FIG. As shown in FIG. 11B showing a cross-sectional configuration of the EE ′ portion, dummy electrode removal spaces ER2 and ER3 are also formed in the region where the dummy first selection gate electrode DD and the dummy second selection gate electrode DS are formed ( Dummy electrode removal process).

  Next, by forming a layered insulating film made of an insulating material such as a high-k material in the dummy electrode removal spaces ER1, ER2, and ER3, as shown in FIG. A layered upper memory gate insulating film 14 is formed on the charge storage layer EC, a wall-shaped memory gate side wall insulating film 15a is formed along one side wall spacer 6, and a wall is formed along the other side wall spacer 7. A memory gate sidewall insulating film 15b may be formed.

  In addition, in the dummy electrode removal space ER2, an upper first selection gate insulating film 18a is formed on the first selection gate insulating film 17a on the fin portion S2, and a side wall-like side is formed along the sidewall portion 22a. A wall sidewall insulating film 20a is formed, and a wall-shaped first selection gate sidewall insulating film 19a can be formed along one sidewall spacer 6.

  Further, in the dummy electrode removal space ER3, an upper second selection gate insulating film 18b is formed on the second selection gate insulating film 17b on the fin portion S2, and a side wall-like side is formed along the sidewall portion 22b. A wall side wall insulating film 20b is formed, and a wall-shaped second select gate side wall insulating film 19b can be formed along the other side wall spacer 7.

  Next, a metal electrode layer made of a metal material such as aluminum (Al), titanium aluminum (TiAl), tantalum carbide (TaC), or silicon tantalum nitride (TaSiN) is formed on the surface of the interlayer insulating layer 25. Thereby, the dummy memory gate electrode DM, the dummy first selection gate electrode DD, and the dummy second selection gate electrode DS are removed, and in the dummy electrode removal spaces ER1, ER2, ER3 where the layered insulating film is formed, Each metal electrode layer is embedded, and then the surface of the metal electrode layer is polished by a planarization process such as CMP, and the surface of the metal electrode layer is planarized according to the surface of the interlayer insulating layer 25.

  Thus, as shown in FIG. 3A, the metal electrode layer is buried in the space where the dummy memory gate electrode DM is formed to form the memory gate electrode MG, and the space where the dummy first selection gate electrode DD is formed. The metal electrode layer is embedded in the first selection gate electrode DG, and the space in which the dummy second selection gate electrode DS is formed is embedded in the second selection gate electrode SG. Thus, the memory cell MC including the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 can be formed (metal gate electrode formation step). Thereafter, in addition to the step of forming an upper interlayer insulating layer, various contacts such as the first select gate contact DGC, the second select gate contact SGC, and the memory gate contact MCG shown in FIG. The nonvolatile semiconductor memory device 1 can be manufactured through a process of forming the interlayer insulating layer at a predetermined position of the interlayer insulating layer.

(7) Operation and Effect In the above configuration, in the memory cell MC, the fin portion S2 is provided on the semiconductor substrate S1 so as to protrude from the insulating layer IS, and the memory gate structure 2 and the first gate are formed across the fin portion S2. The selection gate structure 3 and the second selection gate structure 4 are formed on the insulating layer IS. In this memory cell MC, the drain region 12a connected to the bit line BL is provided on the surface of the fin portion S2 adjacent to the first selection gate structure 3 so as to be insulated from the first selection gate electrode DG. On the other hand, the source region 12b connected to the source line SL is provided on the surface of the fin portion S2 adjacent to the second selection gate structure 4 so as to be insulated from the second selection gate electrode SG, and the drain region 12a and the source The first selection gate structure 3, the memory gate structure 2, and the second selection gate structure 4 are provided between the region 12b.

  In the memory cell MC having such a configuration, the first selection gate structure 3 is surrounded by the memory gate structure 2 when the charge injection into the charge storage layer EC is prevented to prevent data writing. The electrical connection between the fin portion S2 and the bit line BL is interrupted, and the second selection gate structure 4 electrically connects the inside of the fin portion S2 surrounded by the memory gate structure 2 and the source line SL. By disconnecting the general connection, the depletion layer formed along the surface of the fin portion S2 surrounded by the memory gate structure 2 can be integrated to form a depletion layer in the entire fin portion S2, and the depletion layer Thus, the potential difference between the memory gate electrode DG and the fin portion S2 can be reduced.

  Thus, in the memory cell MC, even if the impurity concentration in the fin portion S2 is increased and the drain region 12a and the source region 12b are brought close to each other on the surface of the fin portion S2, the entire inside of the fin portion S2 is achieved. By selecting the shape (height and width) of the fin portion S2 so that a depletion layer is formed, the potential difference between the memory gate electrode DG and the fin portion S2 is reduced, and the electric field applied to the depletion layer is further reduced. Occurrence of disturbance can be suppressed. Thus, the memory cell MC can suppress the occurrence of disturbance while reducing the size.

  In addition, the memory gate structure 2, the first selection gate structure 3, and the second selection gate structure 4 are each formed in a U shape along the both side surfaces and the surface of the fin portion S2, and the gate width Can be replaced with the height of the fin portion S2, so that the height of the fin portion S2 is increased, but the formation area of each gate width can be reduced in the x direction across the fin portion S2. Therefore, downsizing can be realized.

  Further, in the memory cell MC, when data is not written, the memory cell MC is not restricted by the high voltage charge storage gate voltage applied to the memory gate electrode MG, and is directly below the first selection gate structure 3 and the second selection gate structure. 4 Since the voltage value of the bit line BL and the source line SL can be lowered to a voltage value that simply makes the inside of each fin part S2 just non-conductive, according to the voltage reduction at these bit lines and the source line, The film thickness of each of the first selection gate insulating films 17a and 18b of the first selection gate structure 3 and the second selection gate insulating films 17b and 18b of the second selection gate structure 4 can be reduced. It can be realized.

  Further, in the nonvolatile semiconductor memory device 1 in which a plurality of memory cells MC sharing the memory gate line ML are arranged in a matrix, between the memory gate electrode MG generated in the memory cell MC to which no data is written and the fin portion S2. Since the potential difference Vono is small and the electric field applied to the depletion layer is also small, data is not written even if a high voltage charge storage gate voltage is applied to the memory gate electrode MG many times through the memory gate line ML. Generation of disturbance can be suppressed in the cell MC. Therefore, in the nonvolatile semiconductor memory device 1, for example, the memory cells MC arranged in 128 rows or more and 1024 columns or more can suppress the disturbance even if the memory gate line ML is shared, and the number of memory cells that can be processed in a batch of mats. Can be increased dramatically.

(8) Other Embodiments (8-1) Configuration of Memory Cell when Memory Gate Electrode, First Select Gate Electrode, and Second Select Gate Electrode are Formed from Conductive Material Other than Metal Material In the embodiment, the case where the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are formed of a metal material has been described. However, the present invention is not limited to this, and other materials such as polysilicon are used. The memory gate electrode, the first selection gate electrode, and the second selection gate electrode may be formed using various conductive materials.

  Here, an embodiment in which the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are formed of a conductive material (for example, polysilicon) other than the metal material will be described below. In this case, the planar layout of the nonvolatile semiconductor memory device is the same as that shown in FIG. 2, but the cross-sectional configuration taken along the line AA ′ in FIG. 2 is as shown in FIG. The cross-sectional configuration at the BB ′ portion is as shown in FIG. 12B.

  As shown in FIG. 12A, in which parts corresponding to those in FIG. 3A are denoted by the same reference numerals, the memory cell MC1 includes an impurity diffusion region formed by impurity implantation on the surface of the fin portion S2, and a drain region 40a and a source region 40b. The bit line (not shown) is connected to the drain region 40a, and the source line (not shown) is connected to the source region 40b.

The memory cell MC1 has a memory gate structure 2a in which a lower memory gate insulating film 13, a charge storage layer EC, an upper memory gate insulating film 14a, and a memory gate electrode MG1 are stacked in this order on the fin portion S2. The lower memory gate insulating film 13 and the upper memory gate insulating film 14a are formed of the same insulating material (for example, silicon oxide (SiO, SiO ₂ )), and the memory gate electrode MG1 is formed of polysilicon.

  Between the drain region 12a and the memory gate structure 2a, a first select gate structure 3a having a configuration in which a first select gate electrode DG1 made of polysilicon is stacked on the first select gate insulating film 17a is provided. ing. The first select gate structure 3a is formed adjacent to the side wall spacer 6 formed on one side wall of the memory gate structure 2a, and the top of the first select gate electrode DG1 extends from the memory gate electrode MG1. It is formed in a sidewall shape that descends toward the fin portion S2 as it leaves.

  A second selection gate structure 4a having a configuration in which a second selection gate electrode SG1 made of polysilicon is formed on the second selection gate insulating film 17b is provided between the source region 40b and the memory gate structure 2a. It has been. The second selection gate structure 4a is formed adjacent to the side wall spacer 7 formed on the other side wall of the memory gate structure 2a, and the top of the second selection gate electrode SG1 extends from the memory gate electrode MG1. It is formed in a sidewall shape that descends toward the fin portion S2 as it leaves.

  The memory gate structure 2a, the first selection gate structure 3a, and the second selection gate structure 4a are also formed so as to straddle the fin portion S2, and the insulating layer IS in which the fin portion S2 is not formed. The memory gate structure 2a, the first selection gate structure 3a, and the second selection gate structure 4a shown in FIG. 12A are also shown in FIG. 12B with the same reference numerals as the corresponding parts in FIG. 3B. Can be provided.

  Note that such a memory cell MC1 has a sidewall-shaped first selection gate electrode DG1 and a first selection gate electrode DG1 along the sidewall of the memory gate structure 2a, for example, by etching back the layered electrode formation layer in the manufacturing process. Two selection gate electrodes SG1 are formed. Therefore, the memory gate structure 2a, the first selection gate structure 3a, the second selection gate structure 4a, and the side wall spacer are formed at the position where the fin portion S2 is formed and the position where the fin portion S2 is not formed. 6,7 can be formed with the same thickness. Therefore, in the position where the fin portion S2 is formed, the memory gate structure 2a, the first selection gate structure 3a, the first selection gate structure 2a, and the first selection gate structure 3a are compared with the position where the fin portion S2 is not formed by the height of the fin portion S2. The two-selection gate structure 4a and the side wall spacers 6 and 7 may protrude.

  Incidentally, also in the memory cell MC1, as in the above-described embodiment, the distance from the upper surface of the fin portion S2 to the bottom surface of the memory gate electrode MG1 on the insulating layer IS (in-electrode protruding height of the fin portion S2) Hfin and the width Wfin (FIG. 4A and FIG. 4B) of the fin portion S2 in the x direction in which the memory gate structure 2a, the first selection gate structure 3a, and the second selection gate structure 4a straddle the fin portion S2 It can be formed so that the relationship of Hfin> Wfin holds.

  Further, the memory cell MC1 includes the gate length L1 of the first selection gate electrode DG1 in the y direction in which the fin portion S2 extends, the gate length L2 of the second selection gate electrode SG1, and the width Wfin of the fin portion S2. However, the relationship of L1 ≦ 1.5 · Wfin and L2 ≦ 1.5 · Wfin can be established. Further, such a memory cell MC1 also includes, for example, a data write operation, a data non-write operation, a data read operation, according to “(4) Voltages during various operations in the nonvolatile semiconductor memory device” described above. A data erasing operation may be performed.

  Even with the memory cell MC1 having the above-described configuration, the same effect as that of the above-described embodiment can be obtained, and the occurrence of disturbance can be suppressed while downsizing.

(8-2) Configuration of Memory Cell with Cap Insulating Film on Top of Fin Part In the embodiment described above, the memory cell MC in which the lower memory gate insulating film 13 is provided on the top surface of the fin part S2 has been described. The present invention is not limited to this, and a memory cell in which a cap insulating film having a predetermined thickness is provided on the upper surface of the fin portion S2 and the lower memory gate insulating film 13 is provided on the cap insulating film may be used.

  In this case, FIG. 13 shows a nonvolatile semiconductor memory device 31 according to another embodiment, and the nonvolatile semiconductor memory device 31 includes a memory gate structure 32 having a cap insulating film (not shown). A memory cell MC2 is provided. The memory cell MC2 has the same configuration as the memory cell MC shown in FIG. 2, but a cap insulating film is provided on the upper surface of the fin portion S2 covered with the memory gate structure 32. .

  Here, FIG. 14A shows a cross-sectional configuration at the AA ′ portion of FIG. 13, FIG. 14B shows a cross-sectional configuration at the BB ′ portion of FIG. 13, and FIG. 15A shows a CC 'portion of FIG. FIG. 15B shows a cross-sectional configuration in the DD ′ portion of FIG. 13. As shown in FIGS. 14A and 15A, the memory gate structure 32 is provided with a cap insulating film 35 having a predetermined thickness on the upper surface of the fin portion S2, and the lower memory gate insulating layer is formed on the cap insulating film 35. The film 13, the charge storage layer EC, the upper memory gate insulating film 14, and the memory gate electrode MG are sequentially stacked.

  Incidentally, in the case of this embodiment, the memory gate structure 32 in which the lower memory gate insulating film 13 is formed on the cap insulating film 35 has been described. However, the present invention is not limited to this, for example, the cap insulating film 35 is provided as the lower memory gate insulating film 13, and the charge storage layer EC, the upper memory gate insulating film 14, and the memory gate electrode MG are sequentially stacked on the cap insulating film 35, and the cap insulating film 35 is insulated from the lower memory gate. It may be a memory gate structure that acts as a film.

  On the other hand, as shown in FIG. 14B, in the memory gate structure 32, the cap insulating film 35 is not formed at the position where the fin portion S2 is not formed, and the lower memory gate insulating film 13 is formed on the insulating layer IS. The charge storage layer EC, the upper memory gate insulating film 14, and the memory gate electrode MG are sequentially stacked on the lower memory gate insulating film 13. Thus, the memory gate structure 32 has a configuration in which the cap insulating film 35 is provided only in the region where the upper surface of the fin portion S2 is disposed, and the upper surface of the fin portion S2 is covered with the cap insulating film 35. .

The cap insulating film 35 is made of an insulating material such as silicon oxide (SiO, SiO ₂ , SiN), and has a thickness of 4 nm or more, for example. In addition, the cap insulating film 35 may have a configuration in which different types of insulating materials are stacked in addition to a configuration in which the cap insulating film 35 is formed in a layer shape using one type of insulating material.

  As shown in FIGS. 14A, 14B, and 15B, the first selection gate structure 3 does not have the cap insulating film 35, and the first selection gate insulation is provided on the fin portion S2 and the insulating layer IS. The films 17a and 18a and the first selection gate electrode DG are sequentially stacked. Similarly, the second selection gate structure 4 does not have the cap insulating film 35, and the second selection gate insulating films 17b and 18b and the second selection gate electrode SG are formed on the fin portion S2 and the insulating layer IS. It has the structure laminated | stacked in order.

  Incidentally, as a method of manufacturing the memory gate structure 32 having such a cap insulating film 35, for example, in a fin portion forming step, as shown in FIG. 8, a plate-like fin portion forming substrate (not shown) The hard mask 32 used when forming the fin portion S2 by processing is formed of an insulating material, and the hard mask 32 is left as the cap insulating film 35 as it is. Then, in the next first dummy electrode layer forming step, a layered lower memory gate insulating film forming layer 13a, a charge storage layer forming layer ECa are formed on the insulating layer IS and the cap insulating film 35 covering the upper surface of the fin portion S2. Then, the first dummy electrode layer 34 (see FIGS. 9A and 9B) is sequentially stacked.

  At this time, when the lower memory gate insulating film forming layer 13a is formed by an oxidation method, the lower memory gate insulating film forming layer 13a may not be formed on the cap insulating film 35 in some cases. In this case, in the finally formed memory gate structure, the cap insulating film 35 is provided as the lower memory gate insulating film 13, and the charge storage layer EC, the upper memory gate insulating film 14, and the cap insulating film 35 are provided on the cap insulating film 35. The memory gate electrode MG may be stacked in order.

  Further, in the next dummy memory gate structure forming step, the lower memory gate insulating film forming layer 13a, the charge storage layer forming layer ECa and the first dummy electrode layer 34 are patterned, and the fin portion whose upper surface is covered with the cap insulating film 35. A dummy memory gate structure 32 is formed on the insulating layer IS so as to straddle S2, and then the above-described side wall spacer formation process, dummy selection gate electrode formation process, dummy electrode exposure process, metal gate electrode formation process, etc. After that, the memory cell MC2 can be manufactured.

  In the above configuration, in the memory cell MC2, in addition to obtaining the same effect as the above-described embodiment, the cap insulating film 35 that covers the upper surface of the fin portion S2 is provided in the memory gate structure 32. During the data write operation, the cap insulating film 35 can prevent the electric field from concentrating around the sharp corner where the upper surface and the side surface of the fin portion S2 intersect. As a result, it is possible to prevent a writing failure due to an electric field concentrated only around the corner portion during writing, and charge cannot be injected into the charge storage layer film along the fin side wall.

  Incidentally, in the above-described embodiment, the upper surface of the fin portion S2 is added to the memory gate structure 32 of the memory cell MC2 in which the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are formed of a metal material. However, the present invention is not limited to this, and as shown in FIGS. 12A and 12B, the memory gate electrode MG1, the first selection gate electrode DG1, and the second selection gate electrode are provided. A cap insulating film 35 covering the upper surface of the fin portion S2 may be provided on the memory gate structure 2a of the memory cell MC1 in which SG1 is formed of a conductive material such as polysilicon. Even in this case, in the memory cell MC1, during the data erasing operation, the cap insulating film 35 can prevent the electric field from concentrating around the sharp corner where the upper surface and the side surface of the fin portion S2 intersect.

(8-3) Others The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, various voltage values other than the voltage values in “(4) Voltages during various operations in the nonvolatile semiconductor memory device” described above may be applied.

  In the memory cell MC shown in FIGS. 3A and 3B, the first selection gate insulating films 17a and 18a and the second selection gate having a two-layer structure are used as the first selection gate insulating film and the second selection gate insulating film. Although the case where the insulating films 17b and 18b are applied has been described, the present invention is not limited to this, and the first selection gate insulating films 17a and 18a are either one-layer structure or the second selection gate insulating films 17a and 18a. May be one of the one-layer structures.

  Furthermore, in the above-described embodiment, the memory gate electrode MG (FIGS. 3A and 3B) in which the memory gate side wall insulating films 15a and 15b are provided along the side wall has been described. However, the present invention is not limited to this. Either one of the memory gate sidewall insulating films 15a and 15b may be a memory gate electrode provided along one of the sidewalls, or a memory gate electrode without the memory gate sidewall insulating films 15a and 15b.

  Furthermore, in the above-described embodiment, the first selection gate electrode DG (FIGS. 3A and 3B) in which the first selection gate sidewall insulating film 19a and the sidewall sidewall insulating film 20a are provided along the sidewall has been described. The present invention is not limited to this, and the first selection gate electrode in which either one of the first selection gate sidewall insulating film 19a or the sidewall sidewall insulating film 20a is provided along any one of the sidewalls, or the first selection gate A first select gate electrode in which the sidewall insulating film 19a and the sidewall sidewall insulating film 20a are not provided may be used.

  Further, in the above-described embodiment, the second selection gate electrode SG (FIGS. 3A and 3B) in which the second selection gate sidewall insulating film 19b and the sidewall sidewall insulating film 20b are provided along the sidewall has been described. The present invention is not limited to this, and a second selection gate electrode in which either one of the second selection gate sidewall insulating film 19b or the sidewall sidewall insulating film 20b is provided along any one of the sidewalls, or a second selection gate A second select gate electrode in which the sidewall insulating film 19b and the sidewall sidewall insulating film 20b are not provided may be used.

  Further, in the above-described embodiment, the upper memory gate insulating film 14, the memory gate sidewall insulating films 15a and 15b, the first selection gate sidewall insulating film 19a, the sidewall sidewall insulating film 20a, and the second selection gate sidewall insulating film 19b Although the case where the sidewall sidewall insulating film 20b is formed of an insulating material different from that of the sidewall spacers 6 and 7, the present invention is not limited thereto, the upper memory gate insulating film 14, the memory gate sidewall insulating film 15a, 15b, the first select gate sidewall insulating film 19a, the sidewall sidewall insulating film 20a, the second select gate sidewall insulating film 19b, and the sidewall sidewall insulating film 20b may be formed of the same insulating material as the sidewall spacers 6 and 7. Good. Furthermore, the memory cell may be formed on the semiconductor substrate S1 and the fin portion S2 into which N-type impurities have been implanted.

  Further, in the above-described embodiment, the case where the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are formed using one metal metal layer has been described. The present invention is not limited to this. For example, a plurality of types of metal metal layers made of different types of metal materials are sequentially stacked to form a memory gate electrode MG, a first selection gate electrode DG, and a second selection layer having a stacked structure. The gate electrode SG may be formed.

  Furthermore, in the above-described embodiment, the case where the drain region 12a and the source region 12b made of SiGe or the like with a predetermined thickness are formed as the drain region and the source region, for example, by epitaxial growth, has been described. The impurity diffusion region may be formed by injecting impurities into the surface of the fin portion S2, and the drain region and the source region may be used.

  Further, in the above-described embodiment, as the dummy selection gate electrode formation step in the manufacturing method, the selection gate insulating film and the second dummy electrode layer are formed so as to cover the dummy memory gate structure, and then etched back. To form a sidewall-shaped dummy first selection gate electrode so as to straddle the fin portion along one side wall spacer on the side wall of the dummy memory gate structure, and another side wall of the dummy memory gate structure. After forming the sidewall-shaped dummy second selection gate electrode so as to straddle the fin portion along the sidewall spacer, the selection gate insulating film is processed, and the first selection gate insulating film is formed under the dummy first selection gate electrode. Provided, the dummy selection gate electrode forming step of providing the second selection gate insulating film under the dummy second selection gate electrode has been described. The present invention is not limited to this, and may be a dummy selection gate electrode forming step of forming the dummy first selection gate electrode and the dummy second selection gate electrode without forming the selection gate insulating film.

(9) Memory cell in which the thickness of the insulating layer in the region in which the first selection gate structure and the second selection gate structure are provided is reduced. (9-1) Configuration of the memory cell As shown in FIG. 16, the memory cell MC3 provided in the nonvolatile semiconductor memory device 41 includes an insulating layer IS1 in a region where the first selection gate structure 3 and the second selection gate structure 4 are provided. Is different from the above-described embodiment in that it is thinner than the thickness of the insulating layer IS1 in the region where the memory gate structure 2 is provided. Therefore, here, the description will be given focusing on the insulating layer IS1, and the other configurations are the same as those in the above-described embodiment, and thus the description thereof is omitted.

  The insulating layer IS1 is provided on the surface of the semiconductor substrate S1, and the fin portion S2 protrudes from the surface of the insulating layer IS1. The thickness of the insulating layer IS1 in the region provided with the first select gate structure 3 and the second select gate structure 4 is made thinner than the thickness of the insulating layer IS1 in the region provided with the memory gate structure 2 Thus, the insulating layer IS1 includes a layered insulating layer 42 formed on the surface of the semiconductor substrate S1, and a protruding insulating layer provided so as to protrude onto the layered insulating layer 42 in the region where the memory gate structure 2 is provided. 43. The convex insulating layer 43 is made of the same insulating material as the layered insulating layer 42 and is integrated with the layered insulating layer 42. The convex insulating layer 43 is provided along the memory gate structure 2 and extends in the x direction in which the longitudinal direction intersects the longitudinal direction (y direction) of the fin portion S2 as in the memory gate structure 2. ing.

  Here, FIG. 17A in which the same reference numerals are assigned to the corresponding parts to FIG. 3A is a cross-sectional view showing a cross-sectional configuration in the AA ′ part of FIG. As shown in FIG. 17A, the layered insulating layer 42 and the convex insulating layer 43 (FIG. 16) are not provided in the region where the fin portion S2 is provided, and the first selection is made on the surface of the fin portion S2. A gate structure 3, a memory gate structure 2, and a second selection gate structure 4 are provided.

  FIG. 17B, in which parts corresponding to those in FIG. As shown in FIG. 17B, the first selection gate structure 3 and the second selection gate structure 4 are provided on the layered insulating layer 42, and the memory gate structure 2 is provided on the convex insulating layer 43. It has been.

  In the region where the fin portion S2 is not provided (FIG. 17B), from the surface of the semiconductor substrate S1 to the upper surface of the layered insulating layer 42 in the region where the first selection gate structure 3 and the second selection gate structure 4 are provided. Is the distance H5. On the other hand, in the region where the memory gate structure 2 is provided, the distance H4 is from the surface of the semiconductor substrate S1 to the upper surface of the convex insulating layer 43. The distance H4 is larger than the distance H5 by a distance H3 corresponding to the height of the convex insulating layer 43.

  Further, the distance H1 from the semiconductor substrate S1 to the lower surface of the memory gate electrode MG is larger than the distance H2 from the semiconductor substrate S1 to the lower surfaces of the first selection gate electrode DG and the second selection gate electrode SG. The distance H3 corresponding to the film thickness and the film thickness corresponding to the film thickness of the charge storage layer EC are increased. Thus, the lower surface positions of the first selection gate electrode DG and the second selection gate electrode SG are arranged at lower positions closer to the semiconductor substrate S1 than the lower surface position of the memory gate electrode MG.

  As a result, in the memory cell MC3, the first selection transistor T1 and the second selection transistor T2 are turned on and off in the region of the side surface of the fin portion S2 so that the lower surface position is lower than the lower surface position of the memory gate electrode MG. The first selection gate electrode DG and the second selection gate electrode SG can be sufficiently controlled. That is, when a gate-off voltage is applied to the first selection gate electrode DG and the second selection gate electrode SG, the first selection gate electrode DG and the second selection gate electrode SG reliably cover the side surface region of the fin portion S2. Since it can be made non-conductive, a leakage current flows between the drain region 12a and the source region 12b along the side surface region of the fin portion S2 even when the information written in the memory transistor MT has a low threshold voltage Vth. Can be prevented. Therefore, in the memory cell MC3, malfunction during data write operation and data read operation can be prevented.

  For such a malfunction, in “(2) Detailed configuration of memory cell” described above, “distance H1 <distance H2 and the positions of the lower surfaces of the first selection gate electrode DG and the second selection gate electrode SG are as follows. Further, this is described in detail using a comparative example (not shown) arranged at a position higher than the position of the lower surface of the memory gate electrode MG. Here, since the comparative example in which ON / OFF of the first selection transistor T1 and the second selection transistor T2 cannot be sufficiently controlled is described in the above-mentioned “(2) Detailed configuration of the memory cell”, the description thereof will be given. Omitted.

  Here, the distance H3, which is the thickness of the convex insulating layer 43, is preferably at least 1/2 of the width Wfin of the fin portion S2 (FIGS. 18A and 18B). Within the fin portion S2, from the height position of the lower surface of the first selection gate electrode DG and the second selection gate electrode SG toward the upper surface of the fin portion S2, about half (1/2) of the width Wfin of the fin portion S2 When the height is high, there is a possibility that a region where the fin portion S2 (channel layer) cannot be sufficiently controlled by the gate-off voltage applied to the first selection gate electrode DG and the second selection gate electrode SG may remain.

  By optimizing the impurity concentration in the fin portion S2, the fin portion S2 can be easily controlled by the gate-off voltage, but in this case, the first selection transistor T1 and the second selection transistor T2 are formed. It is necessary to set the impurity concentration of the fin portion S2 in the selected region to an optimized value different from the impurity concentration of the fin portion S2 in the region where the memory transistor MT is formed. Here, if the distance H3, which is the film thickness of the convex insulating layer 43, is set to 1/2 or more of the width Wfin of the fin portion S2, there is a region where the fin portion S2 (channel layer) cannot be sufficiently controlled by the gate-off voltage. Since the position is lower than the lower surface position of the memory gate electrode MG, when the information written in the memory transistor MT has a low threshold voltage Vth, the drain region 12a and the source region 12b are arranged along the side surface region of the fin portion S2. It is possible to prevent a leakage current from flowing in between and causing a malfunction. Therefore, it is possible to prevent the occurrence of malfunction without optimizing the impurity concentration of the fin portion S2 in the region where the first selection transistor T1 and the second selection transistor T2 are formed for controlling the fin portion S2 by the gate-off voltage. obtain.

  18A, in which parts corresponding to those in FIG. 4A are assigned the same reference numerals, is a cross-sectional view showing a cross-sectional configuration in the CC ′ part of FIG. The memory gate structure 2 is formed on the convex insulating layer 43 so as to straddle the fin portion S2. Thereby, the memory gate structure 2 can form a channel layer of the memory transistor MT along the surface of the fin portion S2 surrounded by the memory gate structure 2.

  Thus, also in this embodiment, since the gate width of the memory transistor MT is the distance along the surface of the fin portion S2 surrounded by the memory gate structure 2, the memory gate structure 2 A part of the width can be replaced with a height along the side surface of the fin portion S2, and the formation area of the memory transistor MT can be reduced accordingly.

  18B, in which parts corresponding to those in FIG. 4B are assigned the same reference numerals, is a cross-sectional view showing a cross-sectional configuration in the DD ′ part of FIG. As shown in FIG. 18B, the convex insulating layer 43 is not provided on the layered insulating layer 42 in the region where the first selective gate structure 3 is formed, and the first selective gate structure 3 It is formed on the layered insulating layer 42 so as to straddle the part S2. Thus, the first selection gate structure 3 surrounds the surface of the fin portion S2, and the channel layer of the first selection transistor T1 is formed along the surface of the fin portion S2 surrounded by the first selection gate structure 3. obtain.

  As described above, also in this embodiment, since the gate width of the first selection transistor T1 is a distance along the surface of the fin portion S2 surrounded by the first selection gate structure 3, one of the gate widths. The portion can be replaced with a height along the side surface of the fin portion S2, and the area for forming the first selection transistor T1 can be reduced accordingly. Furthermore, the gate width of the first selection transistor T1 is twice as large as the distance H3 corresponding to the film thickness of the convex insulating layer 43, and the on-current of the first selection transistor T1 can be increased correspondingly, thereby contributing to high-speed operation. . Note that the second selection gate structure 4 is also configured on the layered insulating layer 42 so as to straddle the fin portion S2, and has the same configuration as the first selection gate structure 3 shown in FIG. 18B. The description is omitted here.

  The memory cell MC3 according to this embodiment is the same in regard to the above-mentioned “(3) Circuit configuration of the nonvolatile semiconductor memory device” and “(4) Voltage during various operations in the nonvolatile semiconductor memory device”. The description is omitted.

  As a manufacturing method of the insulating layer IS1 in which such a convex insulating layer 43 is provided on the layered insulating layer 42, for example, in a side wall spacer forming step, a layered insulating film is formed and etched back to form a sidewall shape. When the side wall spacers 6 and 7 are formed, the insulating layer IS exposed to the outside may be shaved by overetching by a distance H3 that becomes the height of the convex insulating layer 43.

(9-2) Operation and Effect In the above configuration, in the memory cell MC3 according to this embodiment, similarly to the above-described embodiment, the injection of charges into the charge storage layer EC is prevented to prevent data writing. In this case, a depletion layer can be formed in the entire fin portion S2 surrounded by the memory gate structure 2, and the potential difference between the memory gate electrode DG and the fin portion S2 can be reduced by the depletion layer. As a result, in the memory cell MC3, even if the impurity concentration in the fin portion S2 is increased and the drain region 12a and the source region 12b are brought close to each other on the surface of the fin portion S2, the entire inside of the fin portion S2 is achieved. By selecting the shape (height and width) of the fin portion S2 so that a depletion layer is formed, the potential difference between the memory gate electrode DG and the fin portion S2 is reduced, and the electric field applied to the depletion layer is further reduced. Occurrence of disturbance can be suppressed. Thus, even in the memory cell MC3, it is possible to suppress the occurrence of disturbance while reducing the size.

  In addition, in this memory cell MC3, the distance H4 from the semiconductor substrate S1 to the lower surface of the lower memory gate insulating film 13 is different from each of the first selection gate insulating film 17a and the second selection gate insulating film 17b from the semiconductor substrate S1. The insulating layer IS1 is provided so as to be larger than the distance H5 to the lower surface. Thereby, in the region where the insulating layer IS1 is provided, the lower surface positions of the first selection gate electrode DG and the second selection gate electrode SG are arranged closer to the semiconductor substrate S1 than the lower surface position of the memory gate electrode MG. Can be made.

  Therefore, in this memory cell MC3, the region on the side surface of the fin portion S2 is formed by the first selection gate electrode DG and the second selection gate electrode SG in which the lower surface position is disposed at a position lower than the lower surface position of the memory gate electrode MG. Thus, the on / off of the first selection transistor T1 and the second selection transistor T2 can be controlled more reliably. Thus, in this memory cell MC3, as much as the convex insulating layer 43 is provided, it is possible to more reliably prevent malfunctions during data write operations and data read operations than in the above-described embodiment.

(10) Memory cell in which fin portion is provided on insulating layer (10-1) Configuration of memory cell As shown in FIG. 19 in which the same reference numerals are given to the corresponding parts to FIG. 1, this nonvolatile semiconductor memory device The memory cell MC4 provided in 51 is different from the above-described embodiment in the configuration of the fin portion S3. Therefore, here, description will be given focusing on the fin portion S3, and other configurations are the same as those in the above-described embodiment, and thus description thereof is omitted.

  In the nonvolatile semiconductor memory device 51, an insulating layer IS2 is provided on the semiconductor substrate S1, and a fin portion S3 extending in the y direction is provided on the insulating layer IS2. The insulating layer IS2 includes a layered layered insulating layer 52 formed on the semiconductor substrate S1 and a band-shaped lower insulating layer 53. The lower insulating layer 53 is made of the same insulating material as the layered insulating layer 52 and is integrated with the layered insulating layer 52. The lower insulating layer 53 extends in the y direction, and the fin portion S3 is provided on the surface thereof. In this embodiment, S3 shown in FIG. 19 is referred to as a “fin portion” in accordance with the other embodiments, but it is connected to the semiconductor substrate S1 like the fin portion S2 in FIG. Unlike the fin shape, the fin portion S3 is actually extended in the y direction in a horizontal column shape or a beam shape (beam shape).

  The fin portion S3 is made of a semiconductor material and extends along the lower insulating layer 53. In the case of the embodiment in which the lower insulating layer 53 is provided, the fin portion S3 has a width dimension in a direction (x direction) orthogonal to the extending longitudinal direction (y direction) and the height direction (z direction), The width is selected to be equal to or smaller than the width of the lower insulating layer 53 and is provided only on the lower insulating layer 53.

  Although not shown in FIG. 19, an upper insulating layer 54 (described later with reference to FIGS. 20A and 21) is provided on the upper surface of the fin portion S3 provided with the memory cell MC4. Accordingly, the fin portion S3 has a configuration in which the upper surface and the lower surface are sandwiched between the insulating layers.

  In the fin portion S3, a drain region 12a is provided on the surface adjacent to the first selection gate structure 3, and a source region 12b is provided on the surface adjacent to the second selection gate structure 4. In this embodiment, the upper insulating layer 54 does not exist on the upper surface of the fin portion S3 where the memory cell MC4 is not provided, and the drain region 12a and the source region 12b are formed on the surface of the fin portion S3.

  Here, FIG. 20A in which parts corresponding to those in FIG. 3A are assigned the same reference numerals is a cross-sectional view showing a cross-sectional structure taken along the line AA ′ in FIG. As shown in FIG. 20A, the fin portion S3 is provided with a memory gate structure 2, a first selection gate structure 3, a second selection gate structure 4, sidewall spacers 6 and 7, and sidewall portions 22a and 22b. An upper insulating layer 54 is provided on the surface of the region.

  As described above, in the fin portion S3 in the region where the memory gate structure 2, the first selection gate structure 3, the second selection gate structure 4, the sidewall spacers 6 and 7, and the sidewall portions 22a and 22b are provided, The fin portion S3 is sandwiched between the layer IS2 (in this embodiment, the lower insulating layer 53) and the upper insulating layer 54.

  FIG. 20B in which the same reference numerals are assigned to the corresponding parts to those in FIG. As shown in FIG. 20B, in the region where the fin portion S3 is not formed, the memory gate structure 2, the first selection gate structure 3, the second selection gate structure 4, the sidewall spacers 6 and 7, and the sidewall portion 22a. , 22b are formed on the layered insulating layer 52 of the insulating layer IS2 covering the semiconductor substrate S1.

  FIG. 21A in which parts corresponding to those in FIG. 4A are assigned the same reference numerals is a cross-sectional view showing a cross-sectional configuration in the CC ′ part of FIG. In the case of this embodiment, as shown in FIG. 21A, the upper surface and the lower surface of the fin portion S3 are sandwiched between the upper insulating layer 54 and the insulating layer IS2 (in this embodiment, the lower insulating layer 53). In addition, since the side surface of the fin portion S3 is surrounded by the memory gate electrode MG, a channel layer can be formed on the side surface of the fin portion S3 in the memory transistor MT. Further, since the upper surface and the lower surface of the fin portion S3 are sandwiched between the upper insulating layer 54 and the insulating layer IS2 (lower insulating layer 53 in this embodiment), the memory transistor MT is a fully depleted transistor. It has become. In this embodiment as well, when the height of the fin portion S3 is H1fin, the relationship of Hfin> Wfin is established.

  In the case of this embodiment, as shown in FIG. 21A, the distance H7 from the semiconductor substrate S1 to the lower surface position of the fin portion S3 is the distance from the semiconductor substrate S1 to the memory gate electrode MG in the region where the fin portion S3 is not provided. It is selected to be larger than the distance H1 to the bottom surface position. As a result, the lower surface position of the memory gate electrode can be made lower than the lower surface position of the fin portion S3, and the side surface of the fin portion S3 can be completely covered with the memory gate electrode MG. It is possible to prevent a leakage current from flowing between the region 12a and the source region 12b and causing a malfunction.

  The difference between the distance H7 from the semiconductor substrate S1 to the lower surface of the fin portion S3 and the distance H1 from the semiconductor substrate S1 to the lower surface position of the memory gate electrode MG is preferably at least 1/2 of the width Wfin of the fin portion S3. . A configuration in which the lower insulating layer 53 is not provided will be described later.

  FIG. 21B in which parts corresponding to those in FIG. 4B are assigned the same reference numerals is a cross-sectional view showing a cross-sectional configuration in the DD ′ part of FIG. The upper surface and the lower surface of the fin portion S3 are sandwiched between the upper insulating layer 54 and the insulating layer IS2 (in this embodiment, the lower insulating layer 53), and the side surface of the fin portion S3 is the first selection gate electrode DG. Therefore, in the first selection transistor T1, a channel layer can be formed on the side surface of the fin portion S3. Further, since the upper surface and the lower surface of the fin portion S3 are sandwiched between the upper insulating layer 54 and the insulating layer IS2 (in this embodiment, the lower insulating layer 53) and insulated from the semiconductor substrate S1, The one selection transistor T1 is a fully depleted transistor.

  In the case of this embodiment, as shown in FIG. 21B, the distance H7 from the semiconductor substrate S1 to the lower surface position of the fin portion S3 is the first select gate electrode from the semiconductor substrate S1 in the region where the fin portion S3 is not provided. It is selected to be larger than the distance H2 to the bottom surface position of the DG. As a result, the lower surface position of the first selection gate electrode DG can be made lower than the lower surface position of the fin portion S3, and the side surface of the fin portion S3 can be completely covered with the first selection gate electrode DG. It is possible to prevent leakage current from flowing along.

  Note that the second selection gate structure 4 is also configured on the layered insulating layer 42 so as to straddle the fin portion S3, and has the same configuration as the first selection gate structure 3 shown in FIG. 21B. The description is omitted here.

  The difference between the distance H7 from the semiconductor substrate S1 to the lower surface of the fin portion S3 and the distance H2 from the semiconductor substrate S1 to the lower surface position of the first selection gate electrode DG is at least 1/2 of the width Wfin of the fin portion S3. Is desirable. A configuration in which the lower insulating layer 53 is not provided will be described later.

  The memory cell MC4 according to this embodiment is the same in regard to the above-mentioned “(3) Circuit configuration of the nonvolatile semiconductor memory device” and “(4) Voltage during various operations in the nonvolatile semiconductor memory device”. The description is omitted.

  As a manufacturing method of the memory cell MC4 in which the fin portion S3 is provided on the insulating layer IS1, the semiconductor substrate, the insulating layer, the semiconductor layer to be the fin portion, the upper portion are formed before the fin portion forming step shown in FIG. An insulating layer to be an insulating layer is sequentially stacked, and a semiconductor layer to be a fin portion and a part of the insulating layer are formed by using the patterned insulating layer to be an upper insulating layer as a hard mask in the fin portion forming step. Process it. Alternatively, an SOI (Silicon on Insulator) substrate may be used as the semiconductor substrate, the insulating layer, and the semiconductor layer to be the fin portion.

(10-2) Actions and Effects In the above configuration, even in such a memory cell MC4, in accordance with the same principle as that of the above-described embodiment, charge injection into the charge storage layer EC is prevented to prevent data writing. In this case, the potential difference between the memory gate electrode DG and the fin portion S3 can be reduced, and further, the electric field applied to the depletion layer can be reduced to suppress the occurrence of disturbance. obtain.

  In addition to this, in the memory cell MC4, the upper surface and the lower surface of the fin portion S3 are sandwiched between the upper insulating layer 54 and the insulating layer IS2 (in this embodiment, the lower insulating layer 53). The transistor MT, the first selection transistor T1, and the second selection transistor T2 can be fully depleted transistors. In this case, since the fin portion S3 is insulated from the semiconductor substrate S1, the potential of the fin portion S3 becomes independent from the semiconductor substrate S1, and the potential difference generated between the memory gate electrode MG and the fin portion S3 can be further reduced and the depletion layer is applied. Since the electric field can be further reduced, the occurrence of disturbance can be further suppressed as compared with the fin type (fin portion S2) described above.

  In the memory cell MC4, the lower surface positions of the memory gate electrode MG, the first selection gate electrode DG, and the second selection gate electrode SG are made lower than the lower surface position of the fin portion S3, and the side surface of the fin portion S3 is the memory gate electrode. The MG, the first selection gate electrode DG, and the second selection gate electrode SG can be completely covered, and leakage current can be prevented from flowing along the side surface region of the fin portion S3.

  Also in this memory cell MC4, by providing the upper insulating layer 54 covering the upper surface of the fin portion S3, for example, at the time of data write operation, the upper insulating layer 54 has a sharp corner where the upper surface and the side surface of the fin portion S3 intersect. It is possible to prevent the electric field from concentrating around the part. As a result, it is possible to prevent a writing failure due to an electric field concentrated only around the corner portion during writing, and charge cannot be injected into the charge storage layer film along the fin side wall.

(10-3) Fin portion according to another embodiment In the above-described embodiment, the distance H7 from the semiconductor substrate S1 to the lower surface of the fin portion S3 is in a region where the fin portion S3 is not provided. Although the case where the distance H1 from the semiconductor substrate S1 to the lower surface of the memory gate electrode MG is larger than H1 (H7> H1) has been described, the present invention is not limited to this, and the distance H7 from the semiconductor substrate S1 to the lower surface of the fin portion S3 is The distance from the semiconductor substrate S1 to the lower surface of the memory gate electrode DG in the region where the fin portion S3 is not provided may be equal to or less than H1 (H7 ≦ H1).

  For example, in the configuration in which the lower insulating layer 53 is provided on the layered insulating layer 52, the distance H7 from the semiconductor substrate S1 to the lower surface of the fin portion S3 is larger than the distance H5 from the semiconductor substrate S1 to the surface of the layered insulating layer 52. In addition, the configuration may be smaller than the distance H1 from the semiconductor substrate S1 of FIG. 21A to the lower surface of the memory gate electrode MG (H5 <H7 <H1).

  Further, in the above-described embodiment, the lower insulating layer 53 protruding from the layered insulating layer 52 is provided on the layered insulating layer 52, and from the semiconductor substrate S1, the layered insulating layer 52, the lower insulating layer 53, the fin portion S3, and The structure in which the upper insulating layer 54 is laminated in order has been described. It is good also as a structure laminated | stacked in order. In this case, the lower surface position of the fin portion S3 may be flush with the surface position of the layered insulating layer 52.

  In the above-described embodiment, the configuration in which the upper insulating layer 54 is provided on the fin portion S3 and the semiconductor layer S1, the insulating layer IS2, the fin portion S3, and the upper insulating layer 54 are sequentially stacked has been described. The invention is not limited to this, and the upper insulating layer 54 may not be provided, and the semiconductor substrate S1, the insulating layer IS2, and the fin portion S3 may be stacked in this order.

1,31,41,51 Nonvolatile semiconductor memory device
MC, MC11, MC12,…, MC1n, MC21, MC22,…, MC2n, MCm1, MCm2,…, MCmn, MC1, MC2, MC3, MC4 Memory cells
2,2a Memory gate structure
3,3a First selection gate structure
4,4a Second selection gate structure
12a, 40a Drain region
12b, 40b source region
6,7 Side wall spacer
13 Lower memory gate insulating film
14,14a Upper memory gate insulating film
EC charge storage layer
17a, 18a First selection gate insulating film
17b, 18b Second selection gate insulating film
S1 Semiconductor substrate
S2, S3 Fin part
IS, IS1, IS2 Insulation layer
42,52 layered insulation layer
43 Convex insulation layer
53 Lower insulation layer
54 Upper insulation layer

Claims (8)

A semiconductor substrate covered with an insulating layer;
A fin portion formed on the semiconductor substrate so as to protrude from the insulating layer;
A lower memory gate insulating film, a charge storage layer, an upper memory gate insulating film, and a memory gate electrode, and a memory gate structure formed on the insulating layer so as to straddle the fin portion;
A first select gate electrode is provided on the first select gate insulating film, and is formed on the insulating layer so as to straddle the fin portion along one side wall spacer formed on one side wall of the memory gate structure. A first select gate structure formed;
A second selection gate electrode is provided on the second selection gate insulating film, and is formed on the insulating layer so as to straddle the fin portion along another side wall spacer formed on the other side wall of the memory gate structure. A second select gate structure formed;
A drain region provided on the surface of the fin portion adjacent to the first select gate structure so as to be insulated from the first select gate electrode, and a bit line electrically connected thereto;
A source region that is provided on the surface of the fin portion adjacent to the second selection gate structure so as to be insulated from the second selection gate electrode, and to which a source line is electrically connected;
The first select gate structure, the memory gate structure, and the second select gate structure are provided between the drain region and the source region,
The insulating layer is
The distance from the semiconductor substrate to the lower surface of the lower memory gate insulating film is formed larger than the distance from the semiconductor substrate to the lower surfaces of the first selection gate insulating film and the second selection gate insulating film,
The memory cell, wherein each lower surface position of the first selection gate electrode and the second selection gate electrode is disposed closer to the semiconductor substrate than a lower surface position of the memory gate electrode. The insulating layer is
A layered insulating layer provided on the semiconductor substrate;
A convex insulating layer provided on the layered insulating layer in a region where the memory gate structure is provided;
The memory cell according to claim 1, comprising: The convex insulating layer has a thickness of ½ or more of the width of the fin portion in a direction in which the memory gate structure, the first select gate structure, and the second select gate structure straddle the fin portion. The memory cell according to claim 2, comprising: A semiconductor substrate covered with an insulating layer;
A fin portion formed on the insulating layer;
A lower memory gate insulating film, a charge storage layer, an upper memory gate insulating film, and a memory gate electrode, and a memory gate structure formed on the insulating layer so as to straddle the fin portion;
A first select gate electrode is provided on the first select gate insulating film, and is formed on the insulating layer so as to straddle the fin portion along one side wall spacer formed on one side wall of the memory gate structure. A first select gate structure formed;
A second selection gate electrode is provided on the second selection gate insulating film, and is formed on the insulating layer so as to straddle the fin portion along another side wall spacer formed on the other side wall of the memory gate structure. A second select gate structure formed;
A drain region provided on the surface of the fin portion adjacent to the first select gate structure so as to be insulated from the first select gate electrode, and a bit line electrically connected thereto;
A source region that is provided on the surface of the fin portion adjacent to the second selection gate structure so as to be insulated from the second selection gate electrode, and to which a source line is electrically connected;
The first select gate structure, the memory gate structure, and the second select gate structure are provided between the drain region and the source region,
An upper insulating layer is provided on the upper surface of the fin portion. A memory cell, wherein: The first selection gate structure, the memory gate structure, and the second selection gate structure are provided so as to straddle the fin portion and the upper insulating layer. Memory cells. 5. The memory cell according to claim 3, wherein a lower surface position of the fin portion is higher than a lower surface position of the memory gate electrode in a region where the fin portion is not provided. The insulating layer is
A layered insulating layer provided on the semiconductor substrate;
A lower insulating layer provided on the layered insulating layer and provided with the fin portion on the surface;
The memory cell according to claim 4, wherein the layered insulating layer, the lower insulating layer, the fin portion, and the upper insulating layer are stacked in this order from the semiconductor substrate. A non-volatile semiconductor memory device in which memory cells having memory gate lines connected to memory gate electrodes are arranged in a matrix,
The memory cell according to any one of claims 1 to 7, wherein the memory gate line is shared by a plurality of the memory cells arranged in a matrix. Semiconductor memory device.

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