CN100479176C - Image sensing element and manufacturing method thereof - Google Patents

Abstract

The invention relates to a method for manufacturing an image sensing element, which mainly forms a dielectric protective layer on a light sensing area before forming a grid of an MOS (metal oxide semiconductor), thereby avoiding surface damage of the light sensing area caused by plasma or etching in the process of forming an MOS component and further improving the phenomenon of dark current generation. The invention also discloses an image sensing element manufactured by the method, which is characterized in that the grid electrode is partially laminated above the dielectric protection layer, and the surface of the light sensing area is smooth, so that the image sensing element has good performance.

Description

Image sensing element and its manufacturing method

technical field

The invention relates to an image sensor and its manufacturing method, in particular to a complementary metal oxide semiconductor transistor image sensor using a photosensitive diode and its manufacturing method.

Background technique

Complementary metal oxide semiconductor transistor image sensors (CMOS image sensors, CIS) and charge-coupled devices (charge-coupled devices, CCDs) are optical circuit components commonly used in the prior art to convert light into electronic signals. The application of the two The range is very wide, including scanners, video cameras, and cameras, etc. However, because the carrier coupling device is limited by the high price and large size, currently the complementary metal oxide semiconductor transistor image sensor is more popular in the market. Complementary metal-oxide-semiconductor transistor image sensors are manufactured by traditional semiconductor technology, so the required cost and component size can be greatly reduced. At present, they are roughly divided into two types: linear and surface-type, and linear complementary metal-oxide-semiconductor transistor image sensors Sensors are mainly used in scanners and other products, while area complementary metal oxide semiconductor transistor image sensors are mainly used in digital cameras and other products.

For the performance of CMOS image sensing elements, dark current is an important index, and it is hoped that it does not exist. Dark current is related to shallow trench isolation (STI) (or local oxidation of silicon (LOCOS)) induced defects, plasma defects, wafer impurities, etc. that occur during fabrication. For example, the photodiode layer of the CMOS image sensor device is easily damaged during the plasma etching process, so dark current is severely generated.

U.S. Patent No. 6,906,364 discloses a structure of a CMOS image sensing element to reduce the generation of dark current, which includes a photodiode sensing area, a transistor area element, a self-aligned block (self-aligned block), and A protective layer. The photodiode sensing region and the transistor element region are formed in the substrate, and the self-alignment block is formed on the photodiode sensing region. The protective layer is formed on the entire substrate, covering the self-aligned area. In this way, the sensing area of the photodiode can be protected from damage in the subsequent back-end process, so as to reduce the generation of dark current. However, since the gate is formed before the passivation layer is formed, there is still a risk of damage to the sensing region of the photodiode during the formation of the gate using the plasma etching process.

Therefore, there is still a need for an image sensing device with a lower amount of dark current, and a method for making the same.

Contents of the invention

An object of the present invention is to provide an image sensing device with improved dark current phenomenon.

Another object of the present invention is to provide a method for manufacturing an image sensing device, so as to obtain an image sensing device with improved dark current.

The image sensing device according to the present invention includes a substrate, a photo-sensing region, a dielectric protection layer, a gate insulating layer, a gate, and a doped region. The light sensing area is located in the base. The dielectric protection layer is located on the photo-sensing area to serve as a protection layer for the photo-sensing area. The gate insulation layer is located on the base and adjacent to the dielectric protection layer. The gate is located on the gate insulation layer, and one side of the gate crosses over a part of the dielectric protection layer. The doped region is located in the substrate.

The method for manufacturing an image sensing device according to the present invention includes the following steps. Firstly, a substrate is provided, which includes a light sensing area in the substrate. Secondly, a dielectric protection layer is formed on the photo-sensing area. Then, a gate insulation layer is formed on the base and adjacent to the dielectric protection layer. A gate is formed on the gate insulating layer and one side of the gate is extended to a part of the dielectric protection layer. Finally, a doped region is formed in the substrate on the other side of the gate and a photosensitive layer is formed in the photosensitive region.

In another aspect of the present invention, the method for manufacturing an image sensing device according to the present invention includes the following steps. Firstly, a substrate is provided, which includes a light sensing area in the substrate. Next, a dielectric protection layer is formed on the photo-sensing area. A photosensitive layer is formed in the photosensitive area. Then, a gate insulation layer is formed on the base and adjacent to the dielectric protection layer. A gate is formed on the gate insulating layer and one side of the gate is extended to a part of the dielectric protection layer. Finally, a doped region is formed in the substrate on the other side of the gate.

In yet another aspect of the present invention, the method for manufacturing an image sensor device according to the present invention includes the following steps. Firstly, a substrate is provided, which includes a photo-sensing region and a gate region in the substrate, wherein the gate region is surrounded by the photo-sensing region. Secondly, a dielectric protection layer is formed on the photo-sensing area. A doped region is formed in the base of the gate region. Next, a gate insulation layer is formed on the base of the gate region and adjacent to the dielectric protection layer. A gate is formed on the gate insulating layer and the side of the gate is extended to a part of the dielectric protection layer. Finally, a photosensitive layer is formed in the photosensitive area.

In yet another aspect of the present invention, the method for manufacturing an image sensing device according to the present invention includes the following steps. Firstly, a substrate is provided, which includes a photo-sensing region and a gate region in the substrate, wherein the gate region is surrounded by the photo-sensing region. Secondly, a dielectric protection layer is formed on the photo-sensing area. A photosensitive layer is formed in the photosensitive region and a doped region is formed in the base of the gate region respectively. Next, a gate insulation layer is formed on the base of the gate region and adjacent to the dielectric protection layer. Finally, a gate is formed on the gate insulating layer and the side of the gate is extended to a part of the dielectric protection layer.

According to the image sensing element of the present invention, a dielectric protection layer is first formed on the photo-sensing region as a protection layer, and then a gate is formed on the substrate, especially one side of the formed gate is across the dielectric protection layer. part of the layer. Therefore, this dielectric protection layer can protect the photosensitive layer of the photosensitive area, and can reduce the damage caused by the photoresist removal, gate etching, and spacer etching of the photosensitive layer by plasma, and improve the dark area. current. In addition, in another specific embodiment of the present invention, the gate is located in the area surrounded by the photo-sensing region as far as possible without touching the STI boundary, so that it will not be affected by the defects induced by the STI, and the leakage current can be reduced (that is, dark current). Furthermore, when the gate is not in contact with the STI boundary, there will be no STI narrow width effect, and a barrier will not be formed under the gate, which will affect the charge transfer of the photo-sensing region. Therefore, the image sensing device according to the present invention can have good performance.

Description of drawings

FIG. 1 shows a schematic top view of an embodiment of an image sensing device according to the present invention.

Fig. 2 shows a schematic cross-sectional view along line AA' shown in Fig. 1 .

FIG. 3 shows a schematic top view of another embodiment of an image sensing device according to the present invention.

Fig. 4 shows a schematic cross-sectional view along line AA' shown in Fig. 3 .

5 to 8 show a specific embodiment of the manufacturing method of the image sensing device according to the present invention.

9 to 13 show another specific embodiment of the manufacturing method of the image sensing device according to the present invention.

14 to 15 show another specific embodiment of the manufacturing method of the image sensing device according to the present invention.

FIG. 16 shows yet another specific embodiment of the manufacturing method of the image sensing device according to the present invention.

simple notation

20, 50 Substrate 21 Shallow trench isolation structure

22, 52 photosensitive area 23, 31, 33 photoresist layer

24, 54 Dielectric protective layer 26, 56 Gate insulating layer

27 Ion implantation 28, 58 Grid

29 ion implantation 30, 60 doping region

32, 62 photosensitive layer 34, 64 lightly doped layer

30a, 34a Lightly doped region 35 Light ion implantation

36, 66 heavily doped layer 38, 68 silicon oxide layer

40, 70 Silicon nitride layer 42 Spacer

Detailed ways

Please refer to Figures 1 and 2, Figure 2 is a cross-sectional view along line AA' in Figure 1. The image sensing element according to the present invention can be a CMOS image sensing element, including a substrate 20, a photo-sensing region 22, a dielectric protection layer 24, a gate insulating layer 26, a gate 28, and a doped Miscellaneous area 30. The image sensing device is isolated from other devices by the shallow trench isolation structure 21 . The image sensing device according to the present invention is also suitable for isolation in other ways such as LOCOS.

The substrate 20 can be a p-type or n-type semiconductor substrate. The light sensing region 22 is located in the substrate 20 . The photosensitive region 22 may include a photosensitive layer 32 , which is a photosensitive material. For example, when the substrate 20 is a p-type substrate, the photosensitive layer 32 may include an n-type lightly doped layer 34 and a p-type heavily doped layer 36 . PIN (p-type-intrinsic-n-type) photodiodes, APD photodiodes, or other general photodiodes can be used as the photosensitive layer, but not limited thereto.

例如使用氧化硅层时，其厚度可为50至而氮化硅层可为50至当介电保护层配合适当厚度时，例如300至

亦可具有抗反射层的功用。The dielectric protection layer 24 is located on the photo-sensing region 22 , for example, on the photo-sensing layer 32 , so as to serve as a protection layer for the photo-sensing region 22 . The dielectric protection layer can be a single layer or multiple dielectric layers. The single dielectric layer can be a layer of dielectric material such as a silicon oxide layer. The multilayer dielectric layer can be, for example, a silicon oxide layer 38 and a silicon nitride layer 40 on the silicon oxide layer, or alternately stacked silicon oxide layers and silicon nitride layers. The dielectric protection layer is used to protect the photosensitive region from being damaged in subsequent processes such as plasma processes. The thickness of the dielectric protection layer can be a thickness that does not affect light transmission and can reach a protective function. The preferred total thickness is not more than about

For example, when using a silicon oxide layer, its thickness can be 50 to While the silicon nitride layer can be 50 to When the dielectric protective layer is matched with an appropriate thickness, such as 300 to

It can also function as an anti-reflection layer.

栅极28是位于栅极绝缘层26上，其一侧跨至介电保护层24的一部分上。栅极28包括导电性材料，例如多晶硅。栅极28的侧壁上可进一步具有一间隙壁42。间隙壁可为氧化硅层，或多层介电层。掺杂区30是位于栅极28的另一例的基底20中，以于晶体管功能中作为漏极或源极。掺杂区可包括一部分轻掺杂区及一部分重掺杂区，其电性与感光二极管的轻掺杂层34及重掺杂层36的电性相同。The gate insulating layer 26 is located on the substrate 20 adjacent to the dielectric protection layer 24 . The gate insulating layer can be a gate oxide layer, and the thickness is preferably less than

The gate 28 is located on the gate insulating layer 26 , and one side thereof crosses over a part of the dielectric protection layer 24 . Gate 28 includes a conductive material, such as polysilicon. A spacer 42 may be further provided on the sidewall of the gate 28 . The spacers can be silicon oxide layers, or multiple dielectric layers. The doped region 30 is located in the substrate 20 which is another example of the gate 28 to function as a drain or a source in the transistor function. The doped region may include a part of the lightly doped region and a part of the heavily doped region, and its electrical property is the same as that of the lightly doped layer 34 and the heavily doped layer 36 of the photodiode.

According to the image sensing device of the present invention, a main feature is that the photosensitive layer of the photosensitive region has a dielectric protection layer as the protection layer, and the gate has a side that spans a part of the dielectric protection layer, therefore, The positions of the photo-sensing region, the gate, and the doped region are not particularly limited, as long as the photo-sensing region and the doped region are not in direct contact with the gate. Therefore, the doped region can be located in the substrate on the other side of the gate, or partly located in the substrate below the gate, and the shape is not particularly limited.

Alternatively, the region where the gate is located can be surrounded by the photo-sensing region, as shown in FIG. 3 another specific embodiment of the image sensing element according to the present invention, and FIG. 4 shows a cross-sectional view along line BB' in FIG. 3 . Wherein, the gate 58 is located on the substrate of the area surrounded by the photo-sensing region 52 and spans a part of the dielectric protection layer 54 with its side, and the doped region 60 is partially located in the substrate below the gate 58 . The dielectric protection layer 54 includes a silicon oxide layer 68 and a nitrogen oxide layer 70 on the photosensitive layer 62 to serve as a protective layer for the photosensitive layer 62 . The photosensitive layer 62 may include a lightly doped layer 64 and a heavily doped layer 66 . A gate insulating layer 56 is located on the substrate 50 adjacent to the dielectric protection layer 54 . The gate 58 is located on the gate insulating layer 56 , and its side crosses over a portion of the dielectric protection layer 54 . The doped region 60 is located in the substrate 50 below the gate 58 . The doped region 60 may be located partially in the substrate 50 below the gate 58, or may be located in the substrate 50 on the side of the gate 58 but not below the gate. The advantage of having the gate located on the substrate in the area surrounded by the photo-sensing region is that the gate does not touch the shallow trench structure or the LOCOS boundary, or touches only a small part, so it is not affected by STI. The effect of induced defects can reduce the dark current. Furthermore, when the gate is not in contact with the boundary of the STI, there will be no narrow width effect of the STI, and a barrier will not be formed under the gate to affect the charge transmission of the photo-sensing region.

5 to 8 show a specific embodiment of the manufacturing method of the image sensing device according to the present invention. Referring to FIG. 5 , firstly, a substrate 20 is provided, in which the shallow trench isolation structure 21 has been fabricated and has a photo-sensing region (not shown). A silicon oxide layer can be formed on the surface of the substrate by thermal oxidation, and a silicon nitride layer can be formed on the silicon oxide layer as a dielectric material layer by using silane and ammonia as processing gases by plasma enhanced chemical vapor deposition. This step can be repeated several times, if desired, to produce multiple layers of dielectric material. Then, a photoresist layer 23 with a corresponding pattern is formed by a photolithography process to cover a predetermined area of the dielectric protection layer corresponding to the photo-sensing area, so as to perform etching to remove the part of the dielectric material layer that is not covered. The silicon nitride layer can be etched by dry etching, such as plasma etching. The silicon oxide layer can be etched by dry etching or wet etching. In this way, the dielectric protection layer 24 including the silicon oxide layer 38 and the silicon nitride layer 40 is defined to cover the photo-sensing region. Then, the photoresist layer is removed.

Referring to FIG. 6 , a gate oxide layer process, such as a thermal oxidation process, is performed to form an oxide layer on the substrate 20 as the gate insulating layer 26 adjacent to the dielectric protection layer 24 . Before forming the gate insulating layer, a well (not shown) may also be formed in the substrate 20 if necessary.

Referring to FIGS. 7 and 8, a conductive layer, such as a polysilicon layer and a polycide layer, is formed by, for example, a chemical vapor deposition method, and then photolithography and etching processes are performed to form a gate 28 on the gate insulating layer 26. One side of the gate 28 is formed on a portion of the dielectric capping layer 24 . Since the edge of the formed gate straddles the dielectric protective layer as the protective layer of the photo-sensing area, when the conductive layer is etched (such as plasma etching) to form the gate, or when the gate is removed by etching When the photoresist is placed above, the light sensing layer will not be damaged by etching. Then, the process of forming the doped region and the photosensitive layer is carried out, for example, by ion implantation 27, using the grid 28 as a mask, the substrate 20 is implanted with ions, and a lightly doped layer is formed in the substrate on one side of the grid 28. Zone 30a. In the substrate of the photo-sensing region, ion implantation is also performed to form a lightly doped region 34a. The electrical property of the light doping is n-type or p-type depending on whether the dopant of the substrate 20 is p-type or n-type. The n-type dopant can be, for example, phosphorous or arsenic. The p-type dopant can be, for example, boron.

A spacer 42 can be further formed on the sidewall of the gate 28 , for example, a silicon oxide layer is formed by chemical vapor deposition, and anisotropic etching is performed on the substrate 20 to form a spacer. Afterwards, heavier ion implantation can be further performed to form a heavily doped region (not shown) in the substrate 20 outside the spacer 42 , and to form a heavily doped region in the photo-sensing region 22 . In this way, the image sensing device shown in FIGS. 1 and 2 is produced.

Referring to FIGS. 9 to 13 , in another embodiment according to the present invention, the photosensitive layer can be prepared after forming the dielectric protection layer. Figure 9 shows that after the step of forming the dielectric protection layer 24, ion implantation 29 can be performed, and the photoresist layer 31 can be used as a mask to form a lightly doped layer 34 in the photo-sensing area, and further form a heavily doped layer. The doped layer 36 becomes the photosensitive layer 32 . FIG. 10 shows that after removing the photoresist layer, a gate insulating layer 26 is formed adjacent to the dielectric protection layer 24 . FIG. 11 shows that a gate 28 is formed on the gate insulating layer 26 in the above-mentioned method, and one side of it spans over a part of the dielectric protection layer 24. Therefore, in the process, the photosensitive layer below the dielectric protection layer 24 32 can be protected.

Figure 12 shows the fabrication of doped regions. The photo-sensing region is covered with a patterned photoresist layer 33, and light ion implantation 35 is performed to form a lightly doped region 30a. Referring to FIG. 13 , the spacers 42 are formed as described above, and heavy ion implantation is performed to form a heavily doped region, thus forming the doped region 30 . Then, the photoresist layer 33 is removed to manufacture the image sensing device as shown in FIGS. 1 and 2 .

When the image sensing element according to the present invention is configured as shown in FIGS. 3 and 4 , because the doped region 60 is partly located below the gate 58, it is necessary to form the doped region 60 before forming the gate 58, as shown in FIG. 14 to 15 are shown. FIG. 14 shows a dielectric protection layer 54, which includes a silicon oxide layer 68 and a silicon nitride layer 70, formed over the photo-sensing region. Ion implantation may be performed using the patterned photoresist layer as a mask to form the doped region 60 . The width of the doped region 60 and the pattern of the photo-sensing region 52 will determine the width of the gate 58 together. Next, as shown in FIG. 15 , a gate insulating layer 56 is formed on the substrate 50 and the doped region 60 . Next, a gate 58 is formed on the gate insulating layer 56 , and its side crosses over a portion of the dielectric protection layer 54 . Finally, the ion implantation process is performed, and light ion implantation and heavy ion implantation are performed successively in the photosensitive region 52 to form a lightly doped layer 64 and a heavily doped layer 66, which become the photosensitive layer 62, as shown in Figures 3 and 4. image sensing element.

Alternatively, in another embodiment, the doped region 60 and the photosensitive layer 62 may be formed before forming the gate 58 . As shown in FIG. 16, a dielectric protection layer 54, which includes a silicon oxide layer 68 and a silicon nitride layer 70, has been formed over the photo-sensing region. The doped region 60 (which may include a lightly doped region and a heavily doped region) and the photosensitive layer 62 (which may include a lightly doped layer 64 and a heavily doped layer 66 ) are formed by ion implantation. Next, a gate insulating layer 56 is formed on the substrate 50 and the doped region 60 , and then a gate 58 is formed, the side of which crosses over a portion of the dielectric protection layer 54 . Image sensing devices as shown in FIGS. 3 and 4 can also be fabricated.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (26)

1. Image Sensor comprises:

Substrate;

Optical sensing area is arranged in this substrate;

Dielectric protection layer is positioned on this optical sensing area, with the protective layer as this optical sensing area;

Gate insulator is positioned in this substrate, in abutting connection with this dielectric protection layer;

Grid is positioned on this gate insulator, and the one side is striden to the part of this dielectric protection layer; And

Doped region is arranged in this substrate.

2. Image Sensor as claimed in claim 1, wherein this optical sensing area comprises photosensitive layer, and this dielectric protection layer is to be positioned on this photosensitive layer, with as protective layer.

3. Image Sensor as claimed in claim 1, wherein this dielectric protection layer comprises multilayer dielectric layer.

4. Image Sensor as claimed in claim 3, wherein this multilayer dielectric layer comprises that one deck silicon oxide layer and one deck silicon nitride layer are positioned on this silicon oxide layer.

5. Image Sensor as claimed in claim 3, wherein this multilayer dielectric layer comprises alternately the multilayer silicon oxide layer and the nitride multilayer silicon layer of storehouse.

6. Image Sensor as claimed in claim 1 comprises that also clearance wall is positioned on the sidewall of this grid.

7. Image Sensor as claimed in claim 1, wherein this doped region is this substrate that is arranged in the opposite side of this grid.

8. Image Sensor as claimed in claim 1, wherein this grid be positioned at by in the substrate of this optical sensing area area surrounded and with its side on the part of this dielectric protection layer, and the part of this doped region is arranged in this substrate of this grid below.

9. Image Sensor as claimed in claim 1, wherein this grid be positioned at by in the substrate of this optical sensing area area surrounded and with its side on the part of this dielectric protection layer, and this doped region is this substrate that is arranged in the opposite side of this grid.

10. a method of making Image Sensor comprises the following steps:

Substrate is provided, and it comprises that optical sensing area is in this substrate;

Form dielectric protection layer on this optical sensing area;

Form gate insulator in this substrate and in abutting connection with this dielectric protection layer;

Form grid on this gate insulator and a side of this grid is extended on the part of this dielectric protection layer; And

Respectively at forming doped region in this substrate of the opposite side of this grid and forming photosensitive layer in this optical sensing area.

11. method as claimed in claim 10 wherein should form the step of dielectric protection layer on this optical sensing area, comprising:

Form dielectric materials layer in this substrate and cover this optical sensing area, and

Partly remove this dielectric materials layer by photoetching process and etch process.

12. method as claimed in claim 10 wherein should form dielectric protection layer and form multilayer dielectric layer on this optical sensing area in the step on this optical sensing area.

13. method as claimed in claim 12, wherein this multilayer dielectric layer comprises that one deck silicon oxide layer and one deck silicon nitride layer are on this silicon oxide layer.

14. method as claimed in claim 11, the step that wherein should form a dielectric materials layer is for forming one deck silicon oxide layer and forming one deck silicon nitride layer.

15. method as claimed in claim 14 wherein is somebody's turn to do the step that partly remove this dielectric materials layer by photoetching process and etch process, comprising:

Form the photoresist pattern, wherein the photoresist layer of this photoresist pattern covers this optical sensing area;

Carry out dry ecthing to remove this silicon nitride layer;

Carry out wet etching to remove this silicon oxide layer; And

This photoresist pattern is removed.

16. method as claimed in claim 11, wherein the step of this formation dielectric materials layer is the step that hockets and repeatedly form one deck silicon oxide layer and form one deck silicon nitride layer.

17. method as claimed in claim 10 in forming gate insulator in this substrate and before the step of this dielectric protection layer, further forms trap in this substrate.

18. method as claimed in claim 10, wherein this forms doped region and in the step of this optical sensing area formation photosensitive layer, comprising in this substrate of the opposite side of this grid:

In this substrate, form a light doping section with the light ion injection technology, and form lightly-doped layer in this optical sensing area;

Sidewall in this grid forms clearance wall; And

With heavy ion injection technology this light doping section top, form heavily doped region, and form a heavily doped layer in this lightly-doped layer top in a side of this clearance wall.

19. a method of making Image Sensor comprises the following steps:

Substrate is provided, and it comprises that optical sensing area is in this substrate;

Form a dielectric protection layer on this optical sensing area;

Form photosensitive layer in this optical sensing area;

Form gate insulator in this substrate and in abutting connection with this dielectric protection layer;

Form grid on this gate insulator and a side of this grid is extended on the part of this dielectric protection layer; And

In the substrate of the opposite side of this grid, form doped region.

20. method as claimed in claim 19 wherein should form the step of dielectric protection layer on this optical sensing area, comprising:

Form dielectric materials layer in this substrate and cover this optical sensing area, and

Partly remove this dielectric materials layer by photoetching process and etch process.

21. method as claimed in claim 20, the step that wherein should form dielectric materials layer is for forming one deck silicon oxide layer and forming one deck silicon nitride layer.

22. method as claimed in claim 21 wherein is somebody's turn to do the step that partly remove this dielectric materials layer by photoetching process and etch process, comprising:

Form the photoresist pattern, wherein the photoresist layer of this photoresist pattern covers this optical sensing area;

Carry out dry ecthing to remove this silicon nitride layer;

Carry out wet etching to remove this silicon oxide layer; And

This photoresist pattern is removed.

23. method as claimed in claim 19, wherein this forms the step of doped region in this substrate of the opposite side of this grid, comprising:

In this substrate, form light doping section with the light ion injection technology;

Sidewall in this grid forms clearance wall; And

With heavy ion injection technology this light doping section top, form heavily doped region in a side of this clearance wall.

24. method as claimed in claim 19 wherein should comprise in the step of this optical sensing area formation photosensitive layer:

Form lightly-doped layer with the light ion injection technology in this optical sensing area; And

Form heavily doped layer with the heavy ion injection technology in this lightly-doped layer top.

25. a method of making Image Sensor comprises the following steps:

Substrate is provided, and it comprises optical sensing area and gate regions in this substrate, and wherein this gate regions is surrounded by this optical sensing area;

Form dielectric protection layer on this optical sensing area;

In the substrate of this gate regions, form doped region;

Form gate insulator in the substrate of this gate regions and in abutting connection with this dielectric protection layer;

Form grid on this gate insulator and the side of this grid is extended on the part of this dielectric protection layer; And

In this optical sensing area, form photosensitive layer.

26. a method of making Image Sensor comprises the following steps:

Substrate is provided, and it comprises optical sensing area and gate regions in this substrate, and wherein this gate regions is surrounded by this optical sensing area;

Form dielectric protection layer on this optical sensing area;

Respectively at forming photosensitive layer in this optical sensing area and in the substrate of this gate regions, forming doped region;

Form gate insulator in the substrate of this gate regions and in abutting connection with this dielectric protection layer; And

Form grid on this gate insulator and the side of this grid is extended on the part of this dielectric protection layer.

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