WO2019008889A1 - Substrate mounting stand for heating semiconductor substrate - Google Patents

Abstract

The substrate mounting table for heating the semiconductor substrate is divided into concentric circles when viewed from the mounting surface side and a ceramic disk-shaped portion having the mounting surface configured to mount the semiconductor substrate on the upper surface And a plurality of heating circuits respectively embedded in the disk-shaped portion so as to extend in parallel with the mounting surface in a plurality of regions defined thereby. Of the plurality of heat generating circuits, the heat generating circuit on the inner side is disposed closer to the mounting surface than the heat generating circuit on the outer side.

Description

Substrate mounting table for heating semiconductor substrates

The present disclosure relates to a substrate mounting table for heating a semiconductor substrate. This application claims priority based on Japanese Patent Application No. 2017-133496 filed on Jul. 7, 2017, and incorporates all the contents described in the aforementioned Japanese Patent Application.

In a semiconductor manufacturing apparatus for manufacturing semiconductor devices such as LSIs, various thin film processes such as film formation processes represented by CVD and sputtering and etching processes are performed on a semiconductor substrate (semiconductor wafer) which is an object to be processed . Since these thin film processes are generally performed while the semiconductor substrate is heated to a predetermined temperature, the semiconductor substrate is placed during the thin film process in the vacuum chamber in which the process is performed. A substrate heater, also called a susceptor, which heats from the lower surface is mounted.

In the past, as disclosed in Patent Document 1, this substrate heater has a structure in which a resistance heating element is enclosed in a casing made of a material which does not transmit reaction gas such as quartz, for a substrate mounting table. This structure has the advantage that a space exists inside the casing, and electrical connection between the resistance heating element and the electrode terminal can be easily made in this space, but heat transfer is generated in this space. As a result, it has been pursued to increase the heat uniformity on the substrate mounting surface, and in recent years, instead of this, integration is achieved by embedding a heat generating circuit such as a thin film resistance heating element inside a ceramic disk member. The substrate heater of the structure is in the mainstream.

For example, as disclosed in Patent Document 2, the substrate heater of this integrated structure has a substrate mounting table made of a ceramic disk-shaped member having a flat substrate mounting surface on the upper surface, and the substrate mounting table from the lower surface side. A heating circuit such as a resistance heating element or an electric heating coil having a predetermined circuit pattern is embedded in a plane parallel to the substrate mounting surface, which is composed of a cylindrical support to be supported and the inside of the substrate mounting table. ing. Electrode terminals provided on the lower surface side of the substrate mounting table are electrically connected to both ends of the heat generating circuit, and the power is supplied to the heat generating circuit from an external power source through the electrode terminals and their lead wires.

Japanese Patent Application Laid-Open No. 63-278322 JP 2001-217059 A

The substrate mounting table for heating a semiconductor substrate according to the present disclosure has a ceramic disk shape portion having a mounting surface configured to mount the semiconductor substrate on the upper surface, and a concentric shape viewed from the mounting surface side. And a plurality of heating circuits respectively embedded in the disk-shaped portion so as to extend in parallel to the mounting surface in a plurality of regions defined by the division. Of the plurality of heat generating circuits, the heat generating circuit on the inner side is disposed closer to the mounting surface than the heat generating circuit on the outer side.

FIG. 1 is a longitudinal cross-sectional view of one specific example of a substrate mounting table according to the present disclosure, in which two heating circuits are embedded in a central region and an outer peripheral region, respectively. FIG. 2 is an arrow view of a section II-II of the substrate mounting table of FIG. 1, and shows a circuit pattern of the heat generation circuit in the central region. FIG. 3 is an arrow view of section III-III of the substrate mounting table of FIG. 1, and shows a circuit pattern of the heat generating circuit in the outer peripheral region. FIG. 4 is a longitudinal sectional view of a conventional substrate mounting table, in which two heating circuits are embedded in a central region and an outer peripheral region, respectively. FIG. 5 is an arrow view of a cross section VV of the substrate mounting table of FIG. 4, and shows a circuit pattern of the heat generating circuit in the outer peripheral region. FIG. 6 is an arrow view of section VI-VI of the substrate mounting table of FIG. 4, and shows a circuit pattern of the heating circuit in the central region. FIG. 7 is a longitudinal cross-sectional view of another specific example of the substrate mounting table according to the present disclosure, in which three heating circuits are embedded in the central region, the outer peripheral region, and the middle region thereof. FIG. 8 is a cross-sectional view of the embedded portion of the conventional substrate mounting table in which the heating circuit in the central area and the heating circuit in the outer peripheral area are embedded in the same plane, and the circuit patterns of both heating circuits are shown. .

In the substrate heater of the integrated structure as described above, the heat uniformity on the substrate mounting surface is enhanced so that the quality of the semiconductor device to be a product does not vary, and the semiconductor substrate is uniformly spread over the entire surface during thin film processing. Heating is required. Therefore, the circuit pattern of the heating circuit is made precise to prevent temperature unevenness, or the substrate mounting surface is divided into a plurality of regions (also referred to as multi-zones) separately for the heating circuit disposed in each of them. Fine temperature control is performed for each divided area by supplying power.

However, the electrode terminal connected to the above heating circuit needs to be installed inside the cylindrical support in order to protect it from the atmosphere in the corrosive chamber, and as shown in Patent Document 2, two heating circuits are provided. In the case of respectively embedding in the outer peripheral area and the central area of the substrate mounting surface, it is necessary to electrically connect both ends of the heat generating circuit embedded in the outer peripheral area of the former to the electrode terminals inside the cylindrical support. Therefore, it is necessary to draw the both ends into the central area and to make the electrode terminal connected to the tip penetrate the embedded surface of the heat generating circuit in the central area. As a result, precise temperature control of the heating circuit in the central region becomes difficult, and the thermal uniformity of the substrate mounting surface may be reduced.
[Problems to be solved by the present disclosure]

The present disclosure has been made in view of the above-described conventional problems, and a heating circuit is provided in each of a plurality of regions defined by concentrically dividing the substantially circular substrate mounting surface of the substrate mounting table. Even in the case of embedding, the temperature distribution of the heating circuit embedded in the area on the inner side of the substrate mounting surface is not easily affected by the heating circuit embedded in the area on the outer side thereof, and thus the substrate mounting An object of the present invention is to provide a substrate mounting table for heating a semiconductor substrate capable of improving the temperature uniformity of the mounting surface.
[Effect of the present disclosure]

According to the present disclosure, it is possible to precisely control the temperature of the substrate mounting surface, and it is thus possible to improve the heat uniformity of the substrate mounting surface.

First, embodiments of the present disclosure will be listed and described. The embodiment of the present disclosure is defined by dividing the disc-shaped portion made of ceramic having a mounting surface configured to mount the semiconductor substrate on the upper surface and concentrically viewed from the mounting surface side. And a plurality of heating circuits respectively embedded in the disk-shaped portion so as to extend in parallel with the mounting surface in the plurality of regions. Among the plurality of heat generating circuits, the substrate mounting table for heating a semiconductor substrate is one in which the heat generating circuit on the inner side is disposed closer to the mounting surface than the heat generating circuit on the outer side. As a result, the temperature of the substrate mounting surface can be precisely controlled, and the heat uniformity of the substrate mounting surface can be improved.

In the above-described embodiment of the substrate mounting table for heating a semiconductor substrate, the disk-shaped portion further includes a plurality of electrode terminals respectively connected to the end portions of the plurality of heat generating circuits on the lower surface opposite to the mounting surface. It is also good. Preferably, each of the plurality of heating circuits is configured to be individually controllable. As a result, even if the heat uniformity of the mounting surface of the substrate mounting table is disturbed, the heat uniformity of the substrate mounting table can be maintained.

Next, as a specific example of the substrate heating heater having a substrate mounting table for heating a semiconductor substrate according to the present disclosure, a substrate mounted in a vacuum chamber of a semiconductor manufacturing apparatus for performing etching processing or CVD processing on a semiconductor substrate. The heater will be described. As shown in FIG. 1, the substrate heating heater 1 of the present disclosure has a substrate mounting surface 10a for mounting a semiconductor substrate W on the upper surface thereof, and a substantially disk-shaped substrate mounting table 10 preferably made of ceramic. And a cylindrical support 20 which is joined to the center of the lower surface on the opposite side and supports the substrate mounting table 10 from the lower surface side thereof and which is preferably made of ceramic.

The upper and lower end portions of the cylindrical support 20 are provided with flange portions bent outward. The upper and lower end portions of the cylindrical support 20 are formed on the lower surface of the substrate mounting table 10 by connecting means such as an O-ring (not shown) provided on the annular end face of the flange and sealing members such as gaskets and screws not shown. And a bottom surface of a vacuum chamber (not shown). This makes it possible to isolate the inside of the cylindrical support 20 from the corrosive gas atmosphere in the vacuum chamber.

As a ceramic which is a suitable material of said substrate mounting base 10 and the cylindrical support body 20, aluminum nitride, silicon nitride, silicon carbide, aluminum oxide etc. can be mentioned, for example. Among these, aluminum nitride having high thermal conductivity is preferable. The substrate mounting table 10 and the cylindrical support 20 are preferably made of the same material. This allows expansion and contraction in the same way during heating and cooling. Therefore, problems such as warping of the substrate mounting surface 10a due to thermal stress and breakage of the joint between the substrate mounting table 10 and the cylindrical support 20 can be prevented from occurring easily.

In the substrate heater 1 of the present disclosure, a heating circuit is embedded in each of a plurality of regions defined by concentrically dividing the substantially circular substrate mounting surface 10 a of the substrate mounting table 10. Here, the concentric division is to divide the substrate mounting surface 10a into a plurality of zones with the center of the substantially circular substrate mounting surface 10a being shared and the circles having different radius being a boundary, as shown in FIG. When the substrate mounting surface 10a is divided into two as in the substrate mounting table 10 of one embodiment of the present invention shown in 1, it is defined as dividing into a circular central region and an annular peripheral region around it. .

That is, in the substrate mounting table 10 of the present disclosure, the central heating circuit 11 is embedded in the central area, and the outer heating circuit 12 is embedded in the outer peripheral area. A pair of terminal portions 11a and 12a are electrically connected to both ends of each of the two heat generating circuits 11 and 12 by joining means such as caulking, welding, brazing, or screwing. The terminal portions 11 a and 12 a protrude in the region on the inner side of the above-described cylindrical support 20 on the lower surface of the substrate mounting table 10. The heating circuits 11 and 12 are individually supplied with power from external power supplies (not shown) via leads (not shown) connected to the projecting portions. This enables each of the two heating circuits 11, 12 to be temperature controlled individually.

Each of the two heat generating circuits 11 and 12 has a circuit pattern extending in parallel with the substrate mounting surface 10 a inside the substrate mounting table 10. That is, the central heating circuit 11 has a circuit pattern shown in FIG. The circuit pattern shown in FIG. 2 has a one-stroke writing form including a plurality of concentrically curved conductive portions and a linear conductive portion connecting adjacent ones of the curved conductive portions. A pair of electrode terminals 11a are connected to both ends of the circuit pattern. On the other hand, the outer peripheral heating circuit 12 has a circuit pattern shown in FIG. That is, the circuit pattern shown in FIG. 3 is formed in a one-stroke writing shape by a plurality of concentrically curved conductive portions and a linear conductive portion connecting adjacent ones of the curved conductive portions. At both ends of the circuit pattern, two extended portions 12b extending in parallel to each other toward the center of the substrate mounting surface 1a are formed. A pair of electrode terminals 12a is connected to the tip of the two extension portions 12b.

The substrate mounting table 10 of the present disclosure is embedded such that the separation distance between the central heating circuit 11 and the substrate mounting surface 10 a is shorter than the separation distance between the outer peripheral heating circuit 12 and the substrate mounting surface 10 a. There is. With this configuration, physical interference between the two extension portions 12b of the outer peripheral heating circuit 12 and the central heating circuit 11 can be avoided. Furthermore, it is not necessary to partially make the circuit pattern of the central heating circuit 11 sparse because of the electrode terminals 12 a connected to the outer peripheral heating circuit 12. Therefore, temperature control of the substrate mounting surface 10 a can be performed more precisely. That is, the heat uniformity of the substrate mounting surface 10a can be improved.

On the other hand, as in the case of the substrate mounting table 110 shown in FIG. 4, if the distance between the heating circuit 112 in the outer peripheral area is shorter than the heating circuit 111 in the central area to the substrate mounting surface 110a, as shown in FIG. As described above, since the electrode terminal 112a of the outer peripheral heating circuit 112 in the outer peripheral area is connected to the tip of the extension portion 112b, the electrode terminal 112a passes through the embedded surface of the central heating circuit 111 in the central area, and the substrate mounting table It is necessary to project from the lower surface of 110. Therefore, in order to avoid physical interference with the electrode terminal 112a, as shown in FIG. 6, it is necessary for the central heating circuit 111 to secure a space in a portion where the electrode terminal 112a crosses in the circuit pattern. As a result, the temperature uniformity of the central portion of the mounting surface 110a is disturbed.

In the case of a disk-like substrate mounting table, the peripheral region is likely to be at a lower temperature than the central region due to the heat radiation from the outer edge portion of the substrate mounting surface. Therefore, if the heat generating circuit in the outer peripheral area is far apart from the substrate mounting surface than the heat generating circuit in the central area, the temperature drop in the outer peripheral area may become more noticeable. In particular, semiconductor devices are becoming increasingly finer in recent years, and there may be a problem of local temperature reduction of the mounting surface to an extent that is not a problem in the past. If this is a problem, as shown in FIG. 3, make the pitch of the conductive lines of the heating circuit in the outer peripheral region narrower than that in the central region, or set the voltage applied to the heating circuit in the outer peripheral region higher. Can compensate the heat dissipation from the outer edge.

Although the above-mentioned specific example explained the case where a substrate mounting side was divided into two fields concentrically, the substrate mounting base for semiconductor substrate heating of this indication is not limited to this. The substrate mounting surface may be divided into a plurality of three or more regions substantially concentrically. In this case, the plurality of heating circuits respectively provided in the plurality of regions are embedded in such a manner that the distance to the substrate mounting surface is gradually reduced from the outer edge to the center of the substrate mounting surface. For example, FIG. 7 shows an example in which the substrate mounting surface 210a is concentrically divided into three regions in the substrate mounting table 210 of another specific example. That is, the central heating circuit 211 is embedded in the central region of the substrate mounting surface 210a. An intermediate heating circuit 212 is embedded in the annular intermediate area around it. An outer peripheral heating circuit 213 is embedded in an annular outer peripheral area on the outermost peripheral side.

Of the three heat generating circuits 211, 212, and 213, adjacent ones are shorter in distance to the placement surface 210a than those located on the outside of the substrate placement surface 210a. . That is, the distance between the intermediate portion heating circuit 212 located inside of the outer peripheral portion heating circuit 213 located on the outermost side of the substrate placement surface 210a and the distance to the substrate placement surface 210a is shorter. Further, the distance between the central heating circuit 211 positioned inside the intermediate heating circuit 212 and the substrate mounting surface 210a is shorter.

Terminal portions 211 a, 212 a, 213 a provided inside the cylindrical support 220 are electrically connected to both ends of the three heat generating circuits 211, 212, 213. The heating circuits 212 and 213 embedded around the central region are respectively connected to the terminal portions 212a and 213a through the extension portions 212b and 213b extending toward the center of the substrate mounting surface 210a. ing. Power can be individually supplied from an external power supply (not shown) via the above-mentioned three pairs of terminal portions 211a, 212a, 213a and their lead wires (not shown).
This enables each of the three heating circuits 211, 212, 213 to be temperature controlled individually.

0.5 parts by mass of yttrium oxide as a sintering aid was added to 99.5 parts by mass of aluminum nitride powder, and a binder and an organic solvent were further added, and the resultant was mixed by a ball mill to prepare a slurry. Granules were produced by spraying the obtained slurry by spray drying. Next, the granules were press-formed to produce three sheets of molded articles. These compacts were degreased at 700 ° C. in a nitrogen atmosphere, and then sintered at 1850 ° C. in a nitrogen atmosphere to obtain three sintered bodies of aluminum nitride. The obtained sintered body was processed into a disk shape having a diameter of 330 mm and a thickness of 8 mm. At this time, the surface roughness Ra was 0.8 μm, and the flatness was 50 μm.

Of these three aluminum nitride sintered bodies, a circuit pattern of circular concentric circles shown in FIG. 2 is formed with a line width of 4 mm and a thickness of 20 μm in a circular central zone with a diameter of 160 mm on the upper surface of the sintered body located in the middle. And applied by screen printing using W (tungsten) paste. Furthermore, W paste is used for screen printing to form a circuit pattern of annular concentric circles shown in FIG. 3 with a line width of 4 mm and a thickness of 20 μm in the annular outer peripheral zone outside the central zone of 160 mm in diameter on the lower surface of the same sintered body. Applied. Then, the W paste was subjected to degreasing at 700 ° C. in a nitrogen atmosphere and baking at 1830 ° C. to form a heat generating circuit.

The sintered body positioned in the middle was applied and bonded to the facing surface with an adhesive material containing aluminum nitride as a main component for bonding, and then held between the two sintered bodies remaining after degreasing. A bottomed hole is provided in the lower surface of the joined body obtained in this manner so that the end of the above-mentioned heating circuit is exposed, and an external terminal made of W (tungsten) is inserted therein to Electrically connected. Thus, the substrate mounting table of sample 1 was produced.

For comparison, a sample is prepared in the same manner as the sample 1 except that the heating circuit having the circuit pattern of FIGS. 5 to 6 in which the embedded position of the central heating circuit and the outer heating circuit is reversed to that of the sample 1 is formed. A substrate mounting table 2 was produced. In addition, instead of the three 8 mm-thick aluminum nitride sintered bodies, two 12 mm-thick aluminum nitride sintered bodies were produced, and a heat generating circuit having a circuit pattern shown in FIG. 8 was formed therebetween. In the same manner as in the case of Sample 1 above, a substrate mounting table of Sample 3 was produced.

A cylindrical plate made of AlN (aluminum nitride) having an inner diameter of 60 mm, a height of 150 mm, and a thickness of 2 mm, both ends of which are formed in a flange shape, for each of the substrate mounting tables manufactured in this way. One end of the support member was joined with a screw. A gasket was used to hermetically seal between the flange-like portion and the joint surface of the substrate mounting table. Then, a lead wire was connected to the external terminal located inside the support member, and the other end of the support member was fixed to the bottom of the chamber using a clamp in a hermetically sealed state with a gasket.

Then, for each of the substrate mounting tables of Samples 1 to 3, the heating circuit was supplied with power to heat the substrate mounting table, and the heat uniformity of the mounting surface was evaluated. Specifically, with the heating circuit of the substrate mounting table supplied with power and the substrate mounting table heated to 500 ° C., the substrate mounting surface using the 300 mm 17-point substrate temperature gauge of the SensArray series of KLA-Tencor Corporation. Temperature distribution was measured. The results are shown in Table 1.

As can be seen from Table 1, the variation in temperature was 2.3 ° C. for sample 1, 7.2 ° C. for sample 2 and 9.8 ° C. for sample 3. From this result, among the plurality of heating circuits, the substrate mounting table of the sample 1 in which the heating circuit on the inner side is closer to the mounting surface than the heating circuit on the outer side is the one of the plurality of heating circuits. It can be seen that the heat uniformity of the substrate mounting surface is superior to the substrate mounting tables of the samples 2 and 3 in which the heat generating circuit on the inner side than the heat generating circuit on the outer side is not disposed close to the mounting surface.

It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive in any respect. The present invention is not limited to these exemplifications, but is shown by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.

W semiconductor substrate 1 substrate heating heater 10, 110, 210 substrate mounting table 10a, 110a, 210a substrate mounting surface 11, 111, 211 central portion heating circuit 11a, 111a, 211a terminal portion 12, 112 outer peripheral portion heating circuit 12a, 112a Electrode terminal 12b, 112b, 212b, 213b Extension part 212 Middle heating circuit 213 Outer peripheral heating circuit 113a Electrode terminal 20 Tubular support

Claims (3)

A ceramic disk-shaped portion having a mounting surface configured to mount the semiconductor substrate on the upper surface;
A plurality of regions respectively embedded in the disk-shaped portion so as to extend parallel to the mounting surface in a plurality of regions defined by concentric division when viewed from the mounting surface side And a heating circuit,
A substrate mounting table for heating a semiconductor substrate, wherein a heat generation circuit located inside the heat generation circuit outside the plurality of heat generation circuits is disposed at a position closer to the mounting surface. The substrate for heating a semiconductor substrate according to claim 1, further comprising: a plurality of electrode terminals respectively connected to end portions of the plurality of heating circuits on a lower surface opposite to the mounting surface in the disk shaped portion. Mounting table. The substrate mounting table for heating a semiconductor substrate according to claim 1, wherein each of the plurality of heat generating circuits is configured to be individually controllable.

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