Susceptor and vapor-phase growth device

Abstract

A susceptor according to an embodiment is provided to a vapor-phase growth device. A wafer is placed on the susceptor. The susceptor has a wafer-supporting part. The wafer-supporting part supports the wafer. The wafer-supporting part is annular. The wafer-supporting part has a supporting surface. The supporting surface supports the wafer from beneath. The supporting surface has an inclined surface. The inclined surface extends to the inner edge of the wafer-supporting part. The inclined surface rises toward the radial-direction outer periphery of the wafer-supporting part.

Description

Susceptor and vapor phase growth apparatus

[0001] This application claims priority to Japanese Patent Application No. 2023-117138, filed on July 18, 2023, the contents of which are incorporated herein by reference.

[0002] In a vapor phase growth apparatus, when a wafer is placed on a susceptor and when a film such as SiC is formed on the wafer surface, there is a possibility that the wafer may rotate relative to the susceptor, resulting in a decrease in wafer flatness due to the formation of a SiC film on the back surface of the wafer, and a decrease in the uniformity of the thickness of the film formed on the wafer surface.

[0003] Japanese Patent Application Laid-Open No. 2020-174138

[0004] The problem to be solved by the present invention is to provide a susceptor and a vapor phase growth apparatus that can suppress the occurrence of wafer misalignment, suppress a decrease in wafer flatness, and increase the uniformity of the thickness of a film formed on the wafer surface.

[0005] The susceptor of the embodiment is used in a vapor phase growth apparatus. A wafer is placed on the susceptor. The susceptor has a wafer support portion. The wafer support portion supports the wafer. The wafer support portion is annular. The wafer support portion has a support surface. The support surface supports the wafer from below. The support surface has an inclined surface. The inclined surface is connected to the inner edge of the wafer support portion. The inclined surface is located upward as it moves radially outward from the wafer support portion.

[0006] 1 is a cross-sectional view showing a vapor phase growth apparatus according to an embodiment; 2 is a cross-sectional view showing a portion of the vapor phase growth apparatus according to an embodiment; 3 is a top view showing a portion of the vapor phase growth apparatus according to an embodiment; 4 is a cross-sectional view showing another portion of the vapor phase growth apparatus according to an embodiment; 5 is an enlarged cross-sectional view showing a portion of the vapor phase growth apparatus according to an embodiment; 6 is a top view showing a portion of the vapor phase growth apparatus according to a first modified example of the embodiment; 7 is an enlarged cross-sectional view showing a portion of the vapor phase growth apparatus according to a first modified example of the embodiment; 8 is a top view showing a portion of another vapor phase growth apparatus according to the first modified example of the embodiment; 9 is a top view showing a portion of the vapor phase growth apparatus according to a second modified example of the embodiment;

[0007] Hereinafter, a susceptor and a vapor phase growth apparatus according to an embodiment will be described with reference to the drawings. In each drawing, the Z-axis direction is the vertical direction. The side toward which the Z-axis arrow points (+Z side) is the upper side in the vertical direction. The side opposite to the side toward which the Z-axis arrow points (-Z side) is the lower side in the vertical direction. In the following description, the upper side in the vertical direction will be simply referred to as the "upper side," and the lower side in the vertical direction will be simply referred to as the "lower side."

[0008] The direction in which the rotation axis J shown in each drawing extends is parallel to the Z-axis direction. The rotation axis J is a virtual axis. In the following embodiments, the susceptor rotates around the rotation axis J. In the following description, the radial direction around the rotation axis J is simply referred to as the "radial direction." In the following embodiments, the radial direction of the wafer support is the same as the radial direction around the rotation axis J. The radial direction of the wafer support and the radial direction around the rotation axis J may be different directions. The circumferential direction around the rotation axis J is simply referred to as the "circumferential direction." In the following embodiments, the circumferential direction of the wafer support is the same as the circumferential direction around the rotation axis J. The circumferential direction of the wafer support and the circumferential direction around the rotation axis J may be different directions.

[0009] The vapor phase growth apparatus 10 of this embodiment shown in FIG. 1 is a film formation apparatus that forms an epitaxial film on a surface 60a, which is the upward-facing surface of a wafer 60, by a CVD (Chemical Vapor Deposition) method. In this embodiment, a SiC film is formed on the surface 60a of the wafer 60. The film formed on the surface 60a of the wafer 60 may be a film made of other materials such as Si. The vapor phase growth apparatus 10 includes a chamber 20, a supply pipe 24, a drive unit 31, a susceptor holder 32, a susceptor 34, a wafer guide 38, a first heating unit 41, and a second heating unit 42.

[0010] The chamber 20 accommodates therein a supply pipe 24, a drive unit 31, a susceptor holder 32, a susceptor 34, a wafer guide 38, a first heating unit 41, and a second heating unit 42. The chamber 20 has a main body 21 and a supply unit 22. In this embodiment, the chamber 20 is made of metal.

[0011] The main body 21 accommodates the supply pipe 24, the drive unit 31, the susceptor holder 32, the susceptor 34, the wafer guide 38, the first heating unit 41, and the second heating unit 42. The main body 21 has a cylindrical shape extending vertically. The main body 21 has a main body opening 21a that opens to the upper side. The main body 21 has an exhaust port 21b that opens to the lower side. Excess gas G in the chamber 20 is exhausted from the exhaust port 21b.

[0012] The supply unit 22 is fixed to the upper end of the main body 21. The supply unit 22 is cylindrical and protrudes vertically. The supply unit 22 is provided with a supply port 22a that opens to the upper side. The supply unit 22 is provided with a supply unit opening 22b that opens to the lower side. The interior of the supply unit 22 and the interior of the main body 21 are connected via the supply unit opening 22b and the main body opening 21a. The gas G supplied from the supply port 22a to the interior of the supply unit 22 is supplied to the interior of the main body 21 via the supply unit opening 22b and the main body opening 21a.

[0013] The supply pipe 24 is housed inside the main body 21. The supply pipe 24 is cylindrical and extends vertically. The supply pipe 24 has openings on both the top and bottom. Gas G flows downward inside the supply pipe 24. The gas G flowing downward inside the supply pipe 24 is supplied to the wafer 60. Excess gas G inside the supply pipe 24 is discharged to the outside of the vapor phase growth apparatus 10 through the opening on the bottom of the supply pipe 24 and the exhaust port 21b. In this embodiment, the supply pipe 24 is made of graphite. A coating layer made of a material such as SiC or TaC (tantalum carbide) may be provided on the surface of the supply pipe 24.

[0014] In this embodiment, the gas G contains a source gas, an impurity gas, a carrier gas, and hydrogen chloride (HCl) gas. The source gas contains silane (SiH4) and propane (C3H8). The flow rate of the source gas is preferably in the range of several tens of sccm to several hundreds of sccm. The impurity gas contains nitrogen and TMA (trimethylaluminum). The flow rate of the impurity gas is preferably in the range of several sccm to several hundreds of sccm. The carrier gas is either argon gas or hydrogen gas. More specifically, the carrier gas is argon gas when the wafer 60 is loaded into the vapor phase growth apparatus 10 and placed on the susceptor 34, and when the wafer 60 is removed from the susceptor 34 after film formation and transported out of the vapor phase growth apparatus 10. The carrier gas during film formation is hydrogen gas. The flow rate of the carrier gas is preferably in the range of 100 slm to 200 slm. The flow rate of the hydrogen chloride gas is preferably in the range of several tens of sccm to several slm. The flow rates of the source gas, impurity gas, carrier gas, and hydrogen chloride gas are adjusted by a gas adjusting unit (not shown).

[0015] The first heating unit 41 is annular and surrounds the supply pipe 24. The first heating unit 41 is disposed between the main body 21 and the supply pipe 24. In this embodiment, the vapor phase growth apparatus 10 includes three first heating units 41. The first heating units 41 are disposed at intervals in the vertical direction. Each first heating unit 41 heats the gas G passing through the interior of the supply pipe 24. This increases the temperature of the gas G when it reaches the wafer 60, thereby increasing the deposition rate of the SiC film. The number of first heating units 41 included in the vapor phase growth apparatus 10 may be two or less, or four or more.

[0016] The second heating unit 42 is disposed inside the driving unit 31. The second heating unit 42 is disposed below the susceptor holding unit 32. During film formation, the second heating unit 42 heats each of the susceptor holding unit 32, the susceptor 34, and the wafer 60. During film formation, the second heating unit 42 heats the wafer 60 to a temperature of 1500°C or higher and 1650°C or lower. When gas G is supplied to the surface 60a of the wafer 60 heated to such a temperature and the surface 60a is maintained at this temperature for a certain period of time, a SiC film of a desired thickness is formed on the surface 60a of the wafer 60.

[0017] The drive unit 31 includes a drive device, such as a motor (not shown). The drive unit 31 is rotated around the rotation axis J by the drive device. The drive unit 31 is disposed below the susceptor holder 32. The drive unit 31 is fixed to the susceptor holder 32. The drive unit 31 rotates each of the susceptor holder 32, the susceptor 34, the wafer guide 38, and the wafer 60 around the rotation axis J. Therefore, according to this embodiment, during the film formation process in which an SiC film is formed on the front surface 60a of the wafer 60, the drive unit 31 can rotate the wafer 60 around the rotation axis J. This reduces variations in the supply amount of gas G and the concentration of gas G within the surface 60a. This improves the uniformity of the thickness of the film formed on the wafer 60.

[0018] The susceptor holder 32 has a plate shape extending in a direction perpendicular to the vertical direction. In this embodiment, the susceptor holder 32 has a substantially circular plate shape centered on the rotation axis J. When viewed vertically, the susceptor holder 32 may have other shapes, such as a polygonal shape such as a square shape, or an elliptical shape. As described above, the driver 31 is fixed to the susceptor holder 32. As shown in FIG. 2 , the susceptor 34 is fixed to the holder surface 32a, which is the surface facing upward of the susceptor holder 32. This allows the susceptor holder 32 to hold the susceptor 34. In this embodiment, the susceptor holder 32 is made of graphite. A coating layer made of a material such as SiC or TaC may be provided on the surface of the susceptor holder 32.

[0019] The wafer 60 is placed on the susceptor 34. The susceptor 34 supports the wafer 60 from below. In this embodiment, the susceptor 34 has a substantially circular ring shape centered on the rotation axis J. As described above, the susceptor 34 is held by the susceptor holder 32. The susceptor 34 rotates around the rotation axis J. The susceptor 34 includes a guide support portion 35, a connection portion 36, and a wafer support portion 37. In this embodiment, the susceptor 34 is made of graphite. A coating layer made of a material such as SiC or TaC may be provided on the surface of the susceptor 34.

[0020] The guide support portion 35 has an annular shape centered on the rotation axis J. The guide support portion 35 is a radially outer portion of the susceptor 34. The downward surface of the guide support portion 35 contacts the susceptor holder 32 in the vertical direction.

[0021] The connecting portion 36 protrudes radially inward from the guide support portion 35. The connecting portion 36 has an annular shape centered on the rotation axis J. The downward surface of the connecting portion 36 contacts the susceptor holder 32 in the vertical direction. The upward surface of the connecting portion 36 is located lower than the upward surface of the guide support portion 35. As shown in FIG. 3 , the connecting portion 36 has an exposed portion 36a. The exposed portion 36a is a part of the upward surface of the connecting portion 36, and is a portion that overlaps with the gap between the guide support portion 35 and an orientation flat portion 60d of the wafer 60 (described later) when viewed from the vertical direction. The exposed portion 36a is exposed upward through the gap between the orientation flat portion 60d and the guide support portion 35. Therefore, during film formation, a SiC laminate is formed on the exposed portion 36a.

[0022] The wafer support portion 37 extends in the circumferential direction. In this embodiment, the wafer support portion 37 is annular and surrounds the rotation axis J. The wafer support portion 37 is disposed radially inward of the connecting portion 36. The wafer support portion 37 is connected to the connecting portion 36. As shown in FIG. 2, the upper end of the wafer support portion 37 is located higher than the upper end of the connecting portion 36. The wafer support portion 37 is disposed radially inward of the wafer guide 38. The wafer support portion 37 has a support portion inner surface 37d, a support surface 37e, and a support portion outer surface 37i. As shown in FIG. 3, the wafer support portion 37 has an arc portion 37a, a linear portion 37b, and a plurality of recessed portions 37k. As shown in FIGS. 2 and 4, the wafer 60 is placed on the wafer support portion 37. The wafer support portion 37 supports the wafer 60.

[0023] As shown in Fig. 2, the wafer 60 has a generally circular disk shape that extends in a direction perpendicular to the vertical direction. In this embodiment, the wafer 60 is made of SiC. The wafer 60 may be made of other materials such as Si. As shown in Fig. 3, a linearly extending orientation flat 60d is provided on a portion of the outer periphery of the wafer 60. The orientation flat 60d is formed on the wafer 60 to indicate the crystal orientation of the wafer 60.

[0024] When the wafer 60 is heated by the second heating unit 42 during film formation, the temperature of the back surface 60b of the wafer 60, which is the surface facing downward, becomes higher than the temperature of the front surface 60a of the wafer 60. Therefore, the thermal expansion of the back surface 60b of the wafer 60 is greater than the thermal expansion of the front surface 60a of the wafer 60. Therefore, as shown in FIG. 4 , during film formation, the wafer 60 is thermally deformed so that the central portion in the radial direction is warped downward.

[0025] As shown in FIG. 3 , the arc portion 37a is an arc-shaped portion of the wafer support portion 37 that is centered on the rotation axis J. In this embodiment, the central angle of the arc portion 37a is approximately 320°. The central angle of the arc portion 37a may be smaller or larger than 320°. The linear portion 37b is a linear portion of the wafer support portion 37. Both ends of the linear portion 37b are connected to different circumferential ends of the arc portion 37a. The radially inner portion of the orientation flat 60d of the radially outer edge of the wafer 60 is supported by the linear portion 37b. The remaining portion of the radially outer edge of the wafer 60 other than the radially inner portion of the orientation flat 60d is supported by the arc portion 37a.

[0026] The support portion inner surface 37d is the inner surface of the wafer support portion 37. The support portion inner surface 37d faces radially inward. The support portion inner surface 37d is composed of the radially inner surface of the arc portion 37a and the radially inner surface of the straight portion 37b. The support portion outer surface 37i is the outer surface of the wafer support portion 37. The support portion outer surface 37i faces radially outward. The support portion outer surface 37i is composed of the radially outer surface of the arc portion 37a and the radially outer surface of the straight portion 37b.

[0027] When viewed in the vertical direction, the support surface 37e has an annular shape surrounding the rotation axis J. As shown in Figures 2 and 4, the support surface 37e supports the wafer 60 from below. As shown in Figure 5, the support surface 37e has an inclined surface 37f and a flat surface 37g.

[0028] The inclined surface 37f is connected to the upper end of the support portion inner side surface 37d. That is, the inclined surface 37f is connected to the inner edge of the wafer support portion 37. The inclined surface 37f is an inclined surface located upward as it extends radially outward from the wafer support portion 37. Therefore, according to this embodiment, as described above, even if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 and the inclined surface 37f are likely to come into surface contact. This makes it easy to prevent a decrease in the contact area between the wafer 60 and the wafer support portion 37. This increases the frictional force between the wafer 60 and the wafer support portion 37. Therefore, even if the susceptor 34 on which the wafer 60 is placed is rotated during film formation, wafer misalignment, such as rotational movement of the wafer 60 relative to the susceptor 34, can be prevented. This improves the uniformity of the thickness of the film formed on the wafer 60.

[0029] In a susceptor 34 configured without the inclined surface 37f on the wafer support portion 37, if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 rubs against the upper corners of the support portion inner surface 37d of the wafer support portion 37. This easily generates wear debris from the wafer support portion 37. If such wear debris gets between the wafer 60 and the support surface 37e, the frictional force between the wafer 60 and the wafer support portion 37 decreases. This makes it more likely that the wafer will become misaligned during film formation. In contrast, in this embodiment, the wafer support portion 37 has the inclined surface 37f, which makes it easier for the back surface 60b of the wafer 60 to come into surface contact with the inclined surface 37f. This makes it easier to prevent the back surface 60b of the wafer 60 from rubbing against the corners of the wafer support portion 37. This effectively prevents the generation of wear debris from the wafer support portion 37, thereby increasing the frictional force between the wafer 60 and the wafer support portion 37. Therefore, wafer misalignment can be suppressed during film formation.

[0030] As described above, in this embodiment, wafer misalignment during film formation can be suppressed, thereby suppressing misalignment of the orientation flat 60d of the wafer 60 relative to the susceptor 34 during film formation. This prevents the SiC stack stacked on the exposed portion 36a from vertically facing the wafer 60. Therefore, during film formation, it is possible to prevent a portion of the SiC stack sublimated by heating from adhering to the back surface 60b of the wafer 60. This prevents a decrease in the flatness of the back surface 60b of the wafer 60. This prevents a decrease in the flatness of the wafer 60. Furthermore, when the vertical dimension of the SiC stack stacked on the exposed portion 36a is large, it is possible to prevent the wafer 60 from climbing up on the SiC deposit. Therefore, tilting of the wafer 60 during film formation can be suppressed, thereby improving the uniformity of the thickness of the film formed on the wafer 60.

[0031] As shown in FIG. 3 , the inclined surface 37f extends in the circumferential direction of the wafer support portion 37. The inclined surface 37f is annular and surrounds the rotation axis J. In this embodiment, the inclined surface 37f is divided into multiple portions by multiple recesses 37k. The inclined surface 37f is provided across the arc portion 37a and the linear portion 37b. Therefore, according to this embodiment, the back surface 60b of the wafer 60 and the inclined surface 37f can be brought into contact with each other in the circumferential direction during film formation. This increases the contact area between the back surface 60b of the wafer 60 and the inclined surface 37f, thereby more effectively increasing the frictional force between the wafer 60 and the wafer support portion 37. Therefore, wafer misalignment can be more effectively suppressed during film formation, thereby suppressing the formation of a SiC film on the back surface 60b of the wafer 60. This prevents the flatness of the wafer 60 from decreasing. Furthermore, the uniformity of the thickness of the film formed on the wafer 60 can be more effectively improved.

[0032] As shown in FIG. 5 , the flat surface 37g is the upward-facing surface of the outer surface of the wafer support 37. The flat surface 37g extends in a direction perpendicular to the vertical direction. The flat surface 37g is connected to both the radially outer end of the inclined surface 37f and the upper end of the support outer surface 37i. Therefore, according to this embodiment, as shown in FIG. 2 , when the wafer 60 is placed on the susceptor 34, the back surface 60b of the disk-shaped wafer 60 and the flat surface 37g can be brought into surface contact. This increases the frictional force between the wafer 60 and the wafer support 37. Therefore, during placement, wafer misalignment, such as rotational movement of the wafer 60 relative to the susceptor 34, can be suppressed. As shown in FIG. 3 , the flat surface 37g extends in the circumferential direction of the wafer support 37. The flat surface 37g is annular and surrounds the rotation axis J. In this embodiment, the flat surface 37g is divided into multiple sections by multiple recesses 37k.

[0033] The susceptor 34 has a susceptor groove 34a. The susceptor groove 34a is a groove recessed downward from the upward surface of the susceptor 34. The susceptor groove 34a is formed by the inner surface of the guide support portion 35, the upward surface of the connection portion 36, and the support portion outer surface 37i. As shown in FIG. 3 , the susceptor groove 34a is annular and surrounds the rotation axis J when viewed vertically.

[0034] Each of the plurality of recesses 37k is recessed downward from the support surface 37e. The plurality of recesses 37k are spaced apart along the circumferential direction of the wafer support portion 37. In this embodiment, each recess 37k is a groove extending radially. As shown in FIG. 5, in this embodiment, each recess 37k is provided across the inclined surface 37f and the flat surface 37g. Therefore, as shown in FIG. 2, when the wafer 60 is placed on the susceptor 34, the back surface 60b of the wafer 60 contacts the upper corners of each recess 37k located on the flat surface 37g, i.e., the radially outer portions of the upper corners of each recess 37k. Furthermore, as shown in FIG. 4, during film formation, the back surface 60b of the wafer 60 contacts the upper corners of each recess 37k located on the inclined surface 37f, i.e., the radially inner portions of the upper corners of each recess 37k. Therefore, according to this embodiment, when the wafer 60 attempts to rotate relative to the susceptor 34 during both placement and film formation, the back surface 60b of the wafer 60 catches on the upper corners of the recessed portions 37k. This increases the frictional force between the wafer 60 and the wafer support portion 37. This more effectively prevents the wafer from shifting during both placement and film formation. This prevents a SiC film from being formed on the back surface 60b of the wafer 60, more effectively preventing a decrease in the flatness of the wafer 60 and more effectively improving the uniformity of the thickness of the film formed on the wafer 60.

[0035] As shown in FIG. 3 , in this embodiment, the wafer support portion 37 has 36 recesses 37 k. The number of recesses 37 k in the wafer support portion 37 may be 35 or less, or 37 or more. In this embodiment, each recess 37 k opens to the support portion inner surface 37 d, i.e., the inner surface of the wafer support portion 37, and the support portion outer surface 37 i, i.e., the outer surface of the wafer support portion 37. Therefore, according to this embodiment, as shown in FIG. 2 , when a wafer 60 is placed on the susceptor 34, gas As in the lower space S, which is the space surrounded by the wafer 60, the susceptor 34, and the susceptor holder 32, can be exhausted to the outside of the susceptor 34 through each recess 37 k. This allows the support surface 37 e of the wafer support portion 37 to stably support the wafer 60 during placement. Therefore, when the wafer 60 is placed on the susceptor 34, wafer misalignment can be suppressed. Therefore, it is possible to more effectively prevent the flatness of the wafer 60 from decreasing, and it is possible to more effectively improve the uniformity of the thickness of the film formed on the wafer 60 .

[0036] Furthermore, according to this embodiment, even if the temperature of the gas As in the lower space S rises and the volume of the gas As increases during film formation, the gas As can be discharged to the outside of the susceptor 34 through each recess 37k. This allows the wafer 60 to be stably supported by the support surface 37e during film formation. Therefore, even if the susceptor 34 is rotated during film formation, wafer misalignment can be suppressed. Therefore, a decrease in the flatness of the wafer 60 can be more effectively suppressed, and the uniformity of the film formed on the wafer can be more effectively improved.

[0037] As shown in FIGS. 2 and 4 , the wafer guide 38 is annular and surrounds the rotation axis J. In this embodiment, the wafer guide 38 is annular and centered on the rotation axis J. In this embodiment, the wafer guide 38 is made of poly-SiC. The wafer guide 38 may also be made of graphite. In this case, a coating layer made of SiC may be provided on the surface of the wafer guide 38. In this embodiment, the wafer guide 38 and the susceptor 34 are different components. The wafer guide 38 and the susceptor 34 may be integrally molded. The wafer guide 38 is supported from below by the guide support portion 35 of the susceptor 34. The wafer guide 38 is supported by the guide support portion 35. The wafer guide 38 surrounds the outer edge of the wafer 60 from the radial outside. During film formation, a portion of the inner surface of the wafer guide 38 comes into radial contact with the wafer 60 rotating around the rotation axis J, preventing the wafer 60 from jumping out of the wafer guide 38. Wear particles of the wafer guide 38 generated by the friction between the inner surface of the wafer guide 38 and the wafer 60 are contained inside the susceptor groove 34a. This prevents the wear particles from entering between the wafer 60 and the support surface 37e, thereby preventing a decrease in the friction force between the wafer 60 and the wafer support portion 37. This prevents the wafer from shifting during film formation.

[0038] The imaginary line Lv shown in FIG. 5 is an imaginary line passing through the radially inner end of the inclined surface 37f and the radially outer end of the inclined surface 37f. The imaginary line Lv intersects with the inner surface of the wafer guide 38 facing radially inward. During film formation, centrifugal force is applied to the wafer 60 rotating around the rotation axis J, causing the wafer 60 to move radially outward. As described above, during film formation, the wafer 60 thermally deforms such that the central portion of the wafer 60 warps downward, and the back surface 60b of the wafer 60 comes into surface contact with the inclined surface 37f. Therefore, during film formation, the wafer 60 attempts to move in a direction along the imaginary line Lv. In contrast, according to the present embodiment, as described above, the imaginary line Lv intersects with the inner surface of the wafer guide 38 facing radially inward. Therefore, the inner surface of the wafer guide 38 can be positioned in the direction in which the wafer 60 attempts to move. Therefore, the movement of the wafer 60 can be suppressed by the inner surface of the wafer guide 38 , and the wafer 60 can be prevented from jumping out of the wafer guide 38 .

[0039] In this embodiment, the wafer support portion 37 does not necessarily have to have either the inclined surface 37 f or the plurality of recesses 37 k. If the wafer support portion 37 has either the inclined surface 37 f or the plurality of recesses 37 k, the frictional force between the back surface 60 b of the wafer 60 and the wafer support portion 37 can be increased, as described above. Therefore, it is possible to prevent the wafer from shifting during placement and film formation.

[0040] 6 is a top view showing a part of a vapor phase growth apparatus 110 according to this modification. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof may be omitted.

[0041] In this modification, as shown in FIG. 6 , each of the plurality of recesses 137k provided in the wafer support 137 opens to the support-portion inner surface 37d. None of the recesses 137k opens to the support-portion outer surface 37i. That is, each of the plurality of recesses 137k opens to only one of the support-portion inner surface 37d (i.e., the inner surface of the wafer support 137) and the support-portion outer surface 37i (i.e., the outer surface of the wafer support 137). As shown in FIG. 8 , each of the plurality of recesses 137k may open to the support-portion outer surface 37i. In this case, none of the recesses 137k opens to the support-portion inner surface 37d. Therefore, according to this modification, as shown in FIG. 7 , during film formation, gas G can be prevented from flowing into the lower space S, which is the space surrounded by the wafer 60, the susceptor 134, and the susceptor holder 32, through each recess 137k. This can prevent a SiC film from being formed on the back surface 60b of the wafer 60. Therefore, it can prevent a decrease in flatness of the back surface 60b of the wafer 60. This can prevent a decrease in flatness of the wafer 60. Other configurations of the susceptor 134 of this modified example are similar to other configurations of the susceptor 34 of the above-described embodiment.

[0042] As described above, in this modification, each of the multiple recesses 137k opens to the support inner surface 37d. Therefore, according to this modification, a portion of each recess 137k is recessed downward from the inclined surface 37f. Therefore, even if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 contacts the upper corners of each recess 137k located on the inclined surface 37f, i.e., the radially inner corners of the upper corners of each recess 137k. Therefore, when the wafer 60 attempts to rotate relative to the susceptor 134 during film formation, the back surface 60b of the wafer 60 catches on the upper corners of each recess 137k. This increases the frictional force between the wafer 60 and the wafer support 137, thereby more effectively preventing wafer misalignment. This prevents a decrease in the flatness of the wafer 60. Furthermore, the uniformity of the thickness of the film formed on the wafer 60 can be improved.

[0043] Furthermore, according to this modification, similarly to the above-described embodiment, the wafer support portion 137 has an inclined surface 37f. Therefore, even if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 and the inclined surface 37f are likely to come into surface contact. This increases the frictional force between the wafer 60 and the wafer support portion 137. Therefore, wafer misalignment during film formation can be suppressed, thereby suppressing a decrease in the flatness of the wafer 60 and improving the uniformity of the thickness of the film formed on the wafer 60.

[0044] 9 is a top view showing a part of a vapor phase growth apparatus 210 according to this modification. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0045] In this modification, as shown in FIG. 9 , each of the multiple recesses 237k provided in the wafer support 237 has a circular shape when viewed vertically. In this modification, each recess 237k does not open to either the support inner surface 37d or the support outer surface 37i. Therefore, according to this modification, as in the first modification described above, gas G can be prevented from flowing into the lower space S through each recess 237k during film formation. This prevents a SiC film from being formed on the back surface 60b of the wafer 60. This prevents a decrease in flatness of the back surface 60b of the wafer 60. The other configurations of the susceptor 234 of this modification are similar to those of the susceptor 34 of the above-described embodiment.

[0046] In this modification, a portion of each recess 237k is recessed downward from the inclined surface 37f. Therefore, even if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 contacts the upper corners of each recess 237k, i.e., the radially inner corners of the upper corners of each recess 237k, located on the inclined surface 37f. Therefore, when the wafer 60 attempts to rotate relative to the susceptor 234 during film formation, the back surface 60b of the wafer 60 catches on the upper corners of each recess 237k. This increases the frictional force between the wafer 60 and the wafer support 237, thereby more effectively preventing wafer misalignment. This prevents the flatness of the wafer 60 from decreasing and improves the uniformity of the thickness of the film formed on the wafer 60.

[0047] Furthermore, according to this modification, similarly to the above-described embodiment, the wafer support portion 237 has an inclined surface 37f. Therefore, even if the wafer 60 is thermally deformed and warped downward during film formation, the back surface 60b of the wafer 60 and the inclined surface 37f are likely to come into surface contact. This makes it easy to prevent a decrease in the frictional force between the wafer 60 and the wafer support portion 237. Therefore, during film formation, it is possible to prevent wafer misalignment, such as rotational movement of the wafer 60 relative to the susceptor 234. This makes it possible to prevent a decrease in the flatness of the wafer 60 and to improve the uniformity of the thickness of the film formed on the wafer 60.

[0048] According to the susceptor of the embodiment and modified examples described above, the support surface is connected to the inner edge of the wafer support portion and has an inclined surface that slopes upward toward the radially outer side of the wafer support portion, thereby suppressing wafer misalignment during film deposition and improving the uniformity of the thickness of the film deposited on the wafer surface.

[0049] Furthermore, according to the susceptors of the above-described embodiments and modifications, the wafer support has a plurality of recesses recessed downward from the support surface. This allows the backside of the wafer to come into contact with the upper corners of each recess when the wafer is placed on the susceptor and during film deposition. Therefore, when the wafer attempts to rotate relative to the susceptor during placement and film deposition, the backside of the wafer catches on the upper corners of each recess. This increases the frictional force between the wafer and the wafer support. Therefore, wafer misalignment can be more effectively prevented during placement and film deposition. This prevents a decrease in wafer flatness and more effectively improves the uniformity of the thickness of the film deposited on the wafer.

[0050] The present invention includes the following supplementary aspects. (Supplementary Note 1) A susceptor for use in a vapor phase growth apparatus, on which a wafer is placed, comprising: an annular wafer support portion for supporting the wafer; the wafer support portion has a support surface for supporting the wafer from below; the support surface has an inclined surface connected to an inner edge of the wafer support portion; and the inclined surface is positioned upward as it extends radially outward of the wafer support portion. (Supplementary Note 2) The susceptor according to Supplementary Note 1, wherein the inclined surface extends in the circumferential direction of the wafer support portion. (Supplementary Note 3) The susceptor according to Supplementary Note 1 or Supplementary Note 2, wherein the support surface has a flat portion facing upward, and the flat portion is connected to a radially outer end of the inclined surface. (Supplementary Note 4) The susceptor according to any one of Supplementary Notes 1 to 3, wherein the wafer support portion has a plurality of recesses recessed downward from the support surface, and the plurality of recesses are arranged at intervals along the circumferential direction of the wafer support portion. (Supplementary Note 5) A susceptor provided in a vapor phase growth apparatus and on which a wafer is placed, comprising: an annular wafer support portion that supports the wafer, the wafer support portion having a support surface that supports the wafer from below and a plurality of recesses recessed downward from the support surface, the plurality of recesses being arranged at intervals along the circumferential direction of the wafer support portion. (Supplementary Note 6) The susceptor according to Supplementary Note 4 or Supplementary Note 5, wherein at least one of the plurality of recesses opens onto each of an inner surface and an outer surface of the wafer support portion. (Supplementary Note 7) The susceptor according to Supplementary Note 4 or Supplementary Note 5, wherein each of the plurality of recesses opens onto only one of the inner surface and the outer surface of the wafer support portion. (Supplementary Note 8) The susceptor according to Supplementary Note 7, wherein each of the plurality of recesses opens onto only one of the inner surface and the outer surface of the wafer support portion. (Supplementary Note 9) A vapor phase growth apparatus comprising: the susceptor according to any one of Supplementary Note 1 to Supplementary Note 8; and a drive unit that rotates the susceptor.(Supplementary Note 10) A vapor phase growth apparatus comprising: a susceptor according to any one of Supplementary Note 1 to Supplementary Note 4; a drive unit that rotates the susceptor; and an annular wafer guide that surrounds an outer edge of the wafer, wherein an imaginary line passing through a radially inner end of the inclined surface and a radially outer end of the inclined surface intersects with an inner surface of the wafer guide.

[0051] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents.

Claims

1. A susceptor for use in a vapor phase growth apparatus on which a wafer is placed, comprising: an annular wafer support portion for supporting the wafer, the wafer support portion having a support surface for supporting the wafer from below, the support surface having an inclined surface connected to an inner edge of the wafer support portion, the inclined surface being positioned upward as it moves radially outward of the wafer support portion.

2. The susceptor according to claim 1, wherein said inclined surface extends in a circumferential direction of said wafer support portion.

3. The susceptor according to claim 1, wherein the support surface has a flat portion facing upward, the flat portion being connected to a radially outer end of the inclined surface.

4. A susceptor as described in claim 1, wherein the wafer support portion has a plurality of recesses recessed downward from the support surface, the plurality of recesses being spaced apart along the circumferential direction of the wafer support portion.

5. A susceptor provided in a vapor phase growth apparatus on which a wafer is placed, comprising: an annular wafer support portion that supports the wafer, the wafer support portion having a support surface that supports the wafer from below, and a plurality of recesses recessed downward from the support surface, the plurality of recesses being spaced apart along the circumferential direction of the wafer support portion.

6. A susceptor according to claim 4 or 5, wherein at least one of the plurality of recesses opens onto each of an inner surface of the wafer support and an outer surface of the wafer support.

7. A susceptor according to claim 4 or 5, wherein each of the plurality of recesses is open only to either the inner surface of the wafer support or the outer surface of the wafer support.

8. The susceptor according to claim 7, wherein each of the plurality of recesses opens onto an inner surface of the wafer support.

9. A vapor phase growth apparatus comprising a susceptor according to any one of claims 1 to 5 and a drive unit for rotating the susceptor.

10. A vapor phase growth apparatus comprising a susceptor as claimed in any one of claims 1 to 4, a drive unit for rotating the susceptor, and an annular wafer guide surrounding the outer edge of the wafer, wherein an imaginary straight line passing through the radially inner end of the inclined surface and the radially outer end of the inclined surface intersects with the inner surface of the wafer guide.

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