JP6986872B2 - Wafer support, chemical vapor deposition equipment, and method for manufacturing SiC epitaxial wafers - Google Patents

Description

The present invention relates to a wafer support, a chemical vapor deposition apparatus, and a method for manufacturing a SiC epitaxial wafer.

Silicon carbide (SiC) has characteristics such as a dielectric breakdown electric field that is an order of magnitude larger, a band gap that is three times larger, and a thermal conductivity that is about three times higher than that of silicon (Si). Since silicon carbide has these characteristics, it is expected to be applied to power devices, high frequency devices, high temperature operation devices and the like. For this reason, in recent years, SiC epitaxial wafers have come to be used for the above-mentioned semiconductor devices.

The SiC epitaxial wafer is manufactured by growing a SiC epitaxial film, which is an active region of a SiC semiconductor device, on a SiC substrate (SiC wafer). The SiC substrate is obtained by processing from a bulk single crystal of SiC produced by a sublimation method or the like, and the SiC epitaxial film is formed by a chemical vapor deposition (CVD) method.

As a device for manufacturing a SiC epitaxial wafer, a horizontal self-revolution type epitaxial growth device in which a plurality of wafers are arranged horizontally, each wafer is revolved, and the wafer itself is rotated around the center of the wafer is known. (For example, Patent Document 1 and Patent Document 2).

In this epitaxial growth apparatus, a wafer support base is provided on a rotatable mounting plate (susceptor) so as to surround the rotation axis of the mounting plate in each of the plurality of concave housing portions. Be housed. Since the wafer support is made to rotate by the rotation drive mechanism, the SiC substrate mounted on the wafer mounting surface of the wafer support revolves around the rotation axis of the mounting plate and rotates on its axis. , It is configured to be able to revolve. By this revolution, the raw material gas is devised so as to reach the surface to be treated of the SiC substrate uniformly.

In the epitaxial growth apparatus as described above, the raw material gas is supplied onto the SiC substrate by passing the raw material gas from the outside of the outer peripheral end of the SiC substrate placed on the wafer support. At this time, the epitaxial film is formed by epitaxially growing the epitaxial material on the substrate while maintaining the SiC substrate at a high temperature by the heating means.
This self-revolving epitaxial growth apparatus has a configuration in which the SiC substrate is mounted on the mounting plate via a wafer support, but the substrate is mounted directly in a recess formed in the mounting plate. There is also a device.

Here, the wafer support base usually has an opening for mounting the wafer, and has a ring-shaped portion surrounding the outer periphery of the wafer and a support main body having a wafer mounting surface on which the wafer is mounted. ..
Further, since the material of the wafer support needs to withstand high temperatures, silicon carbide, TaC-coated graphite, or the like is often used.

As a method of mounting the wafer (board) on the wafer support base, the wafer is tilted diagonally so that the outer peripheral surface of the wafer is brought into contact with the inner side surface (inner peripheral surface) of the wafer support base (ring-shaped portion), and then the wafer is contacted. There is a known method of lowering the opposite side of the wafer.

Japanese Patent No. 2771585 Japanese Patent No. 28353338

A method of mounting the wafer on the above-mentioned wafer support will be described with reference to FIGS. 7 (a) and 7 (b). FIG. 7A is a cross-sectional view schematically showing the wafer support base 120, the wafer W, and the vacuum tweezers P holding the wafer when the outer periphery of the wafer is brought into contact with the inner side surface of the wafer support base. be. The wafer support base 120 includes a support base main body 121 having a wafer mounting surface 121s and a ring-shaped portion 122 that surrounds the outer periphery of the wafer. “OF” in the figure indicates a so-called orientation flat. FIG. 7 (b) is a plan view of the wafer W as viewed from above.
As shown in FIG. 7A, when the wafer W is tilted diagonally and the outer peripheral surface Wc of the wafer is brought into contact with the inner side surface (inner peripheral surface) 122a of the ring-shaped portion 122 of the wafer support base 120, the wafer comes into contact with the wafer. Is usually the upper end (upper end of the outer circumference) Wct of the outer circumference. Foreign matter such as the material constituting the ring-shaped portion and silicon carbide adhering to the ring-shaped portion may be scattered on the surface Ws of the wafer W.

In FIG. 8, as shown in FIG. 7 (b), the olifra side of the SiC wafer is held by a vacuum tweezers, the opposite side of the olifra is brought into contact with the inner side surface of the ring-shaped portion, and then the olifra side of the SiC wafer is lowered. This is a candela image obtained by Candela manufactured by KLA Tencor Co., Ltd. for a SiC epitaxial wafer on which a SiC wafer is placed on a wafer mounting surface of a wafer support base and then a SiC epitaxial film is formed in an amount of 10.5 μm. ..
The spots in the image show various defects. It can be seen that the spots are lined up in a streak pattern from the opposite side of the orifra to the orifra side (from top to bottom) (the part surrounded by an oval).

In FIG. 9B, contrary to the case where FIG. 8 is obtained, as shown in FIG. 9A, the opposite side of the olifra is held by the vacuum tweezers, and the olifra side is brought into contact with the inner side surface of the ring-shaped portion. Then, the opposite side of the orientation flat of the SiC wafer is lowered and placed on the wafer mounting surface of the wafer support base of the SiC wafer, and then a candela image of the SiC epitaxial wafer on which the SiC epitaxial film is formed by 10.5 μm.
In this case, the spots are lined up in a streak from the boundary between the part of the olifra and the part other than the olifra, which seems to have touched at the time of setting, instead of the part of the olifra that does not contact the inner side surface of the ring-shaped part. You can see that (the part circled in an oval).
Compared to the set method shown in FIG. 9 (a), the set method shown in FIG. 7 (b) is a type of a plurality of SiC epitaxial wafers of a type that is taken out after manufacturing the SiC epitaxial wafer and inserted from above. There is an advantage that it is easy to check the OF from above when it is put in a carrier that can accommodate.

The results of FIGS. 8 and 9 (b) form a ring-shaped portion as a result of contact of the upper end (upper outer peripheral surface) Wct of the outer peripheral Wc of the wafer with the inner side surface (inner peripheral surface) of the ring-shaped portion of the wafer support base. This indicates that foreign matter such as silicon carbide adhering to the material or the ring-shaped portion is scattered on the surface Ws of the wafer W. In this case, if an epitaxial film is subsequently formed on the wafer, defects will occur in the epitaxial film at the locations of foreign matter adhering to the wafer surface Ws, leading to device failure.

This problem is caused by the fact that the thickness (height) h of the ring-shaped portion 122 is thicker than the thickness t of the wafer W. Therefore, as the ring-shaped portion 122, the thickness h thereof is larger than the thickness t of the wafer W. It seems that it can be solved by using a thin one.
However, when the thickness h of the entire ring-shaped portion 122 is simply made thinner than the thickness t of the wafer W, abnormal growth such as epicrown tends to occur on the outer peripheral portion of the wafer as a new problem. Further, when the wafer becomes hot and the outer peripheral portion thereof is warped so as to be lifted, the wafer may be separated from the wafer support base.
Therefore, simply making the thickness h of the entire ring-shaped portion 122 thinner than the thickness of the wafer W does not cause a new big problem, and the wafer comes into contact with the wafer support during mounting the wafer. The problem of defects in the epitaxial film cannot be solved.

The present invention has been made in view of the above circumstances, and is a wafer support table and chemical vapor deposition that can reduce defects in the epitaxial film caused by contact of the wafer with the wafer support table when the wafer is placed on the wafer support table. It is an object of the present invention to provide a phase growth apparatus and a method for manufacturing a SiC epitaxial wafer.

The present invention provides the following means for solving the above problems.

(1) The wafer support according to one aspect of the present invention is a wafer support used for a chemical vapor deposition apparatus for forming a layer on a wafer, and is mounted on a support main body having a wafer mounting surface. A ring-shaped portion that surrounds the outer periphery of the wafer to be mounted and has a plate thickness equal to or larger than the thickness of the wafer is provided, and the ring-shaped portion is provided from the wafer mounting surface so as to face the outer periphery of the wafer to be mounted. The ring-shaped portion has an upright inner peripheral surface and an outer peripheral surface, and the ring-shaped portion includes an equal-thickness portion having the plate thickness, and a low inner peripheral surface portion in which the height of the inner peripheral surface is lower than the thickness of the wafer. Consists of.

(2) In the wafer support according to (1) above, the low inner peripheral surface portion has a shape in which a portion including the upper end of the inner peripheral surface of the equal thickness portion is cut out with respect to the equal thickness portion. It may be made up of.

(3) In the wafer support according to (1) above, the low inner peripheral surface portion may have an inclined surface connected to the upper end of the inner peripheral surface.

(4) In the wafer support according to any one of (1) to (3) above, the height of the outer peripheral surface of the low inner peripheral surface portion is the same as the height of the outer peripheral surface of the equal thickness portion. May be.

(5) The wafer support according to any one of (1) to (4) above may have a plurality of low inner peripheral surface portions.

(6) In the wafer support according to any one of (1) to (5) above, the support main body and the ring-shaped portion may be separate members.

(7) The chemical vapor deposition apparatus according to one aspect of the present invention includes the wafer support according to any one of (1) to (6) above.

(8) The method for manufacturing a SiC epitaxial wafer according to one aspect of the present invention is a method for manufacturing a SiC epitaxial wafer in which a SiC epitaxial film is grown on the main surface of the SiC wafer by a chemical vapor deposition method, and is concave. Using a chemical vapor deposition apparatus including a mounting plate having an accommodating portion and a wafer support according to any one of (1) to (6) arranged in the concave accommodating portion, the SiC wafer is placed. When a part of the SiC wafer is tilted diagonally and a part of the SiC wafer is applied to the ring-shaped portion of the wafer support and set on the wafer support, the ring-shaped portion to which the part hits becomes the low inner peripheral surface portion. To do so.

According to the wafer support of the present invention, defects in the epitaxial film caused by the wafer coming into contact with the wafer support can be reduced.

It is sectional drawing which shows typically the example of the chemical vapor deposition apparatus which concerns on one Embodiment of this invention. It is a top view of the mounting plate seen from the sealing side of FIG. It is a schematic diagram of an example of a wafer support according to an embodiment of the present invention, (a) is a plan view (also showing a wafer W), and (b) is an XX line of the wafer support of (a). It is a cross-sectional view (wafer W is shown by a dotted line) cut by, and (c) is also a cross-sectional view (not showing a wafer W) cut by XX line of the wafer support base of (a), (d). Is a cross-sectional view of the wafer support base of (a) cut along the YY line (the wafer W is shown by the dotted line). It is sectional drawing to explain the effect by providing the low inner peripheral surface part. It is a schematic cross-sectional view enlarged in the vicinity of the low inner peripheral surface portion, (a) is a diagram for explaining the inclined portion and the flat plate portion, and (b) is a diagram for explaining the shape of the inclined portion. , (C) is a diagram for showing the angle of the inclined surface. Both (a) and (b) are schematic cross-sectional views of an example of a wafer support according to another embodiment of the present invention. It is a schematic diagram explaining the method of setting a wafer on a wafer support stand, (a) is a schematic cross-sectional view, and (b) is a plan view. It is a candela image of a SiC epitaxial wafer when a wafer is set on a wafer support by the method shown in FIG. 7 (b). (A) is a schematic plan view for explaining a method different from FIG. 7 (b) in which the wafer is set on the wafer support, and (b) is a plan view for setting the wafer on the wafer support by the method shown in (a). It is a candela image of a SiC epitaxial wafer when it is set.

Hereinafter, the wafer support according to the embodiment to which the present invention is applied and the chemical vapor deposition apparatus provided with the wafer support will be described in detail with reference to the drawings. In addition, in the drawings used in the following explanation, in order to make the features easy to understand, the featured parts may be enlarged for convenience, and the dimensional ratios of each component may not be the same as the actual ones. No. Further, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effect is exhibited.

[Chemical vapor deposition equipment]
FIG. 1 is a cross-sectional view schematically showing an example of a chemical vapor deposition apparatus according to an embodiment of the present invention. The chemical vapor deposition apparatus of the present invention is not limited to that of FIG. 1, but the present invention will be described below based on the chemical vapor deposition apparatus of FIG. 1 for easy understanding.

The chemical vapor deposition apparatus 100 according to the embodiment of the present invention is, for example, a wafer (SiC wafer) W heated while supplying a raw material gas G into a chamber (deposition chamber) capable of decompression exhaust. A layer is deposited and grown on the surface. For example, when SiC is epitaxially grown, silane (SiH ₄ ), dichlorosilane (SiCl ₂ H ₂ ), trichlorosilane (SiCl ₃ ), silicon tetrachloride (SiCl ₄ ), or the like is used as the raw material gas G as the Si source. _{Propane (C 3} H ₈ ), ethane (C ₂ H ₆ ), ethylene (C ₂ H ₄ ) and the like can be used as the carbon (C) source. Further, as the carrier gas, a gas _{containing hydrogen (H 2} ) or the like can be used.

In the chemical vapor deposition apparatus 100, inside the chamber, a mounting plate (susceptor) 10 on which a plurality of wafers W are mounted and a mounting plate 10 so as to form a reaction space K between the mounting plates 10 It includes a sealing (top plate) 50 arranged to face the upper surface, and a peripheral wall 60 located outside the mounting plate 10 and the sealing 50 and arranged so as to surround the reaction space K.
The sealing 50 is detachably mounted in the chamber. Specifically, the sealing 50 is supported vertically upward by placing the outer peripheral portion thereof on the support portion 61 projecting from the inner peripheral surface of the peripheral wall 60.

In the chemical vapor deposition apparatus 100 shown in FIG. 1, the mounting plate (susceptor) 10 has a concave accommodating portion 11 formed on the upper surface 10a thereof, and the wafer support base (satellite) 20 on which the wafer W is directly mounted is mounted. It has a structure that is a separate member from the plate 10. The wafer support 20 may be a part of the mounting plate 10. In other words, the mounting plate 10 may be configured such that a wafer support portion on which the wafer W is placed and a ring-shaped portion 22 are formed.
When the wafer support base 20 is a part of the mounting plate 10, the wafer support base 20 includes a support base main body 21 having a wafer mounting surface 21s on which the wafer W is mounted and a wafer W. Refers to a portion including a ring-shaped portion 22 that surrounds the outer periphery of the wafer.
Only the wafer support portion is formed on the mounting plate 10 (that is, the wafer support portion is integrated with the mounting plate 10), and the ring-shaped portion 22 may be a separate member from the mounting plate 10.

When a high-frequency current is supplied to the induction coil 70 from a high-frequency power source (not shown), the mounting plate 10 and the sealing 50 are heated by high-frequency induction heating. Then, the wafer W mounted on the wafer support 20 is heated by radiation from the mounting plate 10 and the sealing 50, heat conduction from the wafer support (satellite) 20 arranged on the mounting plate 10, and the like. Can be done. The heating means is not limited to the configuration arranged on the lower surface side of the mounting plate 10 and the upper surface side of the sealing 50, and may be configured to be arranged only on one of these sides. Further, the heating means is not limited to high frequency induction heating, and resistance heating or the like may be used.

In the chemical vapor deposition apparatus 100, the raw material gas G released from the opening 31 passes through the gas introduction pipe 30 and is radially flowed from the inside to the outside of the reaction space K into the plane of the wafer W. On the other hand, it is possible to supply the raw material gas G in parallel. Gas that is no longer needed in the chamber can be discharged to the outside of the chamber from an exhaust port (not shown) provided on the outside of the peripheral wall 60.

The mounting plate 10 has a structure using a so-called planetary (self-revolution) method. The mounting plate 10 has a function as a rotary table that rotates around the rotary shaft 12 in conjunction with the rotary drive of the rotary shaft 12 using a drive motor (not shown).

The upper surface 10a of the mounting plate has a circular shape in a plan view, and a plurality of concave accommodating portions 11 are provided side by side at equal intervals in the circumferential direction (rotational direction) of the mounting plate 10. FIG. 2 is a schematic view of the mounting plate 10 of the chemical vapor deposition apparatus 100 in a plan view. An example shows a case where six concave accommodating portions 11 are provided side by side at equal intervals.

FIG. 2 is a plan view of the mounting plate 10 as seen from the sealing 50 side.
As shown in FIG. 2, the wafer support base 20 is housed in the concave accommodating portion 11 of the mounting plate 10, and the wafer W can be placed on the upper surface. The wafer support base 20 has a wafer mounting surface 21s and a ring-shaped portion 22 that stands up so as to surround the periphery of the wafer to be mounted on the side facing the sealing 50. FIG. 2 shows an example in which the wafer support base 20 is accommodated only in the two concave accommodating portions 11 of the mounting plate 10 for the sake of simplicity. In the wafer W shown in FIG. 2, the orientation flat is omitted. A counterbore may be formed on the wafer mounting surface 21s.
In the present specification, the "wafer mounting surface" is a surface including a portion actually in contact with the wafer.

The wafer support base 20 has a mechanism of being rotationally driven around the central axis by supplying a driving gas different from the raw material gas G between the lower surface thereof and the concave accommodating portion 11. Illustrated). As a result, the film can be evenly formed on the wafer W placed on the wafer support base 20.

[Wafer support]
FIG. 3 shows a schematic view of an example of a wafer support according to an embodiment of the present invention. FIG. 3A is a plan view (wafer W is also shown), and FIG. 3B is a cross-sectional view taken along the line XX of the wafer support base of FIG. 3A (wafer W is shown by a dotted line). 3 (c) is also a cross-sectional view (not showing the wafer W) of the wafer support of FIG. 3 (a) cut by XX lines, and FIG. 3 (d) is of FIG. 3 (a). It is sectional drawing (wafer W is shown by a dotted line) cut by the YY line of a wafer support base.
It should be noted that any cross section of a normal wafer support is as shown in FIG. 3 (d).

The wafer support 20 shown in FIG. 3 is a wafer support used for a chemical vapor deposition apparatus for forming a layer on a wafer, and is a support main body 21 having a wafer mounting surface 21s and a wafer to be mounted. A ring-shaped portion 22 that surrounds the outer peripheral Wc of W and has a plate thickness h equal to or greater than the thickness of the wafer is provided, and the ring-shaped portion 22 is placed on the wafer so as to face the outer peripheral Wc of the wafer W to be mounted. The ring-shaped portion 22 has an inner peripheral surface 22a rising from the surface 21s and an outer peripheral surface 22b, and the ring-shaped portion 22 has an equal-thickness portion 22A having the plate thickness h and a height h _{0 of the inner peripheral surface 22Ba (22a).} It is composed of a low inner peripheral surface portion 22B having a thickness Wt lower than that of the wafer.

Here, the "ring-shaped portion" in the wafer support of the present invention has a flat plate shape having an upper surface and a lower surface substantially parallel to each other as a typical shape when only the ring-shaped portion is extracted and considered. Although it can be considered, the shape is not limited to this, and for example, the upper surface may be a curved surface. When the upper surface is a curved surface, the "plate thickness h" refers to the thickness of the thickest portion.
Further, the "inner peripheral surface" of the "ring-shaped portion" in the wafer support of the present invention is a surface that stands up substantially perpendicular to the wafer mounting surface (that is, the "inner peripheral surface" and the wafer. The mounting surface is substantially 90 °.) On the other hand, the "outer peripheral surface" is substantially parallel to the "inner peripheral surface" as a typical configuration, but is not limited to the case where it is parallel. That is, the "outer peripheral surface" is not limited to a configuration that is a surface that stands up substantially perpendicular to the wafer mounting surface. It should be noted that the fact that the "inner peripheral surface" stands up substantially perpendicular to the wafer mounting surface may be an angle that stands up to such an extent that it exerts a function of supporting the wafer W.

In the "ring-shaped portion" of the wafer support of the present invention, the "equal thickness portion" has the same configuration as the known ring-shaped portion, and only the "low inner peripheral surface portion" is different from the known ring-shaped portion.
That is, the "ring-shaped portion" in the wafer support of the present invention includes an equal-thickness portion having the same configuration as the known ring-shaped portion, and a low inner peripheral surface portion 22B different from the known ring-shaped portion. That is, the wafer support of the present invention is different from the conventional wafer support in that the ring-shaped portion has a low inner peripheral surface portion.

The wafer support 20 shown in FIG. 3 is different from the conventional wafer support in that it is provided with a low inner peripheral surface portion 22B. The effect of providing the low inner peripheral surface portion 22B will be described with reference to FIG.
As shown in FIG. 4, when the wafer W is tilted diagonally and a part of the wafer W is applied to the ring-shaped portion and set on the wafer support base 20, the ring-shaped portion to which the part hits has a low inner circumference. When the surface portion 22B is formed, the upper end Wct of the outer peripheral Wc of the wafer W does not come into contact with the ring-shaped portion 22. As a result, it is possible to prevent the material constituting the ring-shaped portion 22 and foreign matter such as silicon carbide adhering to the ring-shaped portion 22 from being scattered on the surface Ws of the wafer W.

5 (a) to 5 (c) are enlarged views in the vicinity of the low inner peripheral surface portion 22B in order to explain the low inner peripheral surface portion 22B in detail.
As shown in FIG. 5A, the low inner peripheral surface portion 22B has an inclined surface 22Baa continuous from the inner peripheral surface 22a and has an inclined portion 22Bi (inclined portion) having a thickness equal to or less than the thickness h of the equal thickness portion 22A. The thickness of the 22Bi is h ₀ to h), and a flat plate portion 22Bo having the same thickness as the thickness h of the equal-thickness portion 22A, which is arranged on the outer peripheral side of the inclined portion 22Bi. That is, the low inner peripheral surface portion 22B includes an inclined portion 22Bi arranged on the inner peripheral side and a flat plate portion 22Bo arranged on the outer peripheral side. Note that "t" in the figure indicates the thickness of the wafer W, and is shown for convenience of indicating the magnitude relationship between _{h 0 and h.}

The shape of the low inner peripheral surface portion 22B will be described with reference to FIG. 5 (b). FIG. 5B is an enlarged view of the vicinity of the low inner peripheral surface portion 22B as in FIG. 5A, but is a diagram for explaining the difference from the equal thickness portion 22A in particular.
The low inner peripheral surface portion 22B according to the embodiment described with reference to FIGS. 3 to 5 is composed of a flat plate portion 22Bo and an inclined portion 22Bi, but the flat plate portion 22Bo is different from the shape and thickness of the equal thickness portion 22A. No.
On the other hand, the inclined portion 22Bi is indicated by the reference numeral 22cd in the portion (FIG. 5B) including the upper end 22au of the inner peripheral surface 22Ba with respect to the equal thickness portion 22A (the corresponding portion of the equal thickness portion 22A). The part) has a notched shape. Here, the "shape in which the portion including the upper end of the inner peripheral surface is cut out with respect to the equal-thickness portion" is other than the point that the "part including the upper end of the inner peripheral surface" that exists in the equal-thickness portion does not exist. Means that it has the same shape as the equal-thickness part, and does not mean the method of forming the inclined part (that is, it does not mean that it is "cut out (cut off)". ). The upper end of the inner peripheral surface 22Ba indicated by reference numeral 22au in FIG. 5B is the same as the upper end of the inner peripheral surface 22Aa of the equal-thickness portion 22A in the description of the contact at the time of setting the wafer. Therefore, the meaning of the explanation is shown by the same reference numerals in FIG. 3 (d) from the viewpoint of assistance.

Comparing the heights of the inner peripheral surface and the outer peripheral surface of the equal thickness portion 22A and the low inner peripheral surface portion 22B of the wafer support bases of the embodiments shown in FIGS. 3 to 5, the inner peripheral surface 22Ba of the low inner peripheral surface portion 22B is compared. Is lower than the height of the inner peripheral surface 22Aa of the equal-thickness portion 22A, but the height of the outer peripheral surface 22Bb of the low inner peripheral surface portion 22B is the same as the height of the outer peripheral surface 22Ab of the equal-thickness portion 22A.
When the wafer support of the embodiments shown in FIGS. 3 to 5 is used in the chemical vapor deposition apparatus shown in FIG. 1, if the height of the outer peripheral surface is the same over the entire circumference, the opening 31 When the released reaction gas G flows radially from the center side to the outside in the reaction space K, the gas flow flows stably and in parallel on the wafer W as compared with the configuration in which the heights of the outer peripheral surfaces are different. It has the advantage of being easy.

The angle of the inclined surface 22Baa (the angle with respect to the inner peripheral surface (“α” shown in FIG. 5 (c)). It can also be said to be the angle with respect to the vertical axis of the wafer mounting surface) is a part of the wafer W having a ring-shaped portion 22. It is required to be larger than the angle at which the wafer W is tilted diagonally (“β” shown in FIG. 4) when the wafer W is set on the wafer support base 20.
Therefore, the angle α of the inclined surface 22Baa is a value that should be determined depending on the angle β that is tilted when the wafer W is set on the wafer support base 20, but if it is exemplified based on the normal angle β, it is 10 It is above °.
When the angle α of the inclined surface 22Baa becomes larger than a predetermined angle depending on the height of the inner peripheral surface 22Ba, the portion corresponding to the flat plate portion 22Bo shown in FIG. 5A disappears, and the low inner peripheral surface portion The 22B is formed only by the inclined portion 22Bi. When the portion corresponding to the flat plate portion 22Bo disappears, the height of the outer peripheral surface of the low inner peripheral surface portion 22B becomes lower than the height of the outer peripheral surface of the equal thickness portion 22A. As described above, if the height of the outer peripheral surface of the ring-shaped portion is uneven, the flow of the reaction gas radiating from the center side to the outside may be disturbed. The magnitude of the effect on the quality of the epitaxial film is unknown, but from the viewpoint of suppressing such concerns as much as possible, the angle of the inclined surface 22Baa so that the height of the outer peripheral surface of the ring-shaped portion is not uneven as much as possible. An example of a preferable range for α is 10 to 45 °.
Since the preferable range of the angle α depends on the width wd of the ring-shaped portion (see FIG. 5A) and the height of the inner peripheral surface, this numerical range is a guide.

The angle α of the inclined surface 22Baa is not limited to an acute angle, and may be 90 ° or more. The upper limit of the angle α is determined by the width wd of the ring-shaped portion and the height of the inner peripheral surface.

When the angle α is 90 °, as shown in FIG. 6A, the thickness of the low inner peripheral surface portion is the same _{as the height h 0 of the inner peripheral surface.} In this case, the inclined surface 22Baa is not inclined with respect to the wafer mounting surface (that is, parallel to the wafer mounting surface), and the only difference from the equal thickness portion 22A is the thickness. In other words, when the angle α is 90 °, the ring-shaped portion of the wafer support is composed of the equal-thickness portion 22A and the low inner peripheral surface portion 22B which is thinner than the equal-thickness portion 22A. Note that "t" in the figure indicates the thickness of the wafer W, as in FIG.

The case where the angle α exceeds 90 ° is shown in FIG. 6 (b).

In the embodiments shown in FIGS. 3 to 6, as the shape of the low inner peripheral surface portion, a shape having an inclined surface capable of defining an inclined angle is shown, but the shape is not limited to this shape. The surface corresponding to the inclined surface may be a concave surface or a convex surface.
In the present invention, the ring-shaped portion of the wafer support is configured so that the upper end of the outer periphery of the wafer W does not come into contact with the ring-shaped portion when the wafer W is set on the wafer support, so that foreign matter is present on the main surface of the wafer W. It is a technical idea to prevent the wafer from being scattered. Therefore, the shape of the low inner peripheral surface portion is such that the upper end of the outer periphery of the wafer W does not contact the ring-shaped portion on the premise that the height of the inner peripheral surface of the low inner peripheral surface portion is lower than the thickness of the wafer W. For example, the shape is not particularly limited.

Further, in the embodiments shown in FIGS. 3 to 6, the plurality of equal-thickness portions 22A and the plurality of low inner peripheral surface portions 22B each have the same configuration, but may not have the same configuration.

_{The height h 0} of the inner peripheral surface of the low inner peripheral surface portion is lower than the thickness t of the wafer. The preferable range of the height h ₀ of the inner peripheral surface depends on the thickness t of the wafer. For example, the height h ₀ of the inner peripheral surface of the low inner peripheral surface portion is 1/3 to 2/2 / of the thickness t of the wafer. It is preferably 3.
Since the thickness of the wafer currently used is usually 300 to 540 μm, in this case, _{the preferable range of the height h 0} of the inner peripheral surface of the low inner peripheral surface portion is 100 to 360 μm.

The wafer support base 20 shown in FIGS. 3 to 6 is a member separate from the support base main body 21 and the ring-shaped portion 22, but may be an integral member.
The wafer support base 20 shown in FIGS. 3 to 6 has six low inner peripheral surface portions 22B, but if there is even one, the effect of the present invention is exhibited, and the number is not limited.
In the wafer support base 20 shown in FIGS. 3 to 6, the equal-thickness portions 22A and the low inner peripheral surface portions 22B are arranged symmetrically with respect to the central axis at equal intervals on the circumference, but the configurations are evenly spaced. It is not limited to, and may be arranged asymmetrically with respect to the central axis.

"Manufacturing method of SiC epitaxial wafer"
The method for manufacturing a SiC epitaxial wafer according to an embodiment of the present invention is a method for manufacturing a SiC epitaxial wafer in which a SiC epitaxial film is grown on the main surface of the SiC wafer by a chemical vapor deposition method, and is a concave accommodating portion. Using a chemical vapor deposition apparatus provided with a mounting plate having a When the wafer support is set against the ring-shaped portion of the table, the portion of the ring-shaped portion to which the partial portion hits becomes the low inner peripheral surface portion.

In the method for manufacturing a SiC epitaxial wafer according to the present embodiment, a known process can be used except for the above-mentioned setting process of the SiC wafer (SiC substrate) by using the wafer support of the present invention.

20 Wafer support (satellite)
21 Support base body 22 Ring-shaped part 22A Equal thickness part 22B Low inner peripheral surface part 22a Inner peripheral surface (Matching the inner peripheral surface of the equal thickness part and the inner peripheral surface of the low inner peripheral surface part)
22Aa Inner peripheral surface of the equal thickness part 22Ba Inner peripheral surface of the low inner peripheral surface 22b Outer peripheral surface (combining the outer peripheral surface of the equal thickness part and the outer peripheral surface of the low inner peripheral surface portion)
22Ab Outer peripheral surface of equal thickness 22Bb Outer peripheral surface of low inner peripheral surface 21s Wafer mounting surface 100 Chemical vapor deposition device W wafer

Claims (9)

A wafer support used in a chemical vapor deposition device that forms a layer on a wafer.
A support base body having a wafer mounting surface and a ring-shaped portion surrounding the outer periphery of the wafer to be mounted and having a plate thickness equal to or larger than the thickness of the wafer are provided.
The ring-shaped portion has an inner peripheral surface that rises from the wafer mounting surface so as to face the outer periphery of the wafer to be mounted, and an outer peripheral surface.
The ring-shaped portion is composed of an equal-thickness portion having the plate thickness and a low inner peripheral surface portion in which the height of the inner peripheral surface is lower than the thickness of the wafer.
The height of the inner peripheral surface of the low inner peripheral surface portion is 1/3 to 2/3 of the thickness of the wafer on which the wafer is placed. The wafer support according to claim 1, wherein the low inner peripheral surface portion has a shape in which a portion including the upper end of the inner peripheral surface of the equal thickness portion is cut out from the equal thickness portion. The wafer support according to claim 1, wherein the low inner peripheral surface portion has an inclined surface connected to the upper end of the inner peripheral surface. The wafer support according to any one of claims 1 to 3, wherein the height of the outer peripheral surface of the low inner peripheral surface portion is the same as the height of the outer peripheral surface of the equal-thickness portion. The wafer support according to any one of claims 1 to 4, which has a plurality of low inner peripheral surface portions. Wherein a pedestal body and separate member and the ring-shaped portion, the wafer support table according to any one of claims 1 to 5. The wafer support according to claim 3, wherein the angle of the inclined surface with respect to the inner peripheral surface is 10 ° or more and 45 ° or less. A chemical vapor deposition apparatus comprising the wafer support according to any one of claims 1 to 7. A method for manufacturing a SiC epitaxial wafer in which a SiC epitaxial film is grown on the main surface of the SiC wafer by a chemical vapor deposition method.
Using a chemical vapor deposition apparatus including a mounting plate having a concave accommodating portion and a wafer support according to any one of claims 1 to 7 arranged in the concave accommodating portion, the chemical vapor deposition apparatus is used.
When the SiC wafer is tilted diagonally and a part of the SiC wafer is applied to the ring-shaped portion of the wafer support and set on the wafer support, the ring-shaped portion to which the part hits is in the low position. A method for manufacturing a SiC epitaxial wafer so that it becomes a peripheral surface portion.

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