JP2021190547A - Susceptor, chemical vapor deposition device, and manufacturing method for epitaxial wafer - Google Patents

Abstract

To provide a susceptor capable of performing positioning with high accuracy.SOLUTION: A susceptor includes a base including a wafer mounting portion on which a wafer for forming an epitaxial film by vapor phase growth is mounted, and a convex portion formed in the center of a surface opposite to the surface of the base including the wafer mounting portion, and at least three notches are provided on the side surface of the convex portion.SELECTED DRAWING: Figure 1

Description

The present invention relates to a susceptor, a chemical vapor deposition apparatus using the susceptor, and a method for manufacturing an 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 SiC 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 wafer (SiC substrate). The SiC wafer 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) apparatus.

As an example of such a CVD device, a device having a susceptor that rotates about a rotation axis is known. By rotating the SiC wafer placed on the susceptor, the gas supply state in the in-plane direction can be made uniform, and a uniform SiC epitaxial film can be formed on the SiC wafer. The SiC wafer is conveyed inside the CVD apparatus and placed on the susceptor using a manual or automatic transfer mechanism. The susceptor on which the SiC wafer is placed is heated from the back surface, and the reaction gas is supplied from above to the surface of the SiC wafer to form a film.

For example, in Patent Document 1, a SiC wafer is placed on a susceptor (wafer support) outside the film formation space, and then the susceptor on which the SiC wafer is installed is conveyed to the film formation space to carry a SiC epitaxial film. A chemical vapor deposition apparatus configured to form a film is described. In the chemical vapor deposition apparatus described in Patent Document 1, an arm is used as a means for transporting a susceptor.

Japanese Unexamined Patent Publication No. 2017-117850

With the recent miniaturization and high density of semiconductor devices, it is desired to further improve the uniformity of the film thickness with respect to the SiC epitaxial wafer. However, as described in Patent Document 1, in a chemical vapor deposition apparatus configured to transport a susceptor on which a SiC wafer is installed to a film forming space to form a SiC epitaxial film. The position of the susceptor placed in the film formation space may be slightly displaced. Then, due to this slight misalignment of the susceptor, the film thickness of the SiC epitaxial film formed on the SiC wafer may become non-uniform.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a susceptor capable of performing positioning with high accuracy, a chemical vapor deposition apparatus using the susceptor, and a method for manufacturing an epitaxial wafer. To do.

In order to solve the above problems, the present inventors have formed a convex portion in the center of the surface opposite to the surface on which the SiC wafer of the susceptor is placed, and at least on the side surface of the convex portion. The present invention has been completed by finding that the susceptor can be positioned accurately and accurately by providing three notches and inserting protrusions into each of the notches to fix the susceptor.
That is, the present invention provides the following means for solving the above-mentioned problems.

[1] Formed in the center of a base having a wafer mounting portion on which a wafer for forming an epitaxial film is formed by vapor phase growth and a surface of the base opposite to the surface having the wafer mounting portion. A susceptor having a convex portion and at least three notches on the side surface of the convex portion.

[2] The susceptor according to the above [1], wherein the convex portion is a cylinder or a cylinder, and the center of the cylinder or the cylinder is on the center line of the wafer mounting portion.

[3] The susceptor according to the above [1] or [2], wherein the notches are arranged at equal intervals.

[4] A furnace body provided with a susceptor positioning device, a support column for detachably supporting the susceptor, and the susceptor arranged at a predetermined position by the susceptor positioning device are mounted on the furnace body. The susceptor is the susceptor according to any one of the above [1] to [3], and the positioning device for the susceptor is the notch of the susceptor. A chemical vapor deposition apparatus that determines the position of the susceptor by inserting protrusions into each.

[5] A method for manufacturing an epitaxial wafer in which a wafer is conveyed to a film forming space and an epitaxial film is formed on the wafer in the film forming space, and any one of the above [1] to [3]. In the positioning step of arranging the susceptor in a predetermined position by inserting a protrusion into each of the notches of the susceptor according to the above, and in the wafer mounting portion of the susceptor arranged in the predetermined position, the wafer is placed. A mounting step of mounting, a transporting step of transporting the susceptor on which the wafer is mounted to the film forming space, and a formation of an epitaxial film on the wafer mounted on the transported susceptor. A method for manufacturing an epitaxial wafer having a film process.

According to the present invention, it is possible to provide a susceptor capable of performing positioning with high accuracy, a chemical vapor deposition apparatus using the susceptor, and a method for manufacturing an epitaxial wafer.

(A) is a schematic cross-sectional view of a susceptor according to the first embodiment of the present invention, and (b) is a schematic bottom view of the susceptor. It is a conceptual diagram which shows the structure of the chemical vapor deposition apparatus which concerns on 2nd Embodiment of this invention. (A) is a schematic cross-sectional view of a susceptor positioning chamber used in the chemical vapor deposition apparatus shown in FIG. 2, and (b) is a sectional view taken along line bb of (a). It is a perspective view of an example of a protrusion which can be advantageously used in a susceptor positioning chamber. It is a schematic sectional view of the furnace body used in the chemical vapor deposition apparatus shown in FIG.

Hereinafter, a method for manufacturing a susceptor, a chemical vapor deposition apparatus, and an epitaxial wafer according to an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of each component may differ from the actual ones. be. The materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and the present invention can be appropriately modified without changing the gist thereof.

<First embodiment (susceptor)>
1A and 1B are schematic views illustrating a configuration of a susceptor according to a first embodiment of the present invention, FIG. 1A is a cross-sectional view of the susceptor, and FIG. 1B is a bottom view of the susceptor.
As shown in FIG. 1, the susceptor 10 includes a base 11 including a wafer mounting portion 12 on which a SiC wafer W for forming a SiC epitaxial film by vapor phase growth is mounted, and a wafer mounting portion 12. It has a convex portion 13 provided in the center of the surface opposite to the surface.

The base 11 of the susceptor 10 has a disk shape.
The wafer mounting portion 12 is provided in the center of the base portion 11. The wafer mounting portion 12 has a shape that is lowered with respect to the surface of the base portion 11 in order to prevent the position of the SiC wafer W from shifting. _{The diameter φ y} of the wafer mounting portion 12 is preferably in the range of 50% or more and 80% or less with respect to the diameter φ _{x of the base portion 11.}

The convex portion 13 is a cylindrical body. The center of the convex portion 13 is above the center line C of the wafer mounting portion 12. The convex portion 13 has a flat bottom surface. By arranging the bottom surface of the convex portion 13 on a plane, the susceptor 10 can stand on its own. In order to stably self susceptor 10, the diameter phi _x of the base 11, the outer diameter phi _z diameter phi _y and the convex portion 13 of the wafer placing portion 12 has a diameter phi _y <outer diameter phi _z <diameter phi _x It is preferable that (diameter φ _x − outer diameter φ _z ) / (outer diameter φ _z − diameter φ _y ) is in the range of 0.5 or more and 50 or less. _{The height h z} of the convex portion 13 is preferably in the range of 10% or more and 50% or less with respect to the height of the entire susceptor 10 h _x. The thickness t of the convex portion 13 is preferably in the range of 1 mm or more and 10 mm or less.

Three notches 14 are provided on the side surface of the convex portion 13 along the circumferential direction. The three notches 14 are arranged at equal intervals. By inserting a protrusion into each of the three notches 14, the susceptor 10 can be fixed so as not to move. The size of the notch 14 is not particularly limited as long as it does not reduce the strength of the convex portion 13. From the viewpoint of not reducing the strength of the convex portion 13, the size of the width a (length in the circumferential direction of the convex portion 13) of the notch 14 is within the range of 1% or more and 5% or less of the outer peripheral length of the convex portion 13. It is preferable to have. The height h _w of the notch 14 is preferably in the range of 20% or more and 50% or less of _{the height h z} of the convex portion 13. The depth d of the notch 14 is preferably in the range of 20% or more and 50% or less of the thickness t of the convex portion 13.

As the material of the susceptor 10, for example, ceramics such as SiC and metals such as Ta, Mo and W can be used. Further, in addition to the solid wood such as ceramics and metal, a composite material in which the surface of the carbon material is coated with a carbonized metal such as SiC or TaC can be used.

According to the susceptor 10 according to the present embodiment having the above configuration, the susceptor 10 cannot be moved by inserting a protrusion into each of the three notches 14 provided on the side surface of the convex portion 13. Since it can be fixed at a desired position, the position of the susceptor 10 can be determined relatively easily and accurately.

In the susceptor 10 of the present embodiment, the convex portion 13 is a cylindrical body, but the shape of the convex portion 13 is not limited to this. For example, the shape of the convex portion 13 may be a cylinder, a polygonal prism (for example, a triangular prism or a quadrangular prism), or a polygonal cylinder (for example, a triangular prism or a quadrangular prism). However, it is preferable that the convex portion 13 has a circular outer circumference in a plan view. That is, the convex portion 13 is preferably a cylinder or a cylinder.

Further, in the susceptor 10 of the present embodiment, the number of notches 14 provided on the side surface of the convex portion 13 is set to three, but the number is not limited to three. The number of notches 14 is not particularly limited as long as it is three or more. However, if the number of notches 14 becomes too large, the strength of the convex portions 13 may decrease. Therefore, the number of notches 14 is preferably 8 or less, and particularly preferably 6 or less.

Further, in the susceptor 10 of the present embodiment, the three notches 14 are arranged at equal intervals, but the notches 14 do not have to be at equal intervals as long as the susceptors 10 can be fixed so as not to move. ..

Further, in the susceptor 10 of the present embodiment, the bottom surface of the convex portion 13 is flat, and the susceptor 10 can stand on its own, but the present invention is not limited to this. For example, the susceptor 10 may be fixed and the position may be determined by inserting a protrusion into each of the notches 14 while the susceptor 10 is supported by the support.

<Second embodiment (chemical vapor deposition apparatus)>
Next, the chemical vapor deposition apparatus according to the second embodiment of the present invention will be described.
FIG. 2 is a conceptual diagram showing a configuration of a chemical vapor deposition apparatus according to an embodiment of the present invention. 3A and 3B are drawings illustrating a susceptor positioning chamber of the chemical vapor deposition apparatus shown in FIG. 2, where FIG. 3A is a schematic cross-sectional view and FIG. 3B is a sectional view taken along line bb of FIG. 2A. be. FIG. 4 is a perspective view of an example of a protrusion that can be advantageously used in a susceptor positioning chamber. FIG. 5 is a schematic cross-sectional view of the furnace body of the chemical vapor deposition apparatus shown in FIG.

As shown in FIG. 2, the chemical vapor deposition apparatus 100 has a preparation chamber 20, a susceptor positioning chamber 30 connected to the preparation chamber 20, and a furnace body 40.
The preparation room 20 forms a transport space P. The preparation room 20 has an arm 21. The arm 21 functions as a transport means for transporting the susceptor 10 on which the SiC wafer is placed between the preparation chamber 20 and the susceptor positioning chamber 30 or between the preparation chamber 20 and the furnace body 40. The tip portion 21a of the arm 21 is U-shaped (stab-shaped), and the lower portion of the susceptor 10 is supported by sandwiching the convex portion 13 of the susceptor 10 with the U-shaped tip portion 21a to convey the susceptor 10. do.

As shown in FIG. 3, the susceptor positioning chamber 30 is provided with a positioning device 31. The positioning device 31 has a pedestal portion 32 on which the susceptor 10 is arranged, and a protrusion 33 provided on the pedestal portion 32 that can move in the longitudinal direction. The positioning device 31 fixes the susceptor 10 so as not to move by inserting a protrusion 33 into each of the notches 14 provided on the side surface of the convex portion 13 of the susceptor 10 arranged on the pedestal portion 32. Thereby, the position of the susceptor 10 is determined.

The shape of the protrusion 33 is not particularly limited as long as it can be inserted into the notch 14 of the susceptor 10. As the shape of the protrusion 33, as shown in FIG. 4A, the tip is a triangular prism, and as shown in FIG. 4B, the triangular prism is formed so that the lower part of the tip protrudes. It is possible to use a shape that is tilted diagonally. Further, as shown in FIG. 4 (c), a triangular columnar shape whose tip is cut at a corner can be used. Further, as shown in FIG. 4D, it is possible to use a triangular prism having a shape in which a triangular prism with a cut corner is inclined so that the lower part of the tip protrudes.

The susceptor positioning chamber 30 is provided with a wafer mounting device (not shown) for mounting the SiC wafer W on the wafer mounting portion 12 of the susceptor 10, and the wafer mounting portion is provided in the susceptor positioning chamber 30. The SiC wafer W can be placed on the twelve. The step of mounting the SiC wafer W on the wafer mounting portion 12 is preferably performed after the positioning of the susceptor 10 is performed.

The furnace body 40 forms a film forming space R. The film formation space R has a high temperature of about 1600 ° C. at the time of film formation.

Inside the furnace body 40, a susceptor holding portion 41 for detachably holding the susceptor 10 on which the SiC wafer W is placed is provided. The susceptor holding portion 41 includes an installation portion 42 in which the susceptor 10 is arranged, and a support column 43 that supports the installation portion 42. The column 43 is rotatable. Further, a gas supply pipe, a heater and the like (not shown) are installed inside the furnace body 40. The gas supply pipe supplies a gas such as a raw material gas, a carrier gas, and an etching gas to the film forming space R. The heater heats the inside of the film forming space R.

The furnace body 40 and the preparation room 20 are separated by a shutter 50. When the susceptor 10 is transported to the film forming space R, the shutter 50 is kept open, and the shutter 50 is closed except when the susceptor 10 is transported (particularly during film forming). By closing the shutter 50, it is possible to prevent gas and heat during film formation from flowing out from the film formation space R, and to stabilize the environment of the film formation space R. Uniformity is improved.

According to the chemical vapor deposition apparatus 100 according to the present embodiment having the above configuration, the susceptor is formed by using the three notches 14 and the protrusions 33 provided on the side surface of the convex portion 13 of the susceptor 10. Since the 10 can be fixed so as not to move, the position of the susceptor 10 can be accurately determined. Therefore, by using the chemical vapor deposition apparatus 100 of the present embodiment, the susceptor 10 can be arranged on a predetermined installation portion 42 of the furnace body 40, whereby the susceptor 10 can be arranged. A SiC epitaxial film can be uniformly formed on the surface of the SiC wafer W mounted on the wafer mounting portion 12.

Further, in the chemical vapor deposition apparatus 100 of the present embodiment, the susceptor positioning chamber 30 is provided with a wafer mounting device (not shown), and the SiC wafer is placed on the wafer mounting portion 12 in the susceptor positioning chamber 30. W can be placed, but it is not limited to this. The step of mounting the SiC wafer W on the wafer mounting portion 12 may be performed at a place other than the susceptor positioning chamber 30.

<Third Embodiment (Manufacturing method of epitaxial wafer>
Next, the method for manufacturing an epitaxial wafer according to the third embodiment of the present invention will be described by taking as an example the case where the above chemical vapor deposition apparatus 100 is used.
In the method for manufacturing an epitaxial wafer of the present embodiment, first, the susceptor 10 is first arranged on the pedestal portion 32 of the positioning device 31 provided in the susceptor positioning chamber 30.

Next, the protrusion 33 of the susceptor positioning chamber 30 is inserted into each of the notches 14 of the susceptor 10. As a result, the susceptor 10 on which the SiC wafer W is placed is placed at a predetermined position (positioning step). Then, the SiC wafer W is mounted on the wafer mounting portion 12 of the susceptor 10 arranged on the pedestal portion 32 (mounting step).

Next, the susceptor 10 arranged at a predetermined position is conveyed from the susceptor positioning chamber 30 to the preparation chamber 20 by the arm 21, and then, in the preparation chamber 20, the moving direction of the arm 21 is changed to rotate the susceptor 10 into a furnace. It is transported onto the installation portion 42 of the body 40 (transportation process). At this time, the shutter 50 that partitions between the furnace body 40 and the preparation chamber 20 is opened. The susceptor 10 is arranged on the installation portion 42 of the furnace body 40, the arm 21 is returned to the preparation chamber 20, and then the shutter 50 is closed.

When the shutter 50 is closed, the formation of the SiC epitaxial film is started (deposition step). Specifically, a heater (not shown) heats the inside of the film forming space R of the furnace body 40, and a gas supply pipe (not shown) forms gas such as raw material gas, carrier gas, and etching gas. Supply to the membrane space R. In the film formation space R, the SiC epitaxial film is formed by bringing the raw material gas decomposed by heating into contact with the SiC wafer W placed on the susceptor 10 while rotating the susceptor 10 together with the installation portion 42 around the support column 43. Is formed into a film to obtain a SiC epitaxial wafer.

The obtained SiC epitaxial wafer is conveyed from the furnace body 40 to the preparation chamber 20 by the arm 21 together with the susceptor 10. Then, the SiC epitaxial wafer is recovered from the conveyed susceptor 10.

According to the method for manufacturing an epitaxial wafer according to the present embodiment having the above configuration, the susceptor 10 arranged at a predetermined position in the positioning step is installed in the furnace body 40 via the preparation chamber 20. Since the susceptor 10 is conveyed on the 42, the susceptor 10 can be accurately and accurately placed on the installation portion 42, and the placement position of the susceptor 10 can be kept constant. Therefore, by using the method for manufacturing an epitaxial wafer of the present embodiment, it is possible to uniformly form a SiC epitaxial film on the surface of the SiC wafer W.

The method for manufacturing an epitaxial wafer of the present embodiment has been described by taking the case where the above-mentioned chemical vapor deposition apparatus 100 is used as an example, but the method for producing an epitaxial wafer of the present embodiment is other than the above-mentioned chemical vapor deposition apparatus 100. It can be carried out using the device of.

For example, the chemical vapor deposition apparatus 100 has a configuration having a susceptor positioning chamber 30 provided with the positioning apparatus 31, but the arrangement position of the positioning apparatus 31 is not limited to this. For example, the positioning device 31 may be arranged in the preparation room 20.

Further, in the present embodiment, the SiC epitaxial wafer is manufactured as the epitaxial wafer, but the method for manufacturing the epitaxial wafer of the present embodiment can also be used when manufacturing an epitaxial wafer other than the SiC epitaxial wafer.

10 Suceptor 11 Base 12 Wafer mounting 13 Convex 14 Notch 20 Preparation chamber 21 Arm 21a Tip 30 Suceptor positioning chamber 31 Positioning device 32 Pedestal 33 Protrusion 40 Furnace 41 Suceptor holding 42 Installation 43 Support 50 Shutter 100 Chemical vapor deposition equipment

Claims (5)

A base including a wafer mounting portion on which a wafer for forming an epitaxial film by vapor phase growth is mounted, and a base.
It has a surface of the base having the wafer mounting portion and a convex portion formed in the center of the surface opposite to the surface.
A susceptor provided with at least three notches on the side surface of the convex portion. The susceptor according to claim 1, wherein the convex portion is a cylinder or a cylinder, and the center of the cylinder or the cylinder is on the center line of the wafer mounting portion. The susceptor according to claim 1 or 2, wherein the notches are arranged at equal intervals. The susceptor positioning device and
A furnace body provided with a support column for detachably supporting the susceptor, and
It has a transport means for arranging the susceptor arranged at a predetermined position in the susceptor positioning device on the support column of the furnace body.
The susceptor is the susceptor according to any one of claims 1 to 3.
The susceptor positioning device is a chemical vapor deposition device that determines the position of the susceptor by inserting a protrusion into each of the notches of the susceptor. A method for manufacturing an epitaxial wafer in which a wafer is conveyed to a film forming space and an epitaxial film is formed on the wafer in the film forming space.
A positioning step of arranging the susceptor in a predetermined position by inserting a protrusion into each of the notches of the susceptor according to any one of claims 1 to 3.
A mounting step of mounting the wafer on the wafer mounting portion of the susceptor arranged at a predetermined position, and a mounting step of mounting the wafer.
A transfer step of transporting the susceptor on which the wafer is placed to the film forming space, and
A method for manufacturing an epitaxial wafer, which comprises a film forming step of forming an epitaxial film on the wafer placed on the conveyed susceptor.

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