JP2000016870A - Chemical vapor deposition silicon carbide tabularly formed product and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical vapor deposition silicon carbide tabularly formed products that is a thin membrane with reduced warpage. SOLUTION: The main face of the susceptor 10 that is a chemical vapor deposition silicon carbide tabularly formed product is a plurality of small approximately quadrangle areas divided by rib grooves 12a and 12b. Further, the individual small approximately quadrangle areas have each substantially X- shaped rib grooves along the two diagonal lines. These rib grooves 12C presumably works as a reinforcing material to the strain stress, the susceptcr only undergoes reduced warpage, even when it is made a thin film in the process for producing the susceptor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-shaped body of chemical vapor deposition silicon carbide and a method of manufacturing the same, and more particularly, to a plate-shaped body of chemical vapor deposition silicon carbide having less warpage and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device, a thermal oxide film or a thermal nitride film may be formed by rapid thermal processing (RTP). In such rapid heat treatment, rapid temperature rise and rapid cooling of the wafer are required. Therefore, in the rapid heat treatment, it is preferable that the heat capacity of the susceptor on which the wafer is mounted and the peripheral components thereof be as small as possible.

[0003] Therefore, members such as a susceptor used for rapid heat treatment include chemical vapor deposition (CVD).
or a plate-shaped silicon carbide formed body (hereinafter referred to as a “chemical vapor deposition silicon carbide (CVD-SiC) plate-shaped formed body”) formed by the (deposition) method. . From the viewpoint of reducing the heat capacity, such a CVD-SiC plate-shaped molded product has a thickness of, for example, 1 mm.
It is preferable that the thickness be as thin as possible.

[0004]

Generally, CVD-SiC
The plate-shaped molded body is formed on a molded graphite substrate by CVD.
After the C film is formed, the SiC film is processed, and the graphite substrate is burned and removed (ashed). Of these processes, in the graphite incineration process, the CVD-SiC plate-like molded product often warps due to the difference in the coefficient of thermal expansion (CTE) between graphite and silicon carbide. The amount of warpage has the characteristic that it increases as the CVD-SiC plate-like molded product becomes thinner.

[0005] However, if the warpage of the CVD-SiC plate-like molded body becomes large, when such a molded body is used, for example, as a susceptor for rapid heat treatment, the heat distribution of the wafer is deteriorated. For example, there is a problem that a thermal oxide film or a thermal nitride film having desired characteristics cannot be formed.

That is, when a CVD-SiC plate-like molded product is to be used as a susceptor for rapid heat treatment, for example,
Both the thickness and the amount of warpage are required to be small, but the amount of warpage and the thickness of the CVD-SiC plate-shaped body are in a reciprocal relationship, and the smaller the thickness of the CVD-SiC plate-shaped body, the larger the amount of warpage. In order to reduce the amount of warpage, the thickness has to be increased, and it has not been possible to obtain a CVD-SiC plate-like compact having both a small thickness and a small amount of warpage.

It is an object of the present invention to provide a chemical vapor deposited silicon carbide sheet compact having a small amount of warpage even when formed into a thin film, and a method for producing the same.

[0008]

In order to achieve the above object, a plate-shaped chemical vapor deposited silicon carbide article according to claim 1 is provided.
A straight line connecting two points selected so as to maximize a distance between two points on an outer peripheral line of the small area in at least one of the one or more small areas constituting the main surface; A step portion having a substantially X shape along a straight line intersecting the straight line, that is, a shape in which two line segments intersect is provided.

[0009] The chemical vapor deposition silicon carbide plate-like formed body thus configured has a small amount of warpage even when the thickness is reduced. The reason is that the chemical vapor deposition silicon carbide plate-like molded body is drawn on a straight line connecting two points selected so as to maximize the distance between the two points on the outer peripheral line of a certain small area of the main surface of the molded body. Although the strain stress caused by heat in the incineration process of graphite in the manufacturing process of the above greatly acts, the formation of a substantially X-shaped step along this straight line and a straight line that intersects this straight line, This is presumed to be because the phase-deposited silicon carbide plate-like molded product is reinforced and hardly warps. Therefore, when the chemical vapor deposition silicon carbide plate-like molded article of claim 1 is used as, for example, a susceptor for rapid heat treatment, a thermal oxide film or a thermal nitride film having desired characteristics can be obtained.

In the present specification, the cross-sectional shape of the “step” is a concave shape or a convex shape, a rib groove shape that is a concave portion on one main surface side and a convex portion on the other main surface side, or It may have any other shape, and its size (width, height, etc.) is preferably selected as appropriate. In the present specification, the shape of the “small region” may be any shape other than a triangle, a square, and the like. The “small areas” are separated from each other by other steps and openings other than the X-shaped steps, in addition to the outer peripheral end of the molded body, but each small area is not necessarily other It is not necessary to be separated from each other by a step portion or the like, and each small region may be provided so as to be continuously connected.

[0011] Further, in the plate-shaped body of chemical vapor deposition silicon carbide according to claim 2, the at least one small region is substantially quadrangular, and the substantially X-shaped. The step portion of the mold is provided along two diagonal lines of the rectangular small area. According to this, it is possible to effectively suppress the warpage particularly in a small rectangular area.

[0012] In the third aspect of the present invention, the area of the chemical vapor deposition silicon carbide plate-shaped compact has the largest area in at least one of the one or more small areas constituting the main surface. A substantially X-shaped step along two diagonals of the rectangle is provided in the rectangle imagined as follows.

A third aspect of the present invention expresses the invention of the first aspect from another viewpoint. In particular, the small areas provided on the main surface of the molded body are not separated from each other but are provided continuously with each other. In this case, it shows how a substantially X-shaped step is provided on the main surface of the molded body. In the third aspect of the present invention, similarly to the first aspect, even if the thickness is reduced, the amount of warpage is small. It is inferred that the reason is the same as in claim 1.

According to a fourth aspect of the present invention, there is provided a method for producing a plate-shaped body made of chemical vapor deposited silicon carbide.
In at least one of the small regions, a straight line connecting two points selected so as to maximize the distance between the two points on the outer peripheral line of the small region and a straight line intersecting the straight line Providing a substantially X-shaped step along the graphite substrate, forming a silicon carbide layer on the graphite substrate by a chemical vapor deposition method, and machining the silicon carbide layer by machining. A step of selectively removing and exposing a part of the graphite base; and a step of burning and removing the graphite base.

[0015] According to the method of manufacturing a plate-like molded article of chemical vapor deposition silicon carbide according to claim 4, substantially corresponds to a step portion of a substantially X-shape provided on the plate-shaped molded article of chemical vapor deposition silicon carbide. By providing the step having the above-mentioned shape on the graphite base material in advance, it is possible to obtain a chemical vapor deposited silicon carbide plate-like compact having both a small thickness and a small amount of warpage by a relatively simple process.

According to a fifth aspect of the present invention, in the method of manufacturing a plate-shaped body of chemical vapor deposition silicon carbide according to the fourth aspect, the at least one small region is approximately square, The X-shaped step portion is provided along two diagonal lines of the rectangular small area. According to this, it is possible to obtain a chemical vapor deposition silicon carbide plate-like molded product in which the warpage particularly in a small rectangular region is effectively suppressed by a relatively simple process.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a plate-shaped compact made of chemical vapor deposited silicon carbide.
Within at least one of the above-described small regions, a substantially X-shape along two diagonal lines of the rectangular portion is provided in a rectangular portion imagined to have the largest area in the small region. Providing a mold step on the graphite substrate,
Forming a silicon carbide layer on the graphite substrate by a chemical vapor deposition method, and selectively removing the silicon carbide layer by machining to expose a part of the graphite substrate; and Burning the substrate.

According to the method for producing a plate-shaped molded article of chemical vapor deposited silicon carbide of claim 6, a plate-shaped molded article of chemical vapor deposited silicon carbide having both a small thickness and a small amount of warp is compared. It can be obtained by a simple process.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 (a), 1 (b) and 1 (c) are views for explaining the structure of a susceptor which is a plate-shaped chemical vapor deposited silicon carbide according to a first embodiment of the present invention. FIG. 1A is a plan view showing one main surface of a susceptor,
FIG. 1 (b) is a partially enlarged view thereof, and FIG. 1 (c) is FIG. 1 (b).
3 is a sectional view taken along line Ic-Ic. Disc-shaped susceptor 1
Numeral 0 is a plate-shaped formed body of chemical vapor deposition silicon carbide having a diameter of 300 mm and a film thickness of 1 mm. As shown in FIGS. 11 and many rib grooves 12a, 12b, 12c, 12d. The rib groove 12a is provided concentrically with the outer peripheral circle of the susceptor 10. The rib groove 12b is used for the susceptor 1
It is provided radially from the center point of zero. The rib groove 12c is formed of two adjacent rib grooves 12a (or one rib groove 12a and the outer peripheral projection 11) and two adjacent rib grooves 12b (or one rib groove 12b and one rib groove 12b). It is provided substantially in an X shape along two diagonal lines of an approximate square surrounded by the rib grooves 12d). Also, almost U
The U-shaped rib groove 12 d surrounds the center of the susceptor 10 and extends to the outer circumference of the susceptor 10.

In other words, the main surface of the susceptor 10 has a large number of approximately quadrangular small areas separated by the rib grooves 12a, 12b, 12d and the outer peripheral convex portion 11, and the rib groove 12c has a rectangular shape. It is provided substantially in an X shape along two diagonal lines of each small area.

As shown in FIG. 1 (c), the cross-sectional shape of the rib groove 12c is convex on the main surface on the side shown in FIG. 1 (a) and concave on the other main surface on the back side. It is. Further, the cross-sectional shapes of the rib grooves 12a, 12b, and 12d are similar to the rib groove 12c. The outer width W of the rib groove 12a is 5 m
and the height H is about 3 mm. The rib groove 12
The outer width of b, 12c and 12d is about 5 mm and the height is about 3 mm.

Next, a method of manufacturing the susceptor 10 will be described with reference to FIG. In order to manufacture the susceptor 10 as shown in FIG.
In 1, the graphite base material having a bulk density of 1.80 g / cm ³ is processed so that the outer shape is substantially the same as the susceptor 10 of FIG. 1A (φ320 mm × thickness 10 mm). At this time, the rib grooves 12a, 12b, 12d and the outer peripheral convex portion 11
In addition to providing a convex portion which is slightly thinner than these, a substantially X-shaped convex portion which corresponds to the rib groove 12c and is slightly thinner than this is also provided.

Thereafter, in step S2, the graphite substrate obtained in step S1 is placed in a CVD furnace, and the bulk density is 3.21 g / cm ³ on the graphite substrate by a chemical vapor deposition (CVD) method. , Silicon carbide having a thickness of about 1 mm (C
(VD-SiC) film is formed. At this time, the film forming conditions by the CVD method include SiH ₄ and C ₃ H ₈ as source gases,
H ₂ was used as a carrier gas, and the reaction temperature was 1
At 400 ° C., the pressure in the apparatus is 10 kPa, and the reaction time is about 3 hours. Next, in step S3, the CVD-SiC film is selectively removed by mechanical processing, for example, by providing an opening to expose a part of the graphite base material. This step is necessary for burning and removing the graphite substrate in the next step.

Next, in step S4, step S
The CVD-SiC film-formed graphite substrate obtained in 2 to S3 is heated to about 800 ° C. in an oxidizing atmosphere furnace. As a result, the graphite substrate is oxidized and burned off, leaving only the CVD-SiC film having a thickness of about 1 mm.

The susceptor 10 obtained by the above process has a small thickness of about 1 mm.
The amount of warpage is very small as compared with the case where 2c is not provided or the case where the rib groove 12c is not provided along two diagonal lines of the approximate small rectangular area. The susceptor 10 is provided with a substantially X-shaped rib groove 12c along two diagonal lines of the square in an approximately rectangular small area surrounded by the rib grooves 12a and 12b. It is inferred that the rib groove 12c functions as a reinforcing material against a strain stress generated in the combustion removal process of the graphite base material in step S3.

In the susceptor 10 according to the present embodiment, the rib grooves 12c are provided in all of the approximate rectangular small areas surrounded by the rib grooves 12a and 12b.
The rectangular small area in which the rib groove 12c is provided may be appropriately changed. In the present embodiment, the X-shaped rib groove 1 is used.
2c is provided continuously so as to be connected to the rib grooves 12a and 12b, but these may not necessarily be provided continuously so as to be connected, and between the rib groove 12c and the rib grooves 12a and 12b. , An appropriate gap may be provided. In addition, the rib groove 12c can be provided not only in an approximate quadrangular small area but also in a small area of any shape. For example, when a small region having a shape other than a square is formed by another rib groove, a straight line connecting two points selected so as to maximize the distance between two points on the outer peripheral line of the small region and Even if a substantially X-shaped rib groove is provided along a straight line that intersects this straight line, the same effect as in the present embodiment can be obtained.

Next, a second embodiment of the present invention will be described. FIGS. 3A, 3B, and 3C are views for explaining a structure of a susceptor, which is a plate-shaped chemical vapor deposition silicon carbide body according to a second embodiment of the present invention. ,
FIG. 3A is a plan view showing one main surface of the susceptor.
FIG. 3B is a partially enlarged view of FIG. 3C, and FIG.
FIG. 3D is a cross-sectional view taken along the line IIc-IIIc, and FIG. 3D is a cross-sectional view taken along the line IIId-IIId in FIG. The disk-shaped susceptor 20 is a plate-shaped body formed by chemical vapor deposition silicon carbide having a diameter of 300 mm and a thickness of 1 mm, and is shown in FIG.
As shown in FIG.
One and five circular openings 24a, 24b (φ35m
m) and four substantially X-shaped rib grooves 22 are formed.

Out of the five openings 24a and 24b, the opening 24a is provided at the center of the susceptor 20.
The opening 24b is provided at a position substantially intermediate between the opening 24a and the outer peripheral edge and at an angle of 90 ° with respect to the center of the susceptor 20. Further, as shown in FIG. 3B, the four rib grooves 22 are provided with openings 24.
a, a rectangular portion imagined to have the largest area in the small region surrounded by the two adjacent openings 24b and the outer peripheral convex portion 21 (AC surrounded by a broken line).
BD) are provided along two diagonal lines (AB, CD) of the square portion (ACBD).

As shown in FIG. 3D, the cross-sectional shape of the rib groove 22 is convex on the main surface on the side shown in FIG. 3A and concave on the other main surface on the back side. It is. The outer width W of the rib groove 12a is about 5 mm, and the height H is about 3 mm.

As described above, in the present embodiment, the susceptor 2
A substantially X-shaped rib groove 22 is provided in a plurality of small regions which are provided on the main surface of O and are not isolated from each other but are continuously connected. Not only when a plurality of small regions are formed separately from each other as in the first embodiment, but also when a plurality of small regions are not separated from each other as in this embodiment, As in the first embodiment, both the thickness and the amount of warpage of the susceptor 20 can be reduced. That is, the susceptor 20
Although the film thickness is as thin as about 1 mm, for example, the rib groove 12c is not provided, or the rib groove 12c has two diagonal lines (AB, C-C) of a rectangular small area (ACBD).
The amount of warpage is very small as compared with the case where it is not provided along D). The method of manufacturing the susceptor 20 according to the present embodiment is substantially the same as that described in the first embodiment, and a description thereof will not be repeated.

[0032]

EXAMPLES (Examples) By the same method as described in the first embodiment, a chemical vapor deposition silicon carbide plate-like molding as shown in FIGS. 4 (a), 4 (b) and 4 (c) is performed. The body 41 was manufactured. FIG. 4 (a) shows a chemical vapor deposited silicon carbide plate-shaped compact 4
4 (b) is a side view thereof, and FIG. 4 (c) is a cross-sectional view taken along line IVc-IVc of FIG. 4 (a).

As shown in FIGS. 4 (a), 4 (b) and 4 (c), a plate-shaped compact 4 of a chemical vapor deposited silicon carbide having a square shape is formed.
1 has an X-shaped rib groove 42 along its two diagonal lines.
Is provided. The chemical vapor deposition silicon carbide plate-shaped compact 41 is formed in the following dimensions. That is, one side length L1 = L2 = 200 mm of the chemical vapor deposition silicon carbide plate-shaped compact 41, and the length L3 = 1 of the rib groove 42.
70 mm, outer width W of rib groove 42 = 5 mm, height H = 3
mm, and the thickness T of the molded body 41 is 1 mm. The warpage of the CVD-plated body 41 manufactured as described above was measured by a three-dimensional measuring machine. As a result, the amount of warpage was 0.05 mm.

(Comparative Example 1) By a method similar to that described in the first embodiment, a chemical vapor deposition silicon carbide plate-like molded body 51 as shown in FIGS. 5A and 5B is manufactured. did.
FIG. 5 (a) is a plan view of the CVD plate-like compact 51, and FIG. 5 (b) is a side view thereof.

As shown in FIGS. 5 (a) and 5 (b), a square-shaped CVD plate-shaped compact 51 is shown in FIGS. 4 (a), 4 (b) and 4 (c). Is not provided, and the molded body 51 has a mere flat plate shape. The chemical vapor deposition silicon carbide plate-shaped compact 51 is formed in the following dimensions. That is, one side length L1 = L2 of the chemical vapor deposition silicon carbide plate-shaped compact 51
= 200 mm, and the thickness T of the molded body 51 is 1 mm. With respect to the plate-like molded body 51 of chemical vapor deposition silicon carbide manufactured as described above, the amount of warpage was measured by a three-dimensional measuring machine. As a result, the amount of warpage was 1.5 mm.

(Comparative Example 2) By a method similar to that described in the first embodiment, chemical vapor deposition silicon carbide plate-like molding as shown in FIGS. 6 (a), 6 (b) and 6 (c). The body 61 was manufactured. FIG. 6A is a plan view of a CVD plate 61, FIG. 6B is a side view thereof, and FIG.
FIG. 7 is a cross-sectional view taken along the line VIc-VIc in FIG.

As shown in FIGS. 6 (a), 6 (b) and 6 (c), a plate-like compact 6 of chemical vapor deposited silicon carbide is formed as a square.
1 has an X-shaped rib groove 62 along a line segment connecting the midpoints of the opposite sides of the square. The chemical vapor deposition silicon carbide plate-shaped compact 61 is formed in the following dimensions. That is, one side length L1 = L2 = 200 mm of the chemical vapor deposition silicon carbide plate-shaped compact 61, the length L3 = 150 mm of the rib groove 62, the outer width W of the rib groove 62 = 5 mm, the height H = 3 mm, Thickness T = 1 of molded body 61
mm. The warpage of the CVD-plate-shaped body 61 manufactured as described above was measured with a three-dimensional measuring machine. As a result, the amount of warpage was 0.4 mm.

From these Examples and Comparative Examples 1 and 2, it is possible to reduce the warpage of the molded article by providing the rib grooves in the molded article, particularly by providing the rib grooves along two diagonal lines of the rectangular molded article. It can be seen that it is possible to suppress the problem.

[0039]

As described above, according to the present invention,
By providing the rib grooves along the appropriate direction as described above in the CVD plate-shaped body, the amount of warpage can be reduced even when the plate-shaped body is formed into a thin film. It can be made smaller. Therefore,
When this plate-shaped body of chemical vapor deposition silicon carbide is used, for example, as a susceptor for rapid heat treatment, a thermally oxidized film or a thermally nitrided film having desired characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a susceptor, which is a plate-shaped chemical vapor deposition silicon carbide body according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a manufacturing process of the susceptor of FIG.

FIG. 3 is a view showing a susceptor which is a plate-shaped chemical vapor deposition silicon carbide body according to a second embodiment of the present invention.

FIG. 4 is a view showing a plate-shaped compact formed by chemical vapor deposition of silicon carbide according to an embodiment of the present invention.

FIG. 5 is a view showing a plate-shaped formed body of chemical vapor deposition silicon carbide manufactured according to Comparative Example 1 of the present invention.

FIG. 6 is a view showing a plate-shaped formed body of chemical vapor deposition silicon carbide manufactured according to Comparative Example 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Susceptor 11 Outer peripheral convex part 12a, 12b, 12d Rib groove 12c X-shaped rib groove

Claims (6)

[Claims] At least one of the at least one sub-region forming one or more sub-regions of the principal surface is selected to maximize the distance between two points on the outer peripheral line of the sub-region. And a substantially X-shaped step along a straight line intersecting the straight line. 2. The method according to claim 1, wherein the at least one small region is approximately square, and the substantially X-shaped step is provided along two diagonal lines of the small region. The plate-shaped formed body of chemical vapor deposition silicon carbide according to claim 1, characterized in that: 3. A rectangular portion imagined to have the largest area in at least one of the at least one of the at least one sub-region forming the main surface, A chemical vapor-deposited silicon carbide plate-like shaped body provided with a substantially X-shaped stepped portion along a diagonal line of the book. 4. In at least one of the one or more small regions constituting the main surface of the graphite base material, the distance between two points on the outer peripheral line of the small region is selected to be the maximum. Providing a substantially X-shaped step on the graphite substrate along a straight line connecting the two points and a straight line intersecting the straight line; and silicon carbide on the graphite substrate by chemical vapor deposition. Forming a layer; and selectively removing the silicon carbide layer by machining.
A method for producing a plate-shaped body made of chemical vapor deposited silicon carbide, comprising: a step of exposing a part of the graphite base; and a step of burning and removing the graphite base. 5. The method according to claim 1, wherein said at least one small region is approximately square, and said substantially X-shaped step is provided along two diagonals of said small region. 5. The method for producing a plate-shaped formed body of chemical vapor deposition silicon carbide according to claim 4, wherein: 6. A rectangular portion imagined such that an area in at least one of the one or more small regions constituting the main surface of the graphite substrate is maximized in at least one of the small regions. Substantially X along the two diagonals of the square
Providing a U-shaped step on the graphite substrate, forming a silicon carbide layer on the graphite substrate by chemical vapor deposition, and selectively removing the silicon carbide layer by machining.
A method for producing a plate-shaped body made of chemical vapor deposited silicon carbide, comprising: a step of exposing a part of the graphite base; and a step of burning and removing the graphite base.