WO2012050117A1

WO2012050117A1 - Supporting body and wafer film formation method

Info

Publication number: WO2012050117A1
Application number: PCT/JP2011/073403
Authority: WO
Inventors: 和宏牛田
Original assignee: 株式会社ブリヂストン
Priority date: 2010-10-12
Filing date: 2011-10-12
Publication date: 2012-04-19
Also published as: JP2012084683A

Abstract

Disclosed is a supporting body which is used in a semiconductor device manufacturing process and has an upper surface that is provided with a recessed portion in which a wafer is disposed. The supporting body is formed of silicon carbide, and the recessed portion has a generally circular shape when viewed in plan and has a bottom portion that is composed of a plurality of annular steps that are concentrically arranged around the center of the recessed portion when viewed in plan.

Description

Support and wafer film forming method

The present invention relates to a support on which a wafer is placed in a semiconductor device manufacturing process, and a wafer film forming method using the support.

Generally, in a wafer film forming process which is one of semiconductor device manufacturing processes, a support for mounting a wafer is used. At this time, the wafer may be bent due to heating of the wafer or due to its own weight. In order to make the heating of the wafer uniform even when the wafer is bent, a support having a concave portion that is recessed in a spherical shape is known. The wafer is uniformly heated by being placed in a concave portion that is recessed in a spherical shape (see, for example, Patent Document 1).

JP 7-335572 A

Incidentally, the above-described support has the following problems. That is, the support used in the wafer film-forming process is often formed of silicon carbide because heat resistance and high hardness are required. Since silicon carbide is a substance having a very high hardness, for example, in a lens processing method or a ball end mill processing method typified by an Oscar type polishing, a grindstone may be worn. For this reason, it has been difficult to accurately process the concave portion recessed in the spherical shape. Although the die-sinking electric discharge machining method can be used, the die-sinking electric discharge machining method has been difficult to apply to mass production due to the high tool cost and the long machining time.

Therefore, the present invention uses a support that can uniformly heat a wafer and that can be mass-produced at low cost, as well as a support that has a concave portion with a spherical bottom surface. An object of the present invention is to provide a wafer film forming method.

First, the first feature of the present invention is used in a semiconductor device manufacturing process, and is a support (susceptor 1) having an upper surface (upper surface 1a) on which a recess (recess 10) on which a wafer (wafer W) is placed is formed. The support is made of silicon carbide, and the recesses are substantially circular in a plan view, and a plurality of concentric circles centered on the center of the recess in a plan view. And having a bottom portion (bottom portion 10B) formed by an annular step.

According to this, since the bottom of the recess is formed by a plurality of annular steps provided concentrically, compared to a case where the bottom of the recess has a spherical shape, a standard grindstone (diamond grinding stone) ). That is, since processing is easy, it is not necessary to use lens processing, ball end mill processing, and die-sinking electric discharge processing. As a result, it is possible to provide a support that can be mass-produced at low cost.

The depth from the upper surface to the bottom may be increased from the peripheral edge of the concave portion (peripheral step 11S) toward the center of the concave portion.

According to this, the shape of the bottom after processing is a shape in which the depth from the upper surface becomes deeper from the periphery of the recess toward the center. Therefore, when the mounted wafer is bent, the distance between the wafer and the bottom becomes uniform over the entire wafer. As a result, the wafer can be uniformly heated in the wafer film forming process.

In the center of the concave portion, the bottom portion may have a spherical shape.

Another feature of the present invention is a wafer film forming method including a wafer placing step of placing a wafer on a support and a wafer film forming step of forming the wafer, wherein the support is a wafer. And has a top surface formed with silicon carbide, and the recess is substantially circular in plan view, and is concentric with the center of the recess in plan view as the center. A plurality of circular steps provided at the bottom, the depth from the upper surface to the bottom increases from the peripheral edge of the recess toward the center of the recess, and the plurality of circles Each step in the annular step has an inner peripheral end that is an end portion close to the center of the concave portion in plan view, and in the wafer mounting step, among the steps overlapping with the wafer in plan view, Both the gist that the wafer is in contact with the inner peripheral edge of the nearest stage to the upper surface.

In the wafer placing step, the wafer may contact only the inner peripheral edge of the step closest to the upper surface among the steps overlapping the wafer in plan view.

In the wafer placing step, the wafer may contact the inner peripheral ends of a plurality of steps among the steps overlapping the wafer in plan view.

FIG. 1 is a plan view of a support according to the present embodiment. FIG. 2A is a cross-sectional view taken along line A-A ′ in FIG. FIG. 2B is a perspective view of a recess according to this embodiment. FIG. 3 is a diagram schematically showing a method for processing the recess 10. 4A and 4B are views schematically showing the state of the wafer placed in the recess 10 in the wafer film forming process. FIG. 5 is a diagram illustrating the recess 20 according to the embodiment. FIG. 6 is a diagram illustrating the recess 30 according to the embodiment. FIG. 7 is a diagram schematically showing a recess according to another embodiment. FIG. 8 is a diagram schematically showing a recess according to another embodiment.

Embodiments of a pneumatic tire according to the present invention will be described with reference to the drawings. Specifically, (1) the structure of the support, (2) the structure of the recess, (3) the processing method of the recess, (4) the wafer film forming method, (5) the action / effect, (6) the embodiment, (7) Other embodiments will be described.

In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

In the following description and drawings, the vertical direction and the horizontal direction are defined, but these all indicate directions in a posture in which the wafer is placed on the support.

(1) Structure of Support First, the structure of the support (susceptor 1) according to the present embodiment will be described with reference to FIGS. FIG. 1 is a plan view of a support according to the present embodiment. FIG. 2A is a cross-sectional view taken along the line AA ′ in FIG. FIG. 2B is a perspective view of a recess according to this embodiment.

As shown in FIG. 1, the susceptor 1 has a substantially circular shape in plan view. In addition, the susceptor 1 has an upper surface 1a that is a surface on which a wafer is placed and a lower surface 1b that is a surface opposite to the upper surface 1a in the vertical and horizontal cross-sectional views (see FIG. 2 (a)).

The upper surface 1a of the susceptor 1 is provided with four recesses 10 for placing the wafer. The recess 10 is substantially circular in plan view. Here, the substantially circular shape means including a circular shape, an elliptical shape, or a shape in which a part is a straight line.

Further, the size of the recess 10 in a plan view may be set as appropriate as long as it is formed larger than the wafer placed on the recess 10. In the present embodiment, the susceptor 1 is made of silicon carbide.

(2) Configuration of Concave portion As shown in FIGS. 2A and 2B, the concave portion 10 is formed on the upper surface 1a and has a depressed shape that is convex toward the lower surface 1b. That is, the concave portion 10 is formed by a wall portion 10W that is continuous with the upper surface 1a and extends in a direction from the upper surface 1a to the lower surface 1b, and a bottom portion 10B on which the wafer is placed. The wall 10W is formed at an angle of approximately 90 degrees with the upper surface 1a. The bottom 10B is formed by a plurality of annular steps provided concentrically. That is, the bottom portion 10B has a shape having a step. Specifically, among the plurality of steps forming the bottom portion 10B, the step (referred to as the center step 11C in the following description) positioned at the center of the recess 10 in plan view is positioned on the lowermost surface 1b side. The center step 11C is located at the center of the recess 10 in plan view. Of the plurality of steps forming the bottom portion 10B, the step located on the outermost side in plan view (referred to as the peripheral step 11S in the following description) is located on the uppermost surface 1a side. That is, the bottom 10B is formed in an upward staircase shape from the center step 11C toward the peripheral step 11S. Note that the centers of the plurality of annular steps in plan view coincide with the centers of the recesses 10 in plan view. Here, “the centers of the plurality of annular steps in plan view coincide with the centers of the recesses 10 in plan view” means that the centers of the plurality of annular steps in plan view are the centers of the recesses 10. Including substantially matching. Specifically, as long as the wafer can be heated uniformly, the center of the plurality of annular steps and the center of the recess 10 do not coincide with each other.

Further, as shown in FIG. 2A, the thickness hs of the susceptor 1 is larger than the depth hc from the upper surface 1a to the center step 11C. That is, the recess 10 does not penetrate the susceptor 1. In the present embodiment, the bottom 10B is formed in 10 steps when the central step 11C is counted as one step. Further, the step hd in the vertical direction of each step is formed to be 0.01 mm (10 μm) or less.

(3) Processing method of recessed part Next, the processing method of the recessed part 10 is demonstrated with reference to FIG. FIG. 3 is a diagram schematically showing a method for processing the recess 10.

As described above, the concave portion 10 is formed by the wall portion 10W formed at an angle of approximately 90 degrees with the upper surface 1a of the susceptor 1 and the bottom portion 10B formed in a step shape in the vertical and horizontal sectional views. Is formed. Therefore, as shown in FIG. 3, the recess 10 can be processed by the standard polishing jig D. The polishing jig D is composed of a rotating body D1 and a disk-shaped and flat diamond powder aggregate D2 attached to the polishing surface of the rotating body D1. When processing the concave portion 10 of the susceptor 1, the diamond powder aggregate D2 can be processed by pressing it perpendicularly to the upper surface 1a while rotating the rotating body D1.

(4) Wafer Film Formation Processing Method Next, the wafer film formation processing method will be described with reference to the drawings.

Among the wafer film forming methods, the wafer film forming process for forming a wafer is not described because a known technique such as a thermal oxidation method, a CVD method, or a sputtering method can be appropriately employed. Here, the wafer W placed on the recess 10 in the wafer placement process of placing the wafer W on the recess 10 will be described. 4A and 4B are diagrams schematically showing the state of the wafer W placed in the recess 10 in the wafer placing process. In the present embodiment, all steps constituting the recess 10 overlap the wafer W in plan view.

In the wafer mounting process shown in FIG. 4A, the wafer W is supported by the peripheral step 11S among the plurality of steps constituting the recess 10. Specifically, the peripheral step 11S is supported by an inner peripheral end 11Se that is an end portion close to the center of the concave portion 10 in plan view. That is, in the wafer mounting process shown in FIG. 4A, the wafer W does not come into contact with the other bottom 10B except for the inner peripheral end 11Se of the peripheral step 11S.

In this case, the distance between the wafer W and the bottom portion 10B is substantially uniform over the entire wafer at portions other than the inner peripheral end 11Se. Accordingly, the wafer W can be uniformly heated, and as a result, temperature unevenness of the wafer W can be suppressed.

Also, in the wafer placing process, it is possible to place the wafer W as shown in FIG. In FIG. 4B, the wafer W is in contact with all the stages except the central stage 11C. Specifically, the wafer W is supported by the inner peripheral edge in each stage forming the bottom 10B.

As described above, the contact area between the wafer W and the bottom portion 10B can be reduced by bringing the wafer W into contact with only the inner peripheral edge of each stage. In addition, since the inner peripheral edge of each step is formed in a circular shape in plan view, no deviation or variation occurs in the portion where the wafer W and the inner peripheral edge are in contact with each other. As a result, it becomes possible to uniformly heat the entire wafer W, and as a result, temperature unevenness of the wafer W can be suppressed.

(5) Action / Effect Next, the action and effect of the susceptor 1 according to the present embodiment will be described.

According to the present embodiment, the susceptor 1 is formed of silicon carbide, and the recess 10 is substantially circular in a plan view, and is provided concentrically around the center of the recess 10 in a plan view. It has a bottom portion 10B formed by a plurality of annular steps, and is formed so that the depth from the top surface 1a to the bottom portion 10B becomes deeper from the peripheral step 11S of the recess 10B toward the center step 11C of the recess 10B. Yes.

According to this, since the bottom portion 10B of the concave portion 10 is formed in a stepped shape, it is processed by a processing method using a standard grinding jig D as compared with the case where the bottom portion of the concave portion 10 is formed into a spherical shape. be able to. That is, since processing is easy, it is not necessary to use lens processing, ball end mill processing, and die-sinking electric discharge processing. As a result, it is possible to provide a susceptor 1 that can be mass-produced at low cost.

Further, according to the susceptor 1 of the present embodiment, the shape of the bottom portion 10B is such that the depth from the top surface 1a to the bottom portion 10B increases toward the center step 11C from the peripheral step 11S of the recess 10 and the bottom portion The step in the vertical direction of each step forming 10B is formed to be 0.01 mm or less. That is, by making the vertical step of each step 0.01 mm or less, the curve 10 can be linearly interpolated to form the bottom portion 10B having a spherical shape. As a result, the wafer W can be uniformly heated in the wafer film forming process.

(6) Example Next, an Example is described concretely with reference to drawings. FIG. 5 is a diagram illustrating the recess 20 according to the embodiment. FIG. 6 is a diagram illustrating the recess 30 according to the embodiment. Note that the unit of numerical values shown in FIGS. 5 and 6 is millimeters.

The susceptor 2 shown in FIG. 5 has a vertical thickness of 4 mm. Further, the recess 20 provided in the susceptor 2 has a diameter of 152 mm, and the vertical depth from the upper surface 2a of the susceptor 2 to the peripheral step 21S is 0.8 mm. The bottom 20B of the recess 20 shown in FIG. 5 is formed in 10 steps. The step in the vertical direction of each step forming the bottom portion 20B is 0.003 mm.

Further, in the vertical and horizontal cross-sectional views, the length L in the left-right direction of each step forming the bottom portion 20B (in FIG. 5, the second step is taken as an example) is changed from the center step 21C to the peripheral step 21S. It is formed to become shorter as it goes. Specifically, as shown in FIG. 5, when comparing the length L in the left-right direction of each step forming the bottom portion 20B, the length 21CL of the center step 21C (corresponding to the radius of the center step 21C in plan view). ) Is the longest at 15 mm, and the length 21SL of the peripheral step 21S is the shortest.

The susceptor 3 shown in FIG. 6 has a vertical thickness of 2 mm. Further, the recess 30 provided in the susceptor 3 has a diameter of 102 mm, and a vertical depth from the upper surface 3a of the susceptor 30 to the peripheral step 31S is 0.7 mm. The bottom 30B of the recess 30 shown in FIG. 6 is formed in seven steps. The step in the vertical direction of each step forming the bottom portion 30B is 0.006 mm.

Further, in the vertical and horizontal cross-sectional views, the length L in the horizontal direction of each step forming the bottom 30B (in FIG. 6, the second step is taken as an example) is changed from the center step 31C to the peripheral step 31S. It is formed to become shorter as it goes. Specifically, as shown in FIG. 6, when comparing the length L in the left-right direction of each step forming the bottom 30B, the length 31CL of the center step 31C (corresponding to the radius of the center step 31C in plan view). ) Is the longest at 10 mm, and the length 31SL of the peripheral step 31S is the shortest.

(7) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

As shown in FIG. 7, the bottom may be spherical at the center of the recess 10. Specifically, only the central step 11C may have a spherical shape that protrudes toward the lower surface. Since the central step 11C has a spherical shape that protrudes in the direction toward the lower surface 11b, the distance between the wafer W and the susceptor 10 can be made more uniform over the entire wafer W when the wafer W is bent. In the processing of the center step 11C, the diameter of the center step 11C is smaller than the diameter of the recess 10, so that the spherical center step is processed only by replacing the diamond grindstone used at the time of processing with a spherical one. be able to.

As shown in FIG. 8, the bottom 10B may be formed so that the depth from the top surface 1a to the bottom 10B becomes shallower from the peripheral step 11S toward the center step 11C. That is, in the vertical direction, the peripheral step 11S may be positioned closest to the lower surface 1b and may be convex from the peripheral step 11S toward the upper surface 1a. Also in the recess 10 formed in this way, the bottom 10B is formed in a step shape, and therefore can be easily processed by a processing method using a standard grinding jig. As a result, it is possible to provide a susceptor that can be mass-produced at low cost. Furthermore, in the wafer film forming process, even when the wafer center portion in plan view is bent upward in the vertical direction, the wafer can be heated uniformly.

Further, in the embodiment, it has been described that there are four recesses provided in the susceptor 1, but the present invention is not limited to this, and a single-wafer type susceptor provided with one recess may be used. The number of recesses provided in the susceptor 1 can be set as appropriate.

Further, the number of steps of the bottom portion 10B is not limited to the seven or ten steps described in the embodiment, and can be set as appropriate depending on the size and characteristics of the wafer to be placed.

In the embodiment, the vertical steps in the plurality of steps forming the bottom portion 10B are unified, but the present invention is not limited to this. That is, the step in the vertical direction can be increased as the depth from the top surface to the bottom 10B increases. Conversely, the step in the vertical direction can be reduced as the depth from the top surface to the bottom 10B increases. About the structure of a level | step difference, it can set suitably according to the magnitude | size and characteristic of the wafer mounted. Similarly, the length of each step in the left-right direction can be set as appropriate.

Thus, it goes without saying that the present invention includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

Note that the entire contents of Japanese Patent Application No. 2010-229449 (filed on Oct. 12, 2010) are incorporated herein by reference.

According to the present invention, similarly to a support having a concave portion with a spherical bottom surface, the support that can uniformly heat the wafer and can be mass-produced at low cost, and the support are used. The present wafer deposition method can be provided.

Claims

A support used in a semiconductor device manufacturing process and having a top surface on which a recess for mounting a wafer is formed,
The support is formed of silicon carbide;
The concave portion has a substantially circular shape in a plan view and has a bottom formed by a plurality of annular steps provided concentrically around the center of the concave portion in a plan view. Support.
2. The support according to claim 1, wherein a depth from the upper surface to the bottom becomes deeper from a peripheral edge of the recess toward a center of the recess.
In the center of the recess,
The support according to claim 1, wherein the bottom portion has a spherical shape.
A wafer mounting step of mounting the wafer on a support;
A wafer film forming process comprising: forming a wafer;
The support has a top surface on which a recess for mounting a wafer is formed, and is formed of silicon carbide,
The concave portion is substantially circular in plan view, and has a bottom formed by a plurality of annular steps provided concentrically around the center of the concave portion in plan view,
The depth from the upper surface to the bottom increases toward the center of the recess from the peripheral edge of the recess,
Each step in the plurality of annular steps has an inner peripheral end that is an end portion close to the center of the concave portion in plan view,
In the wafer placing step, the wafer is in contact with an inner peripheral end of at least a step closest to the upper surface among the steps overlapping with the wafer in plan view.
5. The wafer film forming method according to claim 4, wherein, in the wafer placing step, the wafer contacts only the inner peripheral edge of the step closest to the upper surface among the steps overlapping with the wafer in plan view.
5. The wafer film forming method according to claim 4, wherein, in the wafer placing step, the wafer contacts an inner peripheral end of a plurality of steps among the steps overlapping with the wafer in plan view.