JPH0554556U - Susceptor - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent cracks and cracks that occur in a susceptor made by coating dense graphite on a graphite material. [Structure] The film thickness of the silicon carbide coating on the peripheral portion of the susceptor is made thinner than other portions.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a susceptor formed by coating a high-purity isotropic graphite material with dense silicon carbide, in particular, a medium-pore disk shape and particularly a vapor phase epitaxial growth apparatus for silicon, and particularly to a susceptor used in a vertical furnace.

[0002]

[Prior Art]

 A disc type susceptor (hereinafter referred to as a pancake type susceptor) has a flat type disc-shaped shape as shown in FIG. 1 in order to flatten a large number of semiconductor wafers, for example, silicon thin plates, and simultaneously perform advanced processing. There is a hole in the center. In FIG. 1, 1 is a pancake type susceptor, 2 is an intermediate hole, 3 is a thin recessed part, and in FIG. 1, this recessed part 3 is partially omitted, and it is provided on the entire surface of the susceptor 1. It is what This is manufactured by coating a high-purity isotropic graphite base material with a SiC film by the CVD method, and the factors that determine the life thereof are as follows.

(1) CVD-SiC film thickness (2) Difference in thermal expansion coefficient between graphite base material and SiC (3) Temperature difference between inner diameter and other parts during epitaxial growth (4) Elastic coefficient, etc. Are complicatedly entangled with each other to cause cracks, pinholes, and peeling.

[0004] Recently, with the demand for mass production and size increase of semiconductor manufacturing equipment, this kind of pancake type susceptor tends to be gradually increased in size. In this case, since the susceptor has a disk shape having a small hole in the central portion, as the disk becomes larger, the peripheral edge portion and the center portion, particularly the peripheral graphite material, and the surface layer It has become important to take into account the absorption of the thermal expansion coefficient of the CVD-SiC film that forms the film.

If this consideration is not enough, if the product is used for a long period of time, repeated temperature changes will cause minute cracks, cracks, etc. in the surface SiC coating layer, especially near the final part, and the life of the susceptor will be significantly shortened. I found out that

[0006]

[Problems to be solved by the device]

 Therefore, the present invention aims to overcome the above problems and provide a long-life susceptor.

[0007]

[Means for Solving the Problems]

 This problem is solved by making the film thickness of the coating layer on the peripheral portion of the susceptor smaller than the film thickness of the coating layer on the other portion of the disk.

Specifically, the present inventors have found that the problem can be solved by thinning the specified portion of the peripheral edge of the susceptor and setting the thickness of the thinnest portion to 50 to 80% of the average film thickness of the whole. I found it.

[0009]

[Function of the device]

 The above-mentioned specified portion means a range in which the area of the coating layer on the peripheral portion 4 of the susceptor corresponds to 2 to 3% with respect to the other portion of the disc as shown in FIGS. 1 and 2.

[0010] As the coating, a isotropic high-purity graphite material of pancake type susceptor coated with CVD-SiC has been generally used, but in this case, a CVD-SiC film forming a surface layer is used. In order to prevent cracks, cracks, and peeling of the graphite material, the graphite material used as the base material is an isotropic graphite material (for example, Toyo It is preferable to use "Grade name 610" manufactured by Carbon Co., Ltd.).

The thickness of the coating layer itself is in the range of 70 to 200 μm, and if it is thinner than this, the effect of the coating is weakened, the oxidation resistance, the effect of suppressing the gas generated from the inside (outgas), etc. is weakened, and vice versa. If the coating layer becomes too thick, it will rather crack, peel, etc., and is not economical.

In the present invention, as described above, among the coatings uniformly applied to the conventional thickness of 70 to 200 μm, preferably 80 to 120 μm, the covering in the vicinity of the peripheral portion is relatively used. This is based on the finding that the life of the susceptor could be remarkably lengthened by making the thickness 50% to 80%.

If the thickness is made too thin, the SiC coating effect is weakened, and if it is too thick and the entire thickness is uniform, it becomes the same as the conventional one.

As a result of various experiments on this, it was found that it is important to control the thickness of the thin film portion to 50 to 80% of the average thickness of other portions.

Further, the thin layer portion and the relatively thick layer portion can be separately controlled by drawing a line, but from the viewpoint of safety of the coating layer and prevention of cracks, they are distinctly controlled. It is not always necessary, but it is desirable to gradually change the thickness from an average thick layer portion to a thin layer portion having a thickness of 50 to 80% of the average thickness.

Further, if the range of thinning is too small, the effect of strain absorption is weakened, and conversely if it is too wide, it affects the depression of the recess for accommodating the wafer.

[0017]

[Effect of the device]

 The present invention has performed various experiments on the pancake type susceptor and has been significantly effective in extending the life, but the same effect is also obtained on the barrel type susceptor. The present invention will be described in detail below with reference to examples.

[0018]

Example 1 For high-purity isotropic graphite (IG-610U) having a total film thickness of 80, 100, and 120 μm, the film thickness of the peripheral portion was 60 to 7 of the average film thickness of the whole, respectively. A susceptor was manufactured by gradually changing it to 0% and used for epitaxial growth. As comparative examples, those of less than 50% and more than 80% were also used. As a result, those with 60 to 70% did not change even after 200 times, but those with less than 50% and more than 80% showed cracking at 45 times and 30 times.

[0019]

[Brief description of drawings]

[0020]

[Figure 1]

FIG. 1 is a perspective view of the susceptor.

[0022]

[Fig. 2]

FIG. 2 is a schematic view of an essential part of the upper surface portion of FIG. 1 ………… Susceptor 2 ………… Medium hole 3 ………… Thin recess 4 ………… Peripheral part

Claims (4)

[Scope of utility model registration request] 1. A susceptor comprising a high-purity isotropic graphite material coated with dense silicon carbide. Of 5
A susceptor characterized by being thinned to 0 to 80%. 2. A susceptor in which the area of the thinned silicon carbide layer around the outer peripheral edge is 2 to 3% of the area of the disk portion. 3. The thickness of the thinned silicon carbide layer near the outer peripheral edge is 60 to 80 μm, and the thickness of the relatively thick coating layer constituting the coating layer of the disc portion is relatively large. Is 80-130
The susceptor of claim 1, which is in microns (μ). 4. An inclined structure in which the thickness of the silicon carbide coating layer from the thinned portion near the outer peripheral edge to the relatively thickened portion gradually increases. Claim 1
Susceptor described in.