JPS59200430A - Supporter for soft loading of semiconductor - Google Patents

Abstract

PURPOSE:To obtain a supporter, the quality of a material thereof has high purity and mechanical strength thereof does not lower even at a high temperature and which has excellent creeping resistance at the high temperature, by using a material, which consists of the quality of the material of Si-SiC and Si content therein is kept within a specific range. CONSTITUTION:A material, which is composed of the quality of a material of Si-SiC of purity of not less than 99.95wt% and Si content therein is 3-25wt%, is used. Consequently, thermal conduction is excellent because Si is made contain, and an extreme temperature gradient is not generated in a supporter. As a result, thermal stress is not generated, and mechanical strength does not lower even at a high temperature. The supporter has excellent creeping resistance at the high temperature because the sintering-bonding of SiC-SiC is large and the purity of the quality of the material is high. Accordingly, the supporter is not deflected even at the high temperature, and the position of a wafer boat is set easily. It is more desirable that the supporter is coated with a CVD-SiC coating in the thickness of 50mum or more.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor soft loading support used for heat treatment of semiconductor Si wafers.

Conventionally, wafer boats have generally had a structure in which the Si wafers placed thereon can be taken in and out of the diffusion furnace by sliding the inner wall of the core tube.

However, when the wafer port is slid onto the inner wall of the furnace core tube,
Even when loading and unloading was carried out slowly, the wafer port vibrated or some dust was scattered within the furnace core tube. This vibration and scattering of dust caused crystal defects in the Si wafer, which was a problem.

For this reason, soft loading methods have recently been considered.

In the soft loading method, the wafer port is placed on a soft loading support and the wafer port is taken in and out without sliding on the inner wall of the furnace core tube.

As a conventional soft loading support, for example, there is a boat 1 (FIG. 1) disclosed in Japanese Patent Application Laid-open No. 56-36129. One bar 2 is placed at the tip of each bow 1 to 1 via a mounting jig 3.

It is posted. 4 is a furnace core tube.

Other conventional soft loading supports include, for example, Japanese Patent Application Laid-Open No. 56-1981. There is a boat 5 (FIG. 2) disclosed in Japanese Patent Publication No. 45020-45020 and a boat support arm 7 (FIG. 3) disclosed in Japanese Patent Application Laid-open No. 57-170523. The wafers 2 are placed on the tips of a boat 5 and a boat support arm 7, respectively, via a storage jig 6 and a wafer boat 8. 9 (FIG. 3) is a furnace core tube, but the furnace core tube is omitted in FIG.

The wafer boat 8 is lowered from the boat support arm 7 and placed directly into the furnace core tube 9. For this reason, the wafer boat 8 is provided with legs 8a.

These conventional supports were mainly made of quartz glass from the viewpoint of purity.

However, in soft loading, one end of the support is inserted into a high-temperature furnace and the other end is fixedly supported at room temperature, so a temperature gradient occurs within the support. This temperature gradient generates thermal stress within the support material, which reduces the mechanical strength of the material as residual stress. Therefore, the material of the soft loading support must of course have high purity, but it is also required to have high strength and excellent creep resistance at high temperatures.

However, as is well known, quartz glass deforms at high temperatures.
Further, there were other problems such as the strength becoming extremely low due to scratches on the surface.

This invention was made in view of the above-mentioned circumstances, and provides a semiconductor soft loading support that is made of highly pure material, does not lose its mechanical strength even at high temperatures, and has excellent creep resistance in AI. The purpose is to do something.

The soft loading support of the present invention has a purity of 99.9.
It is characterized by being made of a Si-8iC material of 5% by weight or more, and having a 3i content of 3 to 25% by weight.

Since the soft loading support of the present invention contains Si at a content of 3 to 25% by weight as described above, heat conduction is good and no extreme temperature gradient occurs within the support. Therefore, no thermal stress is generated and no decrease in mechanical strength is observed even at high temperatures.

In addition, SiC and -8iC have a large sintering -3 onding and have high material purity, so they have excellent creep resistance at high temperatures.

Therefore, the semiconductor soft loading support of the present invention does not bend even at high temperatures. Therefore, according to the present invention, it is very easy to set the position of the wafer boat.

SiC without impregnation with 3i soft loading support
If it is made from chisel, heat conduction is poor due to the presence of about 10% of pores, and a temperature gradient occurs within the support, resulting in a decrease in mechanical strength. Therefore, in the semiconductor soft loading support of the present invention, SiC contains Si to improve heat conduction and prevent a decrease in mechanical strength.

In order to investigate this situation, we used SiC materials and 3i-8iC materials with various 3i contents, and measured the bending strength by placing one end of these materials in and out of a 1200°C furnace. , the rate of decline was measured. The materials used in each case had an outer diameter of 25111111N, an inner diameter of 10III111, and a length of 2000IIIL. The loading and unloading operations were repeated 100 times at a speed of 20IllIll/min. The measurement results are shown in Table 1 (see below).

Those containing 3i of 40% by weight or more were broken before being put in and taken out 100 times. From this measurement result, it was found that the Si-8i C material containing more than 25% Si has a problem as a support for soft loading.

The St-8iC material is a composite constructed by a so-called reaction sintering method. Its characteristics are determined by the composition ratio of Si and SiC.

Therefore, the s+-src material was constructed by changing the 3i content in stages from 5 to 45% by weight, and the s+-5i content at high temperatures was
The characteristics of the C material were investigated, and the shapes of the 7CQ materials were all 25 mm in outer diameter, 15 mm in inner diameter, and 2000 mm in length. In the investigation, as shown in FIG. 4, one end 10a of the material 10 is fixedly supported, and the other end 10b is fixedly supported. The test was carried out by keeping the temperature at 1200°C for 15 hours with a load W of Okq applied, and measuring the displacement of the end 10b, and calculating the ratio of displacement to the total length (
%) was calculated.

The measurement results are shown as graph 13 in FIG.

As a result of the investigation, it was found that the amount of displacement increases rapidly when the Si content reaches around 25% by weight.

Changes in displacement due to differences in 3i content are explained as follows. In other words, 30ndin(+
is correlated with the Si content, and the Si content is 30 to 35
Sintering-Bonding of 3iC-3iC at weight% or more
The number of displacement is small and the displacement becomes large because it approaches the creep characteristics of Si.

Further, for materials containing impurities such as A1 at 500 ppm or more, the amount of displacement was measured under the same conditions as the above measurements. As the amount of impurities increases, the amount of displacement tends to increase.

For this reason, materials containing many impurities are not preferred as the support/tool for semiconductor soft loading of the present invention.

If this displacement is large, it becomes difficult to set the position of the wafer boat during soft loading, which poses a problem.

Displacement is also determined by the shape and size of the support, but
Regardless of the size, if the S1 content exceeds 25% by weight, deformation due to creep characteristics becomes a serious problem. The 1c, 3i content is higher than 255 Juumaru (then S
Since the 30nding of t c - st c becomes smaller, the decrease in mechanical strength is also noticeable, causing a problem in reliability as a support (see Fig. 6).

Using St-5iC moon material with a Si content of 233 layers,
Semiconductor soft loading supports 11 and 12 of the present invention as shown in FIGS. 7A and 8 were manufactured.

The semiconductor soft loading support 11 has a pipe shape, and the semiconductor soft loading support 12 has a flat plate shape. Semiconductor soft loading support 11
．． 12 are supported by support parts 11a and 12a, respectively, and wafer boats are placed on boat mounting parts 11b and 12b.

A 5iO2-wafer boat (not shown) containing 3i wafers was placed on a soft loading support 11.12, and the wafers were processed in a diffusion furnace. Processing is at 1000℃
The temperature was maintained for 2 hours.

Although the wafer weight was about 5.6 kg, the semiconductor soft loading support of the present invention did not have any troubles such as breakage or deformation.

Note that the support for semiconductor soft loading of the present invention includes C.
It is more desirable to coat the VD-8i C coating film with a thickness of 50a or more.

[Brief explanation of the drawing]

Figure 1 is a side view of a conventional support, Figure 2 is a perspective view of a conventional support, Figure 3 is a side view of a conventional support, and Figure 4 is the amount of displacement of the Si-8iC material. Fig. 5 is a graph showing the relationship between Si content and displacement of 5i-st c material, Fig. 6 is a graph showing the relationship between 3i-st c material and displacement amount.
A graph showing the relationship between Si content and mechanical strength of C material,
FIG. 7A is a side view showing an example of the support for semiconductor soft loading of the present invention, FIG. 7B is a front view of the support shown in FIG. 7A, and FIG. 8 is a side view showing an example of the support for semiconductor soft loading of the present invention. It is a perspective view showing an example. 10...5i-8i C material 11.12... Semiconductor soft loading support device procedure correction teeth (voluntary) August Z, 1982 Commissioner of the Patent Office Kazuo Wakasugi Tono 1, Patent application for indication of case 1982 -73899 No. 2, Name of the invention: Semiconductor soft loading support 3, Relationship with the person making the amendment Patent applicant address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name: Toshiba Ceramics Corporation Representative: Fumio Muramatsu 4; Agent Address: Suzumaru Building 6, 2-39-8 Nishi-Shinbashi, Minato-ku, Tokyo, "Detailed Description of the Invention" column and drawing 7 of the specification to be amended, Contents of the amendment 1) No. 1 on page 11 of the specification Correct the table to J: Sea urchin in attached sheet. 2) Correct figures 5 and 6 as shown in the attached sheet.

Claims (1)

[Scope of Claims] A support for semiconductor soft loading, characterized in that it is made of a Si-8iC material with a purity of 99.95% by weight or more, and has a Si content of 3 to 25% by weight.