JPH0786378A - Carbon support for semiconductor manufacturing equipment - Google Patents

Abstract

PURPOSE:To obtain semiconductor products high in yield always through an epitaxial growth process and a plasma etching process by a method wherein a semiconductor support is formed of glassy carbon specified in quality. CONSTITUTION:A semiconductor support is formed of glassy carbon material which has such constitutional and purity properties that a specific gravity is more than 1.47, pores smaller than 20mum in size are contained, porosity is less than 5%, total ash content is less than 5ppm, and sulfur content is less than 10ppm. A structure higher than 1.47 in specific gravity is small is pore content and high in structural density, so that these structural properties enable the structure to be relaxed in degree of wear and tear and lessened in discharge of soot when pares are exposed. On the other hand, a structure has such purity properties that total ash content is less than 5ppm and sulfur content is less than 10ppm, and these purity properties restrain a wafer from being contaminated with impurities so as not to deteriorate a semiconductor device in performance if soot is produced. These structural and purity properties are required to be satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon support for a semiconductor manufacturing apparatus used for mounting a wafer in a process of manufacturing a semiconductor device such as an IC and an LSI.

[0002]

2. Description of the Related Art With the development of information equipment typified by computers, semiconductor integrated circuits (LSIs), which are the main constituent devices of those equipment, are required to have a higher degree of integration. At the time of manufacturing a semiconductor device, from the viewpoint of ensuring performance, it is extremely reluctant to mix impurities not only in the raw material but also in the manufacturing process stage, and therefore work is carried out in a clean environment such as a clean room. It is important for a manufacturing apparatus not to generate impurities, and its constituent members are required to have high purity without containing components that adversely affect the semiconductor device.

An important manufacturing process for semiconductor devices is an epitaxial growth process and a plasma etching process.
The epitaxial growth process is a process for growing a semiconductor single crystal on a wafer substrate, and in the case of a Si semiconductor, a vapor phase growth method by CVD is generally adopted. This method uses Si on the susceptor (supporting table) in the epitaxy device.
A wafer is placed on the wafer, and while heating it to a temperature of around 1000 ° C, a silicon halide compound is introduced while entraining it in hydrogen gas, and the single crystal Si produced by the thermal decomposition reaction is deposited and grown on the wafer. High-purity dense graphite or a material obtained by coating the surface of the graphite plate with high-purity SiC has been conventionally used. On the other hand, the plasma etching process is a process in which plasma is generated between an electrode set in the apparatus and a wafer placed on a support table, and a predetermined pattern is formed on the wafer surface by sputtering. A high-purity carbon material is used as the base.

The reason why the carbon material or the coating material having the carbon material as the base material is used as the wafer support for the semiconductor manufacturing apparatus is that the carbon material has excellent heat resistance and chemical stability. This is because high purification and material processing can be easily performed. However, since an ordinary carbon material has a structure composed of an aggregate of fine particles, fine particles are separated from the structure during the treatment process.
It may scatter and impair the performance and yield of the wafer.

Among the carbon materials, the glassy carbon material has an amorphous glassy continuous dense structure, and is a carbon structure which is completely different from the structure composed of aggregates of carbon powder particles like a normal carbon material. Is. The applicant of the present invention has already proposed an attempt to apply the composition as an electrode material for plasma etching by paying attention to this unique texture (Japanese Patent Application Laid-Open No. 62-252942).

[0006]

Since the glassy carbon material has the vitreous continuous dense structure as described above, the structure does not separate as particles during semiconductor production. However, in addition to the particles, fine soot-like substances may be generated to reduce the product yield.

The inventors of the present invention have made extensive studies on the mechanism of generation of the soot-like substances, and as a result, this has a great relation to the texture properties and the purity characteristics of the glassy carbon material. It has been found that when a semiconductor support is constructed, the harmful influence on the semiconductor device is extremely small even in the semiconductor manufacturing process under severe conditions.

The present invention was developed on the basis of the above findings, and an object thereof is to provide a carbon support for a semiconductor manufacturing apparatus which can always obtain a semiconductor product with a good yield in an epitaxial growth process and a plasma etching process. To do.

[0009]

A carbon support for a semiconductor manufacturing apparatus according to the present invention for achieving the above object comprises:
It has a specific gravity of 1.47 or more, the size of the contained pores is less than 20 μm, the pore content is 5% or less, and the total ash content is 5%.
The structural feature is that it is made of a glassy carbon material having a sulfur content of 10 ppm or less and a sulfur content of 10 ppm or less.

The value of each material property of the glassy carbon specified in the above constitution is J in terms of specific gravity and total ash content.
IS R7222-1979 "Physical test method for high-purity graphite material", sulfur content is measured according to JIS M8813-1988 "Elemental analysis method for coals and cokes", and pore diameter is observed by optical microscope or scanning electron microscope. The maximum pore diameter and the pore content (porosity) measured by are the true specific gravity and calculated values from the specific gravity.

According to a study by the inventor, the microstructure of the glassy carbon material internally contains minute pores which are inevitably formed during the production, and thermal decomposition products are deposited in the form of soot on the inner surface of the pores. It has been clarified. For this reason, when the tissue is consumed from the surface due to heating, impact, etc. and the internal pores are exposed, the fine soot-like material is scattered and various adverse effects are exerted on the wafer. The tissue having a specific gravity of 1.47 or more specified in the present invention has a high tissue compactness with a small amount of internal pores, and this tissue property alleviates the degree of exhaustion, and also has the function of reducing the release of soot-like substances during pore exposure. Run. This function is further promoted when the size of the contained pores in the tissue is less than 20 μm and the pore content is 5% or less.

On the other hand, when the total ash content is 5 ppm or less and the sulfur content is
The purity characteristic of 10 ppm or less is a functional requirement for suppressing the impurity contamination of the wafer to the extent that the performance of the semiconductor device is not deteriorated even when soot is generated.
These texture properties and purity characteristics must be satisfied at the same time. For example, even if the specific gravity is 1.47 or less, the total ash content is 5 pp
If the sulfur content exceeds m and the sulfur content exceeds 10 ppm, it becomes impossible to maintain the above-mentioned function at a level that does not reduce the device performance and yield.

The glassy carbon material having the material properties specified in the present invention can be obtained by appropriately adjusting the conditions of each step in the manufacturing technique by the conventional process. First, in order to increase the density of the material, a phenol-based, furan-based, or polyimide-based resin having a residual carbon rate of at least 40% is selectively used as a thermosetting resin as a raw material. Usually, the form of the raw material resin is powdery or liquid, but depending on the form, select the most suitable molding means from molding, injection molding, cast molding, multiple molding, etc., and use it as a support for the semiconductor manufacturing equipment. Mold into a compatible plate shape and
Curing is performed in the temperature range of ~ 180 ° C. At this time, the target specific gravity, pore diameter, and pore content rate are secured by controlling the conditions of selection of raw material resin, molding and curing.

The firing and carbonizing treatment is carried out by filling the cured resin molded body in a graphite crucible or sandwiching it between graphite plates with nitrogen,
It is carried out by heating in an electric furnace which is replaced with an inert gas such as argon, or by encapsulating and heating in a lead gas furnace of a combustion gas heating system with carbonaceous packing. The treatment temperature is usually about 800 to 1500 ° C, but if necessary, graphitization is performed at a high temperature of 2000 ° C or higher.

Total ash content is 5 ppm or less and sulfur content is 10 ppm
In order to ensure the following purity characteristics, a specially manufactured high-purity raw material resin containing no components other than organic substances is cured and baked in an environment free from external impurity contamination, and manufactured according to a conventional method. A method of performing a secondary refining treatment by heating a glassy carbon material in a halogen-based gas atmosphere, or a means of applying both in combination is used. The high-purity raw material resin is preliminarily subjected to adsorption separation, high-purity distillation, chromatography or the like to remove impurities, and then synthesized in a clean room or an environment equivalent thereto in order to prevent environmental pollution from the outside. In order to prevent contamination of impurities during curing and baking, the processing environment is shielded from the outside and replaced with an inert gas such as ultra-high purity argon or nitrogen gas used in semiconductor manufacturing.

[0016]

The carbon support for a semiconductor manufacturing apparatus of the present invention formed from the glassy carbon material having the above-mentioned specific characteristics has a specific gravity of 1.47 or more, the size of the contained pores is less than 20 μm, and the pore content is 5%. % Or less dense continuous texture properties alleviate consumption when heated or sputtered by plasma, and effectively suppress generation of fine soot-like substances. At the same time, the total ash content is 5ppm or less and the sulfur content is 10ppm.
The following high-purity properties suppress the harmful contamination phenomenon of impurities to the wafer to the extent that they are not accompanied.

With such an action, the wafers mounted on the support are not adversely affected through the epitaxial growth process, the plasma etching process, etc., and the semiconductors are stably maintained while always maintaining an excellent yield. It becomes possible to obtain the product.

[0018]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples.

Examples 1 and 2, Comparative Examples 1 to 3 Using phenol and formalin purified by vacuum distillation as raw materials, addition condensation reaction was carried out according to a conventional method to prepare a phenol resin initial condensate (liquid resin). The phenol resin initial condensate is poured into a polypropylene vat and placed in a vacuum desiccator, degassed under a reduced pressure of 10 torr or less, then transferred to an electric oven and cured at a temperature of 100 ° C to a length and width of 300 mm, thickness. A 4 mm plate was molded. At this time, the degree of pressure reduction and the deaeration time were controlled to adjust the specific gravity and the pore state.

Then, the molded plate-like body is treated with impurities of 5 ppm.
High-purity graphite plate of less than [Tokai Carbon Co., Ltd., G347SS]
Packed in an electric furnace in a state of being sandwiched between, and the surrounding ash content is 5 ppm
After encapsulating with the following high-purity graphite powder, the temperature was raised to 1000 ° C. and calcined and carbonized. Subsequently, while introducing chlorine gas into the furnace, heat treatment was performed at a temperature of 2700 ° C. to perform high-purity purification.

The glassy carbon plates produced in the above manner and having different specific gravities, contained pore sizes, pore contents, total ash content and sulfur content, had a diameter of 200 mm in a clean room,
It was processed into a disk shape with a thickness of 3 mm. The susceptor manufactured in this manner was set in a epitaxial growth apparatus, and a Si wafer was placed on the susceptor for epitaxial operation. A 16 megabit LSI was manufactured using the obtained wafer after vapor phase growth. The LSI yield rate (100 tests) in this case is shown in Table 1 in comparison with the material properties of the glassy carbon material on which the susceptor is formed. Comparative Example 3 is an example of a susceptor made of a graphite material [G347SS manufactured by Tokai Carbon Co., Ltd.] having the same purity as that of the example.

[0022]

[Table 1]

From the results shown in Table 1, the examples using the glassy carbon susceptor of the present invention generate soot due to consumption as compared with the comparative example using the glassy carbon member that does not meet the material property requirements of the present invention. And impurity contamination were effectively suppressed, and the LSI yield rate was significantly improved.

Examples 4 to 6 and Comparative Examples 4 to 5 According to the manufacturing methods of Examples 1 to 3 and Comparative Examples 1 and 2, plate-like glassy carbon materials having different texture properties and purity characteristics were prepared. These glassy carbon materials were processed in a clean room to prepare a boring disk-shaped wafer support, which was mounted in a plasma etching apparatus and fitted with a Si wafer. In this state, a plasma etching process was performed on the Si wafer, and the processed wafer was used to manufacture a 16-megabit LSI. LS in this case
The I retention rate (test number: 100) is shown in Table 2 in comparison with the material properties of the glassy carbon material forming the support.

[0025]

[Table 2]

[0026]

As described above, according to the present invention, there is provided a carbon support for a semiconductor manufacturing apparatus, which is formed of a glassy carbon material having a specific property and can be stably used without adversely affecting the wafer. Therefore, a high-performance LSI can be used as a support for mounting a wafer in a semiconductor epitaxial growth process or a plasma etching process.
And the like can be produced with high yield.

Claims (1)

[Claims] 1. The specific gravity is 1.47 or more, and the size of the contained pores is 20 μm.
Possibility of less than 5% and having a pore content of 5% or less,
A carbon support for a semiconductor manufacturing apparatus, which is formed of a glassy carbon material having purity characteristics such that the total ash content is 5 ppm or less and the sulfur content is 10 ppm or less.