JPH0333007A - Carbon member for plasma device - Google Patents

Abstract

PURPOSE:To improve the oxidation resistance and durability of the carbon member by specifying the porosity and impurity content of a vitreous carbon material obtained by carbonizing and calcining a resin, etc., and in which crystallites are not detected by X-ray diffraction. CONSTITUTION:A thermosetting resin such as furan resin is formed into a desired shape and cured at a low heating rate to obtain a cured body. The cured body is then carbonized and calcined at the heating rate of about 1 deg.C/hr in an inert atmosphere (e.g. inert atmosphere free of oxygen and consisting of >=1 kind selected from He, Ar, N2, H2, etc., reduced pressure, vacuum or atmosphere isolated from air). The obtained calcined product is purified at about 2300 deg.C to obtain a vitreous carbon material having 0.02-0.2% porosity, in which crystallites are not detected by X-ray diffraction and contg. <=5ppm impurities. A carbon member for the plasma device is then produced from this carbon material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a thin film on a silicon wafer for a semiconductor device, which is made of glassy carbon obtained by carbonizing and firing a thermosetting resin. type plasma C
The present invention relates to a carbon member such as a carbon plate or a carbon electrode plate used in a VD device, or a material for a connection between electrodes, and a carbon member for a plasma device used in an electrode plate for a reactive sputter etching device.

[Conventional technology]

In general, when a cured thermosetting resin that has a three-dimensional network structure and is insoluble and infusible is carbonized in an inert atmosphere, it has excellent gas impermeability, high hardness, and an isotropic structure. A glassy carbon material having the following properties is obtained.

This glassy carbon material has the characteristics of light weight, heat resistance, high electrical conductivity, corrosion resistance, high thermal conductivity, mechanical strength, and lubricity that ordinary carbon materials have, and is also homogeneous and suitable for use in sliding parts. It has the property of not producing carbon powder such as shavings, even when exposed to carbon dioxide, and is expected to be used in a wide range of fields, including the electronics industry, nuclear industry, and aviation industry.

Recently, attention has been focused on the characteristics of this glassy carbon material, and by improving the characteristics such as low temperature oxidation resistance by gas required for sputter etching, it has been possible to use the glassy carbon material as an electrode plate for reactive sputter etching. is being considered.

In addition, we are considering using it as a jig for CVD equipment, such as carbon plate or carbon disk electrodes used in hot wall type plasma CVD equipment that forms thin films on silicon wafers for semiconductor devices, or connection material between electrodes. has been done.

Conventionally, easily graphitizable carbon materials made from this kind of pitch etc. have been produced by grinding coke to produce a powdered carbon material, and then adding an appropriate binder to the powdered carbon material and kneading it. After carrying out the process of forming the cross-wire material to form a molded element, the process of firing the molded element is carried out, and the fired element is further graphitized by heat treatment. Ta.

Most of the currently commercialized glassy carbons are
■A thermosetting resin is used as a raw material, and the resin is repeatedly applied and hardened thinly using a brush, spray, or centrifugal method on a base of a predetermined shape, and then it is shaped, and then it is fired. This material was made into resin powder, molded, and then fired to obtain glassy carbon.

[Problem that the invention seeks to solve]

According to the above-mentioned manufacturing method, it is not possible to prevent the formation of pores due to voids during molding, dissipation of volatile components during heat treatment, etc.

Furthermore, the size and distribution of pores vary depending on the size of aggregate particles, the type of binder, the manufacturing process, etc., and the physical properties related to pores become extremely complex.

When conventionally produced glassy carbon materials are observed under a microscope, open pores exist on the surface of the glassy carbon and closed pores exist inside.

Due to the open pores unique to glassy carbon, the specific surface area increases, resulting in a decrease in oxidation properties and strength, and the amount of adsorbed gas on the glassy carbon surface increases, resulting in sputter-etched products and CVD treatment. It has become a problem because it is mixed into products that use ingredients, increasing the impurity content of the products.

Furthermore, if independent closed pores exist in the material part, the internal closed pores will appear on the surface by polishing and become open pores, resulting in a phenomenon similar to the above-mentioned problem.

The method (2) described in detail in the above conventional technique has a problem in that many open pores and closed pores exist in the laminated part of the resin after firing, and the method (2) uses resin powder, so there are no gaps between the particles. Grain boundaries exist in carbon, and properties such as mechanical strength and porosity are inferior to ordinary glassy carbon, and carbon particles tend to fall off.

In any case, regarding the final fired product, it is still impossible to manufacture a thick product because the internal gas cannot be controlled during the resin curing and firing stages.

In particular, silicon wafers for semiconductor devices are placed,
On a carbon jig as an electrode for performing appropriate heat treatment on a silicon wafer for semiconductor devices while inserted into a hot wall type plasma CVD apparatus,
Nitride or oxide adheres, and as the number of times it is used increases, it becomes increasingly difficult to generate stable plasma, resulting in uniform CV on silicon wafers for semiconductor devices.
Since the D film is no longer formed, it is necessary to remove the adhered nitride or oxide, and the carbon jig is periodically cleaned using Freon gas or the like.

However, there is a risk that carbon particles may fall off from the carbon jig during the cleaning, fall off during plasma CVD processing, and adhere to a silicon wafer for a semiconductor device.

In order to prevent this phenomenon of carbon particles falling off, there is a method of forming a glassy carbon film or a pyrolytic carbon film on the surface of the carbon jig, but there are also methods to improve the mechanical strength of the film itself and the peeling of the film itself. There was a problem.

[Means for solving problems]

In view of the above-mentioned problems, in the present invention, the porosity (determined by multiplying the total volume value obtained when a pressure of 1°Okg/aJ is applied by mercury intrusion method by the density) of a glassy carbon material is determined by using conventional impurities. We developed glassy carbon whose content was suppressed to less than one tenth to one tens of thousands of times lower, and aimed to produce glassy carbon without particle interfaces.

That is, by using a fluid thermosetting resin as a starting material, the porosity can be reduced to 0.0002 to 0.0.
020% and whose crystallites are not detected by X-ray diffraction, and have also developed electrode plates and CVD jigs made of glassy carbon materials with an impurity content of 5 ppm or less.

As a result of cumulative research aiming at empirical theoretical values, thermosetting resins polymerized to give fluidity as a starting material were molded and cured in an inert atmosphere (not containing oxygen, usually helium, argon, or nitrogen). , under an atmosphere consisting of at least one type of inert gas such as hydrogen, halogen, etc., under reduced pressure or vacuum, or under a state where the atmosphere is shut off)
Carbonization is carried out at a slow heating rate (e.g. 1°C/hr) in the chamber, and finally a purification treatment is performed to produce glassy carbon with a porosity of 0.0002 to 20%, which is the same as the empirical theory. obtain.

The reason for using a fluid thermosetting resin as the starting material in the above method is that when the aggregate itself is shaped into a resin powder and fired after molding, grain boundaries exist between the particles of the resin powder.
This is to suppress the adverse effects of deterioration of properties such as mechanical strength and porosity.

The porosity of the glassy carbon obtained by carbonization firing is 0.
The reason why the porosity is 0.002 to 0.0020% is 0.002% to 0.0020%.
If it exceeds 0.020%, open pores and closed pores exist, independent closed pores become open pores by polishing, and the oxidation properties and strength are still greatly reduced due to the increase in specific surface area.

Further, when the porosity is reduced to 0.0002% or less, the density of the glassy carbon becomes significant, and when used over many cycles, cracks occur due to the accumulation of thermal stress.

Glassy carbon in which the crystallites of the glassy carbon material are not detected by X-ray diffraction does not have particle interfaces and does not suffer from a decrease in oxidation resistance due to a decrease in strength or an increase in specific surface area.

The impurity content of the glassy carbon material is 511p111
When the amount is below, adverse effects such as contamination on the silicon wafer attached to the counter electrode are suppressed.

Examples of thermosetting resins used in the present invention include furan resins, phenolic resins, epoxy resins, unsaturated polyester resins, urea resins, Melacin resins, alkyd resins, xylene resins, etc. Alternatively, it is preferable to use a modified furan resin by blending or modifying it.

The thermosetting resin used in the present invention is molded according to the purpose before curing, and then carbonized and fired in an inert atmosphere at a temperature of 450°C or higher, preferably 800°C, more preferably 1000°C or higher to achieve the desired glassy shape. Carbon.

If the firing temperature is below 450°C, the thermosetting resin will not carbonize,
The porosity becomes high and does not fall within the desired porosity range, and the characteristics of the glassy carbon targeted for development are not imparted.

Note that the J carbonization firing time can be appropriately selected depending on the firing temperature, but a slower one is preferable.

[Function and Examples]

(Example 1) Furfuryl alcohol monomer and p-toluenesulfonic acid were appropriately stirred and mixed and polymerized to obtain a fluid polymer.

Water generated during polymerization was removed by a vacuum method or the like.

After defoaming the produced furfuryl alcohol polymerization liquid, it is molded into a bottom shape in a mold, and heated at a slow temperature increase rate (1°C/hr) in a drying layer.
) to harden.

The obtained cured body is fired in an inert atmosphere at a heating rate of 2°C/hr, and finally purified at 2300°C to obtain a glassy carbon material for an electrode plate for a reactive sputter etching device with the desired porosity. I got it.

(Tables 1 and 2 and Table 2 1) (Example 2) Powdered furan resin was heated at 150°C, hot-pressed, and the resulting cured product was heated at 2°C/2°C in an inert atmosphere.
Firing was performed at a temperature increase rate of hr, and finally purification treatment was performed at 2300°C to obtain a glassy carbon material. (Table 1 3-4 and Table 2 2) (Comparative Example 1) After molding powdered furan resin at room temperature using a rubber press,
Burning was performed in an inert atmosphere at a heating rate of 2° C./hr, and finally purification treatment was performed at 2300° C. to obtain a glassy carbon material. (Tables 2-3 to 7) Tables 1 and 2 show the relationship between the porosity and life of the glassy carbons of the above Examples and Comparative Examples.

Table 1 Table 2 Note that the life in the above table is A at the opposite end of the glassy carbon material.
A N-quality electrode plate was provided, a silicon wafer was placed on the Al11i electrode plate, and after depressurization CHF3, CF a , A
The SiN film is etched on the silicon wafer by flowing r % He % Oz gas or the like to generate plasma, but the glassy carbon is oxidized and consumed by the flowing oxygen-based gas and the generated plasma.

Here, the initial thickness of the glassy carbon electrode plate was unified to 3H, and the point at which the residual thickness reached 0.5 mm was defined as the life end.

As Tables 1-2 show, the low porosity glassy carbon electrode plates of the present invention provide significant improvements in reactors under oxygen-containing conditions compared to conventional ones.

(Example 3) Adding p to thermosetting resin such as phenolic resin or furan resin
-) After adding an acid catalyst such as luenesulfonic acid, defoaming treatment is performed, and after forming a bottom shape, it is slowly cured at 200°C.

The obtained cured body was heat-treated at 2000°C in an inert atmosphere to obtain glassy carbon, which was then subjected to a purification treatment to form a CVD product made of glassy carbon containing the desired porosity.
A carbon jig for the device was obtained.

(Table 3 1-2) (Example 4) Powdered furan resin was heated at 150°C and subjected to hot press treatment, and the resulting cured product was heated at 200°C in an inert atmosphere.
A heat treatment was performed at 0° C. to obtain glassy carbon, which was then subjected to a purification treatment to obtain a carbon jig for a CVD device. (Table 3 3~
4 and Table 4 1) (Comparative Example 2) After molding powdered furan resin using a rubber press, the resulting cured product was heat treated at 2000°C in an inert atmosphere to obtain glassy carbon and purification. The treatment was carried out to obtain a carbon jig for a CVD device.

(Table 4 2-6) CV of glassy carbon in the above examples and comparative examples
Tables 3 and 4 show the relationship between the porosity and life of the carbon jig for D device.

As shown in Tables 3 and 4, the life of the carbon member for plasma equipment of the present invention is significantly improved compared to the conventional carbon member.

In addition, an oxidation consumption test was conducted in which the carbon CVD jigs of the above examples and comparative examples and the carbon CVD jigs coated with glassy carbon were left in the air at a temperature of 800°C. As shown, the product of the present invention has a low weight loss rate even after 5 hours and has excellent oxidation resistance, whereas the glassy carbon coated product almost loses its shape after 4 hours, and the conventional product has a low weight loss rate even after 5 hours. The oxidation consumption rate is more than twice that of the standard product, and the oxidation resistance is inferior.

〔Effect of the invention〕

The carbon member for plasma equipment of the present invention is produced by molding and curing a fluid thermosetting resin as a starting material, followed by carbonization firing and purification treatment, resulting in a highly pure carbon member with low porosity crystallites that cannot be detected by X-rays. Since glassy carbon is used, it is possible to provide a long-life product with excellent oxidation resistance and durability.

[Brief explanation of drawings]

Figure 1 shows a CVD jig using the carbon member for plasma equipment of the present invention, and a glass-like carbon coating CVD
The results of oxidation consumption tests of CVD jigs and conventional CVD jigs are shown. Δ: Inventive product ○; Conventional product B; Coated product

Claims (1)

[Claims] The porosity of the glassy carbon material obtained by carbonization firing is 0.0002 to 0.0020%, crystallites of the glassy carbon material are not detected by X-ray diffraction, and the impurity content is 5 ppm or less. A carbon member for a plasma device, characterized in that it is made of the glassy carbon material.