JPS6340763A - Carbon tool - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Purpose of the invention [Industrial field of application] Kihatsu 1'J1 relates to a carbon jig, particularly a thin film forming apparatus for forming a thin film on a silicon wafer for semiconductor devices. The present invention relates to a carbon material tool used as a carbon jig that serves both as an electrode and a susceptor, or as a connecting member between electrodes.

[Prior Art] Conventionally, this type of carbon jig involves a step of pulverizing coke to create a powdered carbon material, and then adding a suitable binder to the powdered carbon material and kneading it. , was created by performing a step of molding a cross-wire material to create a molded element, followed by a step of firing the molded element, and then a step of graphitizing the fired element by heat treatment. The carbon jig is placed on a silicon wafer for semiconductor devices and inserted into a hot wall type plasma CVD equipment, and is used as an electrode to perform appropriate heat treatment on the silicon wafer for semiconductor devices. was. Therefore, nitrides or oxides are also deposited on the carbon jig, and as the jig is used over and over again, it becomes increasingly difficult to generate stable plasma, which in turn makes it difficult to form a uniform CVD film on silicon wafers for semiconductor devices. Therefore, it was necessary to remove the attached nitrides or oxides, and the carbon jig was periodically cleaned using Freon gas or the like. With this periodic cleaning, carbon particles tend to fall off from the carbon jig, and there is a risk that they may fall off and adhere to the silicon wafer for semiconductor devices during plasma CVD processing, so this is prevented by IF. Therefore, a SiC film that has good adhesion to carbon and is difficult to peel off is formed on the surface of the carbon jig.

[Problems to be solved] However, with conventional carbon jigs, (1) expensive S
There is a drawback that an iC film must be formed, and (2
) If you try to clean the inside of the plasma CVD equipment with Freon gas, it will react with the Freon gas or SiC and expose the carbon. The cleaning work is complicated and the work is done on the 1st floor.
There were drawbacks such as a decrease in the ratio of 5% and an increase in the cost of cleaning the neck.

Therefore, the present invention aims to eliminate this drawback and provide a carbon gaff tool that does not require the formation of a SiC film and can be cleaned using Freon gas in a plasma CVD apparatus.

(2) Configuration of Problem 11 [IF, means for solving one problem] To this end, the present invention provides the following features:
/CIl:I, bending strength is 400 kgf/cm2 or more,
The carbon jig is characterized by having a specific resistance of 2,000 to 7,000 ΩC, a Shore hardness of 80 or more, and an open porosity of 20% or less.

[Function] The carbon jig of the present invention has a weight of 1.5 to 1.9 g/c■3
This bulk density prevents the surface from becoming too rough and becoming too graphitized.

Having a bending strength of 400 kgf/c or more prevents the bonding force between carbon particles from becoming too weak.
By having a specific resistance of 2,000 to 7,000 gΩC, it prevents the crystallinity of the carbon particles from becoming too good and therefore becoming too flexible, and the amount of heat generated becomes excessive, making it difficult to control the temperature. 80
Having a shore hardness of over 20% prevents it from becoming too flexible, and having an open porosity of 20% or less prevents the voids between carbon particles from increasing too much, which in turn prevents the bonding strength from decreasing too much. As a result, carbon particles are prevented from falling off and adhering during processing of silicon wafers for semiconductor devices in a plasma CVD apparatus.

[Example code] Next, the present invention will be specifically explained with reference to Examples.

(Examples 1 to 7 and Comparative Examples 1 to 10) Next to the step of heat-treating the pitch and making it heavy, the made pitch was crushed by an appropriate crushing means to obtain powdered carbon having an average particle size of 12 gm. Executed the process of creating the material. Powdered carbon material is put into a suitable molding device and molded to 1 ton/cm2.
Next to the process of creating a molded element by molding with an isostatic press under the molding pressure of
A step of firing at a temperature of C was performed. Next, a carbon jig element was created by heat-treating the fired element at 2300°C to graphitize it. Thereafter, the carbon jig body was processed appropriately to create a carbon ftJ box.

The carbon jig element was measured for bulk density and open porosity using the Archimedes method, bending strength was measured using the three-point bending test method, and specific resistance was measured using the voltage drop method.
Shore hardness was measured using a model Shore hardness meter, and true specific gravity was measured using a butanol impregnation method. The measurement results are the first
It was as shown in the table.

The carbon jig was subjected to a life test using a hot wall type plasma CVD device. Table 1 shows the number of cleaning treatments using Freon gas in plasma CVD equipment as the lifespan until carbon particles fall off the surface of the carbon jig and adhere to the silicon wafer for semiconductor devices.

As is clear from Table 1, when the following conditions are satisfied,
You can create carbon jigs with a sufficiently long lifespan.

Bulk density 1.5~1.9g/cm'Bending strength
400kgf/am2 or more Table 1 (“) Life test was discontinued due to risk of cracking.

[c'a'l'/Irf, anti-2000-700
0 uΩc ■ Shore hardness 80 or more Open porosity 20% or less The reason why the bulk density is set to 1.5 to 1.9 g/cm' is that when it is less than 1.5 g/cm3, the surface structure of the carbon jig becomes rough. Moreover, a temperature difference occurs on the surface of the silicon wafer, which is a semiconductor device to be processed, and the thickness of the grown film is kept uniform. Graphitization is good and plasma CVD
The surface of the silicon wafer is easily damaged during plasma cleaning by a plasma CVD apparatus, and carbon particles are also likely to fall off during processing of a silicon wafer for a semiconductor device using a plasma CVD apparatus.

The reason for setting the bending strength to be 400 kgf/c+s2 or higher is that when the bending strength is less than 400 kgf/cm2, the bonding force between the carbon particles that make up the carbon jig is weak and plasma CVD
The surface of the silicon wafer is likely to be scratched during plasma cleaning due to cleaning, and carbon particles are likely to fall off during processing of silicon wafers for semiconductor devices using a plasma CVD apparatus.

In addition, the reason why the resistivity is set to 2000 to 7000 Ωcm is that when the resistivity is less than 2000 gΩcm, the carbon particles constituting the carbon jig have good crystallinity and become flexible, and the surface becomes weaker when plasma cleaning is performed using a plasma CVD device. is easily damaged and carbon particles are likely to fall off when processing silicon wafers for semiconductor devices with plasma CVD equipment.On the other hand, if it exceeds 7000uLΩC■, heat generation of the carbon jig occurs when processing silicon wafers for semiconductor devices with plasma CVD equipment. The amount becomes large, making it difficult to control the temperature.

Furthermore, the reason why the Shore hardness is set to 80 or higher is that if the Shore hardness is less than 80, the carbon jig becomes soft and its surface is easily damaged during plasma cleaning in a plasma CVD device. This is because particles tend to fall off.

Furthermore, the basis for setting the open porosity to 20% or less is that if it exceeds 20%, the voids between the carbon particles that make up the carbon jig will increase, and the bonding strength will decrease.
The problem is that carbon particles tend to fall off when processing silicon wafers for semiconductor devices using the equipment.

As is clear from Table 1, if the true specific gravity is 2.05 or less, the life of the carbon jig can be further extended.

At this time, the basis for setting the true specific gravity to be 2.05 or less is 2.05
If the carbon jig is exceeded, the carbon particles constituting the carbon jig have good crystallinity and are flexible, and the carbon particles are likely to fall off during processing of silicon wafers for semiconductor devices using a plasma CVD apparatus.

(3) Effects of the invention As is clear from the above, the carbon jig of the present invention has a bulk density of 1.5 to 1.9 g/cs' and a bending strength of 400 kg.
f/cm" or more, specific resistance 2000-7000 IL
ΩC■.

Since the Shore hardness is 80 or more and the open porosity is 20% or less, (1) the bonding force of carbon particles is strong and plasma CVD is
It also has the effect of preventing carbon particles from falling off when processing silicon wafers for semiconductor devices with the equipment, and as a result, (2) SiCII! 2, there is no need to perform wet cleaning, and the cleaning work can be carried out at a high rate of cleaning, and (3) the cleaning device can be made at a low cost. Furthermore, the present invention has the advantage of (4) not only providing a member that serves as an electrode susceptor for use in a thin film forming apparatus, but also providing a connecting member between electrodes.

Claims (2)

[Claims] (1) Bulk density 1.5~1.9g/cm^3, bending strength 400kgf/cm^2 or more, specific resistance 2000~
A carbon jig characterized by having a Shore hardness of 7000 μΩcm, a Shore hardness of 80 or more, and an open porosity of 20% or less. (2) The carbon jig according to claim (1), characterized in that the true specific gravity is 2.05 or less.