JPS63162588A - Electroconductive porous silicon carbide sintered body and manufacture - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a novel conductive porous silicon carbide sintered body suitable for use in electrodes of plasma etching equipment, etc., and an effective method for producing the same.

(Prior Art) It is well known that plasma etching is employed in the preparation of silicon wafers and the like. In this plasma etching method, a silicon wafer on which an AQ or SiO□ film is formed and the non-etched areas are masked with resin is placed on the positive electrode, while a punched porous metal plate is attached to the negative electrode, and etched under reduced pressure. A voltage is applied between the two electrodes while supplying chlorine or fluorine gas through the punched hole in the negative electrode plate, and the AQ or SiO□ film is etched with plasma ions.

(Problem that the invention seeks to solve).

However, in the above plasma etching method.

Since plasma ions are emitted only from the punched holes in the porous metal plate, uniform etching is not achieved and so-called uneven etching inevitably occurs.

In the preparation of electronic parts such as silicon wafers, which require increasingly high performance, such etching unevenness has been pointed out as a problem that must be solved as soon as possible.

On the other hand, attempts have also been made to impart electrical conductivity to silicon carbide sintered bodies; one example of this is to add an aluminum compound as an auxiliary agent and a carbon source to a silicon carbide raw material, and then shape and sinter the mixture. It will be done. However, this sintered body was dense and could not be used as an electrode in the plasma etching apparatus.

(Object of the Invention) The present invention has been made in view of the above, and provides a novel silicon carbide sintered body that enables uniform plasma ion emission when used as an electrode of a plasma etching device, and an effective manufacturing method thereof. This is what we intend to provide.

(Means for Solving the Problems) The present invention for achieving the above object will be described in detail. That is, the specific invention of the present invention contains a large number of pores communicating between the inside and outside, and carries residual carbon resulting from sintering decomposition of organic hydrocarbons in the sintered structure, and this residual carbon imparts conductivity. The second invention is a conductive porous silicon carbide sintered body, and the second invention is to mold a fine-grained silicon carbide raw material into a desired shape and sinter it to form a porous sintered body. It is impregnated with a solution of a self-burning organic hydrocarbon compound and fired at a temperature higher than the decomposition temperature of the organic hydrocarbon compound to support residual carbon resulting from the firing decomposition of the organic hydrocarbon in the sintered structure of silicon carbide, thereby making it conductive. The present invention provides a method for producing a conductive porous silicon carbide sintered body that is imparted with properties.

For convenience, the specific invention and the second invention will be explained together.

The conductive porous silicon carbide sintered body of the present invention has a pore diameter of 1 to 6.
It has a diameter of 0 μm, a pore volume of 0.1 to 0.3 cc/g, and contains many pores communicating between the inside and outside. This pore has an average particle size of 5 to 20
It is formed by sintering a 0 μm silicon carbide raw material at about 1900 to 2200°C, and the sintered body has air permeability due to the presence of the pores. In this case, if the pore diameter is less than 1 μm and the pore volume is less than 0.1 cc/g, sufficient air permeability cannot be obtained, whereas if the pore diameter is more than 60 μm and the pore volume is more than 0.3 cc/g, the strength of the sintered body will be becomes weaker.

Additionally, in the structure of the sintered body of the present invention, residual carbon due to sintering decomposition of organic hydrocarbons is present in an amount of 1 to 1 to 100 parts by weight per 100 parts by weight of the sintered body.
15 parts by weight is supported, thereby making the volume-specific low dynamic value of the sintered body 0.05 to 60 Ω·mm. If the supported amount is less than 2 parts by weight, sufficient conductivity will not be imparted to the sintered body,
On the other hand, even if more than 15 parts by weight is supported, no significant change is observed in the volume resistivity value. This residual carbon is supported by molding and sintering the above-mentioned fine-grained silicon carbide raw material into a desired shape, and converting this sintered body into a self-burning organic carbonization material such as phenol resin, furfuryl alcohol, polyphenylene, dibbeds anthracene, and chrysene. Impregnated with a solution of hydrogen compound, about 200
This is done by firing at a temperature of 0°C. The impregnation amount of the organic hydrocarbon compound solution is 4 to 35 parts by weight per 100 parts by weight of the sintered body, and if it is outside this range, it will not be possible to obtain the appropriate amount of residual carbon supported as described above.

(Function) The conductive porous silicon carbide sintered body of the present invention having the above-mentioned structure is formed by molding a fine-grained silicon carbide raw material into a desired shape and firing it. It contains a large number of pores that are evenly distributed and communicate with each other from inside to outside, and has air permeability through these pores. Additionally, the structure of the sintered body carries residual carbon resulting from the sintering decomposition of self-burning organic hydrocarbons, and the presence of this residual carbon reduces the volume resistivity and imparts electrical conductivity. . Therefore, when the sintered body of the present invention is used as a positive electrode of a plasma etching apparatus as shown in Examples below,
! In addition to functioning well as a pole, plasma ions are emitted uniformly through the pores to ensure uniform etching.

(Example) EXAMPLES The present invention will be explained in further detail with reference to Examples below.

(i) Preparation of porous sintered body; A silicon carbide raw material having an average particle size shown in Table 1 below was formed into a plate shape, and this was sintered at 2000°C to obtain a porous sintered body. . The pore diameter and porosity of the pores formed in this sintered body, and the bulk specific gravity of the sintered body were measured. The results are shown in Table 1.

However, the evaluation column in Table 1 mainly evaluates whether the strength is appropriate when used as an electrode in a plasma etching device, where 0 means good, Δ means slightly unsuitable, and × means unsuitable. show.

(n) Imparting conductivity; The porous sintered sample obtained from Na3 in Table 1 was impregnated with a phenolic resin solution, and
It was fired at a temperature of 0°C. The amount of residual carbon and volume resistivity were measured for samples with various amounts of impregnating resin solution. The results are shown in Table 2.

In Table 1, however, the values in the columns of the impregnated amount of phenol resin solution and the amount of residual carbon in Table 2 are parts by weight based on 100 parts by weight of the porous sintered body (sample Nα3).

It is understood from Table 2 that when residual carbon is supported within the structure of the sintered body, the volume resistivity value is extremely reduced and the sintered body is imparted with electrical conductivity. It is also presumed that the volume resistivity value can be arbitrarily changed by adjusting the amount of phenol resin solution impregnated.

(in) Application to plasma etching equipment; Figures 1 and 2 are examples in which the conductive porous silicon carbide sintered body obtained by the procedures in (i) and (ii) above is applied to the positive electrode of a plasma etching equipment. FIG.

In Fig. 1, positive and negative electrodes 3.2 are arranged in a facing relationship in a vacuum box 1, and the cross section is approximately inverted T.
The negative electrode 2 has a plasma gas supply conduit 21, and substantially the entire lower surface of the negative electrode 3 includes the supply conduit 21.
A radiation region 22 of plasma gas is recessed and communicated with the plasma gas. A conductive porous silicon carbide sintered plate 4 of the present invention is fixedly fixed so as to cover the radiation region 22 . On the other hand, a silicon wafer 5 is placed on the positive electrode 3, on which a coating film 51 of AQ or Sin is coated and further a printed resin coating layer 52 of a desired pattern is formed. In this state, while reducing the pressure inside the vacuum box 1 (approximately 0.8 t, o
rr), chlorine or fluorine gas is supplied from the supply pipe 21, and a voltage is applied between the electrodes 2.3 (300s, 13.
5 MHz), the plasma gas emitted from the radiation region 22 through the pores of the sintered plate 4 is ionized, and the coating film 51 of the silicon wafer 5 placed on the positive electrode 3 is ionized.
etching. At this time, since plasma ions are uniformly emitted from the sintered plate 4, the coat film 51 is etched evenly and uniformly.

In FIG. 2, the radiation area 22 of the plasma gas is made larger than the supply pipe 21, which is different from the plasma gas emitted from a wide area as shown in FIG. However, plasma ions are emitted from the sintered plate 4 fixedly fixed to substantially the entire area of the lower surface of the negative electrode 2 from the entire area. That is, the plasma gas that has reached the sintered plate 4 from the supply pipe line 21 is diffused within the sintered plate 4 in the area direction.

The radiation is emitted from substantially the entire area of the lower surface, and the same function as in the case of FIG. 1 is performed.

5 In the above example, an example was shown in which the sintered body of the present invention was applied to a plasma etching device, but it is possible to apply it to other fields by taking advantage of the characteristics of being porous and ceramic. It is.

Furthermore, in addition to supporting residual carbon over the entire surface of the sintered body, for example, when impregnating the sintered body with an organic hydrocarbon solution, conductivity can be imparted only to the desired area of the sintered body by impregnating it partially. It is also possible.

(Effects of the invention) As mentioned above, the conductive porous silicon carbide sintered body of the present invention has the following effects:
It has air permeability due to its large number of pores, and conductivity due to the presence of residual carbon, so if it is used as the positive electrode of a plasma etching device, plasma gas will be emitted uniformly, resulting in even etching. It will definitely be done.

Therefore, it is extremely suitable for preparing silicon wafers, etc., which require increasingly high performance, and will greatly contribute to the technological development of this field. In addition, the method for producing this sintered body is extremely simple and allows the use of conventional equipment, since almost all conventional silicon carbide sintering techniques are applied except for impregnation with organic hydrocarbon and firing. As described above, the usefulness of the present invention is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing an example of a plasma etching apparatus to which the conductive porous silicon carbide sintered body of the present invention is applied;
FIG. 2 is a schematic vertical cross-sectional view showing an example of the same area. (Explanation of symbols) 1...Vacuum box, 2...Negative pole, 2
DESCRIPTION OF SYMBOLS 1... Plasma gas supply pipe line, 22... Plasma gas radiation area, 3... Positive electrode, 4... Conductive porous silicon carbide sintered plate, 5... Silicon wafer, 51 ...Coat film, 52...Printed resin film. -And more-

Claims (1)

[Claims] 1. Contains a large number of pores communicating inside and outside, and supports residual carbon from sintering decomposition of organic hydrocarbons in the sintered structure;
A conductive porous silicon carbide sintered body imparted with conductivity by this residual carbon. 2. Fine-grained silicon carbide raw material is molded into a desired shape and fired to form a porous sintered body, and this sintered body is impregnated with a solution of a self-burning organic hydrocarbon compound, and the organic hydrocarbon compound is impregnated with a solution of a self-burning organic hydrocarbon compound. A conductive porous silicon carbide sintered body which is fired at a temperature higher than the decomposition temperature of the compound to support residual carbon from the sintered decomposition of the organic hydrocarbon in the sintered structure of the silicon carbide, thereby imparting electrical conductivity. Production method.