JPH0560650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma etching apparatus with an improved electrode structure for introducing gas necessary for generating plasma.

[Problems to be solved by conventional technology and invention]

Conventionally, when gas is introduced between the electrode surfaces of opposing electrodes, the material of the gas introduction part has been aluminum, stainless steel,
Graphite, glassy carbon, porous sintered quartz, alumina sintered bodies, etc. have been used.
Using materials such as aluminum and stainless steel,
If a gas inlet with many mechanical holes is used, aluminum, nickel, etc. that make up the material may be spattered, contaminating the workpiece, or causing reaction products to be deposited on the workpiece. However, there were problems in that some residual energy remained and the electrical characteristics deteriorated. In addition, when mechanically perforated glassy carbon is used as the gas introduction part, microcrystals are generated by thermal shock during sputtering, and these microcrystals are deposited on the workpiece. There was a problem that contamination occurred due to adhesion to the surface. Similarly, when graphite is used as the gas introduction part, there is a problem in that part of the graphite peels off and adheres to the workpiece, causing contamination. Furthermore, when porous sintered quartz is used as the gas introduction part, there is a problem in that the porous sintered quartz itself is also etched when etching the silicon dioxide film.

Furthermore, in the case of this sintered quartz, the pore diameter is 90 to 3000 Å, which is quite small, and the flow rate required for dry etching, etc., at a differential pressure of 0.5 to 1 Kgf/cm ² is, for example, about 300 c.c./cm 2 . When trying to obtain min, there is a problem that the number of pores increases and the strength of the porous body becomes weak. Furthermore, since the manufacturing method involves sintering powdered glass whose particle size is uniform to a certain extent, there is a problem in that the pore size and number of pores cannot be controlled as desired.

In addition, the thickness of this porous body is usually 3 mm.
It is desirable to keep the amount below. The reason for this is that the dielectric material corresponding to the thickness is inserted between the electrodes, causing attenuation of the power supplied for plasma generation. Therefore, if a porous sintered body of quartz with a thickness of 3 mm or less is to be made to cover an electrode of a normal size of 150 to 220 mm in diameter, it would be quite difficult to make it strong. Furthermore, in sintered quartz, which has small pore diameters of only 90 to 3000 Å at most, when etching SiO ₂ films, various reaction products generated by gas plasma reactions during etching may be blown out. deposits in the mouth,
There is a problem in that the holes are blocked or the gas blowing becomes non-uniform, resulting in non-uniform etching.

Alumina (Al ₂ O ₃ ) sintered bodies have a large dielectric loss, so placing the sintered bodies between electrodes and applying high-frequency power will reduce the plasma generation efficiency and cause the surface to deteriorate. There was a problem in that when exposed to plasma and spattered, alumina or decomposed aluminum became a source of contamination.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides that a sintered body containing a carbon compound as a main component is disposed on the electrode as a gas introduction part for introducing gas between opposing electrodes, and a sintered body that is attached to the electrode is By employing a configuration in which a conductive homogeneous material is attached to the inside of the sintered body to make electrical connections, it is possible to reduce the occurrence of contamination and improve plasma generation efficiency.

FIG. 1 shows a side sectional view of the basic configuration of the present invention. In the figure, 1 is a gas pipe for introducing gas, 2 is a gas introduction part made of a sintered body whose main component is a carbon compound, and 3 is a conductive material such as a sputtered aluminum film attached to the inside of the gas introduction part. material,
Reference numerals 4 and 6 represent electrodes for generating plasma by discharging, 5 represents a workpiece for performing ion etching, etc., and 7 represents a high frequency power source.

In FIG. 1, the gas introduction section 2 is the gas pipe 1.
It is for introducing the gas that has flowed in between the electrodes 4 and 6, and is made of a sintered body whose main component is a carbon compound. Gas that has flowed in through the gas pipe 1 is introduced between the electrodes 4 and 6 from the gas introduction section 2 . By supplying high frequency power from a high frequency power source 7 between the electrodes 4 and 6, the introduced gas is turned into plasma and the workpiece 5 placed on the electrode 6 is etched.

[Effect]

As shown in FIG. 1, gas that has flowed in through a gas pipe 1 is uniformly blown onto a workpiece 5 via a gas introduction section 2 according to the present invention. In addition, since a sintered body containing a carbon compound as the main component is used as the gas introduction part 2 that sprays gas onto the workpiece 5, even if the gas introduction part 2 is exposed to plasma, it will not be exposed to metal contaminants such as aluminum. Especially when a fluorine-based gas is used, the reaction products are mostly volatile and are not deposited on the workpiece 5. Furthermore, since a conductive substance 3 is attached to the inside of the gas introduction part 2, which is made of a sintered body mainly composed of carbon compounds, to give it conductivity, there is little loss of power, and stable and high-density plasma can be generated. can be generated with good efficiency.

〔Example〕

FIG. 2 shows a side sectional view of one embodiment of the present invention. In the figure, 8 represents a processing tank, and 9 represents an electrode ring for electrically connecting the gas introduction part 2 and the electrode 4. Note that 1 to 7 in the figure correspond to those shown in FIG. 1, respectively.

In FIG. 2, gas flowing in through the gas pipe 1 spreads into the space formed between the electrode 4 and the gas introduction section 2. In FIG. Then, the gas that has passed through the gas introduction section 2 made of a sintered body containing a carbon compound as a main component is blown onto the workpiece 5 placed on the electrode 6. When high frequency power generated by a high frequency power source 7 is supplied between the electrodes 4 and 6 in this state, plasma is generated between the electrodes and the workpiece 5 can be etched.

At this time, using a sintered body containing a carbon compound as a main component as the gas introduction part 2 is effective in preventing contamination of the workpiece 5 and efficiently generating plasma. Carbon compounds, especially covalent carbides, are chemically stable and difficult to be eroded by plasma. Covalent carbides that can be used include silicon carbide (SiC) and boron carbide (B ₄ C).
It is advantageous to use silicon carbide, which is strong in terms of manufacturing strength and easy to obtain as a material with high purity.

Also, as in the present invention, the diameter of the gas nozzle can be
By selecting a diameter of about 0.2 to 0.5 mm, strong discharge is less likely to occur in the hole portion, and by providing holes at appropriate intervals, gas can be ejected with good uniformity. Furthermore, as a porous material, the average pore diameter is 20 or more.
By setting the diameter to about 500 μm, clogging due to reaction products can be prevented, and gas can be blown more uniformly than in the case where the holes are formed mechanically.

When silicon carbide is used as a carbon compound, it has superior corrosion resistance compared to quartz or alumite (aluminum anodic oxide film), and is suitable for use with fluorine gases such as CF ₄ and CHF ₃ used when etching SiO ₂ films. It can withstand plasma well and can be etched uniformly. Also, it has lower thermal shock resistance than alumina.
This is particularly advantageous for gas ejection plates with exposed plasma surfaces that are about 100 to 200 degrees Celsius and difficult to cool.

The conductive film added to the sintered body is applied to a thickness of, for example, 1 μm or more by sputtering or the like in order to obtain the necessary adhesion strength. When this conductive film is deposited, even if the distance between the electrodes 4 and 6 is reduced to perform high-speed etching, for example, the plasma is generated more than when the conductive substance 3 is not deposited. Not only can the plasma be generated in a much more stable manner, but also the distance between the electrodes can be further reduced to increase the plasma density and increase the etching rate. Here, the third section schematically describes the conductive film added to the sintered body.
This will be explained in detail using figures. When a conductive film is sputtered onto a sintered body that has a hole, the sputtered film adheres to the side wall of the hole, as shown in the figure, but the hole is not filled. This means that the diameter of the hole is approximately 0.2 to 0.5 mm, and the thickness of the membrane is 1 μm.
This is because it is sufficiently thin, about 300 ft (m), so that the hole will not be bridged and filled. Also, this thickness is 1μ
By sputtering and adhering a conductive film with a thickness of about m to the sintered body and connecting it to the electrode 4 with the electrode ring 9 shown in FIG. 2, the distance between the opposing electrode 6 can be shortened and the power Stable, high-density plasma can be efficiently generated with less loss.

〔Effect of the invention〕

As explained above, according to the present invention, as a gas introduction section that introduces gas between opposing electrodes,
Since it uses a structure in which a sintered body whose main component is a carbon compound is attached to the electrode, there is no contamination of the workpiece, and the inner surface of the gas introduction part is made of a sintered body of a carbon compound. Because a conductive substance is attached to the surface, stable and high-density plasma can be generated.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the basic configuration of the present invention, FIG. 2 is a side sectional view of one embodiment of the present invention, and FIG.
The figure shows an explanatory view of a sintered body and a conductive film of the present invention. In the figure, 1 is a gas pipe, 2 is a gas introduction part, 3 is a conductive material, 4 and 6 are electrodes, 5 is a workpiece, and 7 is a high frequency power source.

Claims (1)

[Claims] 1. A workpiece placed on the electrodes is processed by introducing gas injected from the electrode surface between opposing electrodes and supplying high frequency power between the electrodes to generate plasma. In a plasma etching device for etching, a sintered body mainly composed of a covalent carbon compound is placed on a corresponding surface of one of opposing electrodes, and the sintered body is A gas introduction part 2 is provided with the inner surface not facing the electrode having good conductivity and electrically connected to the electrode, and the gas injected through the gas introduction part 2 of this sintered body is turned into plasma and the workpiece is heated. A plasma etching device characterized in that it is configured to etch.