JPH04316326A - Plasma processing system - Google Patents

Abstract

PURPOSE:To suppress production of dust in a plasma processing system by coating an upper electrode plate having gas holes completely with an insulating film and preventing the upper electrode plate from being sputtered even if it is exposed directly to plasma. CONSTITUTION:An upper electrode plate 30 is composed of tungsten or molybdenum and the surface thereof is applied completely with an SiC coating 31 through CVD method. When such upper electrode plate is employed, residue is reduced after plasma cleaning and a plasma processing system where production of dust is suppressed can be obtained and thereby the yield of semiconductor device is increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus suitable for etching a semiconductor element substrate using plasma.

0002

2. Description of the Related Art FIG. 2 is a schematic sectional view of a conventional plasma processing apparatus, and first, a schematic plasma processing will be explained using this diagram. 1 is a processing chamber which is kept in a high vacuum state. Reference numeral 2 denotes an upper electrode, on the lower surface of which an upper electrode plate 3 is fastened and fixed with a tightening screw 4 (made of alumina or the like), and has a structure in which electrical current can be passed through a conductive surface 5. 6
7 is a processing gas supply hole provided in the upper electrode 2, and 7 is a large number of processing gas blowing holes provided in the upper electrode plate 3. Reference numeral 8 denotes a lower electrode arranged in parallel with the upper electrode 2 and at a constant interval. A semiconductor wafer 9 is placed on top of the lower electrode 8, and the wafer holder 10 made of an insulating material such as alumina is used to prevent the wafer from moving due to pressure fluctuations, etc. I have to. This lower electrode 8 has a coaxial cable 1
A high frequency power source 12 is connected via 1.

Next, the operation will be explained. When the high frequency power supply 12 is applied with the upper electrode 2 grounded, plasma is generated between the upper electrode 2 and the lower electrode 8, which activates the ions of the processing gas and reaches the surface of the semiconductor wafer 9. Patterns on the surface of a semiconductor wafer are vertically etched while generating reaction products.

By the way, at this time, reaction products generated by etching adhere as deposits in the processing chamber 1, and these deposits become a source of dust. The processing gas for cleaning is used to generate plasma in a sequence similar to that during etching, to remove deposits inside the processing chamber 1 (this is called plasma cleaning), and to keep the inside of the processing chamber 1 in a clean state. , the semiconductor wafer 9 is usually etched again.

FIG. 3 is a partially enlarged sectional view showing how the upper electrode 2 and the upper electrode plate 3 are attached, and the surface of the upper electrode plate 3 made of a conductive material such as Al or SUS is directly exposed to plasma. Therefore, an insulating film 13 made of alumina or the like is coated except for the high-frequency current-carrying surface to prevent sputtering caused by plasma. This insulating film 13 is formed using alumina grains by a plasma spraying method (details are omitted), but because the processing gas outlet 7 has a vertical shape, the plasma spray does not reach the inner surface 7a of the outlet.
Therefore, it is not sufficiently covered.

[0006]

[Problems to be Solved by the Invention] In the above-mentioned conventional apparatus, the parts directly exposed to the plasma, in this case especially the inner surfaces of the processing gas blowing holes of the electrode plate, are not sufficiently coated with an alumina insulating film, and therefore the plasma When exposed to the above, the upper electrode plate base material (Al, SUS, etc.) is sputtered. Also, a small amount of alumina insulating film is sputtered (approximately 1/100 to 1/500 of Al and SUS materials), and this sputtered material is absorbed into the deposits of reaction products that adhere to the processing chamber during plasma processing. It gets complicated. Deposits attached inside the processing chamber are removed by plasma cleaning, but sputtered substances (e.g. Al,
Alumina, etc.) are not removed and remain, which poses a problem as a source of dust generation.

The present invention was made to solve the above-mentioned problems, and its object is to prevent the upper electrode plate and the insulating coating film from being sputtered by plasma.

[0008]

[Means for Solving the Problems] A plasma processing apparatus according to the present invention coats SiC, which is a silicon-based material with strong plasma sputtering properties, on the surface of an upper electrode plate using a CVD method, and heats it as a base material of the upper electrode plate. It uses tungsten or molybdenum material whose expansion coefficient is close to that of SiC.

[0009]

[Operation] The upper electrode plate according to the present invention uses tungsten or molybdenum as the electrode base material, and CV
By coating the SiC film using the D method, sputtering caused by plasma is drastically reduced, and foreign matter during plasma processing is reduced. Since the upper electrode plate is completely covered with a SiC film, the upper electrode plate base material will not be sputtered during plasma generation, and sputtered matter that cannot be removed by plasma cleaning will be incorporated into the deposits in the processing chamber. Therefore, there is less residual material that becomes a source of dust generation after plasma cleaning, and dust generation can be suppressed to a very low level.

0010

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. Note that the entire plasma processing apparatus is the same as the conventional example described above except for the upper electrode plate, so a description thereof will be omitted. FIG. 1 shows a state in which the upper electrode plate 30 of the present invention is tightened and fixed to the upper electrode 2 by a tightening screw 4, and tungsten or molybdenum is used as the base material 30a of the upper electrode plate. 31 is Si
It is a C coating film, and is made using the CVD method (Chemical Vap
or Deposition), the surface of the upper electrode plate base material 30a is coated.

[0011] Here, the SiC film has a much stronger sputtering property by plasma than a conventional alumina film, and is hardly sputtered even if it is directly exposed to plasma. In addition, by using tungsten or molybdenum as the base material, which has a coefficient of thermal expansion close to that of this SiC film, the Si
An upper electrode plate that is stable against plasma sputtering can be realized without cracking the C film.

Furthermore, since the SiC film is manufactured by the CVD method, the inner surface 7 of the processing gas blowing hole 7, which has a diameter in the range of 0.5 to 2.
A can also be sufficiently covered, and an upper electrode plate is obtained in which no tungsten or molybdenum material is exposed except for the conductive surface 5.

[0013] When plasma processing is performed as described above, sputtering due to plasma is drastically reduced, and as explained above, sputtered substances are not incorporated into the deposits adhering to the processing chamber, and the generation after plasma cleaning is reduced. The amount of residual material that becomes a source of dust is reduced, and the generation of foreign matter is greatly reduced.

[0014] In the above embodiment, an upper electrode plate for plasma processing was explained, but a structure composed of a SiC film and a tungsten or molybdenum material is applied to a member that is directly exposed to plasma and sputtered. (For example, wafer holding) Of course.

Further, in the above embodiment, a parallel plate type plasma etching apparatus was explained, but a sputtering apparatus,
Of course, it can also be applied to plasma CVD and the like.

[0016]

[Effects of the Invention] As described above, according to the present invention, it is possible to reduce the amount of residue after plasma cleaning, thereby realizing a plasma processing apparatus in which less foreign matter is generated, and improving the yield of semiconductor devices. be.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and is a partially enlarged sectional view showing a state in which an upper electrode is attached to the upper electrode.

FIG. 2 is a schematic cross-sectional view of the entire conventional plasma processing apparatus.

FIG. 3 is a partially enlarged sectional view showing a conventional example in which an upper electrode plate is attached to an upper electrode.

[Explanation of symbols]

1 Processing chamber 2 Upper electrode 7 Processing gas blowout hole 8
Lower electrode 9 Semiconductor wafer 30 Upper electrode plate 30a Upper electrode plate base material 31
SiC coating film

Claims (1)

[Claims] Claim 1: A plasma processing apparatus comprising, in a processing chamber capable of maintaining a high vacuum, an upper electrode plate having a processing gas blow-off hole and a lower electrode on which a substrate is placed, wherein the base material of the upper electrode plate is made of tungsten or 1. A plasma processing apparatus characterized in that the upper electrode plate is made of molybdenum material, and the upper electrode plate is coated with a SiC thin film except for the current-carrying surface.