JPH04130627A - Plasma etching device - Google Patents

Abstract

PURPOSE:To remove the consumption of a clamper in a plasma etching treatment process so as to dispense with the replacement of a clamper by making the quality of the clamper ceramic. CONSTITUTION:As a clamper 4 equipped in a plasma etching device, the one, whose quality is changed from conventional fluororesin to ceramic of silicon carbide SiC, is used. For ceramic, the plasma resistance is far higher than fluororesin, etc. Accordingly, by making it of ceramic, the consumption of the clamper does not occur in plasma, and even in long-term use, the function of pressing a wafer is maintained stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anode coupling type plasma etching apparatus used in the manufacturing process of semiconductor devices.

[Conventional technology]

In the manufacturing process of semiconductor devices, for example, the etching process for forming contact holes in Si wafers, wet etching and dry etching have conventionally been used, and recently the dry etching has been increasingly used.

In addition, dry etching methods include cathode coupling type active ion etching method and anode coupling type plasma etching method, as is well known, but the latter plasma etching method has a higher etching rate than the former type active ion etching method. It is excellent in terms of rate and selectivity of resist 5 to St.

FIG. 1 shows the main parts of an anode coupling type plasma etching apparatus based on the plasma etching method described above. In the figure, l is the upper electrode, 2 is the lower electrode table on the ground side, and 3 is the lower part 1! An Sl wafer is placed on the electrode table 2, a clamper 4 contacts the peripheral edge of the wafer 3 and presses the wafer onto the lower electrode table 2 from above, and 5 is a clamper holder.

That is, during the plasma etching process, the wafer 3
If the temperature of wafer A rises excessively, there is a risk that the resist on the surface of wafer A will be thermally altered.

Therefore, in the plasma etching apparatus, the wafer 3 is pressed against the lower electrode table 2 by the clamper 4 as described above, and the heat of the wafer is transferred to the lower electrode table 2. The resist is then released to the damper 4 to prevent thermal deterioration of the resist.

Here, in conventional plasma etching equipment, the material of the clamper 4 is fluororesin (Teflon), which has high heat resistance and corrosion resistance.
(product name) is used.

[Problem to be solved by the invention]

By the way, it has become clear that the plasma etching apparatus incorporating the clamper made of fluororesin as described above suffers from the following problems during long-term use.

That is, dry etching gas (CF2.CHF5
If a fluororesin clamper is exposed to plasma for a long time, the clamper itself will gradually wear out and the area of the surface that holds down the clamper will gradually decrease. It becomes a state where the body cannot be held down sufficiently. Therefore, if the etching apparatus is continued to be used in such a state, the effect of cooling the wafer by holding the clamper will decrease, and eventually thermal deterioration of the resist deposited on the wafer surface will occur. For this reason, in the past, the clamper was replaced with a new one after a relatively short period of use, but its maintenance and management was troublesome.

The present invention has been made in consideration of the above points, and provides a plasma etching apparatus in which the above problems are solved by making the clamper from a material with high plasma resistance instead of the conventional fluororesin. With the goal.

[Means to solve the problem]

In order to solve the above problems, in the plasma etching apparatus of the present invention, the material of the clamper is made of ceramic.

Here, as a type of ceramic, silicon carbide (Si
C) or silicon nitride (SlsN4) is preferred.

[Effect]

Ceramic has much higher plasma resistance than fluororesins, etc. Therefore, by making the clamper from ceramic as described above, the clamper will not be worn out in plasma and will have the ability to hold the wafer even after long-term use. is maintained stably. Moreover, ceramic has a higher thermal conductivity than resin, and together with the above-mentioned clamping function for holding down the wafer, it always exhibits a high cooling effect, so there is no risk of the resist being thermally altered during the etching process.

In addition, it has been confirmed from the inspection results of wafers that have actually been etched that even if ceramic is used as the material of the clamper, there is no problem in the etching characteristics of the wafer.

〔Example〕

Example 1: As the clamper 4 installed in the plasma etching apparatus shown in FIG. 1, a clamper 4 made of silicon carbide (SIC) ceramic was used instead of the conventional fluororesin.

Example 2: As the clamper 4 in FIG. 1, a clamper made of silicon nitride (SisNn) as a ceramic material was adopted.

According to the results of actually repeatedly etching wafers over a long period of time by incorporating the clamper of Example 1.2 into an etching apparatus, no wear was observed on the clamper, and the clamper was superior in terms of etching characteristics. It was confirmed that there were no problems of any kind due to the material change. Also,
The increased cooling effect on the wafers made it possible to increase the power applied to the etching equipment, thereby speeding up the etching rate and improving wafer throughput. In addition, in actual etching processing, the end of wafer etching is determined by detecting a light beam with a wavelength of 520 ns emitted from the plasma as the wafer etching process progresses. It has been found that by using this method, it is possible to detect light of the above wavelength with higher sensitivity than when using a fluororesin clamper. This is assumed to be because the clamper material is not decomposed or vaporized by the plasma.

〔Effect of the invention〕

Since the plasma etching apparatus of the present invention is constructed as described above, it achieves the following effects.

(1) Since the material of the clamper has been changed from the conventional fluororesin to ceramic, there is no wear and tear on the clamper during the plasma etching process, and there is no need to replace parts of the clamper. In addition, since the clamper does not wear out, a high cooling effect can always be ensured for the wafer, which not only effectively prevents thermal deterioration of the resist, but also increases the power supplied to the etching equipment and increases the wafer processing capacity. It also allows for smooth driving.

(2) By specifically employing silicon carbide (SIC) or silicon nitride (SisNn) as the ceramic material of the clamper, a clamper with excellent plasma resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts of a plasma etching apparatus. In FIG. 0, 1: upper electrode, 2: lower electrode table, 38 semiconductor wafer, 4: clamper. 112-ゝ...

Claims (1)

[Claims] 1) An anode coupling type plasma etching apparatus used in the manufacturing process of semiconductor devices, which performs etching by pressing a wafer placed on a table with a ground side electrode with a clamper, A plasma etching apparatus characterized in that the material of the clamper is ceramic. 2) The plasma etching apparatus according to claim 1, wherein the ceramic is silicon carbide (SiC). 3) The plasma etching apparatus according to claim 1, wherein the ceramic is silicon nitride (Si_3N_4).