JPS6230267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a dry etching apparatus, particularly when dry etching a film formed on a semiconductor substrate (hereinafter referred to as a wafer) or a substrate, to make the etching rate of a film on a wafer uniform. This invention relates to a dry etching device.

It is effective to use dry etching to form patterns in semiconductor devices. In particular, by using a parallel plate electrode single wafer type dry etching apparatus, etching can be performed with better reproducibility and uniformity compared to conventional batch type dry etching apparatus. At present, a method for uniform etching within a wafer has not been found. The etching rate differs between the center and the outer periphery of the wafer due to non-uniformity in plasma discharge density and the flow of etching gas. The wafer speed within the wafer is greater at the outer periphery of the wafer than at the center due to variations in plasma discharge density. Further, since there is more etchant near the place where the etching gas is injected, the etching speed is faster.

SUMMARY OF THE INVENTION Therefore, the present invention provides a dry etching apparatus in which the distance between the electrodes relative to the center and outer periphery of the wafer is varied to eliminate variations in etching speed. That is, the present invention has a lower electrode for installing a semiconductor substrate and an upper electrode disposed above and facing the electrode, and etching gas is introduced between the two electrodes from one side and flows out from the other. In a dry etching apparatus that performs an etching process on a single semiconductor substrate placed on an electrode, a recess is provided in the center portion of the upper electrode corresponding to the center portion of the semiconductor substrate on the lower electrode, and the outer peripheral end portion is formed from the recess. This dry etching apparatus is characterized in that it has an inclined surface that is inclined upward toward the semiconductor substrate, and the upper electrode is installed parallel to the semiconductor substrate or in an upwardly inclined position along the direction of gas flow.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a conventional parallel plate electrode type single-wafer type dry etching apparatus. Electrode 2a
A wafer 3 is placed on top of the wafer 3, and a film (SiO ₂ , Poly-Si, Si, Au, etc.) or a substrate formed on the wafer 3 is dry etched. 4 is a matching box, and 5 is an RF power supply. Further, a mechanical booster pump 6 and a rotary pump 7 are installed on the exhaust side of the etching chamber 1.

If the pair of electrodes 2a and 2b are parallel, there will be variations in the etching rate between the outer periphery and the center of the wafer.Especially in the case of parallel plate electrodes, the distance between the pair of electrodes is This is a necessary parameter for controlling the etching rate and etching uniformity in etching, and when the distance between the electrodes is shortened, the plasma potential becomes smaller and the etching rate becomes smaller. This phenomenon occurs.

FIG. 2 shows an embodiment of the present invention, in which a depression is provided in the center of the upper electrode 2b, which is arranged parallel to and above the lower electrode 2a for wafer installation, and from the depression to the outer peripheral edge. Forming inclined surfaces 8, 8 that tilt upward toward the wafer 3, the distance between the electrodes 2a, 2b corresponding to the outer circumferential portion of the wafer 3 is made shorter than the distance between the electrodes 2a, 2b corresponding to the central portion of the wafer 3. This is what I did. The etching rate within the wafer is determined by the variation in plasma discharge density.
However, in this embodiment, the distance between the electrodes 2a and 2b corresponding to the outer periphery of the wafer 3, where the etching rate is high, is shortened, so that the etching rate at the outer periphery of the wafer 3 is larger than that at the center. becomes smaller, and the etching rate within the wafer can be corrected.

In addition, FIG. 3 shows an electrode 2 corresponding to the outer periphery of the wafer 3 by tilting the conventional flat plate upper electrode 2b.
The distance a and b on both sides between a and 2b is an example in which the distance a on the gas inlet side A is shorter than the distance b on the gas outlet side B with respect to the direction A in which the etching gas flows. According to this arrangement, etching unevenness in the gas flow direction can be improved. Similarly, in the present invention, by installing the upper electrode 2b shown in FIG. Inconsistency in etching speed within the substrate can also be improved. In this embodiment, the upper electrode 2
The inclination angle of the inclined surfaces 8' and 8' attached to b is the distance a on the inflow side A and the distance b on the outflow side B with the depression as the center.
will change.

As a result of experimenting with the dry etching apparatus according to the above-mentioned embodiment, the dry etching apparatus shown in Fig. 2 was 40% cheaper than the conventional one.
As described above, the variation in etching speed can be corrected by more than 10%, and the variation in etching speed by more than 5.0% compared to the conventional method can be corrected by more than 10% in the one shown in FIG. Further, the apparatus of the embodiment shown in FIG. 2 can be applied to the cathode coupling method when the etching pressure is 100 mTorr or less, and to both the cathode coupling and anode coupling methods when the etching pressure is 200 mTorr or more.

As described above, according to the present invention, the shape of the upper electrode,
The improved arrangement has the effect of correcting variations in the etching rate within one wafer due to non-uniformity in plasma discharge degree and flow of etching gas, and uniformly etching high positions.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of a conventional parallel plate electrode type single wafer dry etching device, Fig. 2, Fig. 3,
FIG. 4 is a configuration diagram of a device having opposing electrodes to which the present invention is applied. 1... Wafer, 2a, 2b... Electrode.

Claims (1)

[Claims] 1. It has a lower electrode for installing a semiconductor substrate and an upper electrode placed above and facing the electrode, and an etching gas is introduced between the two electrodes from one side,
In a dry etching apparatus that performs an etching process on a semiconductor substrate placed on an electrode by causing etching to flow from the other side, a recess is provided in the center part of the upper electrode corresponding to the center part of the semiconductor substrate on the lower electrode, A dry etching apparatus characterized in that the upper electrode is provided with an inclined surface that is inclined upward from the recess toward the outer peripheral end, and the upper electrode is installed in an upwardly inclined position parallel to the semiconductor substrate or along the direction of gas flow.