JPS59114825A - Plasma etching method and apparatus - 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 (1) Technical Field of the Invention The present invention relates to a process for manufacturing a semiconductor device, and more specifically, for example, a method for processing a semiconductor surface using gas plasma.
The present invention relates to a plasma etching method and apparatus for etching.

(2) Background of the technology It is well known that plasma etching technology is important as one of the basic process technologies for semiconductor manufacturing. This technique, called a dry process, generates a large amount of waste liquid that can easily cause pollution compared to conventional etching techniques that use solutions. It has many advantages such as easy etching, easy control of etching conditions, easy equipment maintenance and management, and simplified equipment. Therefore, it is widely used in the manufacturing process of semiconductor devices. ing. Many types of plasma etching apparatuses are known, such as a cylindrical type (capacitive type, coil type), a parallel electrode type, a plasma generation chamber separated type, and the like. Non-invention is one of the above forms.

It can be advantageously applied to a parallel electrode type plasma etching apparatus. Parallel electrode type plasma etching equipment can be roughly divided into two types: one type that etches the sample by placing it on the electrode (high-frequency electrode) to which high-frequency power is applied to the sample, and generating all the plasma (Ka-P coupling method). The method can be divided into two types: 1, and a type in which the wafer is placed on the ground electrode side for etching (anode coupling method). The choice of which type fundamentally depends on factors such as etching properties and effect on electrical damage.

(3) Between the conventional technology and parallel electrode type plasma etching apparatus, an electrostatic chuck or a vacuum chuck is often used as a target (sample stage) for fixing a wafer. In addition to completely cooling the mounted wafer, such a fixing means also serves as an electrode plate for the RF power source if it is connected to an RF high frequency power source. The material for such a sample stage is typically silicone resin in consideration of cushioning properties, thermal conductivity, and processability, and in some cases, polyimide 0-based resin, alumina, etc. . However, in the case of a sample stage (electrostatic chuck) made of silicone-based or polyimide-based resin material, if the size of the sample stage is equal to or larger than the sample, it will be exposed to plasma during the plasma etching process and will be etched at the same time. To avoid this, the dimensions of the sample stage are made slightly smaller than those of the wafer. -The diameter of the sample stage used to hold a wafer with a diameter of 5 inches (approximately 12.5 m+n3) is approximately 100 mm.

Undesirably, if a large portion of the wafer protrudes from the sample stage, the entire wafer will not be cooled uniformly, resulting in non-uniform etching and unacceptably excessive over-etching.

The occurrence of over-etching naturally damages the sample substrate and causes deterioration of device characteristics, resulting in a reduction in the number of effective chips that can be extracted from a single wafer.

(4) Purpose of the Invention The object of the invention is to provide a plasma etching method and apparatus which increases the number of effective chips that can be extracted from a single wafer, that is, which makes it possible to uniformly etch a wafer. The purpose is

It is a further object of the invention to provide a plasma etching method and apparatus capable of achieving uniform etching of a wafer without significant modification to conventional methods and apparatus.

(5) Structure of the Invention The present inventors have recently discovered that the above-mentioned object can be achieved by devising the introduction of gas into the etching chamber of a plasma etching apparatus. That is, the first uninvented invention is a plasma etching method for a sample having dimensions larger than a sample stage, which includes mainly spraying an etching gas onto a portion of the sample that is not placed on the sample stage. The present invention relates to a characteristic plasma etching method. Furthermore, the second uninvented invention is
This plasma etching apparatus is equipped with a sample stage having a small sample size, and is characterized in that an etching gas introduction pipe having a main gas outlet above the periphery of the sample stage is disposed in the etching chamber. Related to plasma etching.

(6) Embodiments of the Invention Hereinafter, the invention will be explained in more detail with reference to the accompanying drawings. Here, for convenience, the invention will be explained using an example of a +1 inch plasma etching apparatus using an electrostatic chuck.

FIG. 1 schematically shows an example of a conventional parallel electrode type plasma etching apparatus. The etching chamber 1 is surrounded by a quartz wall 2, and also has a grounded counter electrode 3 and a sample (
It has a sample stage (electrostatic chuck) 5 on which 4 wafers are supported. The electrostatic chuck 5 is connected to a high frequency power source 6 as shown in the figure.
Since it is connected to , it plays the role of a high frequency electrode. The 1 yen quartz rice 7 in the etching chamber is placed for the sole purpose of preventing contamination of the sample surface. Now, when one person pours etching gas into the etching chamber L as shown by arrow A and discharges it outside as shown by arrow B, some of the wafers 4 protrude from the electrostatic chuck 5. The surrounding area is not cooled enough, and therefore,
Non-uniform etching occurs.

Non-uniform etching is evident from the graph in FIG. This is a graph showing the results of plasma etching performed using the apparatus shown in FIG. 1 under the following conditions. The 8-day sea urchin position is indicated with 0 at the center, plus signs in one direction, and minus signs in the other direction.

Wafer used: Substrate with a diameter of 5 inches (approximately 125+ny+); Electrostatic chuck with a PSG film with a film thickness of 1.5 μm and a diameter of 100 m; Etching gas made of silicone resin: CHF3 and CF4 flow rate 100 CC/% Degree of reduced pressure: 0. I Torr High frequency output crab 100OW Frequency 13.56 MHz As shown in the diagram, the etching depth increases as it goes outward from the center of the wafer. The etching depth at the peripheral edge of the wafer was 1.2 .mu.m, indicating that there was actually 20 inches of overetching (this overetching caused a lot of damage).

A preferred embodiment of the invention is as illustrated in FIG. The illustrated etching apparatus has a donut shape in which a gas introduction pipe 8 for introducing etching gas is placed above the wafer 4 to be etched, and has a large number of gas outlets (not shown). It is basically the same as that in Fig. 1, except for the fact that The etching gas is mainly blown toward the periphery of the pass-through evaporator 4 as indicated by arrow a. That will be understood.

When plasma etching was carried out using the apparatus shown in FIG. 2 under the same conditions as in FIG. 3, the results shown in the graph of the fourth factor were obtained. In this case, there is almost no variation in the etching depth at any location on the wafer, and the depth only increases by about 0.1 μm at the wafer peripheral edge. These results show that according to the present invention, a large number of effective chips can be obtained from one wafer.

In carrying out the invention, it is advantageous to use all of the gas introduction tubes having the L-shaped donut shape described above, but gas introduction tubes having other shapes may also be used as required.

Such a gas introduction tube can be manufactured from, for example, a quartz tube, ceramic (alumina, etc.), anodized aluminum, or the like. The gas outlet of the gas introduction pipe can have any diameter and any spacing depending on the desired cooling effect.

When considering the machining surface, the diameter of the gas outlet should be approximately 0.5~
Generally, the total distance between the three blow-off ports is about 5 to 20.

The etching gas to be introduced is not particularly limited in the practice of the present invention. The choice of such gas will generally depend on the class a of the wafer used. Specifically, for example, Ck'4. Cf (F3゜02, CC
Any gas commonly used in this technical field, such as T4, can be used alone or in combination.

Finally, although many attempts have been made in this technical field to uniformize the gas flow to achieve uniform etching, all of these attempts differ from the present invention in that they focus on intensive cooling of the wafer periphery. I can point out the fact that I haven't.

(7) Effects of the Invention According to the present invention, it is possible to prevent non-uniform etching caused by non-uniform cooling of the wafer, and therefore, it is possible to reduce the number of effective chips in a row without damaging the chips. It is possible to take out 9 pieces from a single wafer. Further, according to the invention, the above effects can be achieved with only slight modifications to conventional plasma etching equipment. The invention can be used to great advantage in large diameter continuous automatic processing equipment.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a conventional plasma etching apparatus; FIG. 2 is a schematic diagram showing one side of an uninvented plasma etching apparatus; FIG. 3 is a schematic diagram of the apparatus shown in FIG. 1. and FIG. 4 is a graph showing the results obtained using the apparatus of FIG. In the figure, 1 is an etching chamber, 2 is a quartz chamber, 3 is a counter electrode, 4 is a sample, 5 is a sample stage, 6 is a high frequency power source, and 8 is a gas introduction tube. Patent Applicant Hara Shitsu Co., Ltd. Head Patent Attorney Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Yukio Uchida Patent Attorney Akiyuki Yamaguchi Figure 1 Figure 2 Figure 3 Figure 4 Position within the wafer ( mm)

Claims (1)

[Claims] 1. A plasma etching method for a sample having dimensions larger than a sample stage, characterized in that an etching gas is mainly sprayed on a portion of the sample that is not placed on the sample stage. Plasma etching method. 2. A plasma etching apparatus equipped with a sample stage having dimensions smaller than the sample, and an etching gas introduction pipe having a main gas outlet above the periphery of the sample stage is disposed in the etching chamber. A plasma etching device characterized by: