JPS58209111A - Plasma generator - Google Patents

Abstract

PURPOSE:To uniform deposition speed, etching speed and the like within the wafer surface and prevent the flying of powder from a wafer-mounting electrode, by coating the wafer-mounting electrode of a parallel plane plasma generator, with SiC, Si or the like. CONSTITUTION:The parallel plane plasma generator produces plasmas for CVD, plasma etching, reactive ion etching and so forth, according to the kind of reaction gas, pressure, high-frequency condition and the like. All the plasmas produce neutral plasma seeds and ionospheric plasma seeds. A wafer-mounting electrode is coated with a semiconductor, which will not contaminate wafers, selected from compound semiconductors of elements of the IV family in the periodic table, such as SiC, and IV-family semiconductors, such as Si. As a result, the state of the charges accumulated on the electrode approximates that on the wafer, and also the plasma seed concentrations approximate each other in both the regions. Therefore, the deposition or etching speed is uniformed. Since a film is simultaneously provided, the flying of powder from the electrode plate of graphite, or the migration of a contaminated metal is prevented to improve manufacturing accuracy and reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The unexploded r3A relates to a so-called parallel plate type plasma generator used for deposition or etching using a plasma gas reaction, and in particular, high-precision control'f! :Relates to electrodes of plasma generators used in the manufacture of semiconductor devices.

[Technical background of the invention]

In recent years, plasma generators have been widely used to deposit thin films such as silicon nitride films and silicon oxide films on semiconductors, and to etch silicon oxide films, polysilicon gate electrodes, and nockle wiring layers. The advantages of using plasma are that plasma deposition can form a thin film at low temperatures, and plasma etching can perform dry etching with high precision. Such a plasma generation device has two row electrodes facing each other, a reactive gas is introduced between the electrodes, high frequency power is applied to form a plasma region, and a semiconductor wafer placed on the electrodes is heated. There is a so-called parallel plate type plasma generator for processing.

Conventionally, metal plates such as stainless steel or aluminum, or graphite plates or other good conductors and heat conductors have been used as electrodes in parallel plate plasma generators to facilitate wafer temperature control. Because it is a source of metal contamination, graphite tends to be used because it is stable at high temperatures and contains contaminant metals.

[Problems with background technology]

When using a metal plate or granoite plate as an electrode and performing plasma deposition on a silicon wafer placed on the electrode, or when etching a silicon oxide film on the wafer, the deposition speed Another problem is that the etching speed is different between the central part and the peripheral part. - For example, when depositing a silicon nitride film, there is a variation in film thickness of about ±10% between the center and the periphery.

Further, although the granoite plate electrode does not become a source of metal contamination like a metal plate, there is a problem in that graphite powder adheres to the surface of the S1 wafer. For example, dense graphite powder is observed at a high density of about 104 particles/cl. In this way, the silicon nitride film deposited on top of the graphite powder has stress concentrated at the graphite powder, which causes cracks to occur in the silicon nitride film, which is originally a hard and crack-resistant film. Become. Further, when etching is performed, etching residue is generated.

[Purpose of the invention] The non-explosion is the positive positive of S] Ueno' knee.
In addition to improving the in-plane uniformity of the can speed or etching speed, the graph from the electrode to the sea urchin...
The present invention provides a plasma generating device for the purpose of improving precision in manufacturing semiconductor cords and improving reliability by preventing scattering of metal powder or migration of contaminated metals.

[Summary of the invention]

The present invention provides a plasma generator having parallel plate electrodes, in which SiC, S
It is characterized by the use of a good conductor coated with a semiconductor such as L. In a parallel plate plasma generator, plasmas such as plasma CVE (CVE), plasma etching, and reactive ion etching are generated depending on the type of reaction gas, gas pressure, high frequency conditions, etc., but in all cases, neutral plasma species, ionization, etc. All of the sexual plasma species are occurring. Therefore, if a semiconductor is coated like the electrode in the present invention, the state of the accumulated charge on the electrode will be...
The deposition rate or etching rate in the center and periphery of the wafer is made uniform by approximating the state of accumulated charge in the wafer, the wafer soil, and the plasma species concentration in the wafer soil. be done.

At the same time, by providing a coating layer, powder scattering from the electrodes and contaminant metal transfer can be prevented, and the above-mentioned problems of the conventional device can be solved at once, which led to the creation of the present invention.

Semiconductors that should be cherished are the fourth in the periodic law, such as SiC.
A compound semiconductor containing an element belonging to the Group 4 or a semiconductor containing an element belonging to the Group 4 such as Sl may be selected from among a compound semiconductor consisting of an element belonging to the Group 4, and a semiconductor having no risk of contaminating the wafer.

[Embodiments of the invention]

First, a polycrystalline SiC film having a thickness of about 200 μm was deposited by step 11 of plasma SiN film deposition. The silicon wafer was brought into close contact with a pocket previously provided on the electrode, placed in a vacuum system of a plasma generator, and evacuated to a temperature of 10-2 Torr or more. The electrode was heated to 400'CVc to increase the heating rate.

Since the electrodes are made of a good thermal conductor such as graphite, the temperature of the electrodes can be made uniform. then 1
00%SiH4f: 150 cc/min flow rate and 100% NH3k 1800 cc/min flow rate were introduced into the vacuum system, and the degree of vacuum was controlled to Q and l'l'orr K, and the radio frequency (RF) power source was activated to generate plasma. I did a deposition. RF frequency is 440 kHz
, RF high output of 150W. As a result, plasma SiN with a refractive index of about 2.0 at a growth rate of 300X Anin
A membrane was obtained.

As a control example, a plasma SiN film obtained under the same conditions as in the example except that it was not deposited on the polycrystalline 5iCjJ (k graphite electrode) was used.

When we measured the variation in the film thickness at the position within the Si plane of the plasma SiN film obtained using the SiCJIIk-deposited electrode, we found that it was compared to the case where a conventional graphite electrode was used. The results are shown in Figure 1. In other words, with the conventional electrode (dashed line), the growth rate of the sea urchin on the horizontal axis at the center is approximately 300 A/min.
However, the film thickness in the left and right peripheral areas is approximately 240 people/min and approximately 270λ/min, and the variation in film thickness between the center and peripheral areas is as much as ±11%. On the other hand, in the device of the present invention (solid line), the central part has a value of approximately 3ooL in, the peripheral part has a value of 310 A/min, and the film thickness variation is as good as about ±2%, which is almost invisible to the naked eye. Ta.

In addition, when investigating the scattering of graphite powder on the wafer, it was found that in the conventional electrode device, the density of Ueno powder was 104 particles x -4, but in the device of the present invention, the density was 10 to 50 particles. ctA and improved fc.

For this reason, it was confirmed through the following experiment that the crack resistance of the plasma SiN film was significantly improved. That is, a sample was created in which Alt was deposited to a thickness of about I Inn on sea urchin, and a plasma SiN film was formed on top of it, and this sample was annealed in N2 air at 500°C for 10 minutes to eliminate the strain caused by the deformation of the AI. was added to the plasma SiN film to generate cracks where graphite powder was present as a foreign material, and then immersed in a VHCl solution and boiled to infiltrate the cracking force.Al d:
I observed the etching situation. As a result, we found that the plasma SiN film had many cracks and
On the other hand, in the apparatus of the present invention, no cracking or etching occurred, whereas At was etched.

A similar effect was obtained with the semiconductor polycrystalline silicon that coated the electrodes. To coat the graphite electrode, S 1H
The coating was performed by pyrolysis of 4-H2 gas. The film thickness of polycrystalline silicon ranges from about 50 μm, which eliminates pinholes, to about I μm, which causes poor adhesion to the electrodes! , you can freely choose between.

Furthermore, the apparatus of the present invention is effective not only in plasma deposition but also in plasma etching to prevent scattering of powder and to ensure uniformity of etching rate. In this case S
It is necessary to take into account that iC and Si are etched little by little.

〔Effect of the invention〕

As explained above, by coating the electrode with a good conductor such as graphite or a semiconductor similar to a wafer such as Si, the uniformity of the plasma deposition rate and etching rate can be improved in the central and peripheral parts of the sea urchin. In addition, scattering of graphite powder from the electrodes and migration of contaminated metals are prevented. I was able to provide it.

[Brief explanation of the drawing]

FIG. 1 is a graph illustrating the uniformity of a plasma SiN film on a substrate using the apparatus of the present invention. Figure 1 Position within wafer

Claims (1)

[Claims] 1. In a plasma generation device that introduces a reactive gas between opposing electrodes to which high-frequency power can be applied, generates plasma by applying high-frequency power, and processes a semiconductor wafer placed on the electrodes. , S as the electrode on which the wafer is placed
iC. A plasma generating device characterized by using a good conductor covered with a semiconductor such as Si.