JP3317935B2 - Plasma processing equipment - Google Patents

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 such as a plasma CVD apparatus or a plasma etching apparatus used for manufacturing a semiconductor substrate, and more particularly to a plasma etching apparatus having an improved electrode structure.

[0002]

2. Description of the Related Art Conventionally, in the process of manufacturing a semiconductor substrate, various apparatuses for forming a thin film on the surface of the semiconductor substrate and performing fine processing using plasma have been used. The basic schematic structure will be described with reference to the longitudinal sectional view of FIG.
First, the upper electrode 1 and the lower electrode 2 are installed in the chamber 3 so as to face each other. Then, the semiconductor substrate 6 is placed on the lower electrode 2, the inside of the chamber 3 is depressurized to a predetermined pressure by a high vacuum system, a reaction gas is introduced, and then high frequency power is applied to the upper electrode 1 from a high frequency power supply. Plasma is generated between the upper electrode 1 and the lower electrode 2, and the plasma is used to form a thin film on the semiconductor substrate 6 or to perform a fine processing.

The upper electrode 1 includes an aluminum intermediate plate 4 having a gas blowing hole 7a and an arc-shaped slit 7b for uniformly dispersing the introduced reaction gas,
It comprises an aluminum shower plate 5 having a large number of blowout holes 7 for further rectifying and blowing out the reaction gas passing through the aluminum intermediate plate 4.

Here, the reason why the intermediate plate is provided on the upper electrode will be described. For example, if an attempt is made to form a thin film on the surface of the semiconductor substrate so that the film thickness becomes uniform, only the gas blowing holes formed in the shower plate require Although there is a rectification effect, the amount of gas ejected from the central portion of the shower plate necessarily increases, and the film thickness at the central portion of the semiconductor substrate tends to be increased. Therefore, it is necessary to provide an intermediate plate for dispersing the reaction gas in the central portion and the peripheral portion above the shower plate. Therefore, the intermediate plate is provided with a plurality of small holes indicated by blow-out holes 7a at the center and a plurality of elongated holes indicated by arc-shaped slits 7b at the peripheral edge to disperse the reaction gas.

[0005]

In the above-described conventional plasma processing apparatus, the intermediate plate, which is a part of the upper electrode, is formed of aluminum. Therefore, the upper electrode formed of the intermediate plate and the shower plate is used. Abnormal discharge occurs when high-frequency power is applied to the internal space of the device. This abnormal discharge occurs in the internal space 13 as shown in the partial sectional view of FIG.
It often occurs between the surface of the aluminum intermediate plate 4 and the corner 8 of the gas blowout hole 7 formed in the shower plate 5.

As means for preventing this abnormal discharge, for example,
As disclosed in Japanese Patent Application Laid-Open No. 10-287987, means for covering the space between the upper electrode and the inner wall of the chamber with an insulating member such as ceramic is used. In this case, a ceramic member is used inside the upper electrode. Therefore, it is not possible to suppress the abnormal discharge generated in the internal space of the upper electrode due to the plasma wraparound.

[0007] Due to the abnormal discharge, reaction products 9 such as SiO grow abnormally on the surface of the aluminum intermediate plate 4 as shown in FIG. And fall off onto the semiconductor substrate from the gas blowing hole 7, and suddenly and locally become large dust, which is a major obstacle to semiconductor manufacturing.

An object of the present invention is to provide a plasma processing apparatus capable of preventing abnormal products generated in the internal space of an upper electrode from being attached to the surface of an intermediate plate, thereby preventing a reaction product from adhering to the surface of the intermediate plate. is there.

[0009]

According to the plasma processing apparatus of the present invention, an upper electrode and a lower electrode are arranged in a chamber so as to face each other, and a reaction gas is passed through an intermediate plate and a shower plate constituting an internal space of the upper electrode. In the plasma processing apparatus, wherein the semiconductor substrate mounted on the lower electrode is processed by plasma generated between the upper and lower electrodes, the intermediate plate has a ceramic portion in a central portion and an outer peripheral portion.
It is characterized by being composed of two parts of an outer ring made of minium .

[0010] Further, the intermediate plate is characterized in that it is divided into two parts, a ceramic part and an aluminum outer peripheral ring having a size in which the ceramic part fits.

Further, when the intermediate plate is attached to the shower plate, only the outer peripheral ring made of aluminum is screwed to attach the intermediate plate so that no external force is applied to the ceramic portion.

The aluminum outer ring of the intermediate plate is formed to have a width that is not exposed to the internal space of the upper electrode where the ceramic portion and the shower plate face each other.

Further, the ceramic portion of the intermediate plate is placed so as to cover an internal space of the upper electrode.

The aluminum outer ring of the intermediate plate also serves as a positioning member for the ceramic portion.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings. Note that the overall configuration of the plasma processing apparatus is the same as that of the conventional structure shown in FIG.

FIG. 1 is a sectional view of an upper electrode used in an embodiment of the plasma processing apparatus according to the present invention. For example, the structure of the upper electrode 1 used in the plasma CVD device is as follows:
It has a shower plate 5 and a ceramic intermediate plate 4 a disposed opposite to the upper portion of the shower plate 5, and firstly reacts the reaction gas introduced into the upper electrode 1 with the ceramic intermediate plate 4.
a, and then rectified by the shower plate 5 and supplied into the chamber 3 (shown in FIG. 5).

The chamber 3 is a processing chamber for forming a thin film on a semiconductor substrate. For example, a TEOS gas, which is a reaction gas, is introduced into the chamber 3 through the upper electrode 1 and the chamber 3 is formed at a high density. Plasma is formed to form a thin film. The chamber 3 is connected to a high vacuum system for generating high-density plasma in the chamber 3, and a high-frequency power supply for generating plasma is connected to the upper electrode 1.

Here, the structure of the ceramic intermediate plate 4a used in the present invention will be described with reference to FIG. The ceramic intermediate plate 4a is formed in a disk shape as shown in the plan view of FIG. 2, a central portion is formed by a ceramic portion 10, and an outer peripheral portion is formed by an aluminum outer ring 11. The ceramic portion 10 has a gas blowout hole 7a uniformly arranged in the center and a circular arc-shaped slit 7b formed along the periphery similarly to the conventional aluminum intermediate plate. In addition, the aluminum outer ring 11
, Screw holes 12 for attachment are formed evenly.

As described above, the ceramic intermediate plate 4a is
The central portion and the outer peripheral portion are divided into two so as to be separable. The outer diameter of the ceramic portion 10 and the inner diameter of the outer peripheral ring 11 made of aluminum are formed in such a size that they can be detachably fitted.

The reason why the entire ceramic intermediate plate 4a is not made of a ceramic material is to prevent the ceramic material from being cracked by tightening screws at the mounting portion when the ceramic intermediate plate 4a is mounted on the shower plate. is there. When attaching the ceramic intermediate plate 4a to the shower plate, the aluminum outer peripheral ring 11
Is partially exposed inside the upper electrode, an abnormal discharge occurs locally in the exposed portion (conductive portion). Therefore, as shown in a partial sectional view of the upper electrode in FIG. By reducing the width, the conductive portion is not exposed in the internal space 13 of the upper electrode.

As a result, the ceramic section 10 is
3 is placed on the shower plate 5 so as to cover it, and in this state, an upper electrode is formed. Further, since the aluminum outer ring 11 is fixed to the shower plate 5, the ceramic portion 10 does not shift in the lateral direction, and the aluminum outer ring 11 serves as a positioning member for the ceramic portion 10.

As described above, according to the present invention, the material of the intermediate plate, which is the reactive gas dispersion plate provided inside the upper electrode, is
By using a highly insulating ceramic material such as alumina, it is possible to suppress occurrence of abnormal discharge inside the upper electrode.

[0023]

According to the present invention, a ceramic material having a high insulating property is used for the material of the intermediate plate constituting the upper electrode, and the width of the aluminum outer peripheral ring which forms the outer periphery of the ceramic material is reduced. By not being exposed to the internal space of the electrode, abnormal discharge occurring between the surface of the intermediate plate and the corner of the gas outlet of the shower plate can be suppressed.

As a result, the reaction product which has been abnormally grown on the surface of the intermediate plate due to the abnormal discharge generated inside the upper electrode can be prevented from peeling off, and the production yield of the semiconductor substrate can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of an upper electrode according to the present invention.

FIG. 2 is a plan view of an intermediate plate according to the present invention.

FIG. 3 is a partial sectional view of an upper electrode according to the present invention.

FIG. 4 is a partial cross-sectional view of a conventional upper electrode.

FIG. 5 is a cross-sectional view illustrating a schematic structure of a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper electrode 2 Lower electrode 3 Chamber 4 Aluminum intermediate plate 4a Ceramic intermediate plate 5 Shower plate 6 Semiconductor substrate 7, 7a Gas blowing hole 7b Arc-shaped slit 8 Corner 9 Reaction product 10 Ceramic portion 11 Aluminum outer ring 12 Screw hole 13 Internal space

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 C23C 16/505 H01L 21/3065 H05H 1/46

Claims (6)

(57) [Claims] An upper electrode and a lower electrode are arranged in a chamber so as to face each other, a reaction gas is introduced through an intermediate plate and a shower plate constituting an internal space of the upper electrode, and the semiconductor substrate is mounted on the lower electrode. In a plasma processing apparatus for performing a processing process by using plasma generated between the upper and lower electrodes, the intermediate plate has a central ceramic portion and an outer peripheral portion.
Consists of two parts of an aluminum outer ring
The plasma processing apparatus characterized by there. 2. The plasma processing apparatus according to claim 1, wherein the intermediate plate is divided into two parts, a ceramic part and an aluminum outer ring that is large enough to fit the ceramic part. Wherein when mounting the intermediate plate in the shower plate, only the aluminum outer peripheral ring screwed, plasma according to claim 1, wherein the ceramic part, characterized in that attached as external force is not applied Processing equipment. 4. Aluminum outer peripheral ring of the intermediate plate, according to claim 1, characterized in that the ceramic part and the shower plate is formed to a width which is not exposed to the inner space of the upper electrode which is formed opposite The plasma processing apparatus as described in the above. 5. The plasma processing apparatus according to claim 1 , wherein the ceramic portion of the intermediate plate is placed so as to close an internal space of the upper electrode. 6. The plasma processing apparatus according to claim 1, wherein the aluminum outer peripheral ring of the intermediate plate also serves as a positioning member for a ceramic portion.