JPS612328A - Plasma processor - 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 [Technical Field] The present invention relates to a plasma processing apparatus, and more particularly to a plasma processing apparatus capable of uniformly performing processes such as plasma etching and plasma film formation over the entire surface of a workpiece.

[Background technology]

Etching technology and film formation (
Deposition) technology that uses plasma has been proposed. (For example, Electronic Materials 1981 published by the Industrial Research Council)
November issue special issue, published November 10, 1981, P77
~P84). For example, FIG. 3 shows a plasma etching apparatus, in which flat plate-type upper and lower electrodes 2 and 3 are arranged facing each other in a chamber 1, and one (lower) electrode 3 is used as a photomask plate or a wafer 4 as an object to be processed. and both electrodes 2
．． Connect a high frequency power source between 3 and 3. And chamber 1
By applying high frequency power between both electrodes 2 and 3 after setting the internal gas pressure to a predetermined gas pressure, plasma P is generated between both electrodes, and the surface of the object to be processed 4 is etched by this plasma P. It turns out.

However, in a plasma processing apparatus having such a parallel plate electrode structure, the distance between the workpiece 4 attached to the lower electrode 3 and the upper electrode 2 is smaller than the distance between the upper and lower electrodes 2 and 3. Moreover, since the peripheral edge of the object to be processed 40 is formed into an angular shape where electric field concentration tends to occur, the plasma P and the object to be processed 40 are
As shown in the figure, a discharge S is likely to be generated between the peripheral edge and the peripheral edge. For this reason, the plasma intensity distribution particularly in the peripheral area of the object to be processed 40 becomes unstable, and there is a problem in that uniform etching cannot be performed over the entire surface of the object to be processed 4.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus that can prevent plasma discharge at the periphery of a workpiece and perform uniform plasma processing over the entire surface of the workpiece.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, an auxiliary electrode is provided on the surface of the opposite electrode on the side that supports the object to be processed so as to surround the object to be processed, so that a discharge can be generated between the auxiliary electrode and the other electrode when plasma is generated. By doing so, it is possible to prevent discharge from occurring between the other electrode and the object to be processed, thereby enabling uniform plasma processing over the entire surface of the object to be processed.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to a plasma etching apparatus, in which a Cr film on the surface of a photomask plate is pattern-etched to form a photomask.

In the figure, a chamber 10 can be kept airtight inside, and a part of it has a gas supply port 11 for introducing etching gas such as C°C, CC, etc., and a gas supply port 11 for evacuating the inside of the chamber 10 to a desired vacuum pressure. A gas exhaust port 12 to be set is opened. Inside the chamber 10, a flat plate-shaped upper electrode 13 and a lower electrode 14 are arranged in parallel so as to face each other.
A high frequency power source 15 is connected to the lower electrode 14, and the lower electrode 14 is grounded. A processing object support section is formed on the upper surface of the lower electrode 14, and a photomask plate 16 as a processing object is placed and supported there. This photomask plate 1
6 is C on the surface of the quartz glass substrate 170 as shown in FIG.
It goes without saying that the r film 18 is formed and a patterned photoresist (not shown) is used as a mask. Furthermore, an auxiliary electrode 19 is formed on the surface of the lower electrode 14 so as to surround the object support section. In this example, the auxiliary electrode 19 has a triangular cross section and extends all the way around the supporting portion, and its top is sharp and protrudes above the surface of the photomask plate 16. It is formed so that In this case, the auxiliary electrode 19 may be formed integrally with the lower electrode 14 or may be formed separately and attached.

According to the above configuration, from the gas supply port 11 to the chamber 10
By supplying processing gas into the chamber 10 and evacuation from the exhaust port 12, the interior of the chamber 10 is set to a required gas pressure atmosphere. Then, by applying high frequency power to the upper and lower electrodes 13.14, the space between the electrodes 13.14 is activated and plasma P is generated as shown in FIG. Then, due to the action of the plasma P, etching gas particles collide with the surface of the photomask plate 160, etching the surface Cr film 18, and so-called dry etching is redundant. At this time, a part of the plasma P flows toward the ground potential and a discharge is generated, but in this example, the auxiliary electrode 19 provided on the surface of the lower electrode 140 is formed closest to the plasma P. Therefore, this discharge connects the plasma P and the auxiliary electrode 19.
It is carried out between. Therefore, no discharge is generated at the corners of the object to be processed (photomask plate) as in the conventional case, and plasma acts on the surface of the photomask plate 160 without any influence of discharge.
Etching will proceed. As a result, uniform etching progresses over the entire surface of the photomask plate 16, resulting in a high-quality etching effect.

〔effect〕

(1) Since an auxiliary electrode is formed on the side electrode of the plasma processing apparatus that supports the object to be processed so as to surround the object to be processed, the discharge generated by the plasma is generated between the auxiliary electrode and the electrode that supports the object to be processed. Since this is prevented from occurring on the object to be processed, the influence of discharge on the surface of the object to be processed can be eliminated and the plasma can be applied uniformly to the entire surface of the object to be processed, thereby achieving uniform plasma processing. I can do it.

]2) If an auxiliary electrode is provided on one electrode, the processing procedure for the object to be processed can be exactly the same as before, and the processing efficiency will not be reduced, while good processing can be achieved as described above. .

(3) The auxiliary electrode can be formed separately and attached, and can be applied to existing plasma devices as is.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, the auxiliary electrodes may not be provided all around the object to be processed, but may be provided intermittently. Further, the object to be processed may be a wafer, and in this case, the auxiliary electrode may be formed in an annular shape. Furthermore, in an apparatus in which the object to be processed is supported on the upper electrode, an auxiliary electrode may be provided on the upper electrode.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to a plasma etching apparatus for manufacturing semiconductor devices, which is the background field of application, but the invention is not limited to this. The present invention can be similarly applied to any processing device that uses plasma, such as a membrane device.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a device according to an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of a lower electrode portion, and FIG. 3 is an overall configuration diagram for explaining conventional problems. 10... Chamber, 11... Gas supply port, 12... Gas exhaust port, 13... Upper electrode, 14... Lower electrode, 15
...High frequency power source, 16.. Processing object (photomask plate), 19.. Auxiliary electrode, P.. Plasma, S.. Discharge. Figure 2

Claims (1)

[Claims] 1. A plasma processing apparatus that includes a pair of opposing electrodes, supports a workpiece on one electrode, generates plasma between the other electrode, and processes the workpiece with plasma, A plasma processing apparatus characterized in that an auxiliary electrode is provided on the one electrode protruding around the object to be processed, and the auxiliary electrode is configured as a discharge electrode. 2. The plasma processing apparatus according to claim 1, wherein the auxiliary electrode is formed to have a triangular cross section, and its sharp tip is positioned to protrude forward from the surface of the object to be processed. 3. The plasma processing apparatus according to claim 1 or 2, wherein the auxiliary electrode is formed all around the object to be processed.