JP2009267070A - Plasma etching apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma etching apparatus causing no contamination of a Si wafer. <P>SOLUTION: In the plasma etching apparatus, Si coating 8 consisting of monocrystalline silicon, polycrystalline silicon or columnar crystalline silicon is applied on an inner wall surface of a vacuum container 1 of the plasma etching apparatus. Preferably, the Si coating is Si coating of sticking Si tiles. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a plasma etching apparatus that does not contaminate a Si wafer.

As an apparatus for etching a Si wafer when manufacturing a semiconductor integrated circuit, a plasma etching apparatus is known. In this conventional plasma etching apparatus, as shown in the cross-sectional explanatory view of FIG. 2, an electrode plate 2 having a through-hole 5 and a pedestal 3 are provided in the vacuum vessel 1 at an interval. In order to etch the Si wafer using the apparatus, the Si wafer 4 is placed on the gantry 3, and an etching gas 7 containing CHF ₃ or CF _{3 in} addition to Ar is provided in the electrode plate 2. A high frequency voltage is applied between the electrode plate 2 and the mount 3 by a high frequency power source 6 while flowing toward the Si wafer 4 through the pores 5, and the supplied etching gas 7 is applied to the electrode plate 2 by applying this high frequency voltage. The plasma 9 is generated in the space between the gantry 3 and the plasma 9 hits the Si wafer 4 so that the surface of the Si wafer 4 is etched.

The vacuum vessel 1 is usually made of stainless steel containing Ni and Cr, but may be made of Al or an Al alloy.
The electrode plate 2 is usually made of carbon, amorphous carbon, silicon carbide or the like, but in recent years, single crystal silicon, columnar silicon or polycrystalline silicon, and further doped single crystal silicon or columnar crystal. It is made of silicon or polycrystalline silicon (see Patent Document 1).
JP 2006-196491 A

In recent years, with the increase in precision of semiconductor integrated circuits, contamination of Si wafers that occur during plasma etching has become a problem.

Therefore, the present inventors have studied to further reduce contamination of the Si wafer when plasma etching the Si wafer. as a result,
(A) As a cause of contamination of the Si wafer, the vacuum vessel wall surface is etched although it is a trace amount, and elements such as Ni, Cr, Fe and Al contained in the stainless steel constituting the vacuum vessel adhere to the Si wafer. And contaminate the Si wafer during plasma etching,
(B) For this purpose, when the wall of the vacuum vessel is coated with Si, the coating is composed of the same components as the Si wafer, so that the Si wafer is contaminated even if the Si coating on the wall of the vacuum vessel is etched. Not
(C) The Si coating is made of single crystal silicon, polycrystalline silicon, or columnar crystal silicon. The Si coating may be formed by any method such as vacuum deposition or thermal spraying, but the Si tile is attached to the wall of the vacuum vessel. Research results have been obtained, such as being most preferable to form.

The present invention has been made based on the results of such research,
(1) A plasma etching apparatus that does not contaminate a Si wafer coated with Si on the inner wall surface of the vacuum vessel of the plasma etching apparatus;
(2) The plasma etching apparatus that does not contaminate the Si wafer according to (1), wherein the Si coating is made of single crystal silicon, polycrystalline silicon, or columnar crystal silicon,
(3) The Si coating is characterized by a plasma etching apparatus that does not contaminate the Si wafer according to (1), which is a Si coating formed by pasting Si tiles.

In the plasma etching apparatus of the present invention, as shown in the cross-sectional explanatory view of FIG. An electrode plate 2 having penetrating pores 5 and a pedestal 3 are provided in the vacuum vessel 1 at an interval. To etch a Si wafer using this plasma etching apparatus, an Si wafer is placed on the pedestal 3. 4, and an etching gas 7 containing CHF ₃ or CF _{3 in} addition to Ar flows through the through-hole 5 provided in the electrode plate 2 toward the Si wafer 4, while the electrode plate 2 is By applying a high frequency voltage between the gantry 3 and applying this high frequency voltage, the supplied etching gas 7 becomes plasma 9 in the space between the electrode plate 2 and the gantry 3, and this plasma 9 is applied to the Si wafer 4. The fact that the surface of the Si wafer 4 is etched is the same as the conventional plasma etching apparatus.

  When plasma etching is performed using the plasma etching apparatus of the present invention, the Si wafer is not contaminated by the components of the members constituting the vacuum vessel, so that no defective product is generated. Etching can be performed and can greatly contribute to the development of the semiconductor device industry.

Example: A single crystal Si tile, a polycrystalline silicon tile, and a columnar silicon tile having dimensions of 120 mm in length, 120 mm in width, and thickness: 0.1 mm were prepared. Three crystal etching devices of the present invention were prepared by adhering crystal silicon tiles to the entire inner wall of a vacuum vessel made of SUS304 stainless steel with an adhesive. Furthermore, a single crystal silicon ingot having a diameter of 300 mm was prepared, and this ingot was cut into a thickness of 9 mm with a diamond band saw to produce a single crystal silicon disk, and the diameter: Set in a single crystal silicon plate plasma etching apparatus having a thickness of 0.5 mm, and further set in three plasma etching apparatuses in which a Si wafer with a diameter of 8 inches was prepared in advance.
Chamber pressure: 9 ^-1 Torr,
Etching gas composition: 90 sccm CHF ₃ +4 sccm O ₂ +150 sccm He,
High frequency power: 2kW
Frequency: 20kHz,
Under the above conditions, plasma etching of the Si wafer surface was performed for 400 hours, and the presence or absence of Ni, Cr and Fe adhering to the Si wafer surface was measured with a secondary ion mass spectrometer, and as a result, adhesion of Ni, Cr and Fe was observed. It was found that there was no contamination during plasma etching.

Plasma etching was performed under the same conditions as in the example without attaching a single crystal Si tile, a polycrystalline silicon tile and a columnar silicon tile to the entire inner wall of the vacuum vessel made of SUS304 stainless steel prepared in the conventional example. The adhesion of Ni, Cr and Fe was observed on the Si wafer surface, and it was found that the Si wafer was contaminated during plasma etching.

It is sectional drawing of the plasma etching apparatus of this invention. It is sectional explanatory drawing of the conventional plasma etching apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Electrode plate 3 Base 4 Si wafer 5 Through-hole 6 High frequency power supply 7 Plasma etching gas 8 Si coating 9 Plasma

Claims (3)

A plasma etching apparatus that does not contaminate a Si wafer, wherein an Si coating is applied to an inner wall surface of a vacuum vessel of the plasma etching apparatus. 2. The plasma etching apparatus according to claim 1, wherein the Si coating is made of single crystal silicon, polycrystalline silicon, or columnar crystal silicon. 3. The plasma etching apparatus according to claim 1, wherein the Si coating is an Si coating formed by attaching an Si tile.

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