Abrading – Machine – Rotary tool
Reexamination Certificate
2000-03-06
2001-03-06
Scherbel, David A. (Department: 3723)
Abrading
Machine
Rotary tool
C451S287000
Reexamination Certificate
active
06196905
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a wafer polishing apparatus, and more particularly to a wafer polishing apparatus which has a retainer ring and presses a wafer against a rotating turn table to polish the wafer whose peripheral edge is enclosed by the retainer ring.
2. Description of Related Art
Japanese Patent Provisional Publication No. 8-229808 discloses a wafer polishing apparatus which has a retainer ring enclosing the periphery of a wafer and presses the retainer ring and the wafer against a turn table to polish the wafer. The wafer polishing apparatus is provided with an annular tube which is arranged between the retainer ring and a wafer holding head. Japanese Patent Provisional Publication No. 8-229808 also discloses a method of adjusting a pressure force of the retainer ring by adjusting the air pressure within the tube, and a method of adjusting the pressure force with use of a diaphragm.
A conventional wafer polishing apparatus, however, cannot uniformly press over the circumference of the retainer ring, since the supply of the air to the tube causes a weak portion thereof to expand excessively. The irregular pressure force causes the polishing pressure against the wafer to be irregular. Thus, the wafer cannot uniformly be polished.
The method of adjusting the pressure force of the retainer ring by means of the diaphragm has a disadvantage because the movable range of the retainer ring is too narrow to obtain a necessary pressure force.
SUMMARY OF THE INVENTION
The present invention has been developed under the above-described circumstances, and has as its object the provision of a wafer polishing apparatus with a retainer ring, in which the apparatus uniformly presses the retainer ring, which is greatly displaced.
To achieve the above-mentioned object, the present invention is directed to a wafer polishing apparatus which presses a wafer against a rotating turn table to polish a face of the wafer, the wafer polishing apparatus comprises: a rotary head body arranged opposite to the turn table; a carrier contained in the head body in a manner that is vertically movable, the carrier supporting the wafer to press the wafer against the turn table; a retainer ring contained in the head body in a manner that is vertically movable, the retainer ring concentrically arranged at the periphery of the carrier, the retainer ring coming into contact with the turn table and holding the periphery of the wafer during polishing; an elastic sheet provided in a space in the head body above the carrier and the retainer ring; a first space which presses the carrier and a second space which presses the retainer ring, the first and second spaces being formed in the head body; and is characterized in that the elastic sheet is concentrically divided into at least a central part included in the first space and a peripheral part included in the second space, and pressure air is supplied to the first and second spaces to elastically deform the central part and the peripheral part of the elastic sheet such that the central part presses the carrier against the turn table and the peripheral part presses the retainer ring against the turn table.
According to the present invention, the wafer polishing apparatus with the retainer ring supplies the pressure air to the first space and elastically deforms the central part of the elastic sheet under the air pressure to press the carrier, thereby pressing the wafer against the polishing pad. Then, the wafer polishing apparatus supplies the pressure air to the second space, and elastically deforms the periphery of the elastic sheet to press the retainer ring, thereby uniformly pressing the retainer ring against the polishing pad. Thus, the present invention uniformly polishes the whole surface of the wafer, and the movement strokes of the retainer ring are longer in the present invention than in the polishing apparatus which uses the diaphragm. For this reason, the retainer ring can be pressed satisfactorily.
Moreover, the present invention is directed to a wafer polishing apparatus which presses a wafer against a rotating turn table to polish a face of the wafer, the wafer polishing apparatus comprises: a rotary head body arranged opposite to the turn table; a carrier contained in the head body in a manner that is vertically movable, the carrier supporting the wafer to press the wafer against the turn table; a retainer ring contained in the head body in a manner that is vertically movable, the retainer ring concentrically arranged at the periphery of the carrier, the retainer ring coming into contact with the turn table and holding the periphery of the wafer during polishing; a sealed first space which presses the carrier and a sealed second space which presses the retainer ring, the first and second spaces being formed in the head body; and is characterized in that pressure air is supplied to the first and second spaces to press the carrier and the retainer ring against the turn table.
According to the present invention, in the wafer polishing apparatus, the pressure air is supplied to the first space to directly press the carrier and the wafer against the polishing pad. The pressure air is supplied to the second space, and the air pressure directly presses the retainer ring, thereby uniformly pressing the whole surface of the wafer. The movement strokes of the retainer ring are longer in the present invention than in the polishing apparatus which uses the diaphragm. For this reason, the retainer ring can be pressed satisfactorily.
According to the present invention, the elastic sheet is made of rubber, metal, or plastic. In other words, it is possible to use any kind of sheets which are elastically deformed by the pressure of the pressure air to press the carrier and the retainer ring.
According to the present invention, the elastic sheet is composed of one sheet, and the number of parts can be reduced as a result.
According to the present invention, the elastic sheet is composed of a circular sheet which is arranged therein, and an annular sheet which is arranged outside the circular sheet.
According to the present invention, the elastic sheet is composed of vertically stacked two elastic sheets. In other words, the two elastic sheets also can form the first and second spaces.
According to the present invention, an air jetting member is provided at the bottom of the carrier and jets the air towards the reverse side of the wafer to thereby form a pressure fluid layer between the carrier and the wafer and press the wafer against the turn table via the pressure fluid layer. Thus, the wafer is uniformly pressed against the turn table, and it is therefore possible to polish the whole surface of the wafer uniformly.
REFERENCES:
patent: 5036630 (1991-08-01), Kaanta et al.
patent: 5538465 (1996-07-01), Netsu et al.
patent: 5584751 (1996-12-01), Kobayashi et al.
patent: 5588902 (1996-12-01), Tominaga et al.
patent: 8-229808 (1996-09-01), None
patent: 9-19863 (1997-01-01), None
patent: 9-201763 (1997-08-01), None
Patent Abstracts of Japan, vol. 14, No. 570 (M-1060), Dec. 18, 1990, JP 2-243263 A (Hitachi Ltd.), Abstract.
Database WPIL on Questel, Week 9502, London: Derwent Publications Ltd., An 95-010404, Class F26B, JP 06-295893 A (Mitsubishi Material Silicon KK and Mitsubishi Materials Corp), Abstract.
Nixon & Peabody LLP
Ojini Anthony
Safran David S.
Scherbel David A.
Tokyo Seimitsu Co. Ltd.
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