Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
1999-05-03
2001-09-04
Morgan, Eileen P. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
C451S285000, C451S288000, C451S398000
Reexamination Certificate
active
06283834
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority from prior French Patent Application No. 98-05615, filed May 4, 1998, the entire disclosure of which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polishing machines, and more specifically to polishing machines for the mechano-chemical polishing of integrated circuit wafers during manufacturing.
2. Description of Related Art
With conventional polishing machines, the wafer to be polished is sandwiched between a pressing diaphragm of a rotary head that rotates the wafer and the surface of a rotary polishing platen. The polishing is performed by virtue of an abrasive in suspension in a liquid that is made to flow between the wafer and the polishing platen. The polishing head includes a disc that bears the diaphragm on its periphery, and a fluid exerts a pressure on this membrane through the disc in order to press the wafer against the polishing surface in a controlled manner. When abrasives in suspension of the colloid type are used with such a polishing machine, there exists a drawback in that the central part of the wafer is perfectly polished but a region near the peripheral edge of the wafer has a significantly smaller thickness removed.
SUMMARY OF THE INVENTION
In view of these drawbacks, it is an object of the present invention to overcome the above-mentioned drawbacks and to provide a diaphragm-support disc for a polishing machine that improves the uniformity of polishing and the flatness of the polished surface. A main annular part projects from a radial front face of the disc in a peripheral region of the radial front face a predetermined distance from the peripheral edge of the radial front face. Thus, the main annular part can act on the work piece to be polished through the diaphragm so as to press the work piece to be polished onto the polishing surface by an axial displacement of the disc with respect to the polishing surface.
Another object of the present invention is to provide a diaphragm-support disc that is specially suited for a polishing machine in which the diaphragm extend across a radial front face of the disc and wraps around the peripheral edge of the front face, with a fluid subjecting pressure on the radial rear face of the diaphragm (i.e., on the disc side). A work piece to be polished is sandwiched between the radial front face of the diaphragm and a polishing surface or cloth. The polishing machine polishes the work piece in a mechano-chemical manner using an abrasive component that flows between the work piece and the polishing surface.
A further object of the present invention is to provide a method for operating a polishing machine that uses such a disc.
Yet another object of the present invention is to provide a polishing machine for the mechano-chemical polishing of a circular integrated circuit wafer using an abrasive component that flows between the wafer and a polishing surface.
One embodiment of the present invention provides a diaphragm-support disc for a polishing machine of the type in which a work piece to be polished is sandwiched between a radial front face of a diaphragm and a polishing surface or cloth. The diaphragm is extended across and wrapped around the peripheral edge of a radial front face of the disc, and a radial rear face of the diaphragm is subjected to pressure from a fluid. The diaphragm-support disc includes a main annular part that projects from the radial front face of the disc and is located in a peripheral region of the radial front face of the disc a predetermined distance from the peripheral edge of the radial front face of the disc. The main annular part can act on the work piece through the diaphragm so as to press the work piece onto the polishing surface or cloth by an axial displacement of the disc with respect to the polishing surface or cloth. In a preferred embodiment, a shorter secondary annular part projects from the radial front face of the disc on the peripheral edge of the radial front face of the disc some distance from the main annular part.
Another embodiment of the present invention provides a method of operating a polishing machine to polish a work piece. The polishing machine is of the type that includes a polishing surface or cloth, a diaphragm-support disc, and a diaphragm positionable so that the work piece is sandwiched between a radial front face of the diaphragm and the polishing surface or cloth. The diaphragm is extended across and wrapped around the peripheral edge of the radial front face of the disc. According to the method, a main annular part is provided so as to project from a peripheral region of the radial front face of the disc a predetermined distance from the peripheral edge of the radial front face of the disc. A fluid is used to exert pressure on a radial rear face of the diaphragm so as to press the work piece onto the polishing surface or cloth, and the main annular part is used to exert pressure on a radial rear face of the diaphragm so as to press a peripheral region of the work piece onto the polishing surface or cloth. In one preferred method, the pressure exerted by the fluid on the diaphragm is less than or equal to the pressure exerted by the main annular part on the diaphragm.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only and various modifications may naturally be performed without deviating from the present invention.
REFERENCES:
patent: 5423716 (1995-06-01), Strasbaugh
patent: 5584746 (1996-12-01), Tanaka et al.
patent: 5624299 (1997-04-01), Shendon
patent: 5635083 (1997-06-01), Breivogel et al.
patent: 5851140 (1998-12-01), Barnes et al.
patent: 5879220 (1999-03-01), Hasegawa et al.
patent: 5964653 (1999-10-01), Perlov et al.
patent: 0 841 123 A1 (1998-05-01), None
patent: 0 879 678 A1 (1998-11-01), None
French Search Report dated Jan. 22, 1999 with annex on French Application No. 98-05615.
Bongini Stephen
Fleit Kain Gibbons Gutman & Bongini P.L.
Galanthay Theodore E.
Morgan Eileen P.
STMicroelectronics S.A.
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