Abrading – Accessory – Dressing
Reexamination Certificate
1999-11-01
2001-03-13
Gerrity, Stephen F. (Department: 3723)
Abrading
Accessory
Dressing
C451S056000, C451S287000, C451S288000, C451S443000, C451S444000
Reexamination Certificate
active
06200207
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dressing apparatus for conditioning and regenerating a chemical mechanical polishing (referred to as CMP hereafter) pad; more specifically, the invention relates to a diamond disc dresser that cleans, flattens, and roughens the polishing pad.
2. Description of Related Art
A CMP device for polishing the surface of a semiconductor wafer includes a carrier for holding the semiconductor wafer and a polishing pad made of porous material polishes the wafer while retaining polishing slurry. The polishing slurry is a polishing fluid of certain grainy property. The carrier and pad are positioned such that the surface of the semiconductor wafer to be polished faces upward. The slurry is fed to the rear of the pad such that the porosity of the polishing pad allows the slurry to penetrate from the rear to the front of the pad.
Conventionally, two types of diamond disc dressers for conditioning the CMP pad are utilized by industry: annular disc type and spiky disc type.
An annular disc type dresser is a ring-shaped dressing apparatus with embedded synthetic diamond tool bits on its working surface. The main functions of the annular disc type dresser are to clean, roughen, and flatten the polishing pad of a CMP device. Nevertheless, it is extremely difficult to control the quality of the annular disc type dresser when it is being manufactured since the tiny diamond tool bits have to be permanently grafted to the working surface of the dresser with extreme evenness and tightness.
A spiky disc type dresser, on the other hand, is a disc dresser with a plurality of replaceable cylindrical spikes, wherein synthetic diamond bits are embedded on the tip portion of the cylindrical spikes. Since only a small area of the spiky type dresser is embedded with synthetic diamond bits, it is much simpler to manufacture the spiky disc type dresser compared with that of the annular disc type dresser. However, the spiky disc type dresser is less effective in cleaning, flattening, and roughening the pad.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to improve on a dressing apparatus for the conditioning and regeneration of a CMP pad which is simple to manufacture and provides effective cleaning, flattening, and roughening of the CMP pad.
The present invention meets this object by providing a dressing apparatus comprising: a rotatable inner shaft defining a first axis; an outer sleeve shaft disposed around the inner shaft; an air cap comprising a bottomless air chamber and at least one opening penetrating its upper surface for receiving compressed air; an air cap support connected to the outer sleeve shaft and supporting the curved air cap; a carrier plate disposed beneath the air cap and having an upper surface, a lower surface, and a plurality of through holes communicating the upper surface and the lower surface, wherein the upper surface is coupled to the inner shaft so as to rotate the carrier plate about the first axis, and the through holes receive compressed air from the air cap when the rotation of the carrier plate brings them under the air cap; and a plurality of dressing tools, each having a mounting surface and a dressing surface, wherein the mounting surfaces of the dressing tools are mounted to the lower surface of the carrier plate with the dressing surfaces facing the working surface of the CMP pad; wherein, the rotation of carrier plate conditions and regenerates the working surface of the CMP pad by action of the dressing surfaces of the dressing tools, and compressed air provided through the air cap is forced through the plurality of through holes in the carrier plate, thereby forcing micro-particles and other types of contamination off the working surface of the CMP pad.
The air cap can be curved, wherein the center of the curvature of the air cap is the first axis, and the air cap spans a spanning angle no greater than 180° and preferably no greater than 120°. A plurality of tiny synthetic diamond bits can permanently grafted onto the dressing surfaces of the dressing tools to enhance the conditioning and regenerating action. A debris collector can be provided for collecting the micro-particles and other types of contamination swept of the working surface of the CMP pad.
REFERENCES:
patent: 5885137 (1999-03-01), Ploessl
patent: 6004193 (1999-12-01), Nagahara et al.
patent: 6036583 (2000-03-01), Perlov et al.
patent: 6123607 (2000-09-01), Ravkin et al.
Darby & Darby
Gerrity Stephen F.
McDonald Shantese
Vanguard International Semiconductor Corp.
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