Abrading – Machine – Combined
Reexamination Certificate
2001-01-05
2003-03-11
Nguyen, George (Department: 3723)
Abrading
Machine
Combined
C451S443000, C451S288000
Reexamination Certificate
active
06530827
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for polishing an object in the form of a plate, such as a semiconductor wafer, a wafer covered with an insulating film in a semiconductor circuit, a wafer on which a metal wire is formed, a magnetic disc or a glass substrate. The invention relates further to a method of doing the same.
2. Description of the Related Art
There have been suggested many apparatuses and methods for polishing an object in the form of a plate, such as a semiconductor wafer, a magnetic disc or a glass substrate.
For instance, Japanese Unexamined Patent Publication No. 5-69310 has suggested an apparatus for polishing an object, including a flexible resilient film on which a wafer lies.
Japanese Unexamined Patent Publication No. 5-309559 has suggested an apparatus and a method of polishing an object, in which a laser beam is radiated to an object, a reflected laser beam is received, and then, a thickness of the object is measured based on the reflected laser beam.
Japanese Unexamined Patent Publication No. 7-105369 has suggested a method including the steps of a coating an organic resist containing a specific molecule, pigment or chemical compound therein, onto a substrate, analyzing used polishing solution, detecting the molecule, pigment and chemical compound, controlling a rotation speed, a load pressure, and a location of an apparatus of polishing an object based on the results of detection.
Japanese Unexamined Patent Publication No. 9-11117 has suggested an apparatus including a dresser for dressing a polishing cloth with which an object is to be polished. The dresser is positioned in a direction of a radius of a polishing plate supporting the polishing cloth therewith.
Japanese Unexamined Patent Publication No. 11-179648 has suggested an apparatus of polishing an object, including a conditioner, and absorbers positioned around the conditioner. Dust generated as the result of conditioning a polishing pad is collected by the absorbers.
Japanese Unexamined Patent Publication No. 11-48122 has suggested an apparatus of polishing an object, including a first dresser and a second dresser. The first dresser grinds and hence planarizes a surface of a polishing pad. Thereafter, the polishing pad is dressed by the second dresser comprised of a cylindrical brush, to thereby recover an original rough grain.
FIG. 1
is a side view of a conventional apparatus of polishing an object, similar to the apparatuses suggested in the above-mentioned Publications.
In operation of the apparatus, an object
132
is kept lied on a surface of a circular polishing plate
131
under a pressure by means of a holder
133
. While the polishing plate
131
is being rotated, polishing solution
134
containing abrasive is supplied to a surface of the polishing plate
131
to thereby polish the object
132
.
FIG. 2
is a graph showing a relation between a polishing rate and a period of time in which the object
132
is polished, in the apparatus illustrated in FIG.
1
. Herein, the polishing rate is defined as A/B wherein A indicates a polished amount of the object and B indicates a polishing time. As is obvious in view of
FIG. 2
, as the polishing time becomes longer, the polishing rate becomes smaller, because a surface of the polishing plate
131
is covered with particles generated by polishing the object
132
. Thus, the conventional apparatus illustrated in
FIG. 1
is accompanied with a problem that objects are polished in different degrees.
In addition, since polishing solution used for polishing the object
132
is wasted each time the object
132
is polished, the conventional apparatus is accompanied with another problem that running costs are unavoidably high.
Hence, the inventor of the present invention has suggested an apparatus for polishing an object, in Japanese Unexamined Patent Publication No. 11-70459, including a rotatable circular polishing plate having a polishing surface on which an object is to be polished, a pressurizer which applies a pressure to an object to make the object contact with the polishing surface, a first unit which is located upstream of the object in a direction of rotation of the polishing plate and which supplies polishing solution containing abrasive, to the polishing surface, a dresser which is located downstream of the object in a direction of rotation of the polishing plate and which dresses the polishing surface, and a second unit which is located downstream of the dresser and upstream of the first unit in a direction of rotation of the polishing plate and which has an absorption surface through which the second unit sucks the polishing solution from the polishing surface.
In practical use, the apparatus works better than the conventional apparatus illustrated in FIG.
1
. However, the apparatus has the following problems.
Firstly, it is necessary to keep a gap between the absorption surface and the polishing surface to be equal to or smaller than 1 mm in order to ensure a sufficient ability of the second unit to absorb the polishing solution. However, if the polishing plate is worn and hence the gap becomes greater, an ability of the second unit to absorb the polishing solution is reduced.
Secondly, each time the polishing plate is exchanged to a new one, it takes much time to properly set the second unit, resulting in deterioration in productivity.
SUMMARY OF THE INVENTION
In view of the above-mentioned problems in the conventional apparatuses, it is an object of the present invention to provide an apparatus and a method of polishing an object, both of which can keep a sufficient ability of the second unit to absorb polishing solution, even if the polishing plate is worn, and which makes it easier to properly set the second unit.
In one aspect of the present invention, there is provided an apparatus for polishing an object, including (a) a rotatable circular polishing plate having a polishing surface on which an object is to be polished, (b) a pressurizer which applies a pressure to an object to make the object contact with the polishing surface, (c) a first unit which is located upstream of the object in a direction of rotation of the polishing plate and which supplies polishing solution containing abrasive, to the polishing surface, (d) a dresser which is located downstream of the object in a direction of rotation of the polishing plate and which dresses the polishing surface, and (e) a second unit which is located downstream of the dresser and upstream of the first unit in a direction of rotation of the polishing plate and which has an absorption surface through which the second unit sucks the polishing solution from the polishing surface, the absorption surface being formed thereon with a plurality of pivots.
In accordance with the apparatus, since the absorption surface of the second unit is designed to have a plurality of pivots, it would be necessary to keep a gap between the absorption surface and the polishing surface equal to a height of the pivots. Thus, the second unit could be readily set each time the polishing plate is exchanged to a new one.
It is preferable that each of the pivots has a rounded summit. This ensures smooth contact between the pivots and the polishing surface of the polishing plate.
Though the pivots may be formed anywhere on the absorption surface, it is preferable that the pivots are formed at four corners of the absorption surface.
This ensures a widest area of the absorption surface.
The pivots may be composed of any material. For instance, the pivots may be composed of Teflon.
The absorption surface may be comprised of a first area facing an inner area of the polishing surface, a second area facing an outer area of the polishing surface entirely surrounding the inner area, and an intermediate area located between the first and second areas, the first area having absorption holes in a greater number than the intermediate area and the second area having absorption holes in a greater number than the intermediate area. The polishing solution is absorbed into
NEC Corporation
Nguyen Dung Van
Nguyen George
Young & Thompson
LandOfFree
Apparatus for polishing wafer and method of doing the same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for polishing wafer and method of doing the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for polishing wafer and method of doing the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3077288