Abrading – Precision device or process - or with condition responsive... – By optical sensor
Reexamination Certificate
2001-09-21
2003-10-28
Hail, III, Joseph J. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
By optical sensor
C451S005000, C451S285000, C156S922000
Reexamination Certificate
active
06638140
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
The present document is based on Japanese Priority Document JP 2000-289444, filed in the Japanese Patent Office on Sep. 22, 2000, the entire contents of which being incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to a polishing method and a polishing apparatus. More specifically, the present invention relates to the method and the apparatus for polishing a surface of a member to be processed having bumps and dips against a plane or a curved surface intended for processing by using slurry including a particle.
2. Description of the Related Art
As disclosed in Japanese Unexamined Patent Application Publication No. H11-288906, a processing method of a CMP (Chemical Mechanical Polishing) has widely been used conventionally in a flattening process of a semiconductor wafer substrate.
According to the conventional CMP processing method as shown in
FIG. 1
, an elastic polishing pad
12
is fixedly glued on a rotatable polishing plate
11
. On the other hand, a silicon wafer
13
is fixed to an end face of a polishing head
14
, and a surface to be polished of the silicon wafer
13
is made crimped to the polishing pad
12
with the bottom up. Under such condition, while slurry
15
is supplied, the polishing plate
11
and the polishing head
14
are respectively rotated, thereby the surface of the silicon wafer
13
is polished.
At this time, the slurry
15
does not flow sufficiently into a portion to be polished because the polishing pad
12
and the silicon wafer
13
are contacted each other under pressurized condition, so that a polishing condition is apt to be unstable. To prevent such unstable polishing condition, the surface of the polishing pad
12
is made dressed by a diamond tool or the like to form a comparatively large bumps and dips for providing slurry puddles. Therefore, on the surface of the polishing pad
12
made of an elastic body, there is formed a fuzzy produced due to scratches caused by the slurry puddles and the dressing tool.
The silicon wafer
13
polished by the CMP processing method as shown in
FIG. 1
includes regularly arranged bumps of a wiring pattern
21
or the like on the surface layer of the silicon wafer
13
as shown in
FIG. 2
, and a thin film layer
22
also covers upper portion of the silicon wafer
13
as an insulation film. Accordingly plural bumps
23
are created on the surface of the thin film layer
22
with an influence of the bumps of the wiring pattern
21
. According to the flattening process by the CMP processing method, the flattening process may be achieved by selectively polishing only the bumps
23
of the bumpy surface of the thin film layer
22
.
Accordingly, trials have been made to polish by contacting only the bumps
23
of the silicon wafer
13
with the polishing pad
12
by increasing a coefficient of elasticity thereof. However, actually as shown in
FIG. 3
, the surface of the polishing pad
12
is composed of the elastic body deformed under the pressure and has the shape of fuzz having been created, so that the surface of the polishing pad
12
contacts not only with the bumps
23
but also the dips of the thin film layer
22
. Namely, it is not possible to selectively polish only the bumps
23
of the thin film layer
22
.
Accordingly, it has been difficult to realize an ideal flattening process to selectively remove the bumps
23
by polishing only the portions of the bumps
23
on a large scale as shown by a removed portion
24
in FIG.
4
. Namely, actually as shown in
FIG. 5
, the removed portion
24
has roughly a constant thickness having no relation with the bumpy surface, and the bumps
23
of the thin film layer
22
formed on the surface of the silicon wafer
13
has been polished in almost uniform even with the progress of polishing, which has presented a problem that flattening is not easy to progress.
Such a phenomenon has been seen also in the case of processing an aspherical lens. Namely, a polishing process is practiced in such method that an aspherical shape obtained normally through a highly accurate grinding process is created, thereafter a damaged surface layer is removed and at the same time a surface roughness as an optical element is secured.
However, according to such polishing process, even if a polishing position and an amount of removal in that position has been calculated in accordance with the prior measurement, the peripheral portion has also been polished at the same time because the shape of removal by polishing has a certain area. In consequence, the region other than intended portion has also been polished, resulting in that accuracy of polishing achieved in the grinding process has been deteriorated on the contrary.
SUMMARY OF THE INVENTION
This invention has been made to solve such above-described problems, and to provide a polishing method and a polishing apparatus for obtaining a plane or a curved surface targeted for polishing by relatively increasing an amount of removal particularly of bumps, when polishing the surface of a member to be processed having bumpy surface.
In the polishing method for polishing the surface of the member to be processed having the bumps and dips against the plane or the curved surface targeted for processing by using a slurry including particles, a principal invention regarding the polishing method relates to the polishing method characterized in that a laser beam is irradiated to a position from which a selectively large amount of removal by polishing is desired to be acquired, thereby relatively increasing the amount of removal by polishing of that position.
Herein, by deciding a traveling route of a laser beam and a scanning position in accordance with a shape of the bumps and dips on the surface of the member, an amount of removal by polishing of the portion irradiated by the laser beam on the surface of the member may relatively be increased. It may also be accepted that a shading mask according to the shape of the bumps and dips on the surface of a member to be processed is disposed in the laser beam path to relatively increase the amount of removal by polishing of the portion irradiated by laser beam on the surface of a member to be processed which is an area exposed through the shading mask.
It may also be accepted that the particles in the slurry are made to be caught and collected on the portion irradiated by the laser beam on the surface of the member through a laser trapping phenomenon occurred by radiation pressure of a laser beam, and concentration rate of the particles in the slurry near the portion irradiated by the laser beam is made locally increased, thereby increasing the amount of removal by polishing on the surface. It may also be accepted that on the portion irradiated by the laser beam on the surface, a chemical reaction layer is made formed by a chemical reaction between the surface of the member and a slurry liquid caused by energy of the laser beam, and the chemical reaction layer is made removed by polishing by the particles in the slurry, thereby increasing the amount of removal by polishing on the surface of the member. It may also be accepted that the particles in the slurry are made to be caught and collected on the portion irradiated by the laser beam on the surface of a member to be processed through the laser trapping phenomenon occurred by the radiation pressure of the laser beam, and the concentration rate of the particles in the slurry near the portion irradiated by the laser beam is made locally increased, and moreover, on the portion irradiated by the laser beam on the surface of the member, the chemical reaction layer is made formed by the chemical reaction between the surface of the member and the slurry liquid caused by energy of the laser beam, and the chemical reaction layer is made removed by polishing with the particles in the slurry, thereby increasing the amount of removal by polishing on the surface of the member to be processed.
It may also be accepted that prior to or during polis
Kimura Keiichi
Miyoshi Takashi
Hail III Joseph J.
Kananen, Esq. Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
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