Abrading – Abrading process – Utilizing fluent abradant
Reexamination Certificate
2003-10-14
2004-11-02
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Utilizing fluent abradant
C451S041000, C451S060000, C451S165000, C451S287000
Reexamination Certificate
active
06811468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polishing apparatus and a polishing method for flattening a semiconductor substrate or other object to be polished by chemical mechanical polishing.
2. Description of the Related Art
In the process of production of a semiconductor device, for example, a polishing apparatus using chemical mechanical polishing is used for flattening the uneven surface resulting from the multilayer structure of the semiconductor device. An example of this polishing apparatus is shown in FIG.
1
and FIG.
2
.
A polishing apparatus
101
shown in FIG.
1
and
FIG. 2
is provided with a polishing plate
121
which is rotatably held by a shaft
122
and to a front surface of which a polishing pad
111
is bonded, a polishing head
102
which is rotatably held by a shaft
103
arranged facing the polishing pad
111
, and a slurry feed nozzle
131
for feeding a mixture
141
of a polishing agent (slurry) made of a mixture of for example potassium hydroxide (KOH) and silicon dioxide (SiO
2
) and pure water onto the polishing pad
111
.
A polishing head
102
of the polishing apparatus
101
, as shown in
FIG. 2
, is formed with a recessed holder
102
a
for holding a wafer W. The wafer W is held at this holder
102
a
via for example a backing film for holding the wafer W at the holder
102
a.
The polishing apparatus
101
feeds the mixture
141
of the slurry and the pure water from the slurry feed nozzle
131
onto a center portion of the polishing pad
111
and makes the polishing head
102
and the polishing plate
121
rotate while pressing the wafer W held at the polishing head
102
against the polishing pad
111
with a predetermined pressing force P.
The mixture
141
of the slurry and pure water disperses toward the outer circumference by the rotation of the polishing pad
111
and enters between the polishing pad
111
and the wafer W, whereby the wafer W is flattened by chemical mechanical polishing.
However, in the polishing apparatus
101
having the above configuration, in order to interpose a sufficient amount of slurry between the polishing pad
111
and the wafer W, it is necessary to continuously feed the slurry from the slurry feed nozzle
131
, so the amount of consumption of the slurry is increased.
The cost of the slurry is relatively high, so if the amount of consumption of the slurry is increased, there is the disadvantage that the running cost (COO: cost of ownership) of the polishing apparatus
101
is increased.
On the other hand, since the slurry is a mixture of potassium hydroxide (KOH) and silicon dioxide (SiO
2
), it naturally easily forms hydrogen bonds—resulting in an increase in the particle size of the slurry.
The slurry having the increased particle size is apt to cause polishing scratches (microscratches and macroscratches) on the wafer W during polishing, therefore there was the disadvantage that the percentage of defective wafers W increased and the yield was lowered.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polishing apparatus using chemical mechanical polishing which is capable of reducing the amount of consumption of the polishing agent and capable of reducing the scratches caused on the object to be polished due to an increase of the particle size in the polishing agent and a polishing method using the same.
According to a first aspect of the present invention, there is provided a polishing apparatus which presses together and makes move relative to each other an object to be polished held at a polishing head and a polishing pad in a state where a polishing agent is interposed between a polishing surface of the object and the polishing pad so as to flatten the polishing surface of the object by chemical mechanical polishing, the polishing head comprising; a polishing agent receiving unit for receiving the polishing agent, a holding means for holding the object to be polished in a holding recess in the polishing head, a contact portion which is positioned at the periphery of the holding recess and is fully contacted to the polishing pad to define a closed space for positioning the polishing agent between the polishing surface of the object to be polished and the polishing pad, a polishing agent feed control means for controlling the feed and the step of the polishing agent from the polishing agent receiving port into the closed space in response to the amount of the polishing agent in the closed space.
Preferably, the polishing agent feed control means comprises a feed port for feeding the polishing agent from the polishing agent receiving portion into the closed space, and a valve means provided with a valve for opening and closing the feed port.
According to a second aspect of the present invention, there is provided a polishing apparatus which presses together and makes move relative to each other a polishing head and a polishing pad in a state where a polishing agent is interposed between a polishing surface of an object to be polished held by the polishing head and the polishing pad so as to flatten the polishing surface of the object by chemical mechanical polishing, the polishing apparatus comprising a vibration imparting means for imparting vibration to the polishing agent.
According to a third aspect of the present invention, there is provided a polishing method in which an object to be polished held at a polishing head and a polishing pad are pressed together and are made move relative to each other in a state where a polishing agent is interposed between a polishing surface of the object polished and the polishing pad so as to flatten the polishing surface by chemical mechanical polishing, the method comprising the steps of defining a closed space between the polishing surface of the object polished and the polishing pad and polishing the polishing surface in a state wherein the polishing agent kept in the closed space.
According to a fourth aspect of the present invention, there is provided a polishing method in which a polishing head and a polishing pad are pressed together and are made move relative to each other in a state where a polishing agent is interposed between a polishing surface of an object to be polished held by the polishing head and the polishing pad so as to flatten the polishing surface by chemical mechanical polishing, the method a step of comprising imparting vibration to the polishing agent.
According to the present invention, when the polishing agent is fed to the polishing agent receiving portion in a state where the contact portion of the polishing head is in full contact with the polishing pad, it is fed into the closed space defined by the contact portion, the polishing pad, and the polishing surface of the object to be polished by the polishing agent feed control means.
When the polishing agent is filled in the closed space, the polishing agent feed control means stops the feed of the polishing agent to give a state where the polishing agent is held in the closed space.
The polishing head and the polishing pad are made to move relative to each other in this state, whereby the polishing surface of the object to be polished is flattened by chemical mechanical polishing.
Further, by applying ultrasonic vibration to the polishing agent, even if the particle size of the polishing agent has increase, the particle size in the polishing agent can be reduced by the ultrasonic vibration, the particle size can equalized, and the formation of macroscratches or microscratches on the polishing surface of the object to be polished can be suppressed.
REFERENCES:
patent: 5140773 (1992-08-01), Miwa et al.
patent: 5144771 (1992-09-01), Miwa
patent: 5449316 (1995-09-01), Strasbaugh
patent: 5584751 (1996-12-01), Kobayashi et al.
patent: 5688364 (1997-11-01), Sato
patent: 5904615 (1999-05-01), Jeong et al.
patent: 5913718 (1999-06-01), Shendon
patent: 5916015 (1999-06-01), Natalicio
patent: 6168502 (2001-01-01), Allman et al.
Hail III Joseph J.
Ojini Anthony
Sonnenschein Nath & Rosenthal LLP
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