Abrading – Machine – Rotary tool
Reexamination Certificate
1999-07-12
2001-04-10
Gerrity, Stephen F. (Department: 3729)
Abrading
Machine
Rotary tool
C451S041000, C451S287000, C451S443000, C451S444000, C451S446000
Reexamination Certificate
active
06213852
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polishing apparatus and to a method of manufacturing a semiconductor device using the polishing apparatus. More specifically, the present invention relates to a polishing apparatus ensuring stable polishing characteristic, and suppressing generation of micro scratches in a step of polishing during manufacturing of a semiconductor device, as well as to a method of manufacturing a semiconductor device using the polishing apparatus.
2. Description of the Background Art
As one of the measures to meet higher degree of integration and miniaturization of semiconductor devices, a method of planarizing a surface of a semiconductor substrate by Chemical Mechanical Polishing (hereinafter referred to as “CMP method”) in the manufacturing process has been known. A polishing apparatus described in Japanese Patent Laying-Open No. 8-294861 as an example of a polishing apparatus for the conventional CMP method will be described in the following.
Referring to
FIGS. 21 and 22
, on a rotary disk
113
rotating in a horizontal plane, a polishing cloth
115
for polishing a surface to be polished is adhered. Above rotary disk
113
, a wafer holding base
114
is arranged for holding a wafer
116
such that the surface to be polished of a semiconductor substrate is opposed to the surface of polishing cloth
115
. The center of rotation of wafer holding base
114
is arranged offset by a prescribed offset distance E from the center D of rotation of. rotary disk
113
.
Above rotary disk
113
, a polishing liquid supply tube
117
for supplying polishing liquid to polishing surface
115
a
of polishing cloth
115
, and a dressing liquid supply tube
120
for supplying dressing liquid to polishing surface
115
a
are provided. Further, above rotary disk
113
, a liquid draining mechanism
123
for draining waste polishing liquid and dressing liquid after polishing from polishing surface
115
a
is provided.
The diameter of wafer holding base
114
is shorter than the radius of rotary disk
113
, and wafer holding base
114
and rotary disk
113
rotate in the directions represented by arrows A and B, respectively. In
FIG. 22
, a two-dotted circle F represents a track drawn near the center of rotation of polishing cloth
115
by an outer periphery of wafer
116
held by wafer holding base
114
.
Main portions of the conventional polishing apparatus are structured as described above.
The operation of the polishing apparatus will be described in the following. To polishing surface
115
a
adhered on rotary disk
113
rotating at a constant rate, a polishing liquid containing fine alumina particles is supplied from polishing liquid supply tube
117
. At the same time, dressing liquid is supplied to polishing surface
115
a
from dressing liquid supply tube
120
. Wafer holding base
114
is moved downward while wafer holding base
114
on which a wafer
116
is fixed is rotated at a constant rate. A surface
116
a
to be polished of wafer
116
is pressed onto polishing surface
115
a
so that the surface
116
a
is polished. After polishing process, the waste polishing liquid and dressing liquid are recovered by liquid draining mechanism
123
. In this manner, wafer
116
is polished.
The polishing process by the above described polishing apparatus, however, has the following problems. Referring to
FIG. 23
, part of the polishing liquid supplied from polishing liquid supply tube
117
may undesirably flow directly to a region of polishing surface
115
a
which goes away from wafer holding base
114
because of the disk
113
rotation, or to a region of polishing surface
115
a
which goes away from dressing liquid supply tube
120
because of disk
113
rotation, as represented by solid arrows. Further, part of the dressing liquid supplied from dressing liquid supply tube
120
may possibly flow directly to a region of polishing surface
115
a
which goes away from liquid draining mechanism
123
because of disk
113
rotation, or to a region of polishing surface
115
a
which goes away from polishing liquid supply tube
117
by disk
113
rotation, as represented by dotted arrows.
Further, it is possible that the waste polishing liquid after polishing directly flows to a region of polishing surface
115
a which goes away from liquid draining mechanism
123
by disk
113
rotation. Accordingly, it is possible that the supplied polishing liquid and dressing liquid are mixed with each other, or polishing liquid and waste polishing liquid are mixed with each other, resulting in variation of polishing amount of the surface to be polished of the wafer, as well as in generation of micro scratches of the surface to be polished of the wafer caused by chippings.
SUMMARY OF THE INVENTION
The present invention was made in view of the above described problems, and its object is to provide a polishing apparatus ensuring stable polishing characteristic and suppressing generation of micro scratches on a surface to be polished of a semiconductor substrate, as well as to provide a method of manufacturing a semiconductor device using the polishing apparatus.
The polishing apparatus in accordance with one aspect of the present invention includes a polishing surface portion, a polishing unit, a chemical liquid supply unit and a waste liquid draining unit. The polishing surface rotates about a center of rotation, and polishes a surface to be polished, or an object surface. The polishing unit is arranged on and opposing to the polishing surface, and performs a series of polishing and washing operations. The polishing unit refers to a unit holding the surface to be polished, or a unit for cleaning the polishing surface. The chemical liquid supply unit is arranged on the polishing surface on a side which comes closer to the polishing unit when the polishing surface the polishing surface portion is rotated, and supplies chemical liquid for polishing to the polishing surface. The waste liquid draining unit is arranged on the polishing surface on a side which goes away from the polishing unit when the polishing surface portion is rotated, and removes the waste liquid on the polishing surface. Around the center of rotation of polishing surface, a partition unit is formed together with the waste liquid draining unit, for preventing flow of the chemical liquid and the waste liquid to a region of the polishing surface which goes away from the waste liquid draining unit when the polishing surface portion is rotated, through the region near the center of rotation. The waste liquid draining unit is arranged continuous from the partition unit to the outer periphery of the polishing surface.
Because of this structure, especially by the partition unit and the waste liquid draining unit arranged continuously from the partition unit to the outer periphery of the polishing surface, the chemical liquid and waste liquid after polishing are surely removed from the polishing surface, without any possibility of flowing to the region of the polishing surface which goes away from the waste liquid draining unit when the polishing surface portion is rotated to be mixed with the chemical liquid to be used for polishing. As a result, it is ensured that the surface to be polished is polished by the chemical liquid which is free of any waste liquid containing chippings, whereby the amount of polishing on the surface is made stable, and further, generation of micro scratches or the like on the surface to be polished caused by chippings can be suppressed. Further, as the chemical liquid and waste liquid after polishing are surely removed from the polishing surface, it is possible to continuously perform polishing operations using different types of chemicals by one same polishing surface, without the necessity of exchanging the polishing surface for the different types of chemicals, so that throughput of the polishing apparatus is improved.
Preferably, the chemical liquid supplying unit has a foam body extending continuously from the partition unit to the outer periphe
Fujii Kazuyuki
Sasaki Takanori
Sawada Mahito
Tsutahara Kouichiro
Gerrity Stephen F.
Kim Paul
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
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