Abrading – Machine – Rotary tool
Reexamination Certificate
2000-06-22
2001-10-09
Banks, Derris H. (Department: 3723)
Abrading
Machine
Rotary tool
C451S060000, C451S446000
Reexamination Certificate
active
06299515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of art to which this invention relates is semiconductor manufacturing techniques. Specifically, this-invention relates to apparatus and methods for planarizing semiconductor wafers.
2. Description of the Related Art
The manufacture of an integrated circuit device requires the formation of various layers (both conductive and non-conductive) above the base substrate to form the necessary components and interconnects. During the manufacturing process, removal of a certain layer or portions of a layer must be achieved in order to pattern and form the various components and interconnects. Generally this removal process is termed “etching” or “polishing.”
One of the techniques available for removal is a chemical-mechanical polishing (hereinafter “CMP”) process in which a chemical slurry is used along with a polishing pad. The mechanical movement of the pad relative to the wafer and the abrasive slurry provide the abrasive force for removing the exposed material off the wafer surface. Planarization is a method of treating a surface to remove discontinuities, such as by polishing (or etching), thereby “planarizing” the surface. Various methods and apparatus have been developed in the art for polishing semiconductor wafers. However, it has been found that during polishing, the load imposed on the wafer leads to a higher concentration of slurry contacting the wafer edges, than its center. As a result, there is greater polishing action at the edges, thus causing center-to-edge non-uniformity in thickness and poor flatness of the wafer.
FIG. 1
shows a typical apparatus for polishing a semiconductor wafer
1
. The apparatus includes a wafer carrier
2
which is coupled to a spindle
3
, which in turn is coupled to any suitable motor or driving means (not shown) for moving the carrier
2
in the directions indicated by arrows
4
a
,
4
b
, and
4
c
(rotation). The spindle
3
supports a load
5
, which is exerted against the carrier
2
and thus against the wafer
2
during polishing. The carrier
2
also includes a wafer retaining ring
6
, which prevents the wafer
1
from sliding out from under the carrier
2
as the carrier
2
moves. The semiconductor wafer
1
, which is to be polished, is mounted to the carrier
2
, positioned between the carrier
2
and the rotatable turntable assembly
7
located below the carrier
2
. The turntable assembly
7
includes a polishing table
8
, on which a polishing pad
9
is positioned, and the polishing table
8
is rotated around the shaft
10
in the direction indicated by arrow
11
by any suitable motor or driving means (not shown).
During polishing, a slurry (not shown) is introduced to the polishing pad
9
which works its way between the wafer carrier
2
and the pad
9
. Due to the load
5
which is imposed on the wafer carrier
2
, a higher concentration of slurry generally contacts the wafer edges, as previously noted, resulting in a greater polishing action at the edges.
Efforts have been made in the art to obtain a more uniform polishing action across the wafer surface. The prior art teaches the various mechanisms employed to maintain the process uniformity and regional rates of removal during the CMP process. These mechanisms generally pump slurry through the platen and a porous polishing pad thereby ensuring an adequate supply of slurry at the polishing surface of the polishing pad.
While this process has its advantages, it also has drawbacks. The prior art mechanisms are expensive and complicated. The conventional polishing systems cannot be easily reconfigured to provide the adequate slurry delivery mechanism. Additionally, the slurry distribution mechanisms of the prior art do not provide for removal and/or recycling of the used slurry.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a CMP apparatus with a built-in slurry distribution system which is inexpensive and uncomplicated as compared to prior art slurry distribution systems.
It is another object of the present invention to provide a CMP apparatus with a built-in slurry distribution system which can be easily reconfigured from a conventional CMP apparatus.
It is yet another object of the present invention to provide a CMP apparatus with a built-in slurry distribution system which also removes slurry for disposal or reuse.
Accordingly, a polishing apparatus for polishing a substrate is provided. The polishing apparatus comprises delivery means for delivering slurry to the apparatus; a porous polishing pad having an upper surface at which the substrate is polished; and a rotating platen upon which the porous pad lies. The rotating platen has a recess. The recess has a first portion in communication with the delivery means for delivering slurry into the first portion, and a second portion extending under the polishing pad. Whereby, slurry is delivered from the first portion to the second portion and to the upper surface of the pad where it aids in the polishing of the substrate.
In a preferred embodiment of the polishing apparatus of the present invention, the first portion of the recess is situated such that the slurry delivered to the top surface returns to the first portion for removal or reuse due to the rotational force of the rotating platen and wafer to the movement of the carrier relative to the polishing pad.
In yet another preferred embodiment of the polishing apparatus of the present invention, the first portion of the recess is a circular groove formed on an outer edge of the rotating platen.
In yet other preferred embodiments of the polishing apparatus of the present invention the second portion of the recess is a diametrical groove extending from the circular groove substantially across a diameter of the rotating platen; the second portion of the recess is a spiral groove extending from the first portion towards a central portion of the rotating platen.
In still yet another embodiment of the polishing apparatus of the present invention, a sprinkler means is disposed in the second portion of the recess for spraying slurry into the porous pad. Preferably, the sprinkler means comprises; a sprinkler hose disposed in the second portion of the recess, the sprinkler hose having an outer wall defining an interior conduit in communication with the slurry in the second portion of the recess, the sprinkler hose further having a plurality of spray holes disposed in the outer wall of the hose, facing the porous pad, and in communication with both the second portion of the recess and the interior cavity of the sprinkler hose; and gas delivery means for delivering pressurized gas into the sprinkler hose thus forcing the slurry to spray from the plurality of holes towards the porous pad.
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Beardsley Gary J.
Huynh Cuc Kim
Messier Steven J.
Walker David L.
Banks Derris H.
International Business Machines - Corporation
Ojini Anthony
Scully Scott Murphy & Presser
Walter, Esq. Howard J.
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