Chemical mechanical polishing device with a pressure mechanism

Details Chemical mechanical polishing device with a pressure mechanism Chemical mechanical polishing device with a pressure mechanism

2000-01-31

2001-08-07

Hail, III, Joseph J. (Department: 3723)

Abrading

Machine

Rotary tool

C451S165000

Reexamination Certificate

active

06270397

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a chemical mechanical polishing (referred to as CMP hereafter) device; more specifically, the invention relates to a CMP device with a pressure-controlling mechanism for planarizing silicon wafers.
2. Description of Related Art
Conventionally, the CMP process has been relied upon heavily for providing a complete planarization process to each of the silicon wafers in the production of ULSI devices. An example of such conventional CMP device is illustrated in FIG.
1
A.
The above-mentioned conventional CMP device comprises at least the following components: an automated rotating polishing plate
110
having a rotating plate
100
and a polishing pad
120
, wherein the main function of the rotating plate
100
is to support and rotate the polishing pad
120
; a slurry supplying system
130
is provided for supplying slurry
150
to a surface of a polishing pad
120
; and a rotating carrier
160
having a spindle
180
for holding and rotating a silicon wafer
140
that is to be polished by the polishing pad
120
and slurry
150
during a CMP process.
Furthermore, a conventional CMP device typically comprises a rotating polishing plate
110
and a rotating carrier, each rotating independently while exerting a pressure force P to opposite sides of the wafer. The slurry used in a CMP process is typically comprised of silica or alumina particles dispersed and suspended in a gel-like acidic or basic etching solution of KOH or NH
4
OH. Then an automated slurry supplying system
130
supplies slurry
150
to the polishing pad
120
in order to maintain a constant and uniform permeation of the slurry
150
on the polishing pad
120
.
The mechanisms involved in the CMP process depend heavily on a chemical polishing, wherein the etching solution in the slurry
150
chemically removes or modifies surface particles of a silicon wafer, while a mechanical polishing of the silicon wafer
140
is achieved through the suspended abrasive particles in the slurry
150
and the rotating action of the polishing pad
120
. In addition, waste particles produced on the wafer
140
surface during the chemical polishing are also mechanically removed. Therefore, the overall polishing rate for the wafers can be accelerated by increasing either the chemical or the mechanical polishing rate.
It has always been a goal with conventional CMP devices or machines to polish the entire surface of a silicon wafer
140
in a uniform fashion. The contributing factors that directly affect the wafer polishing rate include the intensity and distribution of pressure force exerted to the wafer surface, relative velocities among each point of location on the wafer surface to the rotating polishing plate
110
, properties intrinsic to the compositions of the polishing pad and slurry, and complexity of the ULSI circuit layouts formed on the wafer
140
.
Shown in
FIG. 1B
, as the silicon wafer
140
is pressed against the polishing pad
120
, the supposedly flat surface of the polishing pad
120
tends to be deformed due to uneven pressures distributed to the surface of the silicon wafer
140
; specifically, there are four locations on the surface of the polishing pad
120
, namely We, W
e
, W
e
1, W
c
, and W
en
, where the measured contact pressures are the most distinct. Each of the locations, or referred to as contact locations hereafter, has a ring shape which is concentric to all the other contact locations. In particular, the contact location We represents a location on the polishing pad
120
which is in direct contact with the edge of the silicon wafer
140
. W
e
1, on the other hand, represents a contact location on the polishing pad
120
next to W
e
which in not in direct contact with the silicon wafer
140
. W
c
represents a contact location on the polishing pad
120
which is in direct contact with the center of the silicon wafer
140
, and W
en
represents a contact location on the silicon wafer
140
which is situated between W
e
1 and W
c
. Furthermore, since the contact pressure P exerted by the polishing pad
120
to the silicon wafer
140
at the edge location W
e
is the greatest and the contact pressure P at the contact location W
e
1 is the least, an uneven distribution of the contacting pressure is thus unfavorably created as shown in FIG.
1
C. This is then a factor for creating instability.
In addition, the mechanical polishing rate increases as the contacting pressure is increased and vice versa, which in turn generates an unstable physical profile W
s
of the wafer at the above-mentioned contacting and non-contacting positions as indicated by FIG.
1
D. When peaks and troughs appear in the profile W
s
of a wafer as a result of an uneven wafer polishing, waste particles tends to be accumulated on the wafer surface at the position corresponding to W
e
1 while the wafer surface at the position corresponding to W
e
tends to be over-polished.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a CMP device with a pressure-controlling mechanism comprising a rotating polishing plate, a slurry supplying system for supplying slurry to the surface of a polishing pad, a rotating carrier for holding and rotating a silicon wafer which is in constant contact with the slurry and the rotating polishing plate during the CMP process, and a pressure-controlling mechanism for distributing different contact pressures to different locations on the surface of a silicon wafer in response to different polishing rates. By using the device of the present invention, every point of location on the surface of a silicon wafer can be fully planarized in a uniform fashion.


REFERENCES:
patent: 5187899 (1993-02-01), Rhoades
patent: 5688364 (1997-11-01), Sato
patent: 5993300 (1999-11-01), Hashimoto

Affiliated with

Also associated with

Rating

Chemical mechanical polishing device with a pressure mechanism does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Chemical mechanical polishing device with a pressure mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical mechanical polishing device with a pressure mechanism will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2464503