U.S. patent application number 09/444474 was filed with the patent office on 2001-12-13 for chemical-mechanical polishing apparatus with megasonic energy slurry supply system.
Invention is credited to LIN, TSANG-JUNG.
Application Number | 20010050142 09/444474 |
Document ID | / |
Family ID | 26666774 |
Filed Date | 2001-12-13 |
United States Patent
Application |
20010050142 |
Kind Code |
A1 |
LIN, TSANG-JUNG |
December 13, 2001 |
CHEMICAL-MECHANICAL POLISHING APPARATUS WITH MEGASONIC ENERGY
SLURRY SUPPLY SYSTEM
Abstract
An apparatus for chemical-mechanical polishing is disclosed. The
apparatus includes the following elements. A pump is used for
forcing slurry to be flown inward to receive the slurry from a
supply reservoir. A first pipe having a first end, is coupled to an
outlet of the forcing means through which the forced slurry flows
therein. A megasonic generator coupled in approximately midway of
the first pipe and surrounded the first pipe, is used for
generating megasonic wave. A second pipe, coupled to a second end
of the first pipe, is used for conducting the slurry and then
exhausting the slurry through an outlet of the second pipe. A
polishing pad, onto that the slurry from the second pipe is
dropped, is fixed on a polishing table. The polishing table
underlying the polishing pad is used for supporting the polishing
pad. A wafer holder, located above the polishing pad, is used for
fixing the wafer to the wafer holder while in rotational movement
with respect to the polishing pad.
Inventors: |
LIN, TSANG-JUNG; (CHUNG-LI
CITY, TW) |
Correspondence
Address: |
THOMAS T. MOGA
POWELL, GOLDSTEIN, FRAZER & MURPHY, LLP
1001 PENNSYLVANIA AVE, N.W.
SUITE 600
WASHINGTON
DC
20004
US
|
Family ID: |
26666774 |
Appl. No.: |
09/444474 |
Filed: |
November 22, 1999 |
Current U.S.
Class: |
156/345.12 |
Current CPC
Class: |
C23F 3/00 20130101; B24B
37/04 20130101; B24B 57/02 20130101 |
Class at
Publication: |
156/345 |
International
Class: |
C23F 001/02 |
Claims
What is claimed is:
1. A chemical-mechanical polishing apparatus, comprising: means for
forcing slurry to be flown inward to receive the slurry from a
supply reservoir; a first pipe having a first end coupled to an
outlet of said forcing means through which the forced slurry flows
therein, wherein said first pipe has an interior passage way
configured to conduct the slurry; means for generating sonic wave,
coupled in approximately midway of said first pipe and surrounded
said first pipe, therefore said generated sonic wave transmitting
into and affecting the slurry in the interior passage way of said
first pipe, thereby grain size of the affected slurry is made small
enough or the grains of the affected slurry are prevented from
being aggregated, thereby improving the polishing of the
chemical-mechanical polishing apparatus; a second pipe, coupled to
a second end of said first pipe, for further conducting the slurry
and then exhausting the slurry through an outlet of said second
pipe; a polishing pad onto which the slurry from said second pipe
is dropped, wherein said polishing pad is located under the outlet
of said second pipe, therefore a wafer under polishing and said
polishing pad are in rotational contact such that the dropped
slurry facilitates the polishing of the chemical-mechanical
polishing apparatus; a polishing table underlying said polishing
pad for supporting said polishing pad; and a wafer holder, located
above said polishing pad, for fixing the wafer to said wafer holder
while in rotational movement with respect to said polishing
pad.
2. The apparatus according to claim 1, wherein said forcing means
includes a pump.
3. The apparatus according to claim 2, wherein said pump includes a
peristalsis pump.
4. The apparatus according to claim 1, wherein said generating
means includes a megasonic generator.
5. The apparatus according to claim 1, wherein said polishing table
includes a rotary polishing table.
6. The apparatus according to claim 1, wherein said wafer holder
includes a rotary wafer holder.
7. A slurry supply system for chemical-mechanical polishing (CMP),
comprising: means for forcing slurry to be flown inward to receive
the slurry from a supply reservoir; a first pipe having a first end
coupled to an outlet of said forcing means through which the forced
slurry flows therein, wherein said first pipe has an interior
passage way configured to conduct the slurry; means for generating
sonic wave, coupled in approximately midway of said first pipe and
surrounded said first pipe, therefore said generated sonic wave
transmitting into and affecting the slurry in the interior passage
way of said first pipe, thereby grain size of the affected slurry
is made small enough or the grains of the affected slurry are
prevented from being aggregated, thereby improving the polishing of
the chemical-mechanical polishing apparatus; a second pipe, coupled
to a second end of said first pipe, for further conducting the
slurry and then exhausting the slurry through an outlet of said
second pipe;
8. The apparatus according to claim 7, wherein said forcing means
includes a pump.
9. The apparatus according to claim 7, wherein said pump includes a
peristalsis pump.
10. The apparatus according to claim 7, wherein said generating and
transmitting means includes a megasonic generator.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to apparatus for manufacturing
semiconductor, more particularly to apparatus for
chemical-mechanical polishing process.
[0003] 2. Description of the Prior Art
[0004] Chemical-mechanical polishing (CMP) is one of the common
planarizing techniques. The method is used to achieve a planar
surface over the entire chip and wafer, referred to as "global
planarity". It consists of a rotating holder that holds the wafer,
an appropriate slurry, and a polishing pad that is applied to the
wafer at a specified pressure. CMP is not limited to dielectrics.
It is used to planarize deep and shallow trenches filled with
polysilicon or oxide, and various metal films.
[0005] Polishing results from a combination of chemical and
mechanical effects. A suggested mechanism for CMP involves the
formation of a chemically altered layer at the surface of the
material being polished. This layer is mechanically removed from
the surface, beginning the process again. For example, in SiO2
polishing, the altered layer may be a hydrated oxide that can be
mechanically removed or, for metal polishing, a metal oxide may be
formed and removed.
[0006] The slurry composition and pad pressure determine the
polishing rate. Oxide films, for example, polish twice as fast in a
slurry with pH=11 than with pH=7. The hardness of the polishing
particles should be about the same as the hardness of the film
being polished to avoid damaging the film. The particle size should
be uniform, commonly less than 0.1 .mu.m in the diameter, and the
solution free of metallic contaminants. Slurry typically consists
of an abrasive component and a component that chemically interacts
with the surface. A typical oxide polishing slurry may consist of a
colloidal suspension of oxide particles, with and average size of
0.03 .mu.m, in an alkali solution (pH.gtoreq.10). A polishing rate
of about 0.12 .mu.m/min can be achieved with this solution.
[0007] A variety of polishing pads/cloths is available. They are
typically grouped by their mechanical properties. Hard pads produce
better planarity, while soft pads achieve better uniformity and
less surface damage. The choice of pads is application dependent.
For example, while soft pads are used for flat silicon substrates
to avoid scratches, these pads are often not suitable for surfaces
containing patterns.
[0008] Several methods to detect the polish end-point are being
investigated. Some of them rely on the change in frictional forces
between pad and polished surface. The most widely used method is,
however, to measure the thickness of the polished film at several
intervals between polishing and determine the time needed to
achieve the required polished thickness.
[0009] During the polishing process, some polishing particles in
the slurry, such as SiO.sub.2, are easily aggregated together and
then become a gel or a larger grain that has the size more than 0.5
.mu.m. Unfortunately, the gel or larger grain can usually damage
the polished surface of wafer. The aggregation is due to the static
and the gelling effects.
[0010] For the foregoing reason, there is a need to develop an
apparatus, that can avoid the aggregation of the polishing
particles in the slurry during polishing process.
SUMMARY OF THE INVENTION
[0011] In accordance with the present invention, a mechanism is
provided for performing chemical-mechanical polishing, that
substantially prevents the damages on polished surface of wafer
during CMP. In one embodiment, the mechanism includes: a pump for
forcing slurry to be flown inward to receive the slurry from a
supply reservoir; a first pipe having a first end, coupled to an
outlet of the forcing means through which the forced slurry flows
therein; a megasonic generator, coupled in approximately midway of
the first pipe and surrounded the first pipe; a second pipe coupled
to a second end of the first pipe, for further conducting the
slurry and then exhausting the slurry through an outlet of the
second pipe; a polishing pad onto which the slurry from the second
pipe is dropped; a polishing table underlying the polishing pad for
supporting the polishing pad; and a wafer holder, located above the
polishing pad, for fixing the wafer to the wafer holder while in
rotational movement with respect to the polishing pad.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated as the same
becomes better understood by reference to the following detailed
description, when taken in conjunction with the accompanying
drawings, wherein:
[0013] FIG. 1 shows the chemical-mechanical polishing mechanism
introduced by the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] In semiconductor manufacturing, the sonic energy is
generally used for cleaning system to loosen particles on wafers.
The high frequency sonic waves (about 850 kHz) will be generated in
the cleaning process. Similarly, to loosen the particles in
polishing slurry, the sonic energy can also be used for
chemical-mechanical polishing (CMP) to prevent the situation of
polishing particles aggregating together.
[0015] In the present invention, a chemical-mechanical polishing
mechanism including a megasonic energy slurry supply system is
provided. As shown in FIG. 1, mainly, a megasonic generator 12 is
added to the slurry supply system of the conventional CMP
mechanism. The slurry includes polishing particles and a solution.
Each of the polishing particles has the size about less than 0.1
.mu.m in the diameter, and its selected material is according as
the polished object.
[0016] In the mechanism of this invention, a typical peristalsis
pump 10 forces slurry to be flown inward to receive the slurry from
a supply reservoir. A first pipe 11 having a first end is coupled
to an outlet of the peristalsis pump 10 through which the forced
slurry flows therein. Therein, the first pipe 11 has an interior
passage way configured to conduct the slurry. A megasonic generator
12, which can generate megasonic or sonic wave, is coupled in
approximately midway of the first pipe 11 and surrounded the first
pipe 11. Therefore, the generated megasonic or sonic wave transmits
into and affecting the slurry in the interior passage way of the
first pipe 11, thereby grain size of each of the particles in the
affected slurry is made small enough or the grains are prevented
from being aggregated. Accordingly, the polishing of the
chemical-mechanical polishing apparatus can be improved.
[0017] Moreover, a second pipe 13, coupled to a second end of the
first pipe 11, for further conducting the slurry and then
exhausting the slurry through an outlet of the second pipe 13. Then
the slurry from the second pipe 13 is dropped onto a polishing pad
14, therein, the polishing pad 14 is located under the outlet of
the second pipe 13. A wafer 17 under polishing and the polishing
pad 14 are in rotational contact such that the dropped slurry
facilitates the polishing of the chemical-mechanical polishing
apparatus. A rotary polishing table 15 underlying the polishing pad
14 is used to support the polishing pad 14. A wafer holder 16,
located above the polishing pad 14, is used to fixing the wafer 17
to the rotary wafer holder 16 while in rotational movement with
respect to the polishing pad 14.
[0018] Although specific embodiments have been illustrated and
described, it will be obvious to those skilled in the art that
various modifications may be made without departing from what is
intended to be limited solely by the appended claims.
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