U.S. patent application number 10/351589 was filed with the patent office on 2003-07-31 for apparatus for polishing a wafer.
Invention is credited to Baek, Soon-ki, Kim, Hyeung-yeul.
Application Number | 20030143933 10/351589 |
Document ID | / |
Family ID | 27607030 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030143933 |
Kind Code |
A1 |
Baek, Soon-ki ; et
al. |
July 31, 2003 |
Apparatus for polishing a wafer
Abstract
A chemical mechanical polishing (CMP) apparatus includes a
polishing pad, a platen, and a cleaning apparatus which provides a
cleaning fluid for cleaning the polishing head. The cleaning
apparatus includes a shaft located outside a periphery of the
polishing pad, and an arm mounted to the shaft and extending over
the polishing pad such that a bottom surface of the arm confronts
the polishing surface of the polishing pad. Further, a cleaning
fluid path is defined in the arm along a length of the arm, and
first drop holes are defined in the arm which are fluidly connected
to the cleaning fluid path and which drop cleaning fluid onto the
polishing surface of the polishing pad.
Inventors: |
Baek, Soon-ki; (Kyunggi-do,
KR) ; Kim, Hyeung-yeul; (Kyunggi-do, KR) |
Correspondence
Address: |
VOLENTINE FRANCOS, P.L.L.C.
Suite 150
12200 Sunrise Valley Drive
Reston
VA
20191
US
|
Family ID: |
27607030 |
Appl. No.: |
10/351589 |
Filed: |
January 27, 2003 |
Current U.S.
Class: |
451/67 |
Current CPC
Class: |
B24B 55/02 20130101;
B24B 37/04 20130101 |
Class at
Publication: |
451/67 |
International
Class: |
B24B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2002 |
KR |
02-04777 |
Claims
What is claimed is:
1. An apparatus for planarizing wafers, comprising: a polishing
station having a platen to which a polishing pad having a polishing
surface is attached; a polishing head located over the polishing
surface of the polishing pad; and a cleaning apparatus which
supplies a cleaning fluid onto the polishing pad, and which
includes a shaft located outside a periphery of the polishing pad,
and an arm mounted to the shaft and extending over the polishing
pad such that a bottom surface of the arm confronts the polishing
surface of the polishing pad; wherein a cleaning fluid path is
defined in the arm along a length of the arm, and wherein first
drop holes are defined in the arm which are fluidly connected to
the cleaning fluid path and which drop cleaning fluid onto the
polishing surface of the polishing pad.
2. The apparatus as recited in claim 1, wherein the bottom surface
of the arm is a flat surface.
3. The apparatus as recited in claim 1, wherein the bottom surface
of the arm is a curved surface.
4. The apparatus as recited in claim 2, wherein the first drop
holes are formed at the bottom surface of the arm.
5. The apparatus as recited in claim 3, wherein the first drop
holes are formed at the bottom surface of the arm.
6. The apparatus as recited in claim 1, wherein the arm further
includes at least one second drop hole which is fluidly connected
to the cleaning fluid path and which drops the cleaning fluid onto
a side surface of the polishing head.
7. The apparatus as recited in claim 6, wherein the second drop
hole is located at a distal end of the arm adjacent to the side
surface of the polishing head.
8. The apparatus as recited in claim 1, wherein at least one slurry
path is further defined in the arm along the length of the arm, and
wherein the apparatus further includes a nozzle fluidly connected
to the slurry path to supply slurry onto the polishing pad.
9. The apparatus as recited in claim 8, wherein the nozzle is
inserted into a receiving hole which is defined in the arm and
which has a hole, communicating with the slurry path, into which
the nozzle is inserted.
10. The apparatus as recited in claim 1, wherein the arm has a
first portion which extends lengthwise from the base, a second
portion which extends lengthwise at an angle from the first
portion, and a third portion which extends lengthwise at an angle
from the second portion.
11. The apparatus as recited in claim 10, wherein the arm is formed
of a monolithic body.
12. The apparatus as recited in claim 1, wherein the cleaning water
is a de-ionized (DI) water.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to chemical
mechanical polishing (CMP) and, more particularly, the present
invention relates to a CMP apparatus for polishing a film formed on
a wafer surface.
[0003] 2. Description of the Related Art
[0004] Chemical mechanical polishing (CMP) is one accepted method
of planarization. In a typical CMP apparatus, the exposed surface
of a substrate is placed against a polishing pad that is mounted
upon a circular rotatable plate (so-called "platen"). A polishing
head tightly holds the substrate, and a pressure is applied bring
the surface of the substrate against the polishing pad. Slurry is
supplied onto the polishing pad to remove or abrade the surface of
the substrate. A reagent in the slurry reacts on a film formed on
the substrate surface to facilitate the polishing. Reactions of the
substrate surface, the reagent, the polishing pad, and frictional
particles make it possible to polish the film.
[0005] One problem encountered in connection the CMP apparatus is
that the polishing pad can easily become contaminated by materials
removed from the slurry and the substrate. Further, the removed
materials can deteriorate the effectiveness of subsequent polishing
processes. Accordingly, it is a general practice to clean the pad
during and/or between polishing processes.
[0006] One apparatus for cleaning a polishing pad using a rinse arm
is disclosed in U.S. Pat. No. 6,280,299 entitled "COMBINED SLURRY
DISPENSER AND RINSE ARM" issued to the Applied Materials Inc.,
issued on Feb. 16, 2000. In this apparatus, high-pressure
de-ionized (DI) water for cleaning a polishing pad is sprayed at
high pressure through spray nozzles. However, apparatus of this
type suffer a number of drawbacks. For example, the high pressure
of the sprayed DI water cause the slurry to rebound (or splash) so
as to be dispersed all over the polishing apparatus, resulting in
slurries which solidify at the rinse arm and the polishing head,
referred to here as a second contamination. Particularly, most
slurries rebounding off the polishing pad stick to a guard inner
wall of a guard of the rinse arm. The slurries solidified on the
guard inner wall tend to drop down onto the polishing pad in the
polishing process to cause macro and micro snatches, which reduces
yields. These slurries solidified on the guard inner wall are the
principal factor in the generation of particles and scratches.
Further, the high-pressure DI water, which is sprayed through spray
nozzles, results in a fume phenomenon where an inside of the
polishing apparatus is contaminated on an air current. Also, since
the machine operator cannot readily access slurries sticking to the
guard inner wall of the rinse arm, the rinse arm must be detached
from the polishing apparatus in order to clean the rinse arm (or
remove the slurries). Likewise, since the rinse arm is opened to an
end without a guard, any DI water splashed thereto can contaminate
a rotating polishing head that holds the wafer in front of a rinse
arm. Finally, eddy currents may be formed in the rinse arm by the
spray angle of spray nozzles when the high-pressure DI water is
supplied. These eddy current in the rinse arm can disadvantageously
result in a partial oversupply phenomenon.
[0007] Generally, when high-pressure DI water is sprayed so as to
clean a polishing pad after supplying slurries to the polishing
pad, slurries and contaminants on the polishing pad are splashed so
as to adhere to the rinse arm (particularly, the guard inner wall)
and peripheral devices. For example, slurries or contaminants at a
bottom of the polishing pad can mixed with the splashed
high-pressure DI water. If the slurries or contaminants adhere to
each internal part of the polishing apparatus, they can dry
(solidify) to become a source of particle contamination and a
micro-scratches. Micro-scratches are particularly damaging to
yields as they often result in the electrical shorting of
insulating layers, a gate brigdes and so forth. Moreover, if the
slurries and contaminants remain at internal edges of the polishing
apparatus, it is nearly impossible to effectively perform the
cleaning process, thus reducing the overall reliability of the CMP
process.
SUMMARY OF THE INVENTION
[0008] According to an embodiment of the present invention, an
apparatus for planarizing wafers includes a polishing pad, a
platen, and a cleaning apparatus which provides a cleaning fluid
for cleaning the polishing head. The cleaning apparatus includes a
shaft located outside a periphery of the polishing pad, and an arm
mounted to the shaft and extending over the polishing pad such that
a bottom surface of the arm confronts the polishing surface of the
polishing pad. Further, a cleaning fluid path is defined in the arm
along a length of the arm, and first drop holes are defined in the
arm which are fluidly connected to the cleaning fluid path and
which drop cleaning fluid onto the polishing surface of the
polishing pad.
[0009] The arm of the cleaning apparatus may further include a
second drop hole which is fluidly connected to the cleaning fluid
path and which drops the cleaning fluid onto a side surface of the
polishing head. The second drop hole may be located at a distal end
of the arm adjacent to the side surface of the polishing head.
[0010] At least one slurry path may further be defined in the arm
along the length of the arm, and the apparatus further include a
nozzle fluidly connected to the slurry path to supply slurry onto
the polishing pad. A the nozzle may be inserted into a receiving
hole which is defined in the arm and which has a hole,
communicating with the slurry path, into which the nozzle is
inserted.
[0011] The arm of the cleaning apparatus may be formed of a
monolithic body, and may have a first portion which extends
lengthwise from the base, a second portion which extends lengthwise
at an angle from the first portion, and a third portion which
extends lengthwise at an angle from the second portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other aspects and features of the present
invention will become readily understood from the detailed
description that follows, with reference to the accompanying
drawings, in which:
[0013] FIG. 1 is an exploded view of a CMP apparatus according to
an embodiment of the present invention;
[0014] FIG. 2 is a partial top plan view of the CMP apparatus shown
in FIG. 1;
[0015] FIG. 3 is a cross-sectional view of a cleaning arm taken
along a line I-I' of FIG. 2;
[0016] FIG. 4 is a partial cross-sectional view of the cleaning arm
shown in FIG. 2; and
[0017] FIG. 5 is a partial cross-sectional side view of the CMP
apparatus shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Referring initially to FIG. 1, a CMP apparatus 100 according
to an embodiment of the present invention will be described. As
shown, the CMP apparatus 100 generally includes a polishing station
110, a polishing head assembly 150, and a cleaning apparatus
130.
[0019] The polishing head assembly 150 has a polishing head 152, a
drive shaft 154, and a motor 156. A wafer (not shown) is mounted to
the polishing head 152, and the polishing head 152 provides a
controllable pressure so as to push the wafer against the polishing
pad 122. The polishing head 152 may be rotated by means of the
drive shaft 154 at 40-70 rpm. Of course, the rate of rotation may
be higher or lower than 40-70 rpm. Although not shown, two or more
negative air pressure or vacuum channels may be contained in the
polishing head 152 to suction mount the wafer. Of course,
respective pumps would then be connected to such channels.
[0020] The polishing station 110 has a rotatable platen 120 to
which the polishing pad 122 is attached. The platen 120 is coupled
to a platen rotating device such as a motor and rotatable shaft
(not shown). Under an ideal state, the platen rotating device
rotates the platen 120 at 50-80 rpm. Of course, the rate of
rotation may be higher or lower than 50-80 rpm. The polishing pad
122 may be a combination material having a rough polishing surface.
The polishing station 110 may also include a conditioning device
114 as is know in the art.
[0021] The cleaning apparatus 130 serves to clean the polishing pad
122 and a side of the polishing head 152 which are contaminated by
slurry during a planarization process, and further serves to
provide the slurry used in the planarization process. The cleaning
apparatus 130 removes solidified slurry and contaminants on a
surface of the polishing pad 122 and in grooves thereof. For
example, the slurry may include a reagent (e.g., DI water for
oxidation polishing), frictional particles (e.g., silicon dioxide
for oxidation polishing), and a chemical reaction catalyst (e.g.,
calcium hydroxide for oxidation polishing).
[0022] The cleaning apparatus 130 will now be described more fully
with reference to FIG. 2 through FIG. 5, in which like elements are
identified by the same reference numbers. Particularly, FIG. 2 is a
partial top plan view of the CMP apparatus shown in FIG. 1, FIG. 3
is a cross-sectional view of the cleaning arm 134 taken along a
line I-I' of FIG. 2, FIG. 4 is a partial cross-sectional view of
the cleaning arm shown in FIG. 2, and FIG. 5 is a partial
cross-sectional side view of the CMP apparatus shown in FIG. 1.
[0023] The cleaning apparatus 130 includes a shaft 132 that is
disposed outside the periphery of platen 120, and an arm 134 that
is pivotably coupled to the shaft 132 and disposed so as to extend
over the polishing pad 122.
[0024] The arm 134 is pivotably mounted upon the shaft 132 in order
to be rotated between a cleaning position over the polishing pad
122 and a stand-by position adjacent to the platen 120. The arm
134, which is preferably formed of a monolithic (one piece) body,
has a base portion 134a coupled to the shaft 132, a first extension
134b extending from the base 134a, a second extension 134c
extending at an angle relative to and from the first extension
134b, and a third extension 134d extending at an angle relative to
and from the second extension 134c. The extensions 134b, 134c, and
134d that are formed in an angled relation to allow the end 134e of
the arm 134 to be placed closely adjacent to the polishing pad 152
while avoiding a collision between the remainder of the arm 134 and
the polishing pad 152.
[0025] As shown in FIG. 5, a barrier wall 135 may be formed at a
bottom of the base 134a. The barrier wall 135 prevents slurry and
unwanted debris from splashing into the shaft during a
planarization or cleaning process.
[0026] Referring to FIG. 3 and FIG. 4, the arm 134 has a cleaning
water transfer path 136 and a slurry transfer path 140. A cleaning
water is transferred to first drop holes 137 and second drop holes
138 through the cleaning water transfer path 136. Slurry is
transferred to a nozzle 142, which is installed at the third
extension 134d of the arm 134, through the slurry transfer path
140. The first drop holes 137 are spaced apart at a bottom of the
arm 134 along a length of the arm 134. At least one of the first
drop hole 137 may disposed to drop the cleaning water onto a
sidewall of the platen 120 (see FIG. 5). The second drop holes 138
are formed at an end side of the arm 134 (i.e., the third extension
134d). For example, the second drop holes 138 are preferably formed
at a position nearest the side of the polishing head 152. Referring
to FIG. 5, the cleaning water expelled from the first drop holes
137 cleans the polishing pad 122 and a side 120a of the platen 120.
The cleaning water expelled from the second drop hole 138 cleans a
side of the polishing head 152.
[0027] The arm 134 may have a flat bottom surface, but, referring
to FIG. 3, the arm 134 preferably has an arch-shaped bottom surface
139 to minimize surface area which horizontally confronts the
polishing pad 122, thus reducing the amount of unwanted debris
(including slurry) that will stick to the bottom of the arm 134.
Advantageously, the arch-shaped bottom surface 139 also enhances
access to the bottom of the arm 134, thus facilitating cleaning of
the arm by the machine operator. Of course, the bottom surface of
the arm 134 may be formed in other ways, such as by inclined walls
and so on.
[0028] Referring to FIG. 5, cleaning water drops onto a surface of
the polishing pad 122 through the first drop holes 137 to clean the
surface of the polishing pad 122 and a side 120a of the platen 120.
Cleaning water is also dropped from the second drop holes 138 along
a side of the polishing head 152 to prevent unwanted debris
including slurry from being solidified on the side of the polishing
head 152.
[0029] As shown above, the cleaning water flows through and drops
from the drop holes of the arm 134. Since the water is not expelled
under high-pressure by a nozzle, splashing is avoided or minimized.
Likewise, the fume phenomenon can be avoided as well.
[0030] Returning to FIG. 2, the cleaning apparatus 130 has a slurry
transfer path 140 that is formed in the arm 134, and a nozzle 142
that is connected to the slurry transfer path 140 and sprays slurry
onto the polishing pad. The nozzle 142 is for spraying slurry onto
the polishing pad 122 during polishing and is inserted or screwed
into a hole 144. The hole 144 is formed at the third extension of
the arm 134 and is connected to the slurry transfer path 140.
[0031] Although not shown in the figure, paths for sending fluid to
the arm 134 are formed at the shaft 132. Theses paths supply needed
fluid from supply sources associated with the CMP apparatus to the
cleaning water transfer path and the slurry transfer path of the
arm 134.
[0032] The present invention is thus not limited to the details of
the illustrated embodiment. Accordingly, the above description and
drawings are only to be considered illustrative of exemplary
embodiments which achieve the features and advantages of the
present invention. Modifications and substitutions to specific
process conditions and structures may be made without departing
from the spirit and scope of the present invention. Therefore, the
invention is not to be considered as being limited by the foregoing
description and drawings, but is only limited by the scope of the
appended claims.
* * * * *