U.S. patent application number 09/775214 was filed with the patent office on 2001-10-11 for multi-step conditioning process.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Bennett, Doyle E., Li, Jui-Lung, Ma, Yutao.
Application Number | 20010029155 09/775214 |
Document ID | / |
Family ID | 26875140 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010029155 |
Kind Code |
A1 |
Bennett, Doyle E. ; et
al. |
October 11, 2001 |
Multi-step conditioning process
Abstract
Methods and apparatuses are provided that may remove the build
up of polishing by products from the polishing pad without the
reduction in throughput associated with conventional ex-situ
conditioning. The conditioning method comprises holding a wafer
against a polishing pad with a 0 psi force, and applying a
conditioning fluid to the polishing pad while holding the wafer
against the polishing pad with a 0 psi force. Thereafter the
conditioning fluid may be rinsed from the polishing pad or may
remain on the polishing pad while polishing is commenced. The
polishing apparatus has a controller programmed to perform the
conditioning method.
Inventors: |
Bennett, Doyle E.; (Santa
Clara, CA) ; Ma, Yutao; (Fremont, CA) ; Li,
Jui-Lung; (San Jose, CA) |
Correspondence
Address: |
Patent Counsel, M/S 2061
Legal Affairs Dept.
Applied Materials, Inc.
3050 Bowers Avenue
Santa Clara
CA
95054
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
26875140 |
Appl. No.: |
09/775214 |
Filed: |
January 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60179240 |
Jan 31, 2000 |
|
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|
Current U.S.
Class: |
451/56 ; 451/285;
451/287; 451/443 |
Current CPC
Class: |
B24B 53/017 20130101;
B24B 37/042 20130101; B24B 53/013 20130101 |
Class at
Publication: |
451/56 ; 451/443;
451/285; 451/287 |
International
Class: |
B24B 001/00 |
Claims
The invention claimed is:
1. A method configured to condition a polishing pad, the method
comprising: holding a wafer against a polishing pad with a 0 psi
force; applying a conditioning fluid to the polishing pad while
holding the wafer against the polishing pad with a 0 psi force;
applying a rinsing fluid to the polishing pad; increasing the force
between the wafer and the polishing pad; and applying a polishing
solution to the polishing pad so as to polish the wafer.
2. The method of claim 1 wherein applying a conditioning fluid to
the polishing pad comprises removing built up materials from the
polishing pad.
3. The method of claim 1 wherein applying the conditioning solution
to the polishing pad occurs after polishing the wafer.
4. The method of claim 3 wherein the wafer comprises copper
layers.
5. The method of claim 3 wherein the conditioning fluid comprises
citric acid and ammonium hydroxide.
6. The method of claim 1 further comprising conditioning the
polishing pad with an abrasive element while holding a wafer
against a polishing pad with a 0 psi force; applying a conditioning
fluid to the polishing pad while holding the wafer against the
polishing pad with a 0 psi force; applying a rinsing fluid to the
polishing pad; and applying a polishing solution to the polishing
pad so as to polish the wafer.
7. The method of claim 1 wherein the wafer comprises copper
layers.
8. The method of claim 1 wherein the conditioning fluid comprises
citric acid and ammonium hydroxide.
9. A method configured to condition a polishing pad, the method
comprising: holding a wafer against a polishing pad with a 0 psi
force; applying a conditioning fluid to the polishing pad so as to
remove built up materials from the polishing pad while holding the
wafer against the polishing pad with a 0 psi force; increasing the
force between the wafer and the polishing pad; and applying a
polishing solution to the polishing pad.
10. The method of claim 9 wherein applying the conditioning
solution to the polishing pad occurs after polishing the wafer.
11. The method of claim 9 wherein the wafer comprises copper
layers.
12. The method of claim 9 wherein the conditioning fluid comprises
citric acid and ammonium hydroxide.
13. The method of claim 9 further comprising conditioning the
polishing pad with an abrasive element while: holding a wafer
against a polishing pad with a 0 psi force; applying a conditioning
fluid to the polishing pad while holding the wafer against the
polishing pad with a 0 psi force; increasing the force between the
wafer and the polishing pad; and applying a polishing solution to
the polishing pad.
14. An apparatus configured to condition a polishing pad, the
apparatus comprising: a polishing pad; a wafer holder coupled to
the polishing pad and configured to hold a wafer in contact with
the polishing pad; a conditioning arm configured to move across the
polishing pad; at least one supply line configured to supply a
fluid to the polishing; and a controller coupled to the at least
one supply line and the wafer holder, the controller having a
program configured to direct the wafer holder to hold the wafer
against the polishing pad with a 0 psi force and further configured
to direct the at least one supply line to supply a fluid to the
polishing pad while the wafer holder holds the wafer against the
polishing pad with a 0 psi force.
15. The apparatus of claim 14 further comprising a source of
conditioning solution coupled to the first supply line, and wherein
the program is adapted to supply conditioning solution to the
polishing pad while the wafer holder holds the wafer against the
polishing pad with 0 psi force.
16. The apparatus of claim 15 wherein the at least one supply line
comprises three supply lines.
17. The apparatus of claim 16 further comprising: a source of
deionized water coupled to the second supply line; and a source of
polishing solution coupled to the third supply line.
18. The method of claim 9 further comprising: ceasing application
of the conditioning fluid so that the polishing solution dilutes
the conditioning fluid.
19. A method configured to condition a polishing pad, the method
comprising: determining whether a predetermined time interval has
passed, and if so: holding a wafer against a polishing pad with a 0
psi force; applying a conditioning fluid to the polishing pad while
holding the wafer against the polishing pad with a 0 psi force;
applying a rinsing fluid to the polishing pad; increasing the force
between the wafer and the polishing pad; and applying a polishing
solution to the polishing pad so as to polish the wafer.
20. A method configured to condition a polishing pad, the method
comprising: determining whether a predetermined time interval has
passed, and if so: holding a wafer against a polishing pad with a 0
psi force; applying a conditioning fluid to the polishing pad while
holding the wafer against the polishing pad with a 0 psi force;
increasing the force between the wafer and the polishing pad; and
applying a polishing solution to the polishing pad so as to polish
the wafer.
21. The method of claim 1 further comprising: ceasing application
of the conditioning fluid so that the rinsing fluid dilutes the
conditioning fluid; and ceasing application of the rinsing fluid so
that the polishing solution dilutes the rinsing fluid.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and apparatus
configured to polish and/or planarize semiconductor wafers and the
thin films formed thereon. More particularly, the present invention
relates to conditioning a polishing pad.
BACKGROUND OF THE INVENTION
[0002] In the semiconductor industry, semiconductor wafers are
planarized using a chemical mechanical polishing apparatus that
presses the wafer surface against an abrasive pad. As polishing
continues, the surface of the pad may become compacted and lose its
abrasive quality. Such compaction reduces the quality and
efficiency of the polishing process.
[0003] To extend the useful life of the pad, a device known as a
pad conditioner that roughens or "conditions" the polishing pad
surface is employed in-situ, while the polishing pad polishes a
wafer; and/or ex-situ, after wafer polishing is complete. During
ex-situ conditioning, a wafer is conventionally moved away from the
polishing pad. A typical pad conditioner comprises a diamond
surface that roughens the polishing pad surface by pressing
thereagainst. Although roughening of the polishing pad surface,
whether performed using either in-situ or ex-situ conditioning,
typically ensures adequate abrasion (e.g., due to polishing fluid
saturation of the roughened surface) conventional ex-situ
conditioning tends to reduce system throughput as additional time
is required for moving the wafer into and out of contact with the
polishing pad.
[0004] Accordingly, an improved method and apparatus is needed that
may condition a polishing pad without the reduction in throughput
associated with conventional ex-situ conditioning.
SUMMARY OF THE INVENTION
[0005] The present inventors have discovered that polishing of
wafers having certain material layers (e.g., copper layers)
deposited thereon results in the build up of materials on the
polishing pad, which may not be removable via conventional in situ
conditioning methods. Hence an ex-situ conditioning process becomes
necessary. Conventional polishing tools, however, are programmed to
perform either in situ or ex-situ conditioning. Further, as
previously stated, conventional ex-situ conditioning tends to
reduce system throughput as additional time is required for moving
the wafer into and out of contact with the polishing pad.
[0006] Accordingly the present invention provides methods and
apparatuses that may prevent materials from building up on a
polishing pad or may remove the build up of polishing byproducts
from the polishing pad and may do so without the reduction in
throughput associated with conventional ex-situ conditioning.
[0007] In a first aspect, the inventive method comprises
conditioning a polishing pad by holding a wafer against the
polishing pad with a 0 psi force, applying a conditioning solution
to the polishing pad while holding the wafer against the polishing
pad with a 0 psi force, applying a rinsing fluid to the polishing
pad, increasing the force between the wafer and the polishing pad,
and applying a polishing solution to the polishing pad so as to
polish the wafer.
[0008] In a second aspect, the inventive method comprises
determining whether a predetermined interval has passed, and if so,
conditioning the polishing pad prior to resuming polishing. More
specifically the method comprises holding a wafer against a
polishing pad with a 0 psi force, applying a conditioning fluid to
the polishing pad while holding the wafer against the polishing pad
with a 0 psi force, applying a rinsing fluid to the polishing pad,
increasing the force between the wafer and the polishing pad; and
applying a polishing solution to the polishing pad so as to polish
the wafer.
[0009] In a further aspect the inventive conditioning method is
modified to omit the rinsing step, so that the polishing solution
dilutes the conditioning fluid, either partially or completely. A
conditioning arm may be scanned along the polishing pad during any
part of the above aspects.
[0010] The inventive apparatus may comprise a polishing pad, a
wafer holder coupled to the polishing pad and configured to hold a
wafer in contact with the polishing pad, a conditioning arm
configured to condition the polishing pad, at least one supply line
configured to supply a fluid to the polishing pad so as to remove
built up material from the polishing pad, and a controller coupled
to the at least one supply line and to the wafer holder, the
controller having a program configured to direct the wafer holder
to hold the wafer against the polishing pad with a 0 psi force and
further configured to direct the at least one supply line to supply
a conditioning fluid to the polishing pad while the wafer holder
holds the wafer against the polishing pad with a 0 psi force.
[0011] Other features and advantages of the present invention will
become more fully apparent from the following detailed description
of the preferred embodiments, the appended claims and the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a flowchart of a first aspect of an inventive
conditioning method that may be employed in any conventional
polishing device;
[0013] FIG. 2 is a flowchart of a second aspect of an inventive
conditioning method, which is similar to the first aspect of the
inventive conditioning method, but which eliminates the rinse step
of the first aspect;
[0014] FIG. 3 is a schematic top plan view of an inventive
polishing apparatus that may perform the inventive conditioning
method; and
[0015] FIG. 4 is a top plan view of a system configured to polish
wafers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] An inventive conditioning method and an inventive polishing
apparatus are provided that either may prevent materials from
building up on a polishing pad or may remove built up materials
from a polishing pad without the reduction in throughput associated
with conventional ex-situ conditioning. FIG. 1 is a flowchart of a
first aspect of an inventive conditioning method 100a that may be
employed in any conventional polishing device, whether horizontally
or vertically oriented, etc. Referring to the flowchart of FIG. 1,
the inventive conditioning method 100a starts at step 101. In step
102, a wafer is placed against a polishing pad.
[0017] In step 103, the polishing device determines whether the
polishing pad requires conditioning so as to prevent materials from
building up on the polishing pad or so as to remove built up
materials from the polishing pad. For example, the polishing device
may determine whether a predetermined time interval for
conditioning a polishing pad has passed. In this aspect, a
polishing pad is conditioned at a predetermined interval (e.g.,
after every 5 minutes of polishing or after every 5 wafers are
polished, etc.). In one aspect, the polishing device may set a
timer based on the predetermined time interval. When the timer
reaches zero, the polishing pad is conditioned as described below.
Alternatively, the polishing device may employ any other method to
determine whether the polishing pad requires conditioning. For
example, the polishing pad may be conditioned either before and/or
after each wafer is polished, when the built up materials on the
polishing pad reaches a predetermined level, etc.
[0018] If in step 103, the predetermined time interval for
conditioning the polishing pad has passed, the inventive
conditioning method 100a proceeds with steps 105; otherwise, if the
predetermined time interval has not passed, the inventive
conditioning method 100a proceeds with step 113 (described
below).
[0019] In step 105, a wafer is held against a polishing pad with a
0 psi force. The wafer may comprise a material layer (e.g., a
copper layer) deposited thereon, which may result in the build up
of materials during polishing that may not be removable merely via
in-situ conditioning methods. In step 107, a conditioning fluid is
supplied to the polishing pad while the wafer is held against the
polishing pad with a 0 psi force. In one aspect, the conditioning
fluid is supplied at a flow rate of between about 50 to 1,000 mL
per minute for a period of between about 1 to 60 seconds. In one
particular aspect, a flow rate of 200 mL per minute for 15 seconds
is employed. The conditioning fluid reacts with the polishing pad
so as to prevent materials from building up on the polishing pad
and/or so as to remove built up materials from the polishing pad.
Whether material has built up on the polishing pad depends on how
frequent the polishing pad is conditioned. If the polishing pad is
conditioned frequently, the conditioning fluid may prevent
materials from building up on the polishing pad.
[0020] The conditioning fluid may comprise Applied Materials'
ElectraClean, solutions capable of removing CuOx by-products,
solutions capable of removing copper compounds, carboxylic salts,
ammonium compounds, amine based solutions such as Tetramethyl
Ammonium Hydroxide (TMAH), etc. ElectraCleanT.TM. solution may
comprise 61% deionized water, 25.9% citric acid, 3.1% ammonium
hydroxide (each concentration being in wt % (wt/wt)). When
ElectraClean.TM. is used in a polishing device, the dilution ratio
may be 3 parts deionized water to 1 part ElectraClean.TM.. Higher
concentrates of ElectraClean.TM. may be used to decrease the
duration of pad cleaning (if desired).
[0021] In step 109, the flow of conditioning fluid stops and a
rinsing fluid (e.g., a high pressure deionized water spray) is
supplied to the polishing pad so as to remove the conditioning
fluid from the polishing pad. Studies have shown that the
conditioning fluid may undesirably affect polishing solution
behavior so as to affect the polishing rate. For example,
ElectraClean.TM. may undesirably affect EP-C5001 (a polishing
slurry marketed by Cabot, Inc.), such as by changing the rate or
removal profile of polishing. Alternatively, with certain polishing
solutions (such as EP-C5003), it may be desirable to eliminate the
rinse step (step 109) and to allow the conditioning fluid to mix
with the polishing solution as further described below in FIG.
2.
[0022] In step 111, the polishing pad increases the downward force
(e.g., to 1-7 psi) applied to the wafer, and a polishing solution
(e.g., an abrasive slurry) is distributed across the polishing pad
so as to abrade and polish the wafer. The inventive conditioning
method 100a proceeds to step 115. In one aspect, a downward force
of 3 psi is applied to the wafer in step 111. The polishing
solution may comprise Klebosol 1501, marketed by Rodel, Inc.,
EP-C5001.TM. marketed by Cabot, Inc., EP-C5003.TM. marketed by
Cabot, Inc. diluted with 2.5% wt/vol Hydrogen Peroxide or with
another oxidizing agent. In aspects that employ EP-C5003.TM.
marketed by Cabot, Inc., a downward force of 6 psi may be applied
to the wafer in step 111.
[0023] Assuming the predetermined time interval has not passed in
step 103, in step 113, the wafer is held against the polishing pad
with a force greater than 0 psi (e.g., 1-7 psi), and the polishing
solution is distributed across the polishing pad so as to abrade
and polish the wafer.
[0024] In one aspect, the polishing device comprises a wafer
support that has an outer retainer ring that extends around the
circumference of a wafer supported thereby and a central membrane
that extends along a wafer's backside. In step 111 and in step 113
of such aspects, the outer retainer ring of the wafer support may
be placed under pressure on the polishing pad and the polishing
solution may be distributed across the polishing pad while the
wafer is held off of the polishing pad by the central membrane of
the wafer support. Thereafter, the wafer is placed onto the
polishing pad under the desired pressure via the central membrane.
By placing the retainer ring under pressure before the central
membrane, the wafer is prevented from slipping out of the wafer
holder.
[0025] In step 115, the polishing device determines whether the
polishing pad requires conditioning. As with step 103, the
polishing pad may determine whether the predetermined time interval
for conditioning a polishing pad has passed. If the predetermined
time interval for conditioning the polishing pad has passed in step
115, the inventive conditioning method 100a returns to step 105 to
condition the polishing pad; otherwise, if the predetermined time
interval has not passed, the inventive conditioning method 100a
proceeds with step 117.
[0026] Assuming the predetermined time interval has not passed in
step 115, the polishing pad determines whether the wafer is
completely polished in step 117. If the wafer is completely
polished, the inventive conditioning method 100a proceeds with step
119; otherwise, if the wafer is not completely polished, the
inventive conditioning method 100a goes to step 113 to continue
polishing the wafer.
[0027] Assuming the wafer is completely polished in step 117, the
rinsing fluid is optionally supplied to the polishing pad so as to
rinse the polishing pad and the polished wafer in step 119. The
polished wafer is removed from the polishing pad in step 120. In
step 121, the controller optionally may determine whether each
wafer in a wafer carrier has been polished. If each wafer in a
wafer carrier has not been polished, the inventive conditioning
method 100a returns to step 102 placing another wafer against the
polishing pad; otherwise, the inventive conditioning method 100a
ends in step 123.
[0028] It will be understood that throughout each of the above
steps, a conditioning arm may scan back and forth across the
polishing pad so as to aid in the distribution of the various
fluids. Further, the conditioning arm may comprise a pad
conditioner (e.g., a diamond embedded disk) that roughens or
conditions the polishing pad by pressing thereagainst.
[0029] It will also be understood that throughout each of the above
steps, the polishing device may generate relative movement between
the wafer and the polishing pad. In one aspect, the polishing pad
may rotate or translate, while in another aspect, a wafer support
may rotate or translate. Yet, in a further aspect, both the
polishing pad and the wafer support may rotate and/or translate.
The initial rotational rate of the polishing pad or the wafer
support may vary as described below. The polishing pad or the wafer
support may initially not rotate or may rotate at a rate between
10-200 rpm. For aspects that initially do not rotate the polishing
pad or the wafer support, the polishing device may increase the
rotational rate to 10-200 rpm when a wafer is loaded into the
polishing device. In one aspect, the polishing pad or the wafer
support may rotate at 93 rpm. In another aspect, the polishing pad
and the wafer support may accelerate to their desired velocities
when the polishing solution is supplied.
[0030] It will be understood that although a wafer is present on
the polishing pad while the conditioning fluid is supplied to the
polishing pad, the polishing pad is not polishing the wafer because
a force of 0 psi is applied to the wafer. Thus, the polishing pad
is ex-situ conditioned.
[0031] FIG. 2 is a second aspect of an inventive conditioning
method 100b, which is similar to the inventive conditioning method
100a of FIG. 1, but which eliminates the rinse step (step 109) of
the inventive conditioning method 100a. Thus, the conditioning
fluid mixes with the polishing solution in the inventive
conditioning method 100b, unlike the inventive conditioning method
100a wherein the rinse step (step 109) is employed to remove the
conditioning fluid from the polishing pad so as to prevent mixing
between the conditioning fluid and the polishing solution.
[0032] Studies have shown that initiation of polishing and
polishing rates are lower with Cabot EP-C5003 (a polishing solution
as described above) relative to Cabot EP-C5001 under the same
polishing conditions. To obtain similar polishing rates with Cabot
EP-C5003 and Cabot EP-C5001, greater pressure is required when
Cabot EP-C5003 is employed. Cabot EP-C5003 exhibits a slower
initiation of polishing because EP-C5003 has an increased
concentration of corrosion inhibitors (e.g., benzotriazol, BTA),
which compete for the copper surface of the wafer against oxidizing
components (e.g., hydrogen peroxide) of the polishing solution. By
allowing the conditioning fluid to mix with the polishing solution,
the problem of slower polishing initiation rate may be eliminated.
For example, ElectraClean.TM. may initiate polishing by removing
layers of copper oxide on the wafer surface, which may otherwise
act to passivate the copper oxides attack by the polishing
solution's hydrogen peroxide and may thereby deter the initiation
of polishing.
[0033] FIG. 3 is a schematic top plan view of an inventive
polishing apparatus 11 that may perform the inventive conditioning
method 100a. The inventive polishing apparatus 11 may comprise a
platen 15 on which a polishing pad 17 configured to polish
semiconductor wafers is mounted. In one aspect, the platen 15 is
rotatable and the polishing pad 17 has at least one groove 19 and
typically has a plurality of concentric circumferential grooves 19
as shown in FIG. 3. In another aspect, non-grooved pads may be
employed. A wafer mounting head 21 is configured to press a wafer W
against the polishing pad 17.
[0034] The inventive polishing apparatus 11 further comprises a
conditioning arm 23 and a holder or conditioning head 25 mounted to
one end of the conditioning arm 23. A pad conditioner 27, such as a
disk embedded with diamond crystals, may be mounted to the
underside of the conditioning head 25. The conditioning arm 23 is
configured to scan back and forth across the polishing pad 17.
[0035] One or more liquid supply lines 29 are configured to direct
fluid from a liquid source 31 to the polishing pad 17. In one
aspect, the liquid supply lines 29 are coupled to an arm 33 that
extends above the surface of the polishing pad 17, as is
conventionally known in the art. In one aspect, the inventive
polishing apparatus 11 may comprise three supply lines: a
conditioning solution supply line 29a, a deionized water supply
line 29b, and a polishing solution supply line 29c. A first liquid
source 31a may contain a conditioning solution (e.g., Applied
Materials' ElectraClean) and is coupled to the conditioning
solution supply line 29a. A second liquid source 31b may contain
deionized water and is coupled to the deionized water supply line
29b. The deionized water may be pressurized. A third source 31c may
contain a polishing solution (e.g., an abrasive slurry) and is
coupled to the polishing solution supply line 29c. A controller C
is configured to couple to the platen 15, the polishing pad 17, the
mounting head 21, the conditioning arm 23, and the supply lines 29,
and controls the operation thereof. The controller C may comprise a
program stored therein and configured to perform the inventive
conditioning methods 100a-b described above.
[0036] FIG. 4 is a top plan view of a system 39 configured to
polish wafers. The system 39 comprises a plurality of polishing
apparatuses 11.sub.1-11.sub.3 each of which is configured to
perform standard polishing operations, and in one aspect, two of
which are programmed to perform the inventive conditioning method
described above. Among the polishing apparatuses 11.sub.1-11.sub.3
like reference numerals are used to identify corresponding
components.
[0037] The system 39 also includes a load cup 41, and a rotatable
cross bar 43 to which a plurality of wafer mounting heads 21a-d are
coupled. Thus, a wafer W may be loaded onto the load cup 41 and
loaded or mounted therefrom to the first wafer mounting head 21a
while wafer mounting heads 21b-d press wafers against the polishing
pads 17 of the various polishing apparatuses 11.sub.1-11.sub.3.
[0038] In operation, a first wafer W.sub.1 is loaded (e.g., via a
wafer handler that is not shown) onto the load cup 41 and mounted
therefrom to the first wafer mounting head 21a. The rotatable cross
bar 43 is indexed carrying the first wafer W.sub.1 to the first
polishing apparatus 111 where the first wafer W.sub.1 is polished
as previously described, while a second wafer W.sub.2 is loaded
onto the load cup 41 and mounted therefrom to the second wafer
mounting head 21b. The rotatable cross bar 43 is indexed again; the
wafer W.sub.1 is polished by the second polishing apparatus
11.sub.2 (e.g., via a different polishing fluid than that used by
the first polishing apparatus 111); the second wafer W.sub.2 is
polished by the first polishing apparatus 11.sub.1 and a third
wafer W.sub.3 is loaded to the load cup 41 and mounted to the third
wafer mounting head 21c.
[0039] Thereafter, the rotatable cross bar 43 indexes and the first
wafer W.sub.1 is carried to the polishing apparatus 113. Meanwhile
the second wafer W.sub.2 is polished by the second polishing
apparatus 11.sub.2; the third wafer W.sub.3 is polished by the
first polishing apparatus 111, and a fourth wafer W.sub.4 is loaded
onto the load cup 41 and mounted to a fourth wafer mounting head
21d.
[0040] The rotatable cross bar 43 then indexes carrying the first
wafer W.sub.1 to the load cup 41 (as shown in FIG. 4) where the
first wafer mounting head 21a places the first wafer W.sub.1 on the
load cup 41 and a wafer handler (not shown) extracts the first
wafer W.sub.1 from the system 39. The inventive conditioning method
100 may be performed by any number of the polishing apparatuses
11.sub.1-11.sub.3 and in one aspect, is performed by each of the
polishing apparatuses 11.sub.1-11.sub.3 in order to benefit from
any throughput increases the inventive conditioning method 100 may
provide.
[0041] As is evident from the description above, the inventive
conditioning method and the inventive polishing apparatus may
prevent materials from building up on a polishing pad or may remove
built up materials from a polishing pad without the reduction in
throughput associated with conventional ex-situ conditioning
because the wafer may be present on the polishing pad during
ex-situ conditioning. Recall that during ex-situ conditioning, a
wafer is conventionally moved away from the polishing pad. In one
aspect of the invention, however, rather than holding a wafer
against a polishing pad with 0 Psi, the wafer is held aloft, above
the polishing pad (e.g., via the wafer holder).
[0042] The foregoing description discloses only the preferred
embodiments of the invention, modifications of the above-disclosed
apparatus and method which fall within the scope of the invention
will be readily apparent to those of ordinary skill in the art. For
instance, although the invention is described with reference to a
horizontally oriented rotational polishing device, the invention
advantageously may be employed with any polishing device including
vertically oriented polishers and/or polishers which employ
translating polishing pads or conveyor-type polishing bands such as
that described in U.S. Pat. No. 5,692,947. The composition of a
suitable cleaning solution is disclosed in U.S. patent application
Ser. No. 09/359,141 (filed Jul. 21, 1999) and Ser. No. 09/163,582
(filed Sep. 30, 1998). The entire disclosures of both applications
are incorporated herein by this reference.
[0043] The invention may be employed with any type of polishing
pad, hard polishing pads (e.g., cast polyurethane) soft, porous
polishing pads (e.g., PVA or soft polyurethane) either of which may
or may not have grooves formed or scribed therein. The grooves may
form any pattern including an x-y grid, such as the grooves found
in the fixed abrasive pads manufactured by the Minnesota Mining and
Manufacturing Company and described for example in U.S. Pat. No
5,378,251.
[0044] Accordingly, while the present invention has been disclosed
in connection with the preferred embodiments thereof, it should be
understood that other embodiments may fall within the spirit and
scope of the invention, as defined by the following claims.
* * * * *