U.S. patent application number 12/477458 was filed with the patent office on 2009-12-10 for cmp pad identification and layer ratio modeling.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to Ashish Bhatnagar, MICHAEL E. KHAU, Nishal Shah.
Application Number | 20090305609 12/477458 |
Document ID | / |
Family ID | 41400750 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090305609 |
Kind Code |
A1 |
KHAU; MICHAEL E. ; et
al. |
December 10, 2009 |
CMP PAD IDENTIFICATION AND LAYER RATIO MODELING
Abstract
The present invention relates to methods and apparatus for
improving productivity of chemical mechanical polishing (CMP)
processes and lowering operating costs of CMP systems. Embodiments
of the present invention provide a method for improving the ratio
of the layer thickness of composite polishing pads for improved
removal rates. Embodiments of the present also provide specific
polishing pad identification for monitoring and controlling
processes developed for the specific pad to improve overall
productivity and reduce downtime of the CMP system.
Inventors: |
KHAU; MICHAEL E.; (Milpitas,
CA) ; Shah; Nishal; (San Jose, CA) ;
Bhatnagar; Ashish; (Fremont, CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP - - APPM/TX
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
41400750 |
Appl. No.: |
12/477458 |
Filed: |
June 3, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61060003 |
Jun 9, 2008 |
|
|
|
Current U.S.
Class: |
451/5 ; 451/446;
451/533; 451/539; 451/8 |
Current CPC
Class: |
B24B 49/00 20130101;
B24B 37/04 20130101 |
Class at
Publication: |
451/5 ; 451/8;
451/446; 451/533; 451/539 |
International
Class: |
B24B 1/00 20060101
B24B001/00; B24B 37/04 20060101 B24B037/04; B24B 49/00 20060101
B24B049/00; B24B 57/02 20060101 B24B057/02 |
Claims
1. A substrate polishing apparatus, comprising: a platen with a
polishing pad including an identification member attached to or
embedded in the polishing pad; and an identification member reader
configured to read information from the identification member and
transfer the information read from the identification member to a
system controller, wherein the system controller is programmed to
retrieve information specific to the polishing pad from system
controller memory based on the information read from the
identification member.
2. The apparatus in claim 1, wherein the identification member is a
barcode, and wherein the identification member reader is a barcode
scanner.
3. The apparatus in claim 1, wherein the identification member is a
radio frequency identification tag, and wherein the identification
member reader is a radio frequency identification tag reader.
4. The apparatus of claim 1, wherein the system controller is
further programmed to use the retrieved information for controlling
polishing processes.
5. The apparatus of claim 1, further comprising a composition
delivery device, wherein the system controller is further
programmed to use the retrieved information to control the delivery
rate of composition delivered by the composition delivery
device.
6. The apparatus of claim 5, wherein the system controller is
further programmed to use the retrieved information to control a
chemical slurry recipe delivered by the composition delivery
device.
7. The apparatus of claim 1, wherein the system controller is
further programmed to retrieve information specific to burning in
the polishing pad and to control a burn in procedure for the
polishing pad using the retrieved information.
8. The apparatus of claim 1, further comprising a polishing pad
conditioning apparatus, wherein the system controller is further
programmed to use the retrieved information to control parameters
of the polishing pad conditioning apparatus.
9. The apparatus of claim 1, wherein the polishing pad is a
composite polishing pad, comprising: an upper polishing pad; and a
lower polishing pad, wherein the lower polishing pad is more
compliant than the upper polishing pad, and wherein the ratio of
the thickness of the upper polishing pad to the thickness of the
lower polishing pad is between about 0.73 to about 0.57.
10. A method for selectively improving properties of a composite
polishing pad, comprising: selectively testing parameters of a
composite polishing pad having an upper pad and a lower pad,
wherein the polishing pad has an initial overall thickness, an
initial upper pad thickness, and an initial lower pad thickness,
and wherein the parameters are selectively tested while the
thickness of the lower pad is varied until desired parameter
improvements are achieved; identifying an improved lower pad
thickness resulting from the selectively testing composite
polishing pad parameters; computing a second composite polishing
pad thickness comprising the sum of the initial upper pad thickness
and the improved lower pad thickness; computing a thickness ratio,
wherein the thickness ratio comprises the ratio of the initial
upper pad thickness to the improved lower pad thickness; and
resealing the initial upper pad thickness and the improved lower
pad thickness using the computed thickness ratio to achieve a final
composite pad thickness substantially equal to the initial
composite pad thickness.
11. The method of claim 10, wherein the varying the thickness of
the lower pad comprises increasing the thickness of the lower
pad.
12. The method of claim 10, wherein the polishing pad parameters
comprise a feature removal rate for a given chemical slurry
recipe.
13. A method for selectively improving properties of a composite
polishing pad, comprising: selectively testing parameters of a
composite polishing pad having an upper pad and a lower pad,
wherein the polishing pad has an initial overall thickness, an
initial upper pad thickness, and an initial lower pad thickness,
and wherein the parameters are selectively tested while varying the
thickness of the upper pad until desired parameter improvements are
achieved; identifying an improved upper pad thickness resulting
from the selectively testing composite polishing pad parameters;
computing a second composite polishing pad thickness comprising the
sum of the initial lower pad thickness and the improved upper pad
thickness; computing a thickness ratio, wherein the thickness ratio
comprises the ratio of the improved upper pad thickness to the
initial lower pad thickness; and resealing the initial lower pad
thickness and the improved upper pad thickness using the computed
thickness ratio to achieve a final composite pad thickness
substantially equal to the initial composite pad thickness.
14. The method of claim 13, wherein the varying the thickness of
the upper pad comprises increasing the thickness of the upper
pad.
15. The method of claim 13, wherein the polishing pad parameters
comprise a feature removal rate for a given chemical slurry
recipe.
16. A polishing device, comprising: a polishing pad with a
polishing side and a non-polishing side; and an identification
member attached to or embedded in the non-polishing side of the
polishing pad.
17. The polishing device of claim 16, wherein the polishing pad is
a composite polishing pad, comprising: an upper polishing pad; and
a lower polishing pad, wherein the lower polishing pad is more
compliant than the upper polishing pad, and wherein the ratio of
the thickness of the upper polishing pad to the thickness of the
lower polishing pad is between about 0.73 and about 0.57.
18. The polishing device of claim 17, wherein the identification
member is a barcode imprinted on the non-polishing side of the
polishing pad.
19. The polishing pad of claim 17, wherein the identification
member is a radio frequency identification tag embedded within the
non-polishing side of the polishing pad.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application Ser. No. 61/060,003, filed Jun. 9, 2008, which is
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention generally relate to
methods and apparatus for increased productivity and decreased
operating cost of a chemical mechanical polishing system.
[0004] 2. Description of the Related Art
[0005] In the fabrication of integrated circuits and other
electronic devices, multiple layers of conducting, semiconducting,
and dielectric materials are deposited and removed from a
substrate. During integrated circuit fabrication, it is necessary
to polish a surface of the substrate to remove high topography,
surface defects, scratches, or embedded particles. Chemical
mechanical polishing (CMP) is a common process used in polishing
the surfaces of substrates for the removal of such features.
Typically, CMP involves the introduction of chemical slurry during
the polishing process to facilitate high removal rates and
selectivity between features on the substrate surface. In general,
CMP involves holding the substrate against a polishing pad under
controlled pressure, temperature, and rotational velocity of the
pad in the presence of the chemical slurry.
[0006] An important goal of CMP is achieving uniform planarity of
the substrate surface. Uniform planarity includes the uniform
removal of material from the surface of substrates as well as
removing non-uniform layers which have been deposited on the
substrate. Successful CMP also requires process repeatability from
one substrate to the next. Thus, uniformity must be achieved not
only for a single substrate, but also for a series of substrates
processed in a batch.
[0007] Substrate planarity is dictated, to a large extent, by the
construction of the CMP apparatus and the composition of the
consumables, such as the chemical slurry and the polishing pads. A
preferred construction allows for a proper balance between rigidity
and compliance of the polishing device, particularly the polishing
pad. Generally, stiffness is needed to ensure within-die
uniformity, while sufficient compliance provides within-substrate
uniformity. Within substrate uniformity refers to the ability of
the CMP apparatus to remove features across the diameter of the
substrate regardless of the substrate shape and/or the topography
across the surface of the substrate. Within-die uniformity refers
to the ability of the CMP apparatus to remove features within a
die, regardless of feature size and density.
[0008] Additionally, a successful CMP system needs to maximize the
removal rate of features across the substrate. Increased removal
rate without corresponding reduction in the life of consumables
leads to increased production. Moreover, operating costs of a CMP
system may be reduced by reducing downtime of the system, which
includes maximizing pad life and accurately predicting and
scheduling pad replacement intervals.
[0009] Accordingly, a need exists for a CMP system that provides
increased feature removal rate, good uniformity, maximum polishing
pad life, and reduced system downtime to increase system production
and lower the overall operating costs of the system.
SUMMARY OF THE INVENTION
[0010] In one embodiment of the present invention, a substrate
polishing apparatus comprises a platen with a polishing pad
including an identification member attached to or embedded in the
polishing pad and an identification member reader configured to
read information from the identification member and transfer the
information read from the identification member to a system
controller, wherein the system controller is programmed to retrieve
information specific to the polishing pad from system controller
memory based on the information read from the identification
member.
[0011] In another embodiment, a method for selectively improving
properties of a composite polishing pad comprises selectively
testing parameters of a composite polishing pad having an upper pad
and a lower pad, wherein the polishing pad has an initial overall
thickness, an initial upper pad thickness, and an initial lower pad
thickness, and wherein the parameters are selectively tested while
the thickness of the lower pad is varied until desired parameter
improvements are achieved, identifying an improved lower pad
thickness resulting from the selectively testing composite
polishing pad parameters, computing a second composite polishing
pad thickness comprising the sum of the initial upper pad thickness
and the improved lower pad thickness, computing a thickness ratio,
wherein the thickness ratio comprises the ratio of the initial
upper pad thickness to the improved lower pad thickness, and
resealing the initial upper pad thickness and the improved lower
pad thickness using the computed thickness ratio to achieve a final
composite pad thickness substantially equal to the initial
composite pad thickness.
[0012] In another embodiment, a method for selectively improving
properties of a composite polishing pad comprises selectively
testing parameters of a composite polishing pad having an upper pad
and a lower pad, wherein the polishing pad has an initial overall
thickness, an initial upper pad thickness, and an initial lower pad
thickness, and wherein the parameters are selectively tested while
varying the thickness of the upper pad until desired parameter
improvements are achieved, identifying an improved upper pad
thickness resulting from the selectively testing composite
polishing pad parameters, computing a second composite polishing
pad thickness comprising the sum of the initial lower pad thickness
and the improved upper pad thickness, computing a thickness ratio,
wherein the thickness ratio comprises the ratio of the improved
upper pad thickness to the initial lower pad thickness, and
resealing the initial lower pad thickness and the improved upper
pad thickness using the computed thickness ratio to achieve a final
composite pad thickness substantially equal to the initial
composite pad thickness.
[0013] In yet another embodiment of the present invention, a
polishing device comprises a polishing pad with a polishing side
and a non-polishing side and an identification member attached to
or embedded in the non-polishing side of the polishing pad.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0015] FIG. 1 is a schematic view of a chemical mechanical
polishing (CMP) system, which may incorporate embodiments of the
present invention.
[0016] FIG. 2 is a schematic cross-sectional view of a polishing
apparatus.
[0017] FIG. 3 is a flow chart illustrating a process for improving
the thickness ratio of a composite polishing pad to improve a
particular performance parameter and resealing the pad for use in
an existing CMP system according to the present invention.
[0018] FIGS. 4A, 4B, and 4C depict a simplified example of the
process 300.
[0019] FIG. 5 is a schematic representation of a CMP apparatus
including pad identification components according to embodiments of
the present invention.
DETAILED DESCRIPTION
[0020] The present invention relates to methods and apparatus for
improving productivity of chemical mechanical polishing (CMP)
processes and lowering operating costs of CMP systems. Embodiments
of the present invention provide a method for improving the ratio
of the layer thickness of composite polishing pads for improved
removal rates. Embodiments of the present also provide specific
polishing pad identification for monitoring and controlling
processes developed for the specific pad to improve overall
productivity and reduce downtime of the CMP system.
[0021] FIG. 1 is a schematic view of a CMP system 100, which may
incorporate embodiments of the present invention. The CMP system
100 may include a lower machine base 122 with a tabletop 128
mounted thereon with a removable outer cover (not shown). The
tabletop 128 supports a series of polishing stations, which may
include a first polishing station 125, a second polishing station
125, a third polishing station 125, and a transfer station 127. The
transfer station 127 may serve multiple functions, including
receiving individual substrates 110 from a loading apparatus (not
shown), washing the substrates 110, loading the substrates 110 into
carrier heads 180, receiving the substrates 110 from the carrier
heads 180, and transferring the substrates 110 to the loading
apparatus.
[0022] Each polishing station 125 may include a rotatable platen
130 having a polishing pad 120 attached thereto. Each platen 130
may be a rotatable aluminum or stainless steel platen attached to a
platen drive motor (not shown). In one embodiment, the first
polishing station 125 has a first polishing pad 120 disposed on a
platen 130. The platen 130 may be adapted for polishing the
substrate 110 to substantially remove bulk copper-containing
material disposed on the substrate 110. The second polishing
station 125 may have a second polishing pad 120 disposed on the
platen 130 for polishing the substrate 110 to remove residual
copper-containing material disposed on the substrate 110. The third
polishing station 125 may have a polishing pad 120 disposed on the
platen 130 for polishing the substrate 110 to remove barrier layer
material disposed on the substrate 110.
[0023] In one embodiment, the polishing stations 125 each include a
pad conditioner apparatus 140. The pad conditioner apparatus 140
may have a rotatable arm 142 holding an independently rotating
conditioner head 144 and an associated washing basin 146. The pad
conditioner apparatus 140 maintains the condition of the polishing
pad 120 so that it will effectively polish the substrates 110.
[0024] In one embodiment, the polishing stations 125 each have a
composition delivery/rinse arm 152 that includes two or more supply
tubes to provide one or more CMP compositions, cleaning
compositions, and/or water to the surface of the polishing pad 120.
The composition delivery/rinse arm 152 delivers the one or more
chemical slurries in amounts sufficient to cover and wet the entire
polishing pad. Each composition delivery/rinse arm 152 also
includes several spray nozzles (not shown) that can provide a high
pressure fluid rinse onto the polishing pad 120 at the end of each
polishing and conditioning cycle. Additionally, intermediate
washing stations 155 may be positioned between adjacent polishing
stations 125 to clean the substrate 110 as it passes from one
station to the next.
[0025] In one embodiment, a rotatable multi-head carousel 160 is
positioned above the lower machine base 122. The carousel 160 may
include four carrier head systems 170. Three carrier head systems
170 receive or hold the substrates 110 and press them against the
polishing pads 120 disposed on the polishing stations 125. One of
the carrier head systems 170 receives the substrate 110 from and
delivers the substrate 110 to the transfer station 127. The
carousel 160 may be supported by a center post 162 and rotated
about a carousel axis 164 by a motor assembly (not shown) located
within the machine base 122. The center post 162 may also support a
carousel support plate 166 and a cover 188.
[0026] In one embodiment, the four carrier head systems 170 are
mounted on the carousel support plate 166 at equal angular
intervals about the carousel axis 164. The center post 162 allows
the carousel motor to rotate the carousel support plate 166 and
orbit the carrier head systems 170 about the carousel axis 164.
Each carrier head system 170 includes one carrier head 180. A
carrier drive shaft 178 connects a carrier head rotation motor 176
(shown by the removal of one quarter of the cover 188) to the
carrier head 180 so that the carrier head 180 can independently
rotate about its own axis. Additionally, each carrier head 180 may
independently oscillate laterally in a radial slot 172 formed in
the carousel support plate 166.
[0027] The carrier head 180 may perform several functions. The
carrier head 180 may comprise a vacuum mechanism to chuck the
substrate 110. During operation, the carrier head 180 generates
negative pressure behind the surface of the substrate 110 to
attract and hold the substrate 110. Additionally, the carrier head
180 holds the substrate 110 against the polishing pads 120, evenly
distributing a downward pressure across the back surface of the
substrate 110. The carrier head 180 further transfers torque from
the drive shaft 178 to the substrate 110 and ensures that the
substrate 110 does not slip out from beneath the carrier head 180
during CMP operations.
[0028] In one embodiment, the CMP system 100 is equipped with a
system controller 190 programmed to control and carry out various
methods and sequences. The system controller 190 generally
facilitates the control and automation of the overall system and
may include a central processing unit (CPU) 192, memory 194, and
support circuits 196. The CPU 192 may be one of any computer
processors used in industrial settings for controlling various
system functions and processes.
[0029] In one embodiment, the polishing pad 120 may comprise two
pads assembled together into a stack, called a composite polishing
pad. FIG. 2 is a schematic cross-sectional view of a polishing
apparatus 200, such as polishing station 125. The polishing
apparatus 200 includes a metal platen 230, such as platen 130,
having a composite polishing pad 220 mounted thereto. Both the
composite polishing pad 220 and the platen 230 are generally
disc-shaped and of substantially equal diameters. The composite
polishing pad 220 comprises an upper pad 260 and a lower pad 280.
An adhesive 250, such as a pressure sensitive adhesive (PSA) is
provided on the back face of the pads 260, 280 to bond the pads to
one another and to the platen 230, respectively.
[0030] Generally, it is preferable that the upper pad 260 be
stiffer and less compliant than the lower pad 280 to provide a
sufficiently a rigid polishing surface. Typically, a stiff pad
provides better within-die uniformity, while more compliance is
needed to ensure within-substrate uniformity. In one embodiment,
the upper pad 260 comprises cast polyurethane. In one embodiment,
the lower pad 280 comprises polyester felt stiffened with
polyurethane resin. The combination of pads 260, 280 having the
proper proportions of stiffness and compliance achieve good
planarity and uniformity over the surface of the substrate.
[0031] It has been discovered that improvements to the CMP process
may be achieved by varying the ratio of the thickness of the upper
pad 260 with respect to the thickness of the lower pad 280 without
altering the density, compressibility, or other properties of the
individual pads 260, 280. In one embodiment, the thickness ratio of
the composite pad 220 may be modified to maximize the removal rate
of particular films or features on the substrate when the composite
pad 220 is used in combination with a particular recipe of chemical
slurry. Once determined, the thickness ratio of the composite pad
220 may be used to rescale the overall thickness of the composite
pad 220 for use in existing CMP systems.
[0032] FIG. 3 is a flow chart illustrating a process 300 for
improving the thickness ratio of a composite polishing pad to
improve a particular performance parameter and resealing the pad
for use in an existing CMP system. At 310, a composite pad, such as
composite pad 220, with a stiff upper pad, such as pad 260, and a
compliant lower pad, such as pad 280, and having an initial overall
thickness is provided with baseline performance parameters for a
given recipe of chemical slurry. At 320, the thickness of the lower
pad of the composite pad is increased and/or decreased, while
maintaining a constant thickness in the upper pad, until a range of
desired results are achieved for the given recipe of chemical
slurry without altering the individual physical properties of the
lower pad or the upper pad. In one embodiment, the thickness of the
upper pad may be altered while maintaining the thickness of the
lower pad. In another embodiment, both the upper and lower pad
thickness may be altered. Once the desired range of results is
found, the ratio of the thickness of the upper pad to the thickness
of the lower pad is computed at 330. At 340, the overall thickness
of the composite pad is rescaled to a thickness of the initial
overall thickness in 310 within a specified tolerance required for
using the pad in the existing CMP system, while keeping the upper
to lower pad thickness ratio computed in 330.
[0033] FIGS. 4a, 4b, and 4c depict a simplified example of the
process 300. As shown in FIG. 4a, a composite pad 400 with an
initial overall thickness 400a of about 13 mm has an upper pad 460
with an initial upper thickness 460a of about 8 mm and a lower pad
480 with an initial lower thickness 480a of about 5 mm. The
thickness of the lower pad 480 is selectively increased during
testing to increase removal rate without affecting substrate
uniformity. As shown in FIG. 4b, it is found that a lower pad
thickness increase 480b of between about 6 mm to about 9 mm yields
a removal rate increase of between about 6% to about 15% without
affecting substrate uniformity. Therefore, the ratio of the
thickness of the upper pad 460 to the thickness of the lower pad
480 is between about 0.73 to about 0.57. FIG. 4c depicts the
rescaled composite pad 400 having a final overall thickness 400c
substantially the same as the initial overall thickness 400a and
thicknesses ranging from a final upper pad thickness 460c of about
4 mm and a final lower pad thickness 480c of about 7 mm to a final
upper pad thickness 460c of about 5.8 mm to a final lower pad
thickness 480c of about 8 mm.
[0034] Additionally, improvements in CMP productivity and operating
costs may be achieved by providing information about a specific
polishing pad to a system controller of a CMP apparatus. In one
embodiment, shown in FIG. 5, an identification member 523 is
attached to or embedded in polishing pad 520. The identification
member 523 provides specific information about the polishing pad
520 to a system controller 590 of a CMP apparatus 500 via an
identification reader 595. In operation, the identification reader
595 identifies the specific polishing pad 520 by reading the
information stored in the identification member 523. The system
controller 590, which is preprogrammed with information regarding
specific polishing pads, retrieves information regarding the
polishing pad 520 identified by the identification member 523 for
use in CMP processes with the specific polishing pad 520.
[0035] In one embodiment, the identification member 523 is a
barcode imprinted on the polishing pad 520 during its fabrication,
and the identification reader 595 is a scanner that scans the
barcode and relays the information about the specific polishing pad
520 to the system controller 590 via circuitry 596. In one
embodiment, the identification member 523 is a barcode imprinted on
the non-polishing side of the polishing pad 520. In another
embodiment, the identification member 523 is a radio frequency
identification (RFID) tag, and the identification reader 595 is an
RFID tag reader. In one embodiment, the identification member 523
is an RFID tag attached to the non-polishing side of the polishing
pad 520. In one embodiment, the identification member 523 is an
RFID tag embedded within the non-polishing side of the polishing
pad 520. In one embodiment, the polishing pad 520 is spin-balanced
after installing the identification member 523 and prior to
installing in CMP apparatus 500.
[0036] In one embodiment, once the system controller 590 identifies
the specific polishing pad 520, specific information about the
polishing pad 520 identified is accessed for use in the CMP
process. In one embodiment, information regarding specific
polishing pad "burn-in" processes and recipes is accessed, which
leads to increased overall productivity and life of the polishing
pad 520. In one embodiment, information regarding proper CMP
processes and recipes is accessed specific to maximizing
productivity and life of the specific polishing pad 520. In one
embodiment, information regarding the specific polishing pad's
specific wear rate and life is accessed for controlling CMP
processes, such as platen rotation speed, chemical slurry delivery
rate, and pad conditioning parameters. In one embodiment, wear rate
and pad life of specific polishing pads 520 are tracked, and
maintenance and/or replacement schedules are refined to reduce CMP
apparatus downtime. In one embodiment, pad life versus number of
substrates is monitored for specific polishing pads 520 for
refining CMP procedures and chemical slurry recipes. In one
embodiment, wear rate and other operating information for specific
polishing pads 520 is tracked and used for identifying and
troubleshooting excessive pad wear situations.
[0037] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *