U.S. patent application number 13/092628 was filed with the patent office on 2012-10-25 for measurement of pad thickness and control of conditioning.
Invention is credited to Shou-Sung Chang, Hung Chih Chen, Sameer Deshpande, Roy C. Nangoy, Erik S. Rondum.
Application Number | 20120270477 13/092628 |
Document ID | / |
Family ID | 47021687 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120270477 |
Kind Code |
A1 |
Nangoy; Roy C. ; et
al. |
October 25, 2012 |
MEASUREMENT OF PAD THICKNESS AND CONTROL OF CONDITIONING
Abstract
A conditioning process includes rotating a polishing pad about
an axis of rotation, conditioning the polishing pad by sweeping an
abrasive disk in a path across a surface of the polishing pad
between an inner radial distance from the axis of rotation and an
outer radial distance from the axis of rotation, sweeping a sensor
across the polishing pad while conditioning the polishing pad,
measuring a thickness of the polishing pad at a plurality of
positions between the inner radial distance and the outer radial
distance with the sensor, and adjusting at least one of a dwell
time or a pressure of the abrasive disk against the polishing pad
for a portion of the path based on measurements of the thickness by
the sensor such that the polishing pad wears to a more uniform
thickness than without such adjustment.
Inventors: |
Nangoy; Roy C.; (Santa
Clara, CA) ; Chen; Hung Chih; (Sunnyvale, CA)
; Chang; Shou-Sung; (Stanford, CA) ; Rondum; Erik
S.; (San Ramon, CA) ; Deshpande; Sameer;
(Santa Clara, CA) |
Family ID: |
47021687 |
Appl. No.: |
13/092628 |
Filed: |
April 22, 2011 |
Current U.S.
Class: |
451/56 ;
451/443 |
Current CPC
Class: |
B24B 53/017 20130101;
B24B 49/105 20130101; B24B 49/18 20130101; G01B 7/107 20130101;
B24B 37/042 20130101 |
Class at
Publication: |
451/56 ;
451/443 |
International
Class: |
B24B 53/02 20060101
B24B053/02; B24B 1/00 20060101 B24B001/00 |
Claims
1. A method of controlling a conditioning process, comprising:
rotating a polishing pad about an axis of rotation; conditioning
the polishing pad by sweeping an abrasive disk in a path across a
surface of the polishing pad between an inner radial distance from
the axis of rotation and an outer radial distance from the axis of
rotation; sweeping a sensor across the polishing pad while
conditioning the polishing pad; measuring a thickness of the
polishing pad at a plurality of positions between the inner radial
distance and the outer radial distance with the sensor; and
adjusting at least one of a dwell time or a pressure of the
abrasive disk against the polishing pad for a portion of the path
based on measurements of the thickness by the sensor such that the
polishing pad wears to a more uniform thickness than without such
adjustment.
2. The method of claim 1, comprising adjusting the dwell time of
the abrasive for the portion of the path.
3. The method of claim 1, comprising adjusting the pressure of the
abrasive disk against the polishing pad for the portion of the
path.
4. The method of claim 1, wherein sweeping the abrasive disk
includes suspending the abrasive disk from an arm and pivoting the
arm between a first angle and a second angle.
5. The method of claim 4, comprising storing a pressure profile for
the conditioning disk, the pressure profile identifying a pressure
to apply as a function of an angular position of the arm, and
wherein adjusting the pressure comprises adjusting the pressure
profile.
6. The method of claim 4, comprising storing an position profile
for the conditioning disk, the position profile being an angular
position for the arm as function of a time, and wherein adjusting
the dwell time comprises adjusting the position profile.
7. The method of claim 4, comprising suspending the sensor from the
arm.
8. The method of claim 7, wherein the sensor is positioned adjacent
the disk.
9. The method of claim 7, further comprising storing each
measurement of the thickness by the sensor with an angular position
of the arm at a time an associated measurement was made.
10. The method of claim 1, wherein the sensor comprises an eddy
current sensor.
11. A method of operating a polishing system, comprising:
installing a polishing pad on a rotatable platen; sweeping a sensor
across the polishing pad while the polishing pad is on the platen;
measuring a distance between the sensor and the platen at a
plurality of positions between an inner radial distance and an
outer radial distance with the sensor; and detecting an air bubble
trapped between the polishing pad and the sensor based on
measurements of the distance by the sensor.
12. The method of claim 11, further comprising removing the
polishing pad prior to polishing a substrate with the polishing
pad.
13. The method of claim 11, further comprising suspending the
sensor from an arm of a conditioner apparatus.
14. The method of claim 13, wherein sweeping the sensor includes
pivoting the arm.
15. The method of claim 1, wherein the sensor comprises an eddy
current sensor.
16. A conditioner system, comprising: a base secured to a frame of
a chemical mechanical polishing system; an arm connected to the
frame and pivotally movable by the base over a polishing pad of the
chemical mechanical polishing system; a conditioning head suspended
from the arm to hold an abrasive disk against the polishing pad;
and an eddy current sensor suspended from the arm and positioned to
measure a thickness of the polishing pad.
17. The conditioner system of claim 16, wherein the eddy current
sensor is suspended from the conditioning head.
18. The conditioner system of claim 16, wherein the eddy current
sensor is configured to contact the polishing pad.
19. The conditioner system of claim 16, wherein the eddy current
sensor is separated from the polishing pad by a gap.
20. The conditioner system of claim 16, wherein the conditioning
head and arm are configured such that pivoting the arm sweeps the
abrasive disk in a path across a surface of the polishing pad
between an inner radial distance from an axis of rotation of a
platen and an outer radial distance from the axis of rotation, and
comprising a controller configured to adjust at least one of a
dwell time or a pressure of the abrasive disk against the polishing
pad for a portion of the path based on measurements of the
thickness by the sensor such that the polishing pad wears to a more
uniform thickness than without such adjustment.
Description
TECHNICAL FIELD The present disclosure relates to control of
conditioning during chemical mechanical polishing.
BACKGROUND
[0001] An integrated circuit is typically formed on a substrate by
the sequential deposition of conductive, semiconductive, or
insulative layers on a silicon wafer. One fabrication step involves
depositing a filler layer over a non-planar surface and planarizing
the filler layer. For certain applications, the filler layer is
planarized until the top surface of a patterned layer is exposed. A
conductive filler layer, for example, can be deposited on a
patterned insulative layer to fill the trenches or holes in the
insulative layer. After planarization, the portions of the
conductive layer remaining between the raised pattern of the
insulative layer form vias, plugs, and lines that provide
conductive paths between thin film circuits on the substrate. For
other applications, such as oxide polishing, the filler layer is
planarized until a predetermined thickness is left over the
non-planar surface. In addition, planarization of the substrate
surface is usually required for photolithography.
[0002] Chemical mechanical polishing (CMP) is one accepted method
of planarization. This planarization method typically requires that
the substrate be mounted on a carrier or polishing head. The
exposed surface of the substrate is typically placed against a
rotating polishing pad. The carrier head provides a controllable
load on the substrate to push it against the polishing pad. A
polishing liquid, typically including an abrasive slurry, is
supplied to the surface of the polishing pad.
[0003] Over time, the polishing process can heat and compress the
polishing pad surface, creating "glazing" of the polishing pad
which can reduce the polishing rate and adversely affect substrate
uniformity. In addition, the polishing process can embed debris in
the polishing pad, increasing defects. To counteract these
problems, the surface of the polishing pad surface can be
"conditioned," a process which typically presses a rotating
abrasive disk against the surface of the polishing pad. The
conditioning process abrades the polishing pad surface, deglazing
and removing debris from the polishing pad surface.
SUMMARY
[0004] Since conditioning abrades the polishing pad surface, it can
gradually wear away the polishing pad. One problem is that wearing
of the polishing pad from conditioning can be non-uniform, e.g.,
more pad material can removed from an annular region between the
center and edge of the polishing pad. This non-uniform wear results
in non-uniformity in the polishing pad thickness, which can lead to
non-uniformity in the polishing rate. Another unrelated problem is
that if a polishing pad is not properly installed on the platen,
air bubbles can be trapped between the polishing pad and platen.
These air bubbles can create bumps in the pad surface that can lead
to polishing non-uniformity or defects.
[0005] The thickness profile of the polishing pad can be measured
by a sensor, e.g., an eddy current sensor that is attached to the
conditioning head or arm. The dwell time and/or downward pressure
of the conditioning disk can be controlled based on the measured
thickness profile so that the polishing pad is maintained with a
uniform thickness. Alternatively or in addition, air bubbles
between the polishing pad and the platen can be detected.
[0006] In one aspect, a method of controlling a conditioning
process includes rotating a polishing pad about an axis of
rotation, conditioning the polishing pad by sweeping an abrasive
disk in a path across a surface of the polishing pad between an
inner radial distance from the axis of rotation and an outer radial
distance from the axis of rotation, sweeping a sensor across the
polishing pad while conditioning the polishing pad, measuring a
thickness of the polishing pad at a plurality of positions between
the inner radial distance and the outer radial distance with the
sensor, and adjusting at least one of a dwell time or a pressure of
the abrasive disk against the polishing pad for a portion of the
path based on measurements of the thickness by the sensor such that
the polishing pad wears to a more uniform thickness than without
such adjustment.
[0007] Implementations may include one or more of the following
features. The dwell time of the abrasive disk for the portion of
the path may be adjusted. The pressure of the abrasive disk against
the polishing pad for the portion of the path may be adjusted.
Sweeping the abrasive disk may include suspending the abrasive disk
from an arm and pivoting the arm between a first angle and a second
angle. A pressure profile for the conditioning disk may be stored.
The pressure profile may identify a pressure to apply as a function
of an angular position of the arm. Adjusting the pressure may
include adjusting the pressure profile. A position profile for the
conditioning disk may be stored. The position profile may identify
an angular position for the arm as function of a time. Adjusting
the dwell time may include adjusting the position profile. The
sensor may be suspended from the arm. The sensor may be positioned
adjacent the disk. Each measurement of the thickness by the sensor
may be stored with an angular position of the arm at a time an
associated measurement was made. The sensor may be an eddy current
sensor.
[0008] In another aspect, a method of operating a polishing system
includes installing a polishing pad on a rotatable platen, sweeping
a sensor across the polishing pad while the polishing pad is on the
platen, measuring a distance between the sensor and the platen at a
plurality of positions between an inner radial distance and an
outer radial distance with the sensor, and detecting an air bubble
trapped between the polishing pad and the sensor based on
measurements of the distance by the sensor.
[0009] Implementations may include one or more of the following
features. The polishing pad may be removed prior to polishing a
substrate with the polishing pad. The sensor may be suspended from
an arm of a conditioner apparatus. Sweeping the sensor may include
pivoting the arm. The sensor may be an eddy current sensor.
[0010] In another aspect, a conditioner system includes a base
secured to a frame of a chemical mechanical polishing system, an
arm connected to the frame and pivotally movable by the base over a
polishing pad of the chemical mechanical polishing system, a
conditioning head suspended from the arm to hold an abrasive disk
against the polishing pad, and an eddy current sensor suspended
from the arm and positioned to measure a thickness of the polishing
pad.
[0011] Implementations may include one or more of the following
features. The eddy current sensor may be suspended from the
conditioning head. The eddy current sensor may be configured to
contact the polishing pad. The eddy current sensor may be separated
from the polishing pad by a gap. The conditioning head and arm may
be configured such that pivoting the arm sweeps the abrasive disk
in a path across a surface of the polishing pad between an inner
radial distance from an axis of rotation of a platen and an outer
radial distance from the axis of rotation, and a controller may be
configured to adjust at least one of a dwell time or a pressure of
the abrasive disk against the polishing pad for a portion of the
path based on measurements of the thickness by the sensor such that
the polishing pad wears to a more uniform thickness than without
such adjustment.
[0012] Certain implementations can include one or more of the
following advantages. The thickness of the polishing pad can be
measured without halting of the polishing operation, thus improving
throughput. The polishing pad can be maintained with a uniform
thickness, thus improving polishing uniformity and reducing
within-wafer non-uniformity (WIWNU). Air bubbles between the
polishing pad and the platen can be detected, and the polishing pad
can be replaced as a precautionary measure.
[0013] The details of one or more implementations are set forth in
the accompanying drawings and the description below. Other aspects,
features, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic side view of a chemical mechanical
polishing apparatus.
[0015] FIG. 2 is a schematic top view of a chemical mechanical
polishing apparatus.
[0016] FIG. 3 is a graph of sensor signal (in volts) as a function
of thickness of a shim between the sensor and platen.
[0017] FIG. 4 is a flow chart of a method of operating a polishing
system.
[0018] FIG. 5 is a flow chart of a method of controlling a
conditioning process.
[0019] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0020] FIG. 1 illustrates an example of a polishing apparatus 100.
The polishing apparatus 100 includes a rotatable disk-shaped platen
120 on which a polishing pad 110 is situated. The platen is
operable to rotate about an axis 125. For example, a motor 121 can
turn a drive shaft 124 to rotate the platen 120. The polishing pad
110 can be detachably secured to the platen 120, for example, by a
layer of adhesive. The polishing pad 110 can be a two-layer
polishing pad with an outer polishing layer 112 and a softer
backing layer 114.
[0021] The polishing apparatus 100 can include a combined
slurry/rinse arm 130. During polishing, the arm 130 is operable to
dispense a polishing liquid 132, such as a slurry, onto the
polishing pad 110. While only one slurry/rinse arm 130 is shown,
additional nozzles, such as one or more dedicated slurry arms per
carrier head, can be used.
[0022] The polishing apparatus 100 can further include a carrier
head 140. The carrier head 140 may be operable to hold a substrate
10 against the polishing pad 110. While only one carrier head 140
is shown, additional carrier heads can be used and may be
preferable in some implementations. In such embodiments, each
carrier head 140 can have independent or joint control of the
polishing parameters, for example pressure, associated with each
respective substrate.
[0023] The carrier head 140 can be suspended from a support
structure 146, e.g., a carousel, and is connected by a drive shaft
142 to a carrier head rotation motor 144 so that the carrier head
can rotate about an axis 148. Optionally, carrier head 140 can
oscillate laterally, e.g., on sliders on the carousel 146; or by
rotational oscillation of the carousel itself. In operation, the
platen is rotated about its central axis 125 (see arrow A in FIG.
2), and the carrier head is rotated about its central axis 148 and
translated laterally across the top surface of the polishing pad
110.
[0024] Referring to FIGS. 1 and 2, the polishing apparatus 100 also
includes a polishing pad conditioner 150 to abrade the polishing
pad 110 to maintain the polishing pad 110 in a consistent abrasive
state. The pad conditioner 150 can be mounted on an immobile frame
126, e.g., the frame that supports the drive shaft 124 for the
platen, of the polishing apparatus 100. The pad conditioner 150
includes a conditioner head 152, a base 156, and an arm 154. The
arm 154 can have a first end connected to the conditioner head 152,
e.g., the conditioner head 152 is supported from the first end of
the arm 152. A second end of the arm 154 is connected to the base
154.
[0025] The conditioner head 152 includes an abrasive disk 160,
e.g., a disk coated with diamond particle or the like, and an
actuator 162 to apply a downward pressure to abrasive disk 160,
e.g., through a drive shaft 164, in order to press the abrasive
disk 160 against the polishing pad 110. The abrasive disk 160 can
be rotatable. The actuator 162 can be located in the conditioner
head 152 as illustrated in FIG. 1 with only the drive shaft 164
undergoing vertical potion, or the actuator 162 could be located in
the base 156 so that both the arm 152 and entire conditioner head
152 undergo vertical motion. A motor, located in the conditioner
head 152 or the base 156, can rotate the drive shaft 164 to rotate
the abrasive disk 160.
[0026] The base 154 can be secured to frame 126, and can pivotally
connect the arm 154 to the frame 126. A motor 166 in or coupled to
the base 154, e.g., between the base 154 and the frame 126, can
cause the arm 154 to horizontally swing over the platen 120 (and
the polishing pad 110 if it is installed).
[0027] In addition, in some implementations, the arm 154 can pivot
vertically relative to the frame 16. In such implementations, the
actuator 162 can located in the base 156, and can cause the arm 154
to swing vertically (see arrow D in FIG. 1). Thus, the abrasive
disk 160 can be lowered into contact with the polishing pad 110,
and the pressure of the abrasive disk 160 against the polishing pad
110, can be controlled.
[0028] In operation, the motor 166 causes the arm 154 to swing back
and forth, thus causing the conditioner head 152 to sweep back and
forth across the surface of a polishing pad 110 (see arrow B in
FIG. 2). In conjunction, the actuator 162 presses the abrasive disk
160 down on the polishing pad 110 while the abrasive disk 160
rotates, thus conditioning the polishing pad.
[0029] The polishing apparatus 100 can also optionally include a
cup 158, e.g., supported on the frame 126. The cup 158 can contain
a fluid for rinsing the abrasive disk 160, and can include nozzles
to spray the abrasive disk 160 and/or the underside of the
conditioner head 152. Between conditioning operations, the arm 154
can pivot to locate the conditioning head 152 over the cup 158.
[0030] In some implementations, the polishing pad 110 is
conditioned by the pad conditioner 150 while the polishing pad 110
polishes a substrate 10 which is mounted on the carrier head 140.
The conditioner head 152 can sweep across the polishing pad 110
with a motion that is synchronized with the motion of the carrier
head 140 to avoid collision.
[0031] For a conditioning operation, the base 156 can rotate the
arm 154 between a first angle and a second angle. This action
sweeps the abrasive disk in a path across a surface of the
polishing pad 110 between an inner radial distance from the axis of
rotation 125 and an outer radial distance from the axis of rotation
125.
[0032] A sensor 170 is suspended from the arm 154. For example, the
sensor 170 connected directly to, e.g., suspended from, the
conditioner head 152, or the sensor 170 can be connected directly
to the arm 154 near the conditioner head 152. The sensor 170 can be
connected to the actuator 162 such that the sensor 170 moves up and
down with the abrasive disk 160, but does not rotate with the
abrasive disk 160. The sensor 170 can be located at the bottom of a
support 172 that is connected to the arm 154 or conditioner head
172.
[0033] In some implementations, the support 172 is configured such
that the sensor 170 remains separated from the polishing pad 110 by
a gap. For example, assuming that the arm 154 swings vertically
(e.g., the abrasive disk 160 is lowered onto the polishing pad 110
by a change in the angle of inclination of the arm 154), the
projection of the support 172 and sensor 170 below the conditioner
head 152 can be less than the projection of the abrasive disk 160
below the conditioner head 152. Thus, when the actuator 162 lowers
the arm 154 and the abrasive disk 160, the abrasive disk 160
contacts the polishing pad 110 before the sensor 170. This stops
motion of the arm 154, and thus stops further downward motion of
the sensor 170 so that the sensor remains separated from the
polishing pad 110. In addition, since the arm 154 is stopped when
the abrasive disk 160 contacts the polishing pad, the vertical
position depends the thickness of the polishing pad, and
consequently the distance of the sensor 170 from the platen 120
also depends on the thickness of the polishing pad 110.
[0034] In some implementations, the support 172 is configured such
that the sensor 170 contacts the polishing pad 110. For example,
the support 172 can include a spring to press the sensor 170
against the polishing pad 110, or the sensor 170 can simply rest on
the polishing pad 110. In these implementations, since the sensor
170 is contacting the polishing pad 110, the distance of the sensor
170 from the platen 120 depends on the thickness of the polishing
pad 110.
[0035] The sensor 170 is configured to measure a height of the top
of the polishing pad 110 above the platen. In some implementations,
the sensor 170 is an eddy current sensor. For example, an eddy
current sensor can measure the distance between the sensor 170 and
the platen 120. Since the vertical position of the sensor 170
depends on the thickness of the polishing pad 110, the signal
provides either a measure of the height of the top of the polishing
pad or a thickness of the polishing pad.
[0036] A controller 190, e.g., one or more programmable computers,
can be connected to and receive signals from the sensor 170.
Referring to FIG. 3, the sensor 170, e.g., the eddy current sensor,
can be calibrated. For example, shims of known thickness between
the sensor 170 and the platen 120, and a signal strength can be
measured for each of these known thicknesses. A function, e.g., a
line 200, can be fit to the data (i.e., the pairs of thickness and
signal strength values). Returning to FIGS. 1 and 2, this function
can be stored in the controller 190, which can then calculate the
distance of the sensor 170 from the platen 120 for a particular
signal strength from the sensor 170.
[0037] As the arm 154 pivots, the sensor 170 will sweep across
radial positions on the polishing pad between the inner radial
distance and the outer radial distance travelled by the abrasive
disk 160 (see arrow C in FIG. 2). Thus, the sensor 170 generates a
plurality of measurements of the thickness of the polishing pad
110, with at least some of the measurements made at positions
between the inner radial distance and the outer radial
distance.
[0038] The controller 190 can also be connected to the motor 166
and/or the actuator 162. The controller 190 can be configured to
control the motor 166 to control the radial sweep of the abrasive
disk 120 across the polishing pad and/or control the actuator 162
to control the downward pressure of the abrasive disk 120 against
the polishing pad. For example, the controller 190 can store an
position profile for the conditioning disk. The position profile
can identify an angular position for the arm as function of a time.
As another example, the controller 190 can store a pressure profile
for the conditioning disk. This pressure profile can identify a
pressure to apply as a function of an angular position of the
arm.
[0039] Each measurement of the thickness by the sensor 170 can be
stored, e.g., by the controller 190, with an angular position of
the arm 154 at a time an associated measurement was made. This
angular position of the arm 154 can be obtained from the position
profile, or from a rotary encoder the measures the position of the
arm 154.
[0040] FIG. 4 illustrates a method 220 of operating the polishing
system 100 that can take advantage of the measurements from the
sensor 170. Initially, the polishing pad 110 is installed on the
platen 120 (step 222). The sensor 170 is swept across the polishing
pad 110 while the polishing pad 110 is on the platen 120 (step
224). This can use the sensor 170 attached to the arm 154 of the
conditioner system 150 as discussed above, or the sensor 170 could
be attached to another movable part. A distance between the sensor
and the platen is measured at a plurality of positions (step 226).
These positions can be between an inner radial distance and an
outer radial distance of the axis of rotation of the platen. Based
on the measured distances, an air bubble trapped between the
polishing pad and the sensor can be detected (step 228). For
example, a non-uniformity in the thickness measurement that exceeds
a threshold value for a "fresh" polishing pad (i.e., a polishing
pad that has not previously been used for polishing) can indicate
the presence of an air bubble, since the fresh polishing pad should
have good thickness uniformity. The polishing pad 110 can then be
removed, preferably prior to polishing a substrate with the
polishing pad. The controller 190 can be configured to
automatically generate an alert if the thicknesses exhibit a
non-uniformity that exceeds the threshold, or a user could visually
inspect the data, e.g., on a display with a graphical user
interface, and make the determination.
[0041] In some implementations, the controller is configured to
adjusting at least one of a dwell time or a pressure of the
abrasive disk against the polishing pad for a portion of the path
based on measurements of the thickness by the sensor such that the
polishing pad wears to a more uniform thickness than without such
adjustment.
[0042] FIG. 5 illustrates a method 240 of controlling conditioning
that can take advantage of the measurements from the sensor 170.
The rotating polishing pad 110 is conditioned by the abrasive disk
160 (step 242) For example, the abrasive disk 160 can be swept in a
path across a surface of the polishing pad 110 between an inner
radial distance from the axis of rotation 125 and an outer radial
distance from the axis of rotation 125. The sensor 170 is swept
across the polishing pad 110 while the polishing pad 110 is
conditioned (step 244), and a thickness of the polishing pad 110 is
measured at a plurality of positions (step 246). The positions can
be between the inner radial distance and the outer radial distance.
The controller adjusting at least one of a dwell time or a pressure
of the abrasive disk against the polishing pad for a portion of the
path based on measurements of the thickness by the sensor such that
the polishing pad wears to a more uniform thickness than without
such adjustment (step 248). In general, in regions, e.g., radial
regions, where the polishing pad is thinner, the pressure of the
abrasive disk and/or the dwell time can be reduced, thus reducing
the wear on those regions. Alternatively or in addition, in
regions, e.g., radial regions, where the polishing pad is thicker,
the pressure of the abrasive disk and/or the dwell time can be
increased, thus increasing the wear on those regions.
[0043] To adjust the dwell time, the position profile can be
adjusted. In some implementations, only the dwell time is adjusted.
In some implementations, only the pressure is adjusted. In some
implementations, both the dwell time and the pressure are adjusted.
To adjust the pressure, the stored pressure profile can be
adjusted. With the sensor 170 located on the arm 154, since the
thickness measurements can be stored with the associated angular
position of the arm 154, and since the pressure profile and
position profile also use the angular position of the arm 154, it
may be possible for the controller 190 to determine the adjustments
without having to convert measurements made in one frame of
reference to another frame of reference, thereby reducing the
complexity of the control algorithm.
[0044] As used in the instant specification, the term substrate can
include, for example, a product substrate (e.g., which includes
multiple memory or processor dies), a test substrate, a bare
substrate, and a gating substrate. The substrate can be at various
stages of integrated circuit fabrication, e.g., the substrate can
be a bare wafer, or it can include one or more deposited and/or
patterned layers. The term substrate can include circular disks and
rectangular sheets.
[0045] Embodiments of the invention and all of the functional
operations described in this specification can be implemented in
digital electronic circuitry, or in computer software, firmware, or
hardware, including the structural means disclosed in this
specification and structural equivalents thereof, or in
combinations of them. Embodiments of the invention can be
implemented as one or more computer program products, i.e., one or
more computer programs tangibly embodied in an information carrier,
e.g., in a machine-readable non-transitory storage device or in a
propagated signal, for execution by, or to control the operation
of, data processing apparatus, e.g., a programmable processor, a
computer, or multiple processors or computers. A computer program
(also known as a program, software, software application, or code)
can be written in any form of programming language, including
compiled or interpreted languages, and it can be deployed in any
form, including as a stand-alone program or as a module, component,
subroutine, or other unit suitable for use in a computing
environment. A computer program does not necessarily correspond to
a file. A program can be stored in a portion of a file that holds
other programs or data, in a single file dedicated to the program
in question, or in multiple coordinated files (e.g., files that
store one or more modules, sub-programs, or portions of code). A
computer program can be deployed to be executed on one computer or
on multiple computers at one site or distributed across multiple
sites and interconnected by a communication network.
[0046] The processes and logic flows described in this
specification can be performed by one or more programmable
processors executing one or more computer programs to perform
functions by operating on input data and generating output. The
processes and logic flows can also be performed by, and apparatus
can also be implemented as, special purpose logic circuitry, e.g.,
an FPGA (field programmable gate array) or an ASIC
(application-specific integrated circuit).
[0047] The above described polishing apparatus and methods can be
applied in a variety of polishing systems. Either the polishing
pad, or the carrier head, or both can move to provide relative
motion between the polishing surface and the substrate. For
example, the platen may orbit rather than rotate. The polishing pad
can be a circular (or some other shape) pad secured to the platen.
Some aspects of the endpoint detection system may be applicable to
linear polishing systems, e.g., where the polishing pad is a
continuous or a reel-to-reel belt that moves linearly. The
polishing layer can be a standard (for example, polyurethane with
or without fillers) polishing material, a soft material, or a
fixed-abrasive material. Terms of relative positioning are used; it
should be understood that the polishing surface and substrate can
be held in a vertical orientation or some other orientation during
operation.
[0048] Particular embodiments of the invention have been described.
Other embodiments are within the scope of the following claims. For
example, the actions recited in the claims can be performed in a
different order and still achieve desirable results.
* * * * *