U.S. patent application number 11/115634 was filed with the patent office on 2006-02-02 for spray slurry delivery system for polish performance improvement and cost reduction.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Wei-Yung Hsu, Robert L. Jackson, Gary Ka Ho Lam, Lizhong Sun, Lei Zhu.
Application Number | 20060025049 11/115634 |
Document ID | / |
Family ID | 35732950 |
Filed Date | 2006-02-02 |
United States Patent
Application |
20060025049 |
Kind Code |
A1 |
Sun; Lizhong ; et
al. |
February 2, 2006 |
Spray slurry delivery system for polish performance improvement and
cost reduction
Abstract
Methods and apparatus for delivering a polishing fluid to a
chemical mechanical polishing surface is provided. In one aspect,
the apparatus comprises a vertical arm having a delivery portion
located proximate to a circumference of a polishing surface, a
first nozzle disposed on the delivery portion and adapted to
dispense the polishing fluid with a first adjustable droplet size,
and at least a second nozzle disposed on the delivery portion and
adapted to dispense the polishing fluid with a second adjustable
droplet size. In another aspect of the invention, the apparatus
comprises a horizontal arm having a delivery portion disposed at
least partially over a polishing surface, a first nozzle disposed
on the delivery portion and adapted to dispense the polishing fluid
with a first adjustable droplet size across a first region of the
polishing surface, and at least a second nozzle disposed
horizontally spaced from the first nozzle on the delivery portion,
and adapted to dispense the polishing fluid with a second
adjustable droplet size across a second region of the polishing
surface.
Inventors: |
Sun; Lizhong; (San Jose,
CA) ; Zhu; Lei; (Sunnyvale, CA) ; Lam; Gary Ka
Ho; (Santa Clara, CA) ; Jackson; Robert L.;
(San Jose, CA) ; Hsu; Wei-Yung; (Santa Clara,
CA) |
Correspondence
Address: |
PATTERSON & SHERIDAN, LLP
3040 POST OAK BOULEVARD, SUITE 1500
HOUSTON
TX
77056
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
35732950 |
Appl. No.: |
11/115634 |
Filed: |
April 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60592669 |
Jul 30, 2004 |
|
|
|
Current U.S.
Class: |
451/5 |
Current CPC
Class: |
B24B 37/04 20130101;
B24B 57/02 20130101 |
Class at
Publication: |
451/005 |
International
Class: |
B24B 51/00 20060101
B24B051/00 |
Claims
1. A system for delivering a polishing fluid to a chemical
mechanical polishing surface comprising: a horizontal arm having a
delivery portion disposed at least partially over a polishing
surface; a first nozzle disposed on the delivery portion and
adapted to dispense the polishing fluid with a first adjustable
droplet size across a first region of the polishing surface; and at
least a second nozzle disposed horizontally spaced from the first
nozzle on the delivery portion, and adapted to dispense the
polishing fluid with a second adjustable droplet size across a
second region of the polishing surface.
2. The system of claim 1, wherein the first nozzle dispenses
polishing fluid with an adjustable first angle between the arm and
the first region of the polishing surface and the at least second
nozzle dispenses polishing fluid with an adjustable second angle
between the arm and the second region of the polishing surface.
3. The system of claim 1, wherein the first and second nozzles
provide polishing fluid at different flow rates.
4. The system of claim 3, wherein the first and second nozzles
combined provide a total flow rate of less than about 100 mL/min
polishing fluid.
5. A system for delivering a polishing fluid to a chemical
mechanical polishing surface comprising: a vertical arm having a
delivery portion located proximate to a circumference of a
polishing surface; a first nozzle disposed on the delivery portion
and adapted to dispense the polishing fluid with a first adjustable
droplet size; and at least a second nozzle disposed on the delivery
portion and adapted to dispense the polishing fluid with a second
adjustable droplet size.
6. The system of claim 5, wherein the first nozzle provides
polishing fluid with an adjustable first angle between the arm and
the first region of the polishing surface and the at least second
nozzle provides polishing fluid with an adjustable second angle
between the arm and the second region of the polishing surface.
7. The system of claim 5, wherein the first and second nozzles
provide polishing fluid at different flow rates.
8. The system of claim 5, wherein the first and second nozzles
combined provide a total flow rate of less than about 100 mL/min
polishing fluid.
9. The system of claim 8, wherein each nozzle has an independently
adjustable polishing fluid flow rate.
10. The system of claim 5, wherein the first nozzle dispenses
polishing fluid across a first region of the polishing surface and
the at least second nozzle dispenses the polishing fluid across a
second region of the polishing surface.
11. A system for delivering a polishing fluid to a chemical
mechanical polishing apparatus comprising: a delivery arm having a
delivery portion; two or more nozzles disposed on the delivery
portion of the delivery arm with each nozzle adapted to disperse
the polishing fluid with an adjustable droplet size wherein each
nozzle has an aperture that is independently controllable; a tubing
system configured to supply fluid to the two or more nozzles; a
pump system to provide a controlled pressure to the tubing system;
and a control system to independently control each aperture of each
nozzle and the pump system.
12. The system of claim 11, wherein the nozzles provide polishing
fluid droplet delivery streams having adjustable angles between the
arm and a polishing surface.
13. The system of claim 11, wherein the two or more nozzles each
provide polishing fluid at a different flow rate.
14. The system of claim 11, wherein the first and second nozzles
combined provide a total flow rate of less than about 100 mL/min
polishing fluid.
15. The system of claim 14, wherein the polishing fluid flow rates
of each nozzle are independently controllable.
16. The system of claim 11, wherein the delivery arm is a vertical
arm having a delivery portion located proximate to a circumference
of a polishing surface.
17. The system of claim 11, wherein the delivery arm is a
horizontal arm having a delivery portion disposed at least
partially over a polishing surface.
18. A method of supplying a polishing fluid to a chemical
mechanical polishing surface comprising: dispensing the polishing
fluid onto the polishing material with a controlled droplet size
across a first region of the polishing material; and dispensing the
polishing fluid onto the polishing material with a controlled
droplet size across a second region of the polishing material,
wherein a first nozzle provides polishing fluid with an adjustable
first angle between the arm and the first region of the polishing
surface and at least a second nozzle provides polishing fluid with
an adjustable second angle between the arm and the second region of
the polishing surface.
19. The method of claim 18, wherein the individual nozzles provide
polishing fluid at different flow rates.
20. The method of claim 18, wherein the first and second nozzles
combined provide less than about 100 mL/min polishing fluid.
21. The method of claim 20, wherein the polishing fluid flow rates
are independently controlled.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. provisional patent
application Ser. No. 60/592,669, filed Jul. 30, 2004, 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 a
slurry delivery method and apparatus for polishing a substrate in a
chemical mechanical polishing system.
[0004] 2. Description of the Related Art
[0005] Chemical mechanical planarization, or chemical mechanical
polishing (CMP), is a common technique used to planarize
substrates. Chemical mechanical planarization systems generally
utilize a polishing head to retain and press a substrate against a
polishing surface of a polishing material while providing motion
therebetween. In conventional CMP techniques, a substrate carrier
or polishing head is mounted on a carrier assembly and positioned
in contact with a polishing article in a CMP apparatus. The carrier
assembly provides a controllable pressure to the substrate urging
the substrate against the polishing article. The article is moved
relative to the substrate by an external driving force. Thus, the
CMP apparatus effects polishing or rubbing movement between the
surface of the substrate and the polishing article while dispersing
a polishing composition to effect both chemical activity and
mechanical activity.
[0006] Some planarization systems utilize a polishing head that is
moveable over a stationary platen that supports the polishing
material. Other systems utilize different configurations including
a rotating platen to provide relative motion between the polishing
material and the substrate. A polishing fluid is typically disposed
between the substrate and the polishing material during polishing
to provide chemical activity that assists in the removal of
material from the substrate. Some polishing fluids may also contain
abrasives.
[0007] One of the challenges in developing robust polishing systems
and processes is providing uniform material removal across the
polished surface of the substrate. For example, as the substrate
travels across the polishing surface, the edge of the substrate is
often polished at a higher rate. This is due in part to the
tendency of the substrate to nose drive, that is, centrifugal and
frictional forces force the substrate to move toward the exterior
of the support surface as the substrate moves across the support
surface.
[0008] An additional problem with polishing uniformity is the
distribution of slurry on the polishing surface. If the slurry is
unevenly distributed, the polishing surface may not evenly polish
across the substrate surface. If too little slurry is used, the
polishing surface may distort the features of the substrate
surface. If too much slurry is applied, valuable slurry may be
wasted. Therefore, a system for delivering a polishing fluid to a
chemical mechanical polishing surface that adjustably distributes
and conserves slurry is needed.
SUMMARY OF THE INVENTION
[0009] The present invention generally provides a method and
apparatus for delivering a polishing fluid to a chemical mechanical
polishing surface. In one aspect, an apparatus is provided for
delivering a polishing fluid to a chemical mechanical polishing
surface including a vertical arm having a delivery portion located
proximate to a circumference of a polishing surface, a first nozzle
disposed on the delivery portion and adapted to dispense the
polishing fluid with a first adjustable droplet size, and at least
a second nozzle disposed on the delivery portion and adapted to
dispense the polishing fluid with a second adjustable droplet
size.
[0010] In another aspect, an apparatus is provided for delivering a
polishing fluid to a chemical mechanical polishing surface
including a horizontal arm having a delivery portion disposed at
least partially over a polishing surface, a first nozzle disposed
on the delivery portion and adapted to dispense the polishing fluid
with a first adjustable droplet size across a first region of the
polishing surface, and at least a second nozzle disposed
horizontally spaced from the first nozzle on the delivery portion,
and adapted to dispense the polishing fluid with a second
adjustable droplet size across a second region of the polishing
surface.
[0011] In another aspect, an apparatus is provided for delivering a
polishing fluid to a chemical mechanical polishing surface
including a delivery arm, two or more nozzles disposed on a
delivery portion of the delivery arm with each nozzle adapted to
disperse the polishing fluid with an adjustable droplet size
wherein each nozzle has an aperture that is independently
controlled, a tubing system configured to supply fluid to the two
or more nozzles, a pump system to provide a controlled pressure to
the tubing system, and a control system to independently control
each aperture of each nozzle and the pump system.
[0012] In another aspect, a method is provided for delivering a
polishing fluid to a chemical mechanical polishing surface
including dispensing the polishing fluid onto the polishing
material with a controlled droplet size across a first region of
the polishing material, and dispensing the polishing fluid onto the
polishing material with a controlled droplet size across a second
region of the polishing material, wherein a first nozzle provides
polishing fluid with an adjustable first angle between the arm and
the first region of the polishing surface and at least second
nozzle provides polishing fluid with an adjustable second angle
between the arm and the second region of the polishing surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] 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.
[0014] FIG. 1 is a sectional view of a polishing system having one
embodiment of a polishing fluid delivery system.
[0015] FIG. 2 is a plan view of the system of FIG. 1.
[0016] FIG. 3 is a sectional view of an alternative embodiment of a
polishing fluid delivery system.
[0017] FIG. 4 is a sectional view of an additional alternative
embodiment of a polishing fluid delivery system.
DETAILED DESCRIPTION
[0018] The present invention provides a slurry delivery method and
apparatus for polishing a substrate in a chemical mechanical
polishing system. In one aspect, the invention provides a slurry
delivery method and apparatus that utilizes a plurality of nozzles
that may be configured to dispense droplets with adjustable size
and adjustable droplet stream path angles.
[0019] Examples of polishing systems which may be adapted to
benefit from aspects of the invention are disclosed in U.S. Pat.
No. 6,244,935 issued Jun. 12, 2001 by Birang, et al. and U.S. Pat.
No. 5,738,574 issued Apr. 14, 1998 to Tolles, et al., both of which
are incorporated by reference in their entirety.
[0020] FIG. 1 depicts one embodiment of a polishing system 100 for
polishing a substrate 112 having a polishing fluid delivery system
102 that controls the distribution of polishing fluid 114 across a
polishing material 108. Although the polishing fluid delivery
system 102 is described in reference to the illustrative polishing
system 100, the invention has utility in other polishing systems
that process substrates in the presence of a polishing film. The
exemplary polishing system 100 includes a platen 104 and a
polishing head 106. The platen 104 is generally positioned below
the polishing head 106 that holds the substrate 112 during
polishing. The platen 104 is generally disposed on a base 122 of
the system 100 and coupled to a motor (not shown). The motor
rotates the platen 104 to provide at least a portion of a relative
polishing motion between the polishing material 108 disposed on the
platen 104 and the substrate 112. Relative motion between the
substrate 112 and the polishing material 108 may be provided by
alternative mechanisms. For example, at least a portion of the
relative motion between the substrate 112 and polishing material
108 may be provided by moving the polishing head 106 over a
stationary platen 104, moving the polishing material linearly under
the substrate 112, or moving both the polishing material 108 and
the polishing head 106.
[0021] The polishing material 108 is supported by the platen 104 so
that a polishing surface 116 faces upward towards the polishing
head 106. The polishing material 108 is fixed to the platen 104 by
adhesives, vacuum, mechanical clamping, or other means during
processing. Optionally, and particularly in applications where the
polishing material 108 is configured as a web, belt, or linear
polishing material, the polishing material 108 is fixed to the
platen 104 and is releasable, typically by employing a vacuum
disposed between the polishing material 108 and platen 104 as
described in the previously incorporated U.S. Pat. No.
6,244,935.
[0022] The polishing material 108 may be a conventional or a fixed
abrasive material. Conventional polishing material 108 is generally
comprised of a foamed polymer and disposed on the platen 104 as a
pad. In one embodiment, the conventional polishing material 108 is
foamed polyurethane. Such conventional polishing material 108 is
available from Rodel Corporation, located in Newark, Del.
[0023] Fixed abrasive polishing material 108 is generally comprised
of a plurality of abrasive particles suspended in a resin binder
that is disposed in discrete elements on a backing sheet. Fixed
abrasive polishing material 108 may be utilized in either pad or
web form. As the abrasive particles are contained in the polishing
material, systems utilizing fixed abrasive polishing materials
generally utilize polishing fluids that do not contain abrasives.
Examples of fixed abrasive polishing material are disclosed in U.S.
Pat. No. 5,692,950, issued Dec. 2, 1997 to Rutherford, et al., and
U.S. Pat. No. 5,453,312, issued Sep. 26, 1995 to Haas, et al., both
of which are hereby incorporated by reference in their entireties.
Such fixed abrasive polishing material 108 is additionally
available from Minnesota Manufacturing and Mining Company (3M),
located in Saint Paul, Minn.
[0024] The polishing head 106 generally is supported above the
platen 104. The polishing head 106 retains the substrate 112 in a
recess 120 that faces the polishing surface 116. The polishing head
106 typically moves toward the platen 104 and presses the substrate
112 against the polishing material 108 during processing. The
polishing head 106 may be stationary or rotate or move orbitally,
linearly, or in a combination of motions while pressing the
substrate 112 against the polishing material 108. One example of a
polishing head 106 that may be adapted to benefit from the
invention is described in U.S. Pat. No. 6,183,354 B1, issued Feb.
6, 2001 to Zuniga, et al., and is hereby incorporated by reference
in its entirety. Another example of a polishing head 106 that may
be adapted to benefit from the invention is a TITAN HEAD.TM. wafer
carrier, available from Applied Materials, Inc., of Santa Clara,
Calif.
[0025] The polishing fluid delivery system 102 generally comprises
a delivery arm 130, a plurality of nozzles 132 disposed on the arm
130 and at least one polishing fluid source 134. The delivery arm
130 is configured to meter polishing fluid 114 at different flow
rates along the arm 130 to control the distribution of polishing
fluid 114 on the polishing surface 116 of the polishing material
108. As the polishing fluid 114 is generally supplied from a single
source, the polishing fluid 114 may be disposed on the polishing
material 108 in a uniform concentration but in varying volume
across the surface of the polishing material 108.
[0026] The delivery arm 130 is generally coupled to the base 122
proximate to the platen 104. The delivery arm 130 generally has at
least a portion 136 that is suspended over the polishing material
108. The delivery arm 130 may be coupled to other portions of the
system 100 as long as the portion 136 is positioned to deliver
polishing fluid 114 to the polishing surface 116.
[0027] The plurality of nozzles 132 is disposed along the portion
136 of the delivery arm 130 which is disposed above the platen 104.
In one embodiment, the nozzles 132 comprise at least a first nozzle
140 and a second nozzle 142. Typically, the first nozzle 140 is
positioned on the arm 130 radially inward of the second nozzle 142
relative to the center of rotation of the polishing material 108.
The distribution of polishing fluid 114 across the polishing
material 108 may be controlled to flow polishing fluid 114 from the
first nozzle 140 at a rate different than the flow from the second
nozzle 142.
[0028] Nozzles 132 are configured to provide a controlled amount of
fluid at an adjustable delivery angle and a controlled droplet size
to the surface of the polishing material 108. The nozzles 132 have
apertures that may be adjusted to provide flow at a specific angle,
for example between 0 and 90.degree. normal to the substrate. The
apertures may have a hole size of 50 microns or less. The apertures
may also be adjusted to provide a specific droplet size, for
example 15 microns. The improved control over the droplet size and
angle of fluid delivery provides a more tailored slurry application
to the polishing material 108. This improved control facilitates a
more uniform thickness, thinner film across the surface of the
polishing material 108. The film may have a thickness of 100 mils
or less, preferably 50 mils or less. The film may have a thickness
as thin as 1 micron or less. Because the film of polishing fluid is
thinner and more controlled, less fluid than that required by
conventional processes is needed to compensate for fluid losses
such as fluid losses due to centrifugal forces across the surface
of the polishing material. The nozzle position and flow rates of
the first and second nozzles 140 and 142 may be selected to provide
overlapping film streams, providing another slurry film tailoring
mechanism.
[0029] The flow rates exiting the first and second nozzles 140, 142
may vary from each other. The flow rates may be fixed relative to
each other or be independently adjustable. In one embodiment, the
fluid delivery arm 130 includes a polishing fluid supply line 124
that has a tee connection between the first and second nozzles 140,
142. A tee fitting 126 is coupled to the supply line 124 and has a
first delivery line 144 coupled to first nozzle 140 and a second
delivery line 146 branching therefrom that is coupled to the second
nozzle 142.
[0030] At least one of the nozzles 132 is controlled by a flow
control mechanism 150. The flow control mechanism 150 may be a
device which provides a fixed ratio of flow between the nozzles
140, 142 or the flow control mechanism 150 may be adjustable to
provide dynamic control of the flow rates. Examples of flow control
mechanisms 150 include fixed orifices, pinch valves, proportional
valves, restrictors, needle valves, restrictors, metering pumps,
mass flow controllers and the like. Alternatively, the flow control
mechanism 150 may be provided by a difference in the relative
pressure drop between the fluid delivery lines 144, 146 coupling
each nozzle 140, 142 and the tee fitting 126.
[0031] The polishing fluid source 134 is typically disposed
externally to the system 100. In one embodiment, the polishing
fluid source 134 generally includes a reservoir 152 and a pump 154.
The pump 154 generally pumps the polishing fluid 114 from the
reservoir 152 through the supply line 124 to the nozzles 132.
[0032] The polishing fluid 114 contained in the reservoir 152 is
typically deionized water having chemical additives that provide
chemical activity that assists in the removal of material from the
surface of the substrate 112 being polished. As the polishing fluid
114 is supplied to the nozzles 132 from a single source such as the
reservoir 152, the fluid 114 flowing from the nozzles 132 is
substantially homogeneous, not varied in concentration of chemical
reagents or entrained abrasives. Optionally, the polishing fluid
may include abrasives to assist in the mechanical removal of
material from the surface of the substrate. The polishing fluids
are generally available from a number of commercial sources such as
Cabot Corporation of Aurora, Ill., Rodel Inc., of Newark, Del.,
Hitachi Chemical Company, of Japan, and Dupont Corporation of
Wilmington, Del.
[0033] In operation, the substrate 112 is positioned in polishing
head 106 and brought in contact with the polishing material 108
supported by the rotating platen 104. The polishing head 106 may
hold the substrate stationary or may rotate or otherwise move the
substrate to augment the relative motion between the polishing
material 108 and substrate 112. The polishing fluid delivery system
102 flows the polishing fluid 114 through the supply line 124 to
the first and second polishing nozzles 140, 142.
[0034] FIG. 2 depicts a plan view of the system 100 illustrating
the flow of polishing fluid 114 onto the portions 202 and 204 of
the polishing material 108. A first flow 206 of polishing fluid 114
flows out the first nozzle 140 and onto the first portion 202 at a
first rate while a second flow 208 of polishing fluid 114 flows out
the second nozzle 142 and onto the second portion 204 at a second
rate. Generally, the first flow 206 is different than the second
flow 208 thus providing a controlled distribution of polishing
fluid 114 across the polishing surface 116 of the polishing
material 108. In one embodiment, the first flow 206 has a rate that
is at least about 1.15 times a rate of the second flow 208. The
controlled distribution of the polishing fluid 114 across the
polishing material 108 allows material removal from the surface of
the substrate 112 to be tailored across the width of the substrate
112 by controlling the relative flows of polishing fluid 114 onto
the polishing material 108. More polishing fluid 114 may be
provided to either the first portion 202 of the polishing material
108 or the second portion 204. Optionally, additional nozzles may
be utilized to provide different amounts of polishing fluid 114 on
other portions of the polishing material 108 where at least two
portions of the polishing material 108 have polishing fluid 114
disposed thereon at different flow rates.
[0035] In one mode of operation, the substrate 112 being polished
by the system 100 is processed with polishing fluid 114 provided
from the first nozzle 140 and the second nozzle 142. Polishing
fluid 114 is disposed on the polishing material 108 from the first
nozzle 140 at a first rate. Polishing fluid 114 is simultaneously
disposed on the polishing material 108 from the second nozzle 142
at a second rate. In one embodiment, the first flow is about 1.2 to
about 20 times the second flow rate.
[0036] As depicted in FIG. 2, the first nozzle 140 generally
provides polishing fluid 114 at a first rate to a first portion 202
of the polishing surface 116 while the second nozzle 142 provides
polishing fluid 114 at a second rate to a second portion 204 of the
polishing surface 116. The portions 202 and 204 may overlap,
especially when the apertures of nozzles 140, 142 are selected to
target a specific region across polishing material 108. The spray
patterns 206, 208 are selected to provide variable slurry
distribution across polishing material 108, often to provide more
slurry to the exterior or towards the diameter of the polishing
material. For example, portion 204 may require more slurry than
portion 202. In this manner, the distribution of polishing fluid
114 across the width of the polishing material 108 is
regulated.
[0037] The control scheme prevents loss of slurry by creating
uniform slurry overlap of portions 202 and 204 and encourages a
polishing profile that is tailored to specific substrates based on
repeated substrate measurements before and after polishing.
Alternativley, adjusting the control scheme may occur substrate by
substrate. Referring to FIG. 1, configurations having dynamic,
adjustable control mechanisms 150 such as proportional valves,
needle valves, mass flow controllers, metering pumps, peristaltic
pumps and the like, the distribution of polishing fluid 114 on the
polishing material 108 may be tailored during the process. For
example, the rate of polishing fluid from the first nozzle 140 may
be applied to the polishing material 108 at a first rate during one
portion of the process and adjusted to a second rate during another
portion of the process. The rate of polishing fluid 114 delivery
from the second nozzle 142 may also be varied during the polishing
process. The adjustments of polishing fluid flows from nozzles 140,
142 are infinite. The use of additional nozzles disposed between
the first nozzle 140 and the second nozzle 142 allows the
uniformity profile to be further modified and locally shaped by
providing more or less polishing fluid 114 at a nozzle disposed
between the first nozzle 140 and the second nozzle 142 (see
discussion of FIG. 3 below).
[0038] Optionally, a polishing fluid delivery system having dynamic
control over the flow rates from the nozzles 140, 142 may include a
metrology device 118 to provide process feed-back for real-time
adjustment of the polishing fluid distribution. Typically, the
metrology device 118 detects a polishing metric such as time of
polish, thickness of the surface film being polished on the
substrate, surface topography, or other substrate attribute.
[0039] In one embodiment, the polishing material 108 may include a
window (not shown) that allows a metrology device 118 to view the
surface of the substrate 112 disposed against the polishing
material 108. The metrology device 118 generally includes a sensor
162 that emits a beam 164 that passes through the window (not
shown) to the substrate 112. A first portion of the beam 164 is
reflected by the surface of the substrate 108 while a second
portion of the beam 164 is reflected by a layer of material
underlying the polished surface of the substrate 112. The reflected
beams are received by the sensor 162 and a difference in wavelength
between the two portions of reflected beams are resolved to
determine the thickness of the material on the surface of the
substrate 112. Generally, the thickness information is provided to
a controller (not shown) that adjusts the polishing fluid
distribution on the polishing material 108 to produce a desired
polishing result on the substrate's surface. One monitoring system
that may be used to advantage is described in U.S. patent
application Ser. No. 5,893,796, issued Apr. 13, 1999 by Birang, et
al., and is hereby incorporated herein by reference in its
entirety.
[0040] Optionally, the metrology device 118 may include additional
sensors to monitor polishing parameters across the width of the
substrate 112. The additional sensors allow for the distribution of
polishing fluid 114 to be adjusted across the width of the
substrate 112 so that more or less material is removed in one
portion relative to another portion of the substrate 112.
Additionally, the process of adjusting the flow rates from the
nozzles 140, 142 may occur iteratively over the course of a
polishing sequence to dynamically control the rate of material
removal across the substrate 112 at any time. For example, the
center of the substrate 112 may be polished faster by providing
more polishing fluid to the center of the substrate 112 at the
beginning of a polishing sequence while the perimeter of the
substrate 112 may be polished faster at the end of the polishing
sequence by providing more polishing fluid to the perimeter
area.
[0041] FIG. 3 depicts another embodiment of a polishing fluid
delivery system 300 having a plurality of nozzles 302. Angles 320
and 322 illustrate the angles that may be adjusted to modify the
resulting slurry film properties such as distribution profile or
thickness. The system 300 may be configured similarly to the fluid
delivery system 102 of FIG. 1 (having a single polishing fluid
delivery line) or may be configured so that each nozzle 302 has a
dedicated supply line 304 coupled to a fluid source 306. Fluidly
coupled to each supply line 304 is a metering device 308. The
metering device 308 may be a metering pump such as a gear pump, a
peristaltic pump, a positive displacement pump, a diaphragm pump
and the like. Each metering device 308 is coupled to a controller
(not shown) that controls the amount of polishing fluid 114
provided to each nozzle 302 of the system 300. As each metering
device 308 is independently controllable, the flow of polishing
fluid 114 from each of the plurality of nozzles 302 is controlled
independent from the other nozzles so that the distribution of
polishing fluid 114 on the polishing material 108 can be arranged
in practically infinite configurations.
[0042] As described above, each metering device may vary the flow
of polishing fluid delivered to the polishing material 108 over the
course of polishing. For example, one of the nozzles 302 may
increase the flow of polishing fluid 114 flowing therethrough while
the substrate is being polished. Another one of the nozzles may
decrease the flow of polishing fluid 114 during polishing. Of
course, infinite variations in nozzle flow rates at any time may be
configured to produce a desired polishing result. As the flow of
polishing fluid is independently controllable through each nozzle
302, polishing attributes may be tailored across the width of the
substrate over the duration of substrate processing.
[0043] The fluid delivery source 306 may be used in concert with a
metrology device 312 to control the rate or location of material
removal from a surface 318 of the substrate 112 being polished.
Generally, the rate of removal or remaining thickness of material
disposed on the surface 318 of the substrate 112 may be detected by
the metrology device 312 and provided to the controller which, in
turn, adjusts the various flow rates exiting each nozzle 302 to
produce a desired polishing result, for example, faster polishing
on the perimeter of the substrate 112.
[0044] In one embodiment, the polishing material 108 may include a
window 310 that allows the metrology device 312 to view the surface
318 of the substrate 112 disposed against the polishing material
108. The metrology device 312 generally includes a sensor 314 that
emits a beam 316 that passes through the window 310 to the
substrate 112. A first portion of the beam 316 is reflected by the
surface 318 of the substrate 108 while a second portion of the beam
316 is reflected by a layer of material underlying the polished
surface 318 of the substrate 112. The reflected beam is received by
the sensor 314 and a difference in wavelength between the two
portions of reflected beam is resolved to determine the thickness
of the material on the surface 318 of the substrate 112. Generally,
the thickness information is provided to the controller that
adjusts the polishing fluid distribution on the polishing material
108 to produce a desired polishing result on the substrate surface
318.
[0045] Optionally, the metrology device 312 may include additional
sensors to monitor polishing parameters across the width of the
substrate 112. The additional sensors allow for the distribution of
polishing fluid 114 to be adjusted across the width of the
substrate 112 so that more or less material is removed in one
portion relative to another portion of the substrate 112.
Additionally, the process of adjusting the flow rates from the
nozzles 302 may occur iteratively over the course of a polishing
sequence to dynamically control the rate of material removal across
the substrate 112 at any time. For example, the center of the
substrate 112 may be polished faster by providing more polishing
fluid to the center of the substrate 112 at the beginning of a
polishing sequence while the perimeter of the substrate 112 may be
polished faster at the end of the polishing sequence by providing
more polishing fluid to the perimeter area.
[0046] FIG. 4 is an additional alternative embodiment of a slurry
distribution system 400. A delivery arm 401 is vertically
positioned to support the nozzles 402. That is, the delivery arm
401 is static and has less range of motion than the arm of
embodiments of FIGS. 1-3. The polishing fluid 414 flows from the
nozzles 402 at angles 410, 412 to the polishing material 408 that
is supported by the platen 403. Slurry is supplied to the nozzles
402 from the slurry reservoir 452 through the fluid supply line
424. The fluid supply line 424 is pressurized by the pump 454.
[0047] Nozzles 132, 402 are configured to provide a controlled
amount of fluid at an adjustable delivery angle and an adaptable
droplet size to the surface of the polishing material 108, 408. The
nozzles 132, 402 have apertures that may be adjusted, for example,
from 0 to 90.degree. to provide flow at a specific angle 410, 412.
The apertures may also be adjusted to provide a specific droplet
size, for example 15 .ANG.. The improved control over the droplet
size and angle of fluid delivery provides a more tailored slurry
application to the polishing material 108, 408. This improved
control facilitates a more uniform thickness, thinner film across
the surface of the polishing material 108, 408. Because the film of
polishing fluid is thinner and more controlled, less fluid than
that required by conventional processes is needed to compensate for
fluid losses due to centrifugal forces across the surface of the
polishing material.
[0048] 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.
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