U.S. patent application number 10/680631 was filed with the patent office on 2004-04-15 for platen with patterned surface for chemical mechanical polishing.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Arluck, Jack, Leung, Garlen C., McReynolds, Peter, Menk, Gregory E., Osterheld, Thomas H., Prabhu, Gopalakrishna B., Rondum, Erik S., Zhong, Adam H..
Application Number | 20040072518 10/680631 |
Document ID | / |
Family ID | 32074285 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040072518 |
Kind Code |
A1 |
Prabhu, Gopalakrishna B. ;
et al. |
April 15, 2004 |
Platen with patterned surface for chemical mechanical polishing
Abstract
A platen having a patterned upper surface for supporting a
polishing material in a chemical mechanical polishing system is
provided. In one embodiment, a platen for supporting a polishing
material in a chemical mechanical polishing system includes a body
adapted to support a polishing material during processing and
having a substantially rigid non-planar upper support surface for
supporting the polishing material during polishing.
Inventors: |
Prabhu, Gopalakrishna B.;
(San Jose, CA) ; Rondum, Erik S.; (San Ramon,
CA) ; McReynolds, Peter; (San Mateo, CA) ;
Osterheld, Thomas H.; (Mountain View, CA) ; Leung,
Garlen C.; (San Jose, CA) ; Arluck, Jack;
(Santa Clara, CA) ; Zhong, Adam H.; (Milpitas,
CA) ; Menk, Gregory E.; (Pleasanton, CA) |
Correspondence
Address: |
Patent Counsel
Applied Materials, Inc.
P.O. Box 450A
Santa Clara
CA
95052
US
|
Assignee: |
Applied Materials, Inc.
|
Family ID: |
32074285 |
Appl. No.: |
10/680631 |
Filed: |
October 7, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10680631 |
Oct 7, 2003 |
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10619745 |
Jul 15, 2003 |
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10619745 |
Jul 15, 2003 |
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09759556 |
Jan 12, 2001 |
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6592438 |
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09759556 |
Jan 12, 2001 |
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09285508 |
Apr 2, 1999 |
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6220942 |
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Current U.S.
Class: |
451/288 |
Current CPC
Class: |
B24B 37/16 20130101 |
Class at
Publication: |
451/288 |
International
Class: |
B24B 007/22 |
Claims
1. A platen for supporting the polishing material in a chemical
mechanical polishing system, comprising: a body adapted to support
a polishing material during processing; and a substantially rigid
non-planar upper support surface defining an upper surface of the
body for supporting the polishing material.
2. The platen of claim 1, wherein the upper support surface is
concave.
3. The platen of claim 1, wherein the upper support surface is
convex.
4. The platen of claim 1, wherein the upper support surface
includes both convex and concave portions.
5. The platen of claim 1, wherein the upper support surface
includes an inner region and at least one outer region, wherein the
inner region and outer region are at different elevations.
6. The platen of claim 1, wherein the body is rotatable.
7. The platen of claim 1, wherein the body is fixed.
8. The platen of claim 1, wherein the upper surface of the body is
textured.
9. The platen of claim 8, wherein the texture upper surface further
comprises: a plurality of grooves formed in the upper surface of
the body.
10. The platen of claim 1, wherein the upper surface of the body
further comprises: one or more raised portions on the upper surface
defining a mounting surface; and a recessed area defined by the one
or more raised portions.
11. The platen of claim 1, wherein the body further comprises:
magnetic device for coupling the polishing material to the upper
surface.
12. The platen of claim 11, wherein the magnetic device further
comprises: at least one of a magnetic or electromagnet.
13. The platen of claim 12 further comprising: a magnetically
couplable material coupled, embedded or fixed to the polishing
material.
14. The platen of claim 1, wherein the body further comprises:
vacuum port open to the upper surface.
15. The platen of claim 1, wherein the body further comprises:
polishing fluid delivery port open to the upper surface.
16. A platen for supporting the polishing material in a chemical
mechanical polishing system, comprising: a body adapted to support
a polishing material during processing; a substantially rigid
non-planar upper support surface defining an upper surface of the
body for supporting the polishing material; and a plurality of
recesses formed in the upper support surface.
17. The platen of claim 16, wherein the recesses are grooves.
18. The platen of claim 17, wherein the upper support surface has
at area having a concave cross section.
19. A chemical mechanical polishing system comprising: a platen
having a non-planar, substantially rigid upper support surface; a
polishing material disposed on the upper support surface; and a
polishing head adapted to retain a substrate against a working
portion of the polishing material during processing.
20. The chemical mechanical polishing system of claim 19, wherein
the upper support surface further comprises: at least one recessed
area formed therein; at least one area projecting above the
recessed are and defining the non-planar surface.
21. The chemical mechanical polishing system of claim 19, wherein a
distance between the upper support surface and a plane defined by a
lower surface of the polishing head is not uniform:
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 10/619,745, filed Jul. 15, 2003,
which is a continuation of U.S. Pat. No. 6,592,438, issued Jul. 15,
2003, which is a continuation of U.S. Pat. No. 6,220,942, issued
Apr. 24, 2001, all of which are hereby incorporated by reference in
their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus for polishing
substrates. More particularly, the invention relates to a patterned
platen for supporting a polishing material for chemical mechanical
polishing of substrates.
[0004] 2. Background 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 the fabrication process. Often it is necessary to polish a
surface of a substrate to remove material to facilitate the
formation of metal interconnects between devices formed on the
substrate. The polishing process is often referred to as chemical
mechanical polishing (CMP).
[0006] Typically, the polishing process involves the introduction
of a chemical slurry during the polishing process to facilitate
higher removal rates and selectivity between films on the substrate
surface. In general, the polishing process involves moving a
substrate while in contact with a polishing material while under
controlled pressure and velocity in the presence of a polishing
fluid.
[0007] An important goal of CMP is achieving uniform planarity of
the substrate surface. Uniform planarity includes the uniform
removal of material deposited on the surface of substrates as well
as removing non-uniform layers which have been deposited on the
substrate. In many applications, the polishing pressure applied to
the substrate (i.e., the force of the substrate against the
polishing surface) is often higher near the center of the
substrate, resulting in the center of the substrate polishing
faster than the perimeter of the substrate. In order to achieve
good processing results, the tendency of the substrate to polish
faster at its center must be compensated. In other applications, it
may be desirable to polishing one region of a substrate at a rate
different than another region of the substrate. Additionally, it
would be desirable if the measures taken to compensate for the
disparity in polishing rate across the substrate would be part of
the polishing system hardware, thereby minimizing process drift and
enhancing batch to batch uniformity.
[0008] Therefore, there is a need for a platen that enhances
polishing performance.
SUMMARY OF THE INVENTION
[0009] A platen having a patterned upper surface for supporting a
polishing material in a chemical mechanical polishing system is
provided. In one embodiment, a platen for supporting a polishing
material in a chemical mechanical polishing system includes a body
adapted to support a polishing material during processing and
having a substantially rigid non-planar upper support surface for
supporting the polishing material during polishing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] So that the manner in which the above recited features,
advantages and objects of the present invention are attained and
can be understood in detail, a more particular description of the
invention, briefly summarized above, may be had by reference to the
embodiments thereof 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.
[0011] FIG. 1 is a simplified perspective view of a chemical
mechanical polishing system;
[0012] FIG. 2 is a schematic side view of one embodiment of a
polishing station;
[0013] FIGS. 3-6 are a schematic view of various embodiments of a
polishing station; and
[0014] FIG. 7 is a top view of the platen of FIG. 6.
[0015] To facilitate understanding, identical reference numerals
have been used, where possible, to designate identical elements
that are common to the figures.
DETAILED DESCRIPTION
[0016] The present invention generally relates to a platen having a
patterned surface for mounting a pad, such as a polishing pad or
web of polishing material, thereto. The patterned surface is
non-planar, resulting in greater polishing pressure over predefined
portions of the patterned surface during processing, thereby
providing control over the profile of material removal from the
substrate.
[0017] FIG. 1 is a schematic view of a chemical mechanical
polishing system 30 having a patterned platen 41. Two polishing
systems suitable for chemical mechanical polishing are the
MIRRA.RTM. and REFLEXION.RTM. polishing systems available from
Applied Materials, Inc., located in Santa Clara, Calif. Similar
systems are shown and described in U.S. Pat. No. 5,738,574, issued
Apr. 14, 1998, and U.S. Pat. No. 6,244,935, issued Jun. 12, 2001,
and are hereby incorporated herein by reference in their
entireties.
[0018] In the embodiment depicted in FIG. 1, the system 30 has
three polishing stations 32 (two are shown) and a loading station
34 disposed on a base 10. A carousel 37 is coupled to the base 10
and supports a plurality of polishing heads 36 rotationally
disposed above the polishing stations 32 and the loading station
34. A front-end substrate transfer region 38 is disposed adjacent
to the CMP system and typically includes a substrate cleaner and
may optionally include metrology equipment.
[0019] Typically, a first substrate is loaded into one of the
polishing heads 36 at the loading station 34 and is then
sequentially processed at each of the three polishing stations 32.
As the first substrate leaves the loading station for processing, a
second substrate is loaded into the next polishing head so that
each polishing station 32 is engaged with a substrate
simultaneously. At the end of the cycle the substrate is
transferred from the polishing head 36 to the transfer station 34.
The substrate is then returned to the front-end substrate transfer
region 38 and another substrate is placed into the loading station
34 for processing by a robot 20.
[0020] FIG. 2 is a schematic view of one embodiment of the
polishing station 32 showing the platen 41 and polishing head 36.
The polishing head 36 retains a substrate 42 during polishing. The
polishing head 36 may comprise a vacuum-type mechanism to chuck the
substrate 42 against the polishing head 36. During operation, the
vacuum chuck generates a negative vacuum force behind the surface
of the substrate 42 to attract and hold the substrate 42. The
polishing head 36 typically includes a pocket (not shown) in which
the substrate 42 is supported, at least initially, under vacuum.
Once the substrate 42 is secured in the pocket and positioned
against the polishing material 44, the vacuum can be removed. The
polishing head 36 then applies a controlled pressure behind the
substrate, indicated by the arrow 48, to the backside of the
substrate 42 urging the substrate 42 against the polishing material
44 to facilitate polishing of the substrate surface. The polishing
head displacement mechanism 16 rotates the polishing head 36 and
the substrate 42 at a velocity V.sub.s in a clockwise or
counterclockwise direction. The polishing head displacement
mechanism 16 may additionally sweep the polishing head 36 laterally
across the polishing material 44 disposed on the platen 41 as
indicated by arrows 50 and 52. One polishing head suitable for use
with the invention is a TITAN HEAD.TM. wafer carrier, also
available from Applied Materials, Inc. Another suitable polishing
head is described in U.S. Pat. No. 6,183,354, issued Feb. 6, 2001,
and is hereby incorporated by reference in its entirety.
[0021] The polishing station 32 also includes a chemical supply
system 54 for introducing a polishing fluid of a desired
composition to the polishing material 44. In one embodiment, the
polishing fluid may include slurry of alumina or silica particles.
The slurry provides an abrasive material which facilitates the
polishing of the substrate surface. During operation, the chemical
supply system 54 introduces the polishing fluid as indicated by
arrow 56 on the polishing material 44 at a selected rate.
Alternatively, the polishing fluid may be supplied to the upper
surface of the polishing material 44 from a alternative chemical
supply source 71 though a port 70 formed in the platen 41. The
polishing material 44 disposed on the platen 41 may includes holes
72 formed therethrough to allow polishing fluid to flow out of the
port 70 and through the polishing material 44 and into contact with
the substrate 42.
[0022] The polishing station 32 includes a polishing material 44
secured to an upper patterned surface 14 of the platen 41. The
polishing material 44 may be any polishing material suitable for
chemical mechanical processing, such as commercially available
polyurethane pads 59 as depicted in FIG. 2 or a web 60 of fixed
abrasive polishing material as depicted in the polishing station
32A shown in FIG. 3. Optionally, a subpad 18 may be disposed
between the platen 41 and polishing material 44 to tailor the
compliance of the polishing material 44 and the polishing results.
It is contemplated that the subpad 18 may be utilized in any of the
embodiments described herein.
[0023] The polishing material 44 is retained to the upper surface
14 of the platen 41. In the embodiment depicted in FIG. 2, the
polishing material 44 is held by vacuum to the platen 41. A port 68
is formed through the upper surface 14 and coupled to a vacuum
source 69 so that a vacuum may be drawn between the polishing
material 44 and platen 41.
[0024] Alternatively, in embodiments where a magnetic layer 65,
such as a sheet of metal, disposed, is coupled to or embedded in
the polishing material 44, the polishing material 44 may be
magnetically coupled to the platen 41. For example, the platen 41
may include a magnetic device 66, such as a permanent magnet or an
electromagnet powered by a power source 67, that attracts and
secures the polishing material 44 to the platen 41.
[0025] The platen 41 is coupled to a motor 46 disposed below the
base 10 or other suitable drive mechanism to impart rotational
movement to the platen 41. During operation, the platen 41 is
rotated at a velocity V.sub.p about a center axis X such that the
polishing material 44 and a substrate 42 retained by the polishing
head 36 (shown in an elevated position) are moved relative each
other while in contact therebetween. The platen 41 may be rotated
in either a clockwise or counterclockwise direction, and in one
embodiment, is rotated in the same direction as the polishing head
36. It is contemplated that other relative motion between the
polishing material 44 and the substrate 42 retained by the
polishing head 36 may be utilized, including, but not limited to
linear and/or orbital motion, among others. It is also contemplated
that one of the platen 41 or polishing head 36 motion within the
plane of the polishing material 44 may be fixed.
[0026] To enhance control of the polishing profile of the substrate
42, the upper patterned surface 14 has a non-planar configuration.
The non-planar configuration of the upper patterned surface 14
positions the overlying polishing material 44 at a various
elevations relative to the substantially planar orientation of the
substrate 42 retained in the polishing head 36. A reference line 24
that is perpendicular to the axis X is provided to illustrate the
non-planarity of the upper surface 14. As the polishing head 36 is
lowered to contact the substrate 42 with the polishing material 44,
the difference in elevation across the upper patterned surface 14
(which are exaggerated for purposes of illustration) results in
areas of more polishing force 48 near the high portions of the
upper surface 14. Since the upper surface 14 of the platen 41 is
substantially rigid, the non-planar orientation of the upper
surface 14 is maintained after multiple polishes, thereby
contributing to enhanced substrate to substrate repeatability and
predictable polishing results. The patterned differences in
elevations fabricated into the hard platen top surface is somewhat
converted by the flexible, compressible polishing material 44
disposed on top of the platen to a same pattern of differences of
pressures asserted between the substrate and polishing material
during polishing that is more the direct effect affecting the
desired process of non-uniform material removal from the substrate.
In one embodiment of the invention utilizing a web of polishing
material such as depicted in FIG. 3, the upper surface 14 of the
platen 41 may have at least one change in elevation (and/or relief)
in range between about 2 to about 24 mils.
[0027] In the embodiment depicted in FIG. 2, the upper surface 14
is convex resulting in portions of the substrate contacting the
polishing material 44 closer to the center axis X having a greater
polishing force 48, thereby locally increasing the rate of polish.
As the motion of the substrate relative to the polishing material
44 may be set in a predefined polishing routine, the polishing
profile of the substrate may be controlled by pre-determining which
portions of the substrate 42 are in contact with higher elevations
of the upper patterned surface 14 during a specific polishing
routine.
[0028] It is contemplated that other configurations of the
patterned upper surface 14 may be utilized to produce different
polishing results. For example, in the embodiment of a polishing
station 32B depicted in FIG. 4, an upper patterned surface 14A of
the platen 41 is concave.
[0029] FIG. 5 depicts another embodiment of a polishing station
32C. The polishing station 32C includes a platen 41 comprised of a
substantially rigid material, such as aluminum or
polyetheretherketone, among others. The platen 41 has an upper
patterned surface 14B that has a plurality of high and low portions
that support the polishing material 44. In one embodiment, at least
one of a high and low portion of the upper patterned surface 14B of
the platen 41 is located in a working area 80. The working area 80
of the upper patterned surface 14B is defined as the portion of the
upper patterned surface 14B upon with the substrate 42 is disposed
during processing. The working area 80 may be large or small; for
example, the working area 80 may be smaller than the diameter of
the substrate (on small pad systems, not shown), or may be greater
than or equal to the diameter of the substrate (up to the entire
pad diameter).
[0030] In the embodiment depicted in FIG. 5, the working area 80
includes an inner working area 82 and an annular outer working area
81. The transition between the inner working area 82 and the outer
working area 81 may be smooth, defining an undulating or wavy upper
surface 14. The inner working area 82 is configured to be recessed
relative to the outer working area 81. As the center of the
substrate 42 is in contact during processing with a portion of the
polishing material 44 positioned over the inner working area 82 for
a longer period than that portion of the polishing material 44
disposed over the outer working area 81, the perimeter of the
substrate 42 experiences more polishing force 48 during processing
than the center of the substrate, resulting in a faster polish at
the perimeter of the substrate. The relative difference in
elevation between the outer and inner working areas 82, 81 may be
tailored to compensate of other processing parameters that would
cause faster polishing rates in the reverse orientation, thereby
resulting in a planar, polished surface of the substrate 42. It is
contemplated that the working area 80 may be divided into multiple
(i.e., more than two) regions of high and low areas, and that the
areas may be configured in geometries other an annular, such as,
for example, a plurality of mounds, ridges, bumps, or grids.
[0031] FIG. 6 shows a side view of another embodiment of a
polishing station 32D. The platen 41 of the polishing station 32D
includes a patterned upper surface 14C whereon the polishing
material 44 may be disposed. Generally, the patterned upper surface
14C has features formed therein defining a raised area and a
recessed area. In the embodiment shown in FIG. 6, the raised area
consists of a plurality of protrusions 60 while the recessed area
is a plurality of intersecting grooves 62 defined by the
protrusions 60. The height of the individual protrusion 60 is
selected such that the upper surface 14C is non-planar. More
specifically, the recessed area consists of two parallel sets of
equally spaced orthogonally intersecting grooves 62 in a
checkerboard pattern. Each groove 62 traverses the upper surface
14C of the platen 41 from one perimeter to the another. Thus, the
grooves 62 are not contained, or blocked, at either end. However,
the present invention also contemplates an embodiment having
blocked grooves.
[0032] The protrusions 60 cooperate to provide a substantially
non-planar mounting surface 64 along a common surface defining the
upper surface 14C for supporting a polishing material 44 as shown
in FIGS. 6-7. The polishing material 44 may be attached using a
commercially available pressure sensitive adhesive (PSA). In this
embodiment, the present invention eliminates the need for a subpad
by controlling the ratio between raised and recessed area to
control polishing material compliance. The protrusions 60 ensure
sufficient rigidity (or stiffness) while the grooves 62 allow the
proper proportion of pad compliance to accommodate a substrate's
varying topography.
[0033] The dimensions of the patterned surface may be varied to
achieve the desired proportions of compliance and rigidity. In
general, the mounting surface 64 makes up to between about 20 to 95
percent of the total upper surface area but may be varied according
to the pad thickness and modulus, as well as the applied polishing
pressure. In a specific embodiment shown in FIGS. 6-7, where the
platen 41 diameter is about twenty (20) inches, the groove depth is
about 0.250 inches and the groove width is about 0.062 inches.
Thus, the total surface area of the mounting area 64 is about 20-95
percent of the total area of the platen 41. The diameter of the
platen 41 may be varied to accommodate any substrate size such as
100 mm, 200 mm or 300 mm substrates. As a result, relative sizes of
the grooves and protrusions will vary accordingly.
[0034] It is to be understood that the present invention allows for
virtually limitless design variations. FIGS. 6-7 show only one
possible embodiment according to the invention. In another
embodiment, the raised area and recessed areas of the platen 41 may
be defined by intersected radial grooves. The embodiments described
above are merely illustrative and a person skilled in the art will
recognize other embodiments within the scope of the present
invention.
[0035] While foregoing is directed to the preferred embodiment 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.
* * * * *