U.S. patent application number 10/367439 was filed with the patent office on 2004-03-25 for polishing media for chemical mechanical planarization (cmp).
This patent application is currently assigned to LAM RESEARCH CORPORATION. Invention is credited to Charatan, Robert, Lin, Jibing.
Application Number | 20040058623 10/367439 |
Document ID | / |
Family ID | 32033242 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058623 |
Kind Code |
A1 |
Lin, Jibing ; et
al. |
March 25, 2004 |
Polishing media for chemical mechanical planarization (CMP)
Abstract
A polishing media for chemical mechanical planarization (CMP)
includes a layer comprised of a CMP pad material having a
water-soluble material comprised of cyclodextrin dispersed therein.
The layer may form part of a pad configured for rotary CMP or part
of a belt pad configured for linear CMP. In one method for
conducting a CMP operation, a polishing media having a layer
comprised of a CMP pad material with a water-soluble material
comprised of cyclodextrin dispersed therein is contacted with a
slurry, water, or an aqueous solution to remove the water-soluble
material comprised of cyclodextrin from the CMP pad material. In
another method, the water-soluble material comprised of
cyclodextrin is removed from the CMP pad material before the CMP
operation.
Inventors: |
Lin, Jibing; (Fremont,
CA) ; Charatan, Robert; (Portland, OR) |
Correspondence
Address: |
MARTINE & PENILLA, LLP
710 LAKEWAY DRIVE
SUITE 170
SUNNYVALE
CA
94085
US
|
Assignee: |
LAM RESEARCH CORPORATION
4650 CUSHING PARKWAY
FREMONT
CA
94538
|
Family ID: |
32033242 |
Appl. No.: |
10/367439 |
Filed: |
February 14, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10367439 |
Feb 14, 2003 |
|
|
|
10251324 |
Sep 20, 2002 |
|
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Current U.S.
Class: |
451/41 |
Current CPC
Class: |
B24B 37/24 20130101;
B24D 3/348 20130101; B24D 3/32 20130101; B24B 37/22 20130101 |
Class at
Publication: |
451/041 |
International
Class: |
B24B 001/00 |
Claims
What is claimed is:
1. A polishing media for chemical mechanical planarization (CMP),
comprising: a layer comprised of a CMP pad material having a
water-soluble material comprised of cyclodextrin dispersed
therein.
2. The polishing media of claim 1, wherein the CMP pad material is
comprised of a thermoplastic material selected from the group
consisting of polyurethane, polyurea, polyester, polyacrylate, and
polyvinyl chloride.
3. The polishing media of claim 1, wherein the layer forms part of
a pad configured for rotary CMP.
4. The polishing media of claim 1, wherein the layer forms part of
a belt pad configured for linear CMP.
5. The polishing media of claim 1, wherein the layer contains 1% by
volume to 60% by volume of the water-soluble material comprised of
cyclodextrin.
6. The polishing media of claim 1, wherein the layer is formed by a
fabrication process including one of spray coating, extrusion,
molding, and casting.
7. A polishing media for chemical mechanical planarization (CMP),
comprising: a layer comprised of a polyurethane-based material
having a water-soluble material comprised of cyclodextrin dispersed
therein.
8. The polishing media of claim 7, wherein the layer forms part of
a pad configured for rotary CMP.
9. The polishing media of claim 7, wherein the layer forms part of
a belt pad configured for linear CMP.
10. The polishing media of claim 7, wherein the layer contains 1%
by volume to 60% by volume of the water-soluble material comprised
of cyclodextrin.
11. The polishing media of claim 7, wherein the layer is formed by
a fabrication process including one of spray coating, extrusion,
molding, and casting.
12. A method for conducting a chemical mechanical planarization
(CMP) operation, comprising: providing a polishing media having a
layer comprised of a CMP pad material with a water-soluble material
comprised of cyclodextrin dispersed therein; and contacting the
layer with at least one of a slurry, water, and an aqueous solution
to remove the water-soluble material comprised of cyclodextrin from
the CMP pad material.
13. The method of claim 12, wherein the layer has an overall
porosity in a range from 1% to 60%.
14. The method of claim 12, wherein the contacting of the layer
with at least one of the slurry, water, and the aqueous solution
occurs in a rotary CMP operation.
15. The method of claim 12, wherein the contacting of the layer
with at least one of the slurry, water, and the aqueous solution
occurs in a linear CMP operation.
16. The method of claim 12, wherein the CMP pad material is
comprised of a thermoplastic material selected from the group
consisting of polyurethane, polyurea, polyester, polyacrylate, and
polyvinyl chloride.
17. A method for conducting a chemical mechanical planarization
(CMP) operation, comprising: providing a polishing media having a
layer comprised of a CMP pad material with a water-soluble material
comprised of cyclodextrin dispersed therein; removing the
water-soluble material comprised of cyclodextrin from the layer;
and contacting the layer with a substrate in the presence of a
slurry to planarize the substrate.
18. The method of claim 17, wherein the layer has an overall
porosity in a range from 1% to 60%.
19. The method of claim 17, wherein the contacting of the layer
with the substrate occurs in a rotary CMP operation.
20. The method of claim 17, wherein the contacting of the layer
with the substrate occurs in a linear CMP operation.
21. The method of claim 17, wherein the CMP pad material is
comprised of a thermoplastic material selected from the group
consisting of polyurethane, polyurea, polyester, polyacrylate, and
polyvinyl chloride.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 10/251,324, filed Sep. 20, 2002, the
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to semiconductor
fabrication and, more particularly, to polishing media for chemical
mechanical planarization (CMP) and to methods for conducting a CMP
operation.
[0003] In the fabrication of semiconductor devices, chemical
mechanical planarization is used to planarize globally the surface
of an entire semiconductor wafer. To planarize a wafer surface
using CMP, a polishing surface, e.g., a pad, is contacted against
the wafer surface in the presence of a slurry. Generally speaking,
to obtain a uniformly high polishing rate, the polishing surface
area should be maximized. Thus, from this perspective, the
polishing surface should be free from grooves, scribes,
imperfections, etc. To effectively deliver slurry to and remove
slurry byproducts from the wafer surface, however, the polishing
surface must have grooves or pores.
[0004] Current commercially available CMP pads are typically formed
of porous polymeric materials. In these CMP pads, the pores are
usually closed pores. Unfortunately, it is difficult to control the
pore size distribution and the pore density of closed pores in
polymeric materials. As pores may play a significant role in slurry
delivery, it is difficult to produce consistent CMP pads having
closed pores because of the variations in pore size distribution
and pore density.
[0005] In view of the foregoing, there is a need for a polishing
media for CMP that can be manufactured by a process that allows the
porosity and pore size distribution of closed pores to be
controlled more reliably.
SUMMARY OF THE INVENTION
[0006] Broadly speaking, the present invention fills this need by
providing a polishing media for chemical mechanical planarization
(CMP) that may be formed by blending cyclodextrin into a CMP pad
material and subsequently removing the cyclodextrin. The present
invention also provides methods for conducting a CMP operation.
[0007] In accordance with one aspect of the present invention, a
polishing media for CMP is provided. The polishing media includes a
layer comprised of a CMP pad material having a water-soluble
material comprised of cyclodextrin dispersed therein. The layer may
form part of a pad configured for rotary CMP or part of a belt pad
configured for linear CMP. In one embodiment, the layer contains 1%
by volume to 60% by volume of the water-soluble material comprised
of cyclodextrin.
[0008] In one embodiment, the CMP pad material is comprised of a
thermoplastic material such as, for example, polyurethane,
polyurea, polyester, polyacrylate, and polyvinyl chloride. In one
embodiment, the CMP pad material is a polyurethane-based CMP pad
material. As used in connection with the description of this
embodiment, the term "polyurethane-based CMP pad material" refers
to any material suitable for use in a CMP pad that contains more
than 50% by weight of polyurethane.
[0009] In accordance with another aspect of the present invention,
a first method for conducting a CMP operation is provided. In this
method, a polishing media having a layer comprised of a CMP pad
material with a water-soluble material comprised of cyclodextrin
dispersed therein is provided. The layer is contacted with at least
one of a slurry, water, and an aqueous solution to remove the
water-soluble material comprised of cyclodextrin from the CMP pad
material. The contacting of the layer with the slurry, water, or
the aqueous solution may occur in either a rotary CMP operation or
a linear CMP operation.
[0010] In accordance with yet another aspect of the present
invention, a second method for conducting a CMP operation is
provided. In this method, a polishing media having a layer
comprised of a CMP pad material with a water-soluble material
comprised of cyclodextrin dispersed therein is provided. The
water-soluble material comprised of cyclodextrin is removed from
the layer. The layer is then contacted with a substrate in the
presence of a slurry to planarize the substrate. The contacting of
the layer with the substrate may occur in either a rotary CMP
operation or a linear CMP operation.
[0011] One advantage of a CMP pad material containing cyclodextrin
is that the cyclodextrin may complex with the CMIP byproducts and
thereby provide an efficient and highly effective mechanism for
removing such byproducts from the substrate being planarized during
a CMP operation. To minimize variations in pore size distribution,
the cyclodextrin can be processed to provide particles having a
specific size distribution. To minimize variations in pore
distribution, the cyclodextrin can be homogeneously blended with
the CMP pad material, e.g., by mechanical mixing. Additional
advantages of the polishing media of the present invention will be
apparent to those skilled in the art upon consideration of the
specification and practice of the invention.
[0012] It is to be understood that the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated in and
constitute part of this specification, illustrate exemplary
embodiments of the invention and together with the description
serve to explain the principles of the invention.
[0014] FIG. 1 is a simplified cross-sectional view of a polishing
media for chemical mechanical planarization having a polishing
layer with continuous pores in accordance with one embodiment of
the invention.
[0015] FIG. 2 is a simplified cross-sectional view of a polishing
media for chemical mechanical planarization having a polishing
layer with closed pores in accordance with another embodiment of
the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] Several exemplary embodiments of the invention will now be
described in detail with reference to the accompanying
drawings.
[0017] FIG. 1 is a simplified cross-sectional view of polishing
media 100 for chemical mechanical planarization (CMP) in accordance
with one embodiment of the invention. As shown therein, polishing
media 100 includes substrate 102 and polishing layer 104, which is
disposed over substrate 102. Substrate 102 may be any underlayer or
combination of underlayers such as, for example, those found in
conventional pads for rotary CMP or conventional belt pads for
linear CMP. Polishing layer 104 is comprised of a CMP pad material
and has continuous pores therein, as will be described in more
detail later. As used in connection with the description of the
invention, the term "CMP pad material" means any material suitable
for polishing a substrate, e.g., a semiconductor wafer, in a CMP
operation. Exemplary CMP pad materials include, but are not limited
to, polyurethane, polyurea, polyester, polyacrylate, and polyvinyl
chloride. It will be apparent to those skilled in the art that
polishing media 100 can be configured either as a pad for use in a
rotary CMP operation or as a belt pad for use in a linear CMP
operation.
[0018] As mentioned above, polishing layer 104 has continuous pores
therein. The continuous pores may be formed by dispersing a
water-soluble material appropriately in the CMP pad material, as
will be described in more detail later. After the polishing media
has been fabricated, the water-soluble material may be removed
before a CMP operation by placing the polishing media in water (or
an aqueous solution) to dissolve the water-soluble material.
Alternatively, the polishing media can be used directly in a CMP
operation without removing the water-soluble material. In this
case, the water-soluble material will be removed during the CMP
operation either when the water-soluble material comes into contact
with the slurry during polishing or when the water-soluble material
comes into contact with water or an aqueous solution, e.g., during
cleaning, conditioning, or wet cycling of the polishing media.
[0019] For polishing media intended for use in the semiconductor
industry, the water-soluble material should be compatible with the
cleanliness requirements of the semiconductor industry. Suitable
water-soluble materials include both natural and synthetic
water-soluble materials. Exemplary natural water-soluble materials
compatible with the cleanliness requirements of the semiconductor
industry include, but are not limited to, starch, urea, and guar
gum. Exemplary synthetic water-soluble materials compatible with
such requirements include, but are not limited to, polyvinyl
alcohol, polyacrylic acid, polyacrylimide, polyaspartate, and
polysaccharide.
[0020] An exemplary method for forming the polishing media will now
be described. A CMP pad material and a water-soluble material (both
in powder form) are first blended together. The blended powder
mixture is then spray coated onto a suitable substrate. By way of
example, to form a belt pad for a linear CMP operation, the
substrate may be a belt formed of a suitable fabric, e.g.,
Kevlar.TM.. Next, the substrate is heated to an operating
temperature with a heat source, e.g., an infrared (IR) lamp, to
melt the blended powder mixture. To obtain continuous pores, both
the CMP pad material and the water-soluble material are required to
melt but not to decompose at the operating temperature, which is
typically below 250.degree. C. for CMP pad materials. Thorough
mixing of the water-soluble material in the CMP pad material is
obtained by melting the water-soluble material. If the
water-soluble material does not melt, then the resulting polishing
media will have closed pores.
[0021] After the heating operation, a cooling operation is
performed to cool the melted mixture of the CMP pad material and
the water-soluble material. In one embodiment, the cooling
operation is carried out with a cooling drum. Once the melted
mixture has been cooled, the substrate may be subjected to any
desired machining operations. By way of example, to form pads for
use in rotary CMP operations, the substrate may be cut into
circular shapes. Other machining operations that may be performed
include grinding, grooving, or embossing. In the event it is
desired to remove the water-soluble material from the polishing
media at this point, the substrate may be placed in water (or an
aqueous solution) to dissolve the water-soluble material.
Alternatively, as described above, the water-soluble material may
be left intact for subsequent removal either just before a CMP
operation or during the CMP operation. Thereafter, any other needed
operations may be performed, e.g., applying an adhesive.
[0022] The overall porosity of the polishing media may be
controlled by varying the amount of the water-soluble material
dispersed in the CMP pad material. In one embodiment, the amount of
the water-soluble material is in the range from 1 volume % to 60
volume %. Thus, in this embodiment, when the water-soluble material
is removed, the overall porosity of the polishing media will be in
the range from 1% to 60%. In some applications, it may be desirable
to have the overall porosity of the polishing media in a narrower
range, e.g., from 10% to 40%. One advantage of polishing media
having continuous pore structures is that, particularly at higher
porosity levels, it may be possible to eliminate the grooving
normally provided to facilitate slurry distribution.
[0023] The pore size distribution of the continuous pores within
the CMP pad material can be controlled by adjusting the cooling
rate used to cool the melted mixture of the CMP pad material and
the water-soluble material. Thus, by controlling the amount of the
water-soluble material and the cooling rate, polishing media having
desirable continuous pore structures can be fabricated
consistently. This is technically significant because it enables
consistent polishing performance to be obtained in CMP operations
conducted using such polishing media.
[0024] It will be apparent to those skilled in the art that methods
other than the exemplary spray coating method described above can
be used to form polishing media having continuous pores. By way of
example, polishing media having continuous pores also can be formed
by extrusion, molding, or casting. As mentioned above, continuous
pores will be obtained so long as the water-soluble material melts
(but does not decompose) during the fabrication process. It will be
further apparent to those skilled in the art that suitable
water-soluble materials are not limited to those specifically named
herein. Rather, in the case of polishing media for the
semiconductor industry, any water-soluble material that 1) melts
but does not decompose at the melting temperature required for
fabrication of the polishing media, and 2) meets the cleanliness
requirements of the semiconductor industry is suitable for use in
forming polishing media having continuous pores.
[0025] In the case of polyurethane-based CMP pad materials, the
temperature required for fabrication of the polishing media is
typically in the range of 180.degree. C. and 200.degree. C.
Consequently, any water-soluble material to be dispersed in a
polyurethane-based CMP pad material must be stable up to at least
200.degree. C. Thus, certain water-soluble materials, e.g., urea,
which decomposes at a temperature of about 120.degree. C., are not
suitable for use in the fabrication of polyurethane-based CMP
pads.
[0026] FIG. 2 is a simplified cross-sectional view of polishing
media 100' for chemical mechanical planarization (CMP) in
accordance with another embodiment of the invention. As shown
therein, polishing media 100' includes substrate 102 and polishing
layer 104', which is disposed over substrate 102. As set forth
above, substrate 102 may be any underlayer or combination of
underlayers such as, for example, those found in conventional pads
for rotary CMP or conventional belt pads for linear CMP. Polishing
layer 104' is comprised of a CMN pad material and has closed pores
therein, as will be described in more detail later. It will be
apparent to those skilled in the art that polishing media 100' can
be configured either as a pad for use in a rotary CMP operation or
as a belt pad for use in a linear CMP operation.
[0027] The closed pores in polishing layer 104' may be formed by
dispersing a water-soluble material comprised of cyclodextrin
appropriately in the CMP pad material, e.g., in the manner
described above in connection with the description of polishing
media 100, which includes a polishing layer having continuous
pores. After the polishing media 100' has been fabricated, the
cyclodextrin may be removed before a CMP operation by placing the
polishing media in water (or an aqueous solution) to dissolve the
cyclodextrin. Alternatively, the polishing media can be used
directly in a CMP operation without removing the cyclodextrin. In
this case, the cyclodextrin will be removed during the CMP
operation either when the cyclodextrin comes into contact with the
slurry during polishing or when the cyclodextrin comes into contact
with water or an aqueous solution, e.g., during cleaning,
conditioning, or wet cycling of the polishing media.
[0028] Generally speaking, cyclodextrins are bucket-shaped
molecules formed of glucose units. As used in connection with the
description of the invention, the term "cyclodextrin" includes the
three known forms of cyclodextrin, i.e., alpha-cyclodextrin,
beta-cyclodextrin, and gamma-cyclodextrin. Cyclodextrin is soluble
in water, has a high temperature stability (it is stable up to
300.degree. C.), and does not melt before it starts to decompose.
By virtue of its high temperature stability, cyclodextrin is
suitable for use in the fabrication of polyurethane-based CMP pads.
The incorporation of cyclodextrin in a CMP pad material and the
subsequent removal thereof will not result in the formation of
continuous pores. Instead, closed pores will be formed in the CMP
pad material because cyclodextrin does not melt before it starts to
decompose.
[0029] One of the unique aspects of cyclodextrin is that the
internal cavity of cyclodextrin can complex with other molecules.
Thus, when a CMP pad material containing cyclodextrin is used in a
CMP operation, the cyclodextrin may complex with the CMP byproducts
and thereby provide an efficient and effective mechanism for
removing such byproducts from the substrate being planarized. In
addition, to minimize variations in pore size distribution, the
cyclodextrin can be processed to provide particles having a
specific size distribution. To minimize variations in pore
distribution, the cyclodextrin can be homogeneously blended with
the CMP pad material, e.g., by mechanical mixing.
[0030] As noted above, the polishing media of the invention can be
configured either as a pad for use in a rotary CMP operation or as
a belt pad for use in a linear CMP operation. As is well known to
those skilled in the art, the rotary or linear CMP system in which
the polishing media of the invention is implemented may form part
of a cluster tool, which includes other processing modules, e.g.,
clean, etch, etc.
[0031] In summary, the present invention provides a polishing media
for CMP and methods for conducting a CMP operation. The invention
has been described herein in terms of several exemplary
embodiments. Other embodiments of the invention will be apparent to
those skilled in the art from consideration of the specification
and practice of the invention. The embodiments and preferred
features described above should be considered exemplary, with the
invention being defined by the appended claims and equivalents
thereof.
* * * * *