U.S. patent application number 09/944257 was filed with the patent office on 2002-03-14 for method and apparatus for mechanical and chemical-mechanical planarization of microelectronic substrates.
Invention is credited to Moore, Scott E..
Application Number | 20020031984 09/944257 |
Document ID | / |
Family ID | 21695502 |
Filed Date | 2002-03-14 |
United States Patent
Application |
20020031984 |
Kind Code |
A1 |
Moore, Scott E. |
March 14, 2002 |
METHOD AND APPARATUS FOR MECHANICAL AND CHEMICAL-MECHANICAL
PLANARIZATION OF MICROELECTRONIC SUBSTRATES
Abstract
A method and apparatus for mechanically and/or
chemical-mechanically planarizing microelectronic substrates. In
one embodiment in accordance with the principles of the present
invention, a microelectronic substrate is planarized or polished on
a planarizing medium having a thin film and a plurality of
micro-features on the film. The film may be an incompressible sheet
or web substantially impervious to a planarizing solution, and the
micro-features may be configured in a selected pattern on the film
to restrain fluid flow of the planarizing solution across the
surface of the film under the substrate. The micro-features, for
example, may be configured in a selected pattern that has a
plurality of support points and at least one cavity to entrap a
substantially contiguous, uniform distribution of the solution
under the substrate during planarization. Additionally, the
selected pattern of micro-features may be reproduced from a master
pattern of micro-features to duplicate the selected pattern on
several sections of film so that a consistent planarizing surface
may be provided for a large number of substrates.
Inventors: |
Moore, Scott E.; (Meridian,
ID) |
Correspondence
Address: |
Steven H. Arterberry, Esq.
DORSEY & WHITNEY LLP
Suite 3400
1420 Fifth Avenue
Seattle
WA
98101
US
|
Family ID: |
21695502 |
Appl. No.: |
09/944257 |
Filed: |
August 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09944257 |
Aug 29, 2001 |
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09444754 |
Nov 22, 1999 |
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09444754 |
Nov 22, 1999 |
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09001333 |
Dec 30, 1997 |
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6139402 |
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Current U.S.
Class: |
451/36 ; 451/527;
451/59 |
Current CPC
Class: |
B24B 37/26 20130101 |
Class at
Publication: |
451/36 ; 451/59;
451/527 |
International
Class: |
B24B 001/00 |
Claims
1. A planarizing medium for planarizing microelectronic substrates,
comprising: a planarizing film impervious to a solution; and a
plurality of micro-features configured in a selected, duplicated
pattern on the film, the selected pattern having a plurality of
first raised features defining support points, at least one cavity
below the support points, and a plurality of second raised features
between and below the support points.
2. The planarizing medium of claim 1 wherein the film is composed
of a substantially incompressible polymer and the first and second
raised features are formed from the film.
3. The planarizing medium of claim 2 wherein the polymer comprises
polyester.
4. The planarizing medium of claim 2 wherein the copolymer
comprises polycarbonate.
5. The planarizing medium of claim 2 wherein the polymer comprises
polyurethane.
6. The planarizing medium of claim 2 wherein the polymer comprises
nylon.
7. The planarizing medium of claim 2 wherein the first and second
raised features comprise nodules having a plurality of shapes and
heights, the nodules being patterned on the film to form a
plurality of depressions between the nodules and so that at least a
portion of the nodules define the support points.
8. The planarizing medium of claim 7 wherein the first raised
features have flat tops terminating at a constant maximum height
across the planarizing surface of the film.
9. The planarizing medium of claim 7 wherein the nodules are
embossed on the film.
10. The planarizing medium of claim 9 wherein the selected pattern
is substantially random configuration of nodules across an
operating region of the planarizing surface.
11. The planarizing medium of claim 10 wherein the polymer
comprises polyester.
12. The planarizing medium of claim 10 wherein the copolymer
comprises polycarbonate.
13. The planarizing medium of claim 1 wherein: the film comprises a
polymer body with an upper surface; and the micro-features comprise
a fine mesh on the upper surface of the film having woven strands,
the first raised features being high points along the strands and
the second raised features being side portions of the strands.
14. The planarizing medium of claim 13 wherein: the polymer
comprises polyester; and the fine mesh comprises small nylon fibers
woven in a mesh with 0.5% to 5% openings.
15. The planarizing medium of claim 14 wherein the nylon fiber
comprise 2.0 .mu.m to 5.0 .mu.m fibers.
16. The planarizing medium of claim 1 wherein the film comprises a
flexible web wrapped around a supply roller and a take-up roller,
and wherein the pattern of micro-features is duplicated across the
web.
17. The planarizing medium of claim 16 wherein a first portion of
the web is held at a work station of a planarization machine to
planarize a first substrate, and the web is subsequently advanced
to position a second portion of the web at the work station to
planarize a second substrate.
18. The planarizing medium of claim 1 wherein the planarizing film
comprises a separate sheet removably attached to a work station of
a planarization machine.
19. A planarizing medium for planarizing a microelectronic
substrate, comprising: an impermeable planarizing film; and a
plurality of non-abrasive micro-features on the planarizing film
defining a planarizing surface, the micro-features being formed in
a defined, consistently reproduced pattern on the planarizing film
to contain planarizing solution between the micro-features and
under the substrate during planarization.
20. The planarizing medium of claim 19 wherein the film is composed
of a substantially incompressible polymer and the micro-features
are formed from the film.
21. The planarizing medium of claim 20 wherein the micro-features
comprise nodules having a plurality of shapes and heights, the
nodules being patterned on the film to form a plurality of
depressions between the nodules that entrap the solution.
22. The planarizing medium of claim 20 wherein a portion of the
nodules have flat tops terminating at a constant maximum height
across the planarizing surface of the film.
23. The planarizing medium of claim 20 wherein the nodules are
embossed on the film.
24. The planarizing medium of claim 20 wherein the depressions are
etched into the film.
25. The planarizing medium of claim 20 wherein the selected pattern
is substantially random configuration of nodules across an
operating region of the planarizing surface.
26. The planarizing medium of claim 19 wherein: the film comprises
a polymer body with an upper surface; and the micro-features
comprise a fine mesh on the upper surface of the film.
27. The planarizing medium of claim 19 wherein the film comprises a
flexible web wrapped around a supply roller and a take-up roller,
wherein the selected pattern of micro-features is duplicated across
the web.
28. The planarizing medium of claim 27 wherein a first portion of
the web is held at a work station of a planarizing machine to
planarize a first substrate, and the web is subsequently advanced
to position a second portion of the web at the work station to
planarize a second substrate.
29. The planarizing medium of claim 19 wherein the planarizing film
comprises a separate sheet removably attached to a work station of
a planarizing machine.
30. The planarizing medium of claim 19 wherein the film comprises
polyester.
31. The planarizing medium of claim 19 wherein the film comprises
polycarbonate.
32. The planarizing medium of claim 19 wherein the film comprises
polyurethane.
33. The planarizing medum of claim 19 wherein the film comprises
nylon.
34. A planarizing medium for planarizing a microelectronic
substrate, comprising: a support base positionable on a planarizing
machine; and a separate non-abrasive, incompressible planarizing
film positioned on the base, the planarizing film having a
plurality of micro-features configured in a selected pattern on the
film for restraining fluid flow of a solution across a planarizing
surface of the film, the selected pattern being reproduced from a
master pattern of micro-features so that the planarizing medium may
be duplicated.
35. The planarizing medium of claim 34 wherein the film comprises a
flexible web wrapped around a supply roller and a take-up roller,
and wherein a portion of the web extending between the supply and
take-up rollers is held over the base.
36. The planarizing medium of claim 35 wherein the web is held
stationary over the base during planarization by tensioning the web
between the supply and take-up rollers.
37. The planarizing medium of claim 34 wherein the film comprises a
separate sheet removably attached to the base.
38. The planarizing medium of claim 37 wherein the sheet is clamped
to the base under tension.
39. The planarizing medium of claim 34 wherein the base comprises
an incompressible plate.
40. The planarizing medium of claim 34 wherein the film is composed
of a substantially incompressible polymer and the micro-features
are formed from the film.
41. The planarizing medium of claim 34 wherein the micro-features
comprise nodules having a plurality of shapes and heights, the
nodules being patterned on the film to form a plurality of
depressions between the nodules that entrap the solution.
42. The planarizing medium of claim 41 wherein a portion of the
nodules have flat tops terminating at a constant maximum height
across the planarizing surface of the film.
43. The planarizing medium of claim 41 wherein the nodules are
embossed on the film.
44. The planarizing medium of claim 41 wherein the depressions are
etched into the film.
45. The planarizing medium of claim 41 wherein the selected pattern
is substantially random configuration of nodules across an
operating region of the planarizing surface.
46. The planarizing medium of claim 34 wherein: the film comprises
a polymer; and the micro-features comprises a fine mesh on the
film.
47. A planarizing machine, comprising: a table with a support base;
a planarizing medium having a planarizing film and a plurality of
micro-features on the film configured in a selected, repeated
pattern, the pattern having a plurality of first raised features
defining support points, at least one cavity below the support
points, and a plurality of second raised features between and below
the support points; and a carrier assembly having a substrate
holder positionable over the film, wherein at least one of the film
and the holder moves to translate a substrate across the film
during planarization.
48. The planarizing machine of claim 47 wherein the film is
composed of a substantially incompressible polymer and the
micro-features are formed from the film.
49. The planarizing machine of claim 48 wherein the micro-features
comprise nodules having a plurality of shapes and heights, the
nodules being patterned on the film to form a plurality of
depressions between the nodules that entrap the solution.
50. The planarizing machine of claim 48 wherein a portion of the
nodules have flat tops terminating at a constant maximum height
across the planarizing surface of the film.
51. The planarizing machine of claim 48 wherein the nodules are
embossed on the film.
52. The planarizing machine of claim 48 wherein the depressions are
etched into the film.
53. The planarizing machine of claim 48 wherein the selected
pattern is substantially random configuration of nodules across an
operating region of the planarizing surface.
54. The planarizing machine of claim 47 wherein: the film comprises
a polymer; and the micro-features comprises a fine mesh on the
film.
55. The planarizing machine of claim 47 wherein: the film comprises
a flexible web upon which the selected pattern of micro-features is
duplicated; and the planarizing machine further comprises a supply
roll around which an unused part of the web is wound and a take-up
roll around which a used part of the web is wound, the supply and
take-up rolls selectively advancing the web to position desired
portions of the web over the base, and the web being selectively
tensioned between the supply and take-up rolls to hold the web
stationary during planarization.
56. The planarizing machine of claim 47 wherein the planarizing
film comprises a plurality of separate sheets removably attached to
the base, wherein each sheet has the selected pattern of
micro-features.
57. A planarizing medium for planarizing microelectronic
substrates, comprising: a disposable mono-layer planarizing film
having a thickness of between approximately 0.0005 and 0.050 inches
and a planarizing surface with a plurality of micro-features, the
plurality of micro-features defining fine depressions across the
planarizing surface having depths between 0.5 and 100 .mu.m.
58. The planarizing medium of claim 57 wherein the film comprises a
flexible web adapted to be wrapped around a supply roller and a
take-up roller so that the web may be indexed across a planarizing
station of a planarizing machine.
59. The planarizing medium of claim 58 wherein the web comprises a
polymer material.
60. The planarizing medium of claim 59 wherein the polymer material
comprises polyester.
61. The planarizing medium of claim 59 wherein the polymer material
comprises polycarbonate.
62. The planarizing medium of claim 59 wherein the polymer web has
a thickness approximately between 0.0005 and 0.003 inches.
63. The planarizing medium of claim 62 wherein the depths of the
depressions formed by the micro-features is approximately between 1
and 10 .mu.m.
64. The planarizing medium of claim 63 wherein the web has a
plurality of sections and each section has an identical pattern of
micro-features.
65. The planarizing medium of claim 57 wherein the film comprises a
sheet adapted to be attached to a planarizing station of a
planarizing machine.
66. The planarizing medium of claim 65 wherein the sheet comprises
a polymer material.
67. The planarizing medium of claim 66 wherein the polymer material
comprises polyester.
68. The planarizing medium of claim 66 wherein the polymer material
comprises polycarbonate.
69. The planarizing medium of claim 66 wherein the copolymer sheet
has a thickness approximately between 0.0005 and 0.003 inches.
70. The planarizing medium of claim 69 wherein the depths of the
depressions formed by the micro-features is approximately between 1
and 10 .mu.m.
71. The planarizing medium of claim 70 wherein the sheet has a
plurality of sections and each section has an identical pattern of
micro-features.
72. The planarizing medium of claim 57 wherein the depths of the
depressions formed by the micro-features is approximately between
0.5 .mu.m and 10 .mu.m.
73. A method of planarizing a microelectronic substrate,
comprising: engaging the substrate with a planarizing medium;
moving at least one of the substrate and the medium with respect to
the other to translate the substrate across a planarizing surface
of the medium; and restraining fluid flow of a solution under the
substrate with raised features that do not contact the substrate as
the substrate translates across the planarizing surface to maintain
a substantially contiguous distribution of solution under the
substrate.
74. The method of claim 73 wherein restraining fluid flow of the
solution step comprises: providing a planarizing medium including a
film impervious to the solution and a plurality of micro-features
configured in a selected pattern on the film that entrap small
volumes of solution under the substrate while the substrate
translates across the planarizing surface; and depositing the
solution onto the film.
75. The method of claim 74 wherein the planarizing medium comprises
a first portion and a second portion, the selected pattern being
duplicated on the first and second portions, and wherein the method
further comprises: engaging a first substrate with the first
portion; moving at least one of the first substrate and the first
portion with respect to the other to translate the first substrate
across a planarizing surface of the first portion; replacing the
first portion with the second portion after planarizing the first
substrate; engaging a second substrate with the second portion;
moving at least one of the second substrate and the second portion
with respect to the other to translate the second substrate across
a planarizing surface of the second portion.
76. The method of claim 75 wherein: the first and second portions
are formed together in a continuous web; and replacing the first
portion with the second portion comprises advancing the web to
remove the first portion from a base of a planarizing machine and
to position the second portion on the base.
77. The method of claim 75 wherein: the first and second portions
are separate sheets; and replacing the first portion with the
second portion comprises unclamping the first portion from a base
of a planarizing machine, removing the first portion from the base,
positioning the second portion on the base, and clamping the second
portion on the base.
78. The method of claim 74 wherein: the film is composed of a
substantially incompressible polymer and the micro-features
comprise a plurality of nodules formed from the film, the nodules
having a plurality of different shapes and heights; and the method
further comprises preparing the medium for planarization prior to
engaging the substrate with the medium by flattening a portion of
the nodules at a maximum height across the planarizing surface.
79. The method of claim 78 wherein flattening a portion of the
nodules comprises planarizing a sacrifice substrate on medium.
80. A method of planarizing a microelectronic substrate,
comprising: engaging the substrate with a planarizing medium
including a film impervious to the solution and a plurality of
micro-features configured in a selected pattern on the film; moving
at least one of the substrate and the medium with respect to the
other to translate the substrate across a planarizing surface of
the medium; supporting the substrate with at least a portion of the
micro-features having the greatest heights; and entrapping small
volumes of solution between the micro-features and under the
substrate as the substrate translates across the planarizing
surface.
81. The method of claim 80 wherein entrapping small volumes of the
solution step comprises: configuring the selected pattern of
micro-features on the film to inhibit fluid flow of the solution
under the substrate as the substrate translates across the
planarizing surface; and depositing the solution onto the film.
82. The method of claim 81 wherein the planarizing medium comprises
a first portion and a second portion, and wherein the method
further comprises: engaging a first substrate with the first
portion; moving at least one of the first substrate and the first
portion with respect to the other to translate the first substrate
across a planarizing surface of the first portion; replacing the
first portion with the second portion after planarizing the first
substrate; engaging a second substrate with the second portion;
moving at least one of the second substrate and the second portion
with respect to the other to translate the second substrate across
a planarizing surface of the second portion.
83. The method of claim 82 wherein: the first and second portions
are formed together in a continuous web; and replacing the first
portion with the second portion comprises advancing the web to
remove the first portion from a base of a planarizing machine and
to position the second portion on the base.
84. The method of claim 82 wherein: the first and second portions
are separate sheets; and replacing the first portion with the
second portion comprises unclamping the first portion from a base
of a planarizing machine, removing the first portion from the base,
positioning the second portion on the base, and clamping the second
portion on the base.
85. The method of claim 81 wherein: the film is composed of a
substantially incompressible polymer and the micro-features
comprise a plurality of nodules formed from the film, the nodules
having a plurality of different shapes and heights; and the method
further comprises preparing the medium for planarization prior to
engaging the substrate with the medium by flattening a portion of
the nodules at a maximum height across the planarizing surface.
86. The method of claim 85 wherein flattening a portion of the
nodules comprises planarizing a sacrifice substrate on medium.
87. A method of planarizing a microelectronic substrate,
comprising: depositing a planarizing solution onto a planarizing
medium having a film impervious to the solution and a planarizing
surface with a plurality of micro-features, the micro-features
being configured in a selected pattern to entrap a volume of the
solution between the micro-features, and the selected pattern being
reproduced from a master pattern of micro-features so that the
planarizing medium may be duplicated; engaging the substrate with
the planarizing surface; and moving at least one of the substrate
and the medium with respect to the other to translate the substrate
across a planarizing surface of the medium.
88. The method of claim 87 wherein the planarizing medium comprises
a first portion and a second portion, the selected pattern being
duplicated on the first and second portions, and wherein the method
further comprises: engaging a first substrate with the first
portion; moving at least one of the first substrate and the first
portion with respect to the other to translate the first substrate
across a planarizing surface of the first portion; replacing the
first portion with the second portion after planarizing the first
substrate; engaging a second substrate with the second portion;
moving at least one of the second substrate and the second portion
with respect to the other to translate the second substrate across
a planarizing surface of the second portion.
89. The method of claim 88 wherein: the first and second portions
are formed together in a continuous web; and replacing the first
portion with the second portion comprises advancing the web to
remove the first portion from a base of a planarizing machine and
to position the second portion on the base.
90. The method of claim 88 wherein: the first and second portions
are separate sheets; and replacing the first portion with the
second portion comprises unclamping the first portion from a base
of a planarizing machine, removing the first portion from the base,
positioning the second portion on the base, and clamping the second
portion on the base.
91. The method of claim 87 wherein: the film is composed of a
substantially incompressible polymer and the micro-features
comprise a plurality of nodules formed from the film, the nodules
having a plurality of different shapes and heights; and the method
further comprises preparing the medium for planarization prior to
engaging the substrate with the medium by flattening a portion of
the nodules at a maximum height across the planarizing surface.
92. The method of claim 91 wherein flattening a portion of the
nodules comprises planarizing a sacrifice substrate on medium.
93. A method of manufacturing microelectronic substrate polishing
pads, comprising: forming a defined pattern of non-abrasive
micro-features on a planarizing surface of a first portion of a
film impervious to a planarizing solution; and duplicating the
defined pattern of micro-features on a planarizing surface of a
second portion of the film.
94. The method of claim 93 wherein: the film comprises a polymer;
and forming the defined pattern of micro-features on the first
portion of film comprises providing a die having a plurality of
recesses arranged in the defined pattern to form a plurality of
first and second raised features, and embossing the first portion
of film with the die to form the defined pattern of first and
second raised features on the surface of the film.
95. The method of claim 94 wherein duplicating the defined pattern
of micro-features on the second portion of film comprises embossing
the second portion of film with the die to duplicate the defined
pattern of first and second raised features on the surface of the
film.
96. The method of claim 93 wherein: the film comprises a polymer;
and forming the defined pattern of micro-features on the first
portion of film comprises attaching a portion of fine mesh of woven
strands to the first portion of film.
97. The method of claim 96 wherein duplicating the defined pattern
of micro-features on the second portion of film comprises attaching
another portion of the fine mesh of woven strands to the second
portion of film.
98. The method of claim 96 wherein the film comprises a polymer;
and forming the defined pattern of micro-features on the first
portion of film comprises etching the film through a master pattern
to from a plurality of first and second raised features across the
surface of the film.
99. The method of claim 98 wherein etching the film comprises:
forming a protective layer on the film having openings
corresponding to depressions between the first and second raised
features; and etching the film through the openings.
100. The method of claim 98 wherein duplicating the defined pattern
of micro-features on the second portion of film comprises
duplicating the master pattern on the second portion of film and
etching the film through the duplicated master pattern to from a
plurality of first and second raised features across the surface of
the film.
Description
TECHNICAL FIELD
[0001] The present invention relates to mechanical and
chemical-mechanical planarization of microelectronic substrates.
More particularly, an embodiment of the present invention relates
to a planarization polishing pad for enhancing the performance
and/or reducing the costs of planarizing substrates, and to methods
of using and making the polishing pad.
BACKGROUND OF THE INVENTION
[0002] Mechanical and Chemical-Mechanical planarization processes
remove material from the surface of semiconductor wafers, field
emission displays and many other microelectronic substrates to form
a flat surface at a desired elevation in the substrates. FIG. 1
schematically illustrates a planarizing machine 10 with a platen
20, a carrier assembly 30, a polishing pad 40, and a planarizing
solution 44 on the polishing pad 40. The planarizing machine 10 may
also have a compressible under-pad 25 attached to an upper surface
22 of the platen 20 for supporting the polishing pad 40. In many
planarizing machines, a drive assembly 26 rotates (arrow A) and/or
reciprocates (arrow B) the platen 20 to move the polishing pad 40
during planarization.
[0003] The carrier assembly 30 controls and protects a substrate 12
during planarization. The carrier assembly 30 generally has a lower
surface 32 with a pad 34 that holds the substrate 12 via suction,
and an actuator assembly 36 is typically attached to the carrier
assembly 30 to rotate and/or translate the substrate 12 (arrows C
and D, respectively). However, some carrier assemblies 30 are
weighted, free-floating disks (not shown) that slide over the
polishing pad 40.
[0004] The polishing pad 40 and the planarizing solution 44 may
separately, or in combination, define a polishing environment that
mechanically and/or chemically removes material from the surface of
the substrate 12. The polishing pad 40 may be a conventional
polishing pad made from a relatively compressible, porous
continuous phase matrix material (e.g., polyurethane), or it may be
an abrasive polishing pad with abrasive particles fixedly bonded to
a suspension medium. The planarizing solution 44 may be a
chemical-mechanical planarization slurry with abrasive particles
and chemicals for use with a conventional non-abrasive polishing
pad, or the planarizing solution 44 may be a liquid without
abrasive particles for use with an abrasive polishing pad. To
planarize the substrate 12 with the planarizing machine 10, the
carrier assembly 30 presses the substrate 12 against a planarizing
surface 42 of the polishing pad 40 in the presence of the
planarizing solution 44. The platen 20 and/or the carrier assembly
30 then move relative to one another to translate the substrate 12
across the planarizing surface 42. As a result, the abrasive
particles and/or the chemicals in the polishing environment remove
material from the surface of the substrate 12.
[0005] Planarizing processes must consistently and accurately
produce a uniformly planar surface on the substrate to enable
precise fabrication of circuits and photo-patterns on the
substrate. As the density of integrated circuits increases, the
uniformity and planarity of the substrate surface is becoming
increasingly important because it is difficult to form sub-micron
features or photo-patterns to within a tolerance of approximately
0.1 .mu.m when the substrate surface is not uniformly planar. Thus,
planarizing processes must create a highly uniform planar surface
on the substrate.
[0006] In conventional planarizing processes, the substrate surface
may not be uniformly planar because the rate at which material is
removed from the substrate surface (the "polishing rate") typically
varies from one region on the substrate to another. The polishing
rate depends, in part, upon the distribution of abrasive particles
and chemicals between the substrate surface and the polishing pad.
One particular problem with conventional planarizing devices and
methods is that the perimeter of the substrate wipes a significant
amount of the planarizing solution off of the polishing pad. As
such, the planarizing solution builds up in a high zone along a
leading edge of the substrate, which reduces the volume of
planarizing solution contacting the center of the substrate.
Conventional planarizing devices and methods, therefore, typically
produce a non-uniform, center-to-edge planarizing profile across
the substrate surface.
[0007] To reduce such a center-to-edge planarizing profile, several
conventional non-abrasive polishing pads have holes or grooves on
their upper surfaces to transport a portion of the planarizing
solution below the substrate surface during planarization. A Rodel
IC-1000 polishing pad, for example, is a relatively soft, porous
polyurethane pad with a number of large slurry wells approximately
0.05-0.10 inches in diameter that are spaced apart from one another
across the planarization surface by approximately 0.125-0.25
inches. The large wells are expected to hold small volumes of
slurry below the planarizing surface so that the substrate may draw
the slurry out of the wells as the substrate translates over the
pad. However, such pads still produce a significant center-to-edge
planarizing profile indicating that the perimeter of the substrate
presses some of the slurry out of the wells ahead of the center of
the substrate. U.S. Pat. No. 5,216,843 describes another polishing
pad with a plurality of macro-grooves formed in concentric circles
and a plurality of micro-grooves radially crossing the
macro-grooves. Although such grooves may improve the planarity of
the substrate surface, substrates planarized with such pads still
exhibit non-uniformities across the substrate surface indicating an
inadequate distribution of planarizing solution and abrasive
particles across the substrate.
[0008] Other types of polishing pads also do not adequately resolve
the center-to-edge planarizing profile. For example, conventional
porous polishing pads with small micro-pores at the planarizing
surface are generally subject to producing a center-to-edge
planarizing profile indicating that the perimeter of the substrate
presses the planarizing solution out of the pores before the center
of the substrate passes over the pores. Additionally, even
fixed-abrasive polishing pads that have a uniform distribution of
abrasive particles may produce a center-to-edge planarizing profile
because the perimeter of the substrate also tends to sweep the
planarizing solution off of abrasive polishing pads. Therefore,
conventional polishing pads typically produce an undesired
center-to-edge planarizing profile on the substrate surface.
[0009] To improve the distribution of slurry under the substrate,
U.S. Pat. No. 5,489,233 discloses a polishing pad composed of a
solid, uniform polymer sheet having no intrinsic ability to absorb
or transport slurry particles. One type of polymer sheet disclosed
in U.S. Pat. No. 5,489,233 is Mylar.RTM. manufactured by E.I. du
Pont de Nemours of Wilmington, Del. The Polymer sheet has a surface
pattern or texture that has both large and small flow channels to
permit the transport of slurry across the surface of the polishing
pad. The channels are mechanically produced on the pad. In a
preferred embodiment, the pad has a macro-texture produced prior to
planarization and a micro-texture produced by abrading the pad with
a plurality of small abrasive points at regular selected intervals
during planarization. Although the pad disclosed in U.S. Pat. No.
5,489,233 improves the uniformity of the substrate surface in some
circumstances, it may not provide consistent planarization
characteristics because scratching the surface with small abrasive
points may not duplicate the micro-texture from one pad to the
next. Thus, the polishing pad described in U.S. Pat. No. 5,489,233
may not provide consistent results from one substrate to the
next.
[0010] Another factor affecting the uniformity of the substrate
surface is the condition of the polishing pad. The planarizing
surface of the polishing pad typically deteriorates after polishing
a number of substrates because waste matter from the substrate,
planarizing solution and/or the polishing pad accumulates on the
planarizing surface. The waste matter alters the local planarizing
characteristics of the pad, and the waste matter typically does not
accumulate uniformly across the planarizing surface. Thus, the
waste matter accumulations cause the polishing rate to vary across
the surface of the polishing pad.
[0011] Polishing pads are accordingly "conditioned" by removing the
waste matter from the pad to restore the polishing pad to a
suitable condition for planarizing substrates. However, even
conditioning polishing pads may produce non-uniformities in the
substrate surface because it is difficult to consistently condition
a polishing pad so that it has the same planarizing characteristics
from one conditioning cycle to the next. Conditioning the polishing
pads, moreover, is time-consuming and requires costly equipment and
labor. Therefore, in addition to the problems associated with
providing an adequate distribution of planarizing solution between
the substrate surface and the polishing pad, conditioning
conventional polishing pads may also reduce the uniformity of the
planarized substrate surface.
SUMMARY OF THE INVENTION
[0012] The present invention is a method and apparatus for
mechanically and/or chemical-mechanically planarizing
microelectronic substrates. In one embodiment in accordance with
the principles of the present invention, a microelectronic
substrate is planarized or polished on a planarizing medium having
a thin film and a plurality of micro-features on the film. The film
may be an incompressible sheet or web substantially impervious to a
planarizing solution, and the micro-features may be configured in a
selected pattern on the film to restrain fluid flow of the
planarizing solution across the surface of the film under the
substrate. The micro-features, for example, may be configured in a
selected pattern with a plurality of substantially incompressible
first raised features defining support points, at least one cavity
below the support points, and a plurality of second raised features
between and below the support points. The support points, cavity,
and second raised features may operate to entrap a substantially
contiguous, uniform distribution of the solution under the
substrate during planarization. Additionally, the selected pattern
of micro-features may be reproduced from a master pattern of
micro-features to duplicate the selected pattern on the film so
that a consistent planarizing surface may be provided for a large
number of substrates.
[0013] The planarizing film may be composed of a number of
different materials, and the micro-features may have a number of
different configurations. For example, the film may be composed of
a suitable polymeric material (e.g., Mylar.RTM. or Lexan.RTM.), or
other flexible and substantially incompressible materials. The
micro-features may be nodules with a plurality of shapes and
heights formed from the film material, or the nodules may be a fine
mesh of woven fibers formed separately from the film. The nodules
are generally patterned on the film to form a plurality of
depressions that entrap the solution under the substrate, and a
portion of the nodules preferably have flat tops terminating at a
constant maximum height across the planarizing surface of the film
to define the first raised features. The selected pattern of
nodules and depressions may be produced by embossing the nodule
pattern on the film, etching the depressions into the film, or
other suitable techniques that may consistently reproduce the
selected pattern of nodules on the planarizing film.
[0014] Planarizing mediums in accordance with the invention may be
adapted to work with a variety of different planarizing machines.
In one embodiment, for example, the film is a contiguous, flexible
web with a plurality of sections that each have a planarizing
surface with the selected pattern of micro-features. The flexible
web may be indexed with respect to a work station or planarizing
station of the planarizing medium so that all or only a part of a
section is moved across the work station. When all of a section is
advanced across the work station, a first section of the web may be
held at the work station to planarize a first substrate and then a
second section of the web may be held at the work station to
planarize subsequent substrates. In another embodiment, the
planarizing film may have a plurality of separate sheets in which
each sheet has a planarizing surface, with one or more sections
having the selected pattern of micro-features. As such, a first
sheet is used to planarize a number of substrates until it
deteriorates beyond an acceptable point, and then it may be
replaced by a second sheet to planarize a number of additional
substrates. In either the web or sheet films, the sections may be
integral with one another or they may be separate segments attached
to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic view of a planarizing machine in
accordance with the prior art.
[0016] FIG. 2 is a schematic view of a planarizing machine with a
planarizing medium in accordance with an embodiment of the
invention.
[0017] FIG. 3 is a partial isometric view of a planarizing medium
with a planarizing film and a plurality of micro-features in
accordance with one embodiment of the invention.
[0018] FIG. 4 is a partial schematic cross-sectional view of the
planarizing medium shown in FIG. 3 along section 44.
[0019] FIG. 5 is a partial schematic cross-sectional view of the
planarizing medium of FIG. 4 shown planarizing a substrate using a
planarizing solution with abrasive particles in accordance with an
embodiment of the invention.
[0020] FIG. 6 is a partial schematic isometric view of another
planarizing medium in accordance with another embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention is an apparatus and method for
mechanical and/or chemical-mechanical planarization of substrates
used in the manufacturing of microelectronic devices. Many specific
details of certain embodiments of the invention are set forth in
the following description and in FIGS. 2-6 to provide a thorough
understanding of such embodiments. One skilled in the art, however,
will understand that the present invention may have additional
embodiments and may be practiced without several of the details
described ill the following description.
[0022] FIG. 2 is a schematic view of an embodiment of a planarizing
machine 100 and a planarizing medium 140 for planarizing a
substrate 12. The S features and advantages of the planarizing
medium 140 are best understood in the context of the structure and
operation of the planarizing machine 100. Thus, the general
features of the planarizing machine 100 will be described
initially.
[0023] The planarization machine 100 may have a support table 110
carrying a base 112 at a workstation or a planarization station
where a section "A" of the planarizing medium 140 is positioned.
The base 112 is generally a substantially incompressible support
member attached to the table 110 to provide a flat, solid surface
to which a particular section of the planarizing medium 140 may be
secured during planarization. The planarizing machine 100 also has
a plurality of rollers to guide, position and hold the planarizing
medium 140 over the base 112. In one embodiment, the rollers
include a supply roller 120, first and second idler rollers 121a
and 121b, first and second guide rollers 122a and 122b, and a
take-up roller 123. The supply roller 120 carries an unused part of
the planarizing medium 140, and the take-up roller 123 carries a
used part of the planarizing medium 140. The supply roller 120 and
take-up roller 123 are driven rollers to sequentially advance
unused portions of the planarizing medium 140 onto the base 112. As
such, unused portions of the planarizing medium may be quickly
substituted for worn used portions to provide a consistent surface
for planarizing the substrate 12. Each portion of the planarizing
medium 140 may correspond to an individual section "A" of the
planarizing medium 140, but each portion may also be more or less
than an individual section "A." The first idler roller 121a and the
first guide roller 122a position the planarizing medium 140
slightly below the base 112 so that the supply and take-up rollers
120 and 123 stretch the planarizing medium 140 under tension to
hold it stationary on the base 112 during planarization.
[0024] The planarization machine 100 also has a carrier assembly
130 to translate the substrate 12 across the planarizing medium
140. In one embodiment, the carrier assembly 130 has a substrate
holder 132 to pick up, hold and release the substrate 12 at
appropriate stages of the planarization process. The carrier
assembly 130 may also have a support gantry 134 carrying an
actuator 136 so that the actuator 136 can translate along the
gantry 134. The actuator 136 preferably has a drive shaft 137
coupled to an arm assembly 138 that carries the substrate holder
132. In operation, the gantry 134 raises and lowers the substrate
12, and the actuator 136 orbits the substrate 12 about an axis B-B
via the drive shaft 137. In another embodiment, the arm assembly
138 may also have an actuator (not shown) to drive a shaft 139 of
the arm assembly 138 and thus rotate the substrate holder 132 about
an axis C-C as the substrate holder 132 also orbits about the axis
B-B. One suitable planarizing machine is manufactured by EDC
Corporation. In light of the embodiment of the planarizing machine
100 described above, a specific embodiment of the planarizing
medium 140 will now be described.
[0025] FIG. 3 is a partial isometric view of an embodiment of the
planarizing medium 140, and FIG. 4 is a partial schematic
cross-sectional view of the planarizing medium 140 shown in FIG. 3
taken along section 4-4. The planarizing medium 140 has a
planarizing film 142 and a plurality of micro-features 146
configured in a selected pattern on the film 142. The planarizing
film 142 may be composed of a thin, inexpensive material that is
impervious to the planarizing solution or generally impermeable to
fluids. The planarizing film 142 is also preferably a flexible, yet
substantially incompressible material that has a relatively high
tensile strength. For example, the planarizing film may be a
disposable material with a thickness between approximately 0.0005
inches and 0.050 inches. In some particular embodiments of the
planarizing medium 140, the planarizing film 142 may be a
mono-layer web or sheet composed of polymeric or other suitable
materials. For example, two specific polymers suitable for the
planarizing film 142 are polyester (e.g., Mylar manufactured by
E.I. du Pont de Nemours Co.) and polycarbonate (e.g., Lexan
manufactured by General Electric Co.). Other suitable polymers
include polyurethane and nylon.
[0026] The micro-features 146 may be configured in a selected
pattern on the film 142 to restrain fluid flow or otherwise entrap
small micro-volumes of the planarizing solution (not shown) under a
substrate surface (not shown) across the film 142. The selected
pattern of micro-features 146 may be reproduced from a master
pattern that consistently duplicates the selected pattern across
all or a portion of the planarizing medium 140. In one embodiment,
for example, the selected pattern is duplicated on portions of the
planarizing medium 140 corresponding to the size of the section "A"
at the planarization station of the planarizing machine 100 (FIG.
2). Accordingly, the planarizing characteristics of the planarizing
medium 140 are consistent from one section to the next to enhance
the accuracy of the planarizing process. The selected pattern of
micro-features 146 may be a substantially random distribution of
features across the planarizing film 142, or the micro-features may
be formed in a substantially symmetrical, uniform pattern. The
micro-features 146 may also be formed integrally with the film 142,
or the micro-features may be composed of a separate material
attached to a flat sheet of film.
[0027] As shown in FIGS. 3 and 4, the micro-features 146 may be
nodules with different shapes and heights that form depressions 148
in the film 142 between the nodules 146. As best shown in FIG. 4,
the planarizing film 142 has a contiguous portion 144 up to a
height HB, and the nodules 146 extend upwardly from the height HB
to a plurality of different heights. For example, a few of the
nodules 146 may extend to a plurality of intermediate heights
H.sub.1 and H.sub.2, while other nodules are flat-top nodules 147
terminating at a substantially constant height H.sub.max defining a
planarizing surface 150 (FIG. 4 only) of the planarizing medium
140. The flat-top nodules 147 may define first raised features that
act as support points on the planarizing surface 150 to engage or
otherwise support the substrate 12, and the remaining nodules 146
with intermediate heights may define second raised features.
Additionally, the depressions 148 may form at least one cavity
below the flat-top nodules 147. In another embodiment, even the
highest nodules may have rounded peaks 149 (shown in phantom in
FIG. 4) instead of the flat-top nodules 147. The nodules 146
preferably have heights of 0.5 .mu.m to 100 .mu.m with respect to
the height HB, and they are approximately 50 .mu.m to 500 .mu.m
across at their base.
[0028] The selected pattern of micro-features 146 and depressions
148 illustrated in FIGS. 3 and 4 represents only one embodiment of
a planarizing medium 140 suitable for planarizing microelectronic
substrates. As such, virtually any pattern of micro-features that
provides an adequate distribution of planarizing solution and
abrasive particles underneath a substrate during planarizing may be
used. Additionally, the nodules 146 may have other sizes and
heights outside of the ranges set forth above.
[0029] The micro-features 146 may be formed on the planarizing film
142 by a number of methods. For example, when the planarizing film
142 is composed of a polymeric material, the selected pattern of
micro-features 146 may be duplicated on the planarizing medium 140
by embossing the selected pattern of micro-features onto the
planarizing film 142 with a die or stamp having the inverse of the
selected pattern of micro-features. The die may be pressed against
the planarizing film at a temperature sufficient to allow the film
to permanently conform to the topography of the die. In the
embodiment of the planarizing medium 140 illustrated in FIGS. 3 and
4, the micro-features 146 are formed by embossing a 0.010 to 0.020
inch thick film of Lexan with a die having a pattern of rounded
nodules, and then planarizing a sacrifice wafer on the rounded
nodules to form the flat-top nodules 147 at the maximum height
H.sub.max. In another embodiment, the selected pattern may be
photo-patterned and then etched into the planarizing film. Thus,
unlike micro-features that are scratched or abraded into a thin
sheet, the selected pattern may be accurately duplicated across all
or part of the planarizing medium to provide consistent
planarization characteristics from one substrate to the next.
[0030] FIG. 5 is a schematic cross-sectional view that illustrates
the operation and some advantages of the planarizing medium 140. In
operation, a supply line (not shown) deposits planarizing solution
44 onto the planarizing medium 140 as the carrier assembly 30 (FIG.
1) translates the substrate 12 over the flat-top nodules 147. A
small volume of the planarizing solution 44 accumulates in the
depressions 148 between the nodules 146. Additionally, when the
planarizing solution contains abrasive particles 45, a portion of
the abrasive particles 45 may also accumulate in the depressions
148. The depressions 148 accordingly provide at least one large
cavity under the flat-top nodules 147 to preferably hold a
substantially uniform, contiguous distribution of planarizing
solution 44 and abrasive particles 45 under a surface 14 of the
wafer 12. The nodules 146 restrain the flow or otherwise entrap the
planarizing solution 44 and the abrasive particles 45 to inhibit
the perimeter of the substrate 12 from sweeping the solution 44 and
the particles 45 off of the medium 140. Additionally, when nodules
146 are substantially incompressible, the flat-topped nodules 147
prevent the substrate 12 from penetrating into the depressions 148
and forcing the planarizing solution 44 and the abrasive particles
45 out of the depressions 148.
[0031] Compared to conventional polishing pads, the planarizing
medium 140 is expected to produce highly uniform, planar surfaces
on semiconductor wafers and other microelectronic substrates. The
planarizing medium 140 is believed to improve the planarizing
performance because the micro-features 146 restrain the fluid flow
or otherwise entrap a substantially uniform, contiguous
distribution of planarizing solution 44 and abrasive particles 45
in the depressions 148 underneath the surface 14 of the substrate
12. Additionally, the film 142 may be a highly planar,
substantially incompressible sheet or web that does not conform to
the topography of the substrate surface 14. The planarizing medium
140 accordingly imparts high mechanical energy to high points on
the substrate surface 14, while inhibiting the substrate 12 from
sweeping the planarizing solution 44 and abrasive particles 45 off
of the planarizing medium 140.
[0032] In addition to the advantages described above, the
planarizing medium 140 illustrated in FIGS. 3-5 may also provide a
very consistent, inexpensive surface for planarizing substrates.
Unlike conventional polishing pads composed of polyurethane or
containing fixed abrasive particles, the planarizing medium 140 may
be composed of an inexpensive, disposable film 142 that may be
economically thrown away after the planarizing surface 150 is no
longer in a state suitable for planarizing substrates. As a result,
expensive conditioning equipment and skilled labor are not
necessary to provide a clean planarizing surface. Additionally,
because the selected pattern of micro-features may be duplicated
across the planarizing medium 140, consistent planarizing
characteristics may be maintained over a larger number of
substrates. Therefore, the planarizing medium 140 may not only
eliminate the need to constantly condition the planarizing surface,
it may also enhance the consistency of the planarizing
characteristics over a large number of substrates.
[0033] FIG. 6 is a partial schematic isometric view illustrating
another embodiment of a planarizing medium 240 in accordance with
the invention with a planarizing film 242 and a plurality of
micro-features 246 formed separately from the planarizing film 242.
The planarizing film 242 may be similar to the film 142 discussed
above with respect to FIGS. 3-5. The micro-features 246, however,
may be a fine woven mesh of strands attached to the film 242. For
example, the micro-features 246 may be a woven mesh of 2.0 .mu.m to
5.0 .mu.m diameter nylon strands spaced apart by openings 248 that
define approximately 0.5% to 5% of the surface area of the mesh.
The woven mesh accordingly has a plurality of first raised features
defined by high points 247 along the strands, a plurality of second
raised features 249 defined by the remainder of the strands above
the film 242, and at least one cavity below the high points 247 of
the strands defined by the openings 248. The micro-features 246 and
openings 248 of the planarizing medium 240 may thus capture and
contain a planarizing solution (not shown) beneath the high points
247 of the micro-features 246 to provide a substantially uniform
distribution of planarizing solution and abrasive particles
underneath the substrate (not shown) during planarization. The
embodiment of the planarizing medium 240 illustrated in FIG. 6,
therefore, may achieve many of the same advantages described above
with respect to the embodiment of the planarizing medium 140
illustrated in FIGS. 3-5.
[0034] From the foregoing it will be appreciated that, although
specific embodiments of the invention have been described herein
for purposes of illustration, various modifications may be made
without deviating from the spirit and scope of the invention. For
example, other patterns of micro-features may be used, and the
woven mesh shown in FIG. 6 may be composed of strands made from
other materials. Additionally, planarizing media in accordance with
the invention are not necessarily limited or required to achieve
substantially the same results as the embodiments of planarizing
media 140 and 240 described above. The invention, therefore, is not
limited except as by the appended claims.
* * * * *