U.S. patent number RE39,195 [Application Number 10/054,692] was granted by the patent office on 2006-07-18 for polishing pad refurbisher for in situ, real-time conditioning and cleaning of a polishing pad used in chemical-mechanical polishing of microelectronic substrates.
This patent grant is currently assigned to Micron Technology, Inc.. Invention is credited to Trung T. Doan, Gurtej S. Sandhu.
United States Patent |
RE39,195 |
Doan , et al. |
July 18, 2006 |
Polishing pad refurbisher for in situ, real-time conditioning and
cleaning of a polishing pad used in chemical-mechanical polishing
of microelectronic substrates
Abstract
A pad refurbisher that provides in situ, real-time conditioning
and/or cleaning of a polishing surface on a polishing pad used in
chemical-mechanical polishing of a semiconductor wafer and other
microelectronic substrates. The pad refurbisher has a body adapted
for attachment to a wafer carrier of a chemical-mechanical
polishing machine, and a refurbishing element connected to the
body. The body has a distal face positioned proximate to a
perimeter portion of the wafer carrier and facing generally toward
the polishing surface of the polishing pad. The body travels with
the wafer carrier as the wafer carrier moves over the polishing
pad. The refurbishing element is connected to the distal face of
the body so that the refurbishing element can operatively engage
the polishing surface substantially adjacent to the perimeter of
the wafer carrier. The refurbishing element is a pad conditioning
device and/or a pad cleaning device that conditions and/or cleans
the polishing surface of the pad to remove waste particles from the
polishing surface of the polishing pad and place the pad in a
desired polishing condition. In operation, the refurbishing element
travels with the wafer carrier and is selectively engaged with the
polishing surface while the wafer carrier presses the wafer against
the polishing surface to selectively condition and/or clean
generally only the deteriorated areas on the pad.
Inventors: |
Doan; Trung T. (Los Gatos,
CA), Sandhu; Gurtej S. (Boise, ID) |
Assignee: |
Micron Technology, Inc. (Boise,
ID)
|
Family
ID: |
21863810 |
Appl.
No.: |
10/054,692 |
Filed: |
December 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09032230 |
Feb 27, 1998 |
06004196 |
Dec 21, 1999 |
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Current U.S.
Class: |
451/443; 451/287;
451/290; 451/444 |
Current CPC
Class: |
B24B
53/017 (20130101); B24D 7/18 (20130101) |
Current International
Class: |
B24B
7/08 (20060101) |
Field of
Search: |
;451/287,288,290,443,444 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rose; Robert A.
Attorney, Agent or Firm: Dorsey & Whitney LLP
Claims
We claim:
1. A pad refurbisher for in situ, real-time refurbishing of a
polishing surface on a polishing pad used in chemical-mechanical
polishing of a semiconductor wafer, comprising: a body adapted for
attachment to a wafer carrier of a chemical-mechanical polishing
machine with the body having .Iadd.a first ring and a second ring
each with .Iaddend.a face positioned proximate to a perimeter
portion of the wafer carrier and facing the polishing surface of
the polishing pad, the body being adapted to travel with the wafer
carrier as the wafer carrier moves over the polishing pad wherein
the body is movably attached to the wafer carrier; and .[.a
refurbishing element connected to the face of the body.]. .Iadd.a
first refurbishment element connected to the face of the first ring
and a second refurbishment element connected to the face of the
second ring, the first ring operably coupled to a first linear
actuator configured to independently move the first ring downwardly
to selectively engage the first refurbishment element with the
polishing surface and upwardly with respect to the wafer carrier
and the second ring to selectively disengage the first
refurbishment element from the polishing surface and the second
ring operably coupled to a second linear actuator configured to
independently move the second ring downwardly to selectively engage
the second refurbishment element with the polishing surface and
upwardly with respect to the wafer carrier and the first ring to
selectively disengage the second refurbishment element from the
polishing surface, the first ring being positioned radially outward
from the perimeter of the wafer carrier and the second ring being
positioned radially outward from the first ring, .Iaddend.the
.Iadd.first and the second .Iaddend.refurbishing .[.element.].
.Iadd.elements .Iaddend.being adapted to engage the polishing
surface substantially adjacent to the perimeter portion of the
wafer carrier and traveling with the wafer carrier while the wafer
carrier moves the wafer over the polishing surface.
2. The pad refurbisher of claim 1 wherein the body is fixed to the
wafer carrier.
3. The pad refurbisher of claim 1 wherein the body is slidably
attached to the wafer carrier.
4. The pad refurbisher of claim 3, further comprising a linear
actuator attached to the body, wherein the actuator independently
moves the body with respect to the wafer carrier along an axis
substantially normal to the polishing surface to selectively engage
the refurbishing element with areas on the polishing surface in
need of cleansing and to selectively disengage the refurbishing
element from areas on the pad in adequate condition.
5. The pad refurbisher of claim 1 wherein the face is a distal face
of the body defining a ring positioned radially outwardly from the
perimeter of the wafer carrier.
6. The pad refurbisher of claim 1 wherein .[.the body has.].
.Iadd.the first ring and the second ring each include .Iaddend.a
plurality of arcuate segments positioned radially outwardly from
the perimeter of the wafer carrier, the arcuate segments being
spaced apart from one another around the wafer carrier and each
arcuate segment having a distal face facing generally towards the
polishing surface of the polishing pad.
7. The pad refurbisher of claim 1 wherein .Iadd.one of .Iaddend.the
refurbishing .[.element.]. .Iadd.elements .Iaddend.is a brush
comprising a plurality of bristles extending downwardly from the
face towards the polishing surface, the bristles engaging the
polishing surface to clean waste particles from the pad.
8. The pad refurbisher of claim 1 wherein .Iadd.one of .Iaddend.the
refurbishing .[.element.]. .Iadd.elements .Iaddend.is a pad
conditioner that removes a layer of pad material from polishing
surface of the pad to form a new polishing surface on the polishing
pad.
9. The pad refurbisher of claim 8 wherein the pad conditioner
comprises a pad with a plurality of embedded diamonds, the pad
being connected to the distal surface of the body.
10. The pad refurbisher of claim 1 wherein the body has a first
ring with a first refurbishing element and a second ring with a
second refurbishing element, the first ring being positioned
radially outwardly from the perimeter of the wafer carrier and the
second ring being positioned radially outwardly from the first
ring.
11. The pad refurbisher of claim 10 wherein the first refurbishing
element is a pad cleaner and the second refurbishing element is a
pad conditioner.
12. The pad refurbisher of claim 1 wherein the body is adapted to
be symmetrically positioned about the center of the wafer
carrier.
13. A polishing machine for chemical-mechanical polishing of a
semiconductor wafer, comprising: a platen having an upper surface;
a polishing pad positioned on the upper surface of the platen, the
polishing pad having a polishing surface facing away from the
platen, a wafer carrier for carrying the wafer, the wafer carrier
being positioned over the polishing pad and moveable along an axis
substantially normal to the upper surface of the platen to engage
the wafer with the polishing pad, wherein at least one of the
platen and the wafer carrier moves with respect to the other to
impart relative motion between the wafer and the polishing pad; and
a pad refurbisher having a body .Iadd.including a first ring and a
second ring each .Iaddend.with a face positioned proximate to a
perimeter portion of the wafer carrier and facing generally towards
the polishing surface .[.and a refurbishing element connected to
the face.]. , .Iadd.the first ring having a first refurbishment
element connected to the face thereof, the first ring operably
coupled to a first linear actuator configured to independently move
the first ring downwardly to selectively engage the first
refurbishment element with the polishing surface and upwardly with
respect to the wafer carrier and the second ring to selectively
disengage the first refurbishment element from the polishing
surface and the second ring having a second refurbishment element
connected to the face thereof, the second ring operably coupled to
a second linear actuator configured to independently move the
second ring downwardly to selectively engage the second
refurbishment element with the polishing surface and upwardly with
respect to the wafer carrier and the first ring to selectively
disengage the second refurbishment element from the polishing
surface, the first ring being positioned radially outward from the
perimeter of the wafer carrier and the second ring being positioned
radially outward from the first ring, .Iaddend.the body being
attached to the wafer carrier so that the body and .Iadd.the first
and the second .Iaddend.refurbishing .[.element.]. .Iadd.elements
.Iaddend.travel with the wafer carrier as the wafer carrier moves
with respect to the polishing pad, wherein the .Iadd.first
.Iaddend.refurbishing element engages the polishing surface
substantially adjacent to the perimeter portion of the wafer
carrier while the wafer carrier moves the wafer over the polishing
surface and wherein the body is movably attached to the wafer
carrier.
14. The polishing machine of claim 13 wherein the body is fixed to
the wafer carrier.
15. The polishing machine of claim 13 wherein the body is slidably
attached to the wafer carrier.
16. The polishing machine of claim 15, further comprising a linear
actuator attached to the body, wherein the actuator independently
moves the body downwardly and upwardly with respect to the wafer
carrier along an axis substantially perpendicular to the polishing
surface to selectively engage the refurbishing element with areas
on the polishing surface in need of cleansing and to selectively
disengage the refurbishing element from areas on the pad in
adequate condition.
17. The polishing machine of claim 13 wherein the face of the body
is a ring positioned radially outwardly from the perimeter of the
wafer carrier.
18. The polishing machine of claim 13 wherein .[.the body has.].
.Iadd.the first ring and the second ring each include .Iaddend.a
plurality of arcuate segments positioned radially outwardly from
the perimeter of the wafer carrier, the arcuate segments being
spaced apart from one another around the wafer carrier and each
arcuate segment having a distal face facing generally towards the
polishing surface of the polishing pad.
19. The polishing machine of claim 13 wherein .Iadd.one of
.Iaddend.the refurbishing .[.element.]. .Iadd.elements .Iaddend.is
a brush comprising a plurality of bristles extending downwardly
from the face towards the polishing surface, the bristles engaging
the polishing surface to clean waste particles from the pad.
20. The polishing machine of claim 13 wherein .Iadd.one of
.Iaddend.the refurbishing .[.element.]. .Iadd.elements .Iaddend.is
a pad conditioner that removes a layer of pad material from
polishing surface of the pad to form a new polishing surface on the
polishing pad.
21. The polishing machine of claim 20 wherein the pad conditioner
comprises a pad with a plurality of embedded diamonds, the pad
being connected to the distal surface of the body.
22. The polishing machine of claim 13 wherein the body has a first
ring with a first refurbishing element and a second ring with a
second refurbishing element, the first ring being positioned
radially outwardly from the perimeter of the wafer carrier and the
second ring being positioned radially outwardly from the first
ring.
23. The polishing machine of claim 13 wherein the first
refurbishing element is a pad cleaner and the second refurbishing
element is a pad conditioner.
24. The polishing machine of claim 13 wherein the pad refurbishing
element is symmetrically positioned about the center of the wafer
carrier.
25. A method for refurbishing a polishing pad, comprising the steps
of: providing a pad refurbisher having a body .Iadd.including a
first ring and a second ring each .Iaddend.with a face positioned
proximate to a perimeter portion of a wafer carrier of a
chemical-mechanical polishing machine and facing generally towards
the polishing surface, and a .Iadd.first .Iaddend.refurbishing
element connected to the face of the .[.body.]. .Iadd.first ring
and a second refurbishment element connected to the face of the
second ring.Iaddend., the body being movably attached to the wafer
carrier; .Iadd.selectively .Iaddend.engaging .[.the pad.].
.Iadd.one of the first and the second .Iaddend.refurbishing
.[.element.]. .Iadd.elements .Iaddend.with the polishing pad; and
moving at least one of the wafer carrier and the polishing pad with
respect to the other to pass .Iadd.at least one of .Iaddend.the
refurbishing .[.element.]. .Iadd.elements .Iaddend.across the
polishing pad.
26. The method of claim 25 wherein the .Iadd.selectively
.Iaddend.engaging step comprises selectively lowering the body
towards the polishing pad while the wafer carrier presses a wafer
against the polishing pad and moves the wafer over the polishing
pad to polish the wafer.
27. The method of claim 26 wherein the method further comprises
selectively disengaging .Iadd.one of .Iaddend.the refurbishing
.[.element.]. .Iadd.elements .Iaddend.from the .Iadd.polishing
.Iaddend.pad.
28. The method of claim 25 wherein the engaging step comprises
lowering the wafer carrier until .Iadd.one of .Iaddend.the
refurbishing .[.element.]. .Iadd.elements .Iaddend.and a wafer abut
the polishing pad.
29. The method of claim 25 wherein the .Iadd.first
.Iaddend.refurbishing element comprises a pad conditioner and
.Iadd.the second refurbishment element comprises .Iaddend.a pad
cleaner, and wherein the engaging step comprises pressing the pad
conditioner and the pad cleaner against the polishing pad.
30. The method of claim 26 wherein .Iadd.one of .Iaddend.the
refurbishing .[.element.]. .Iadd.elements .Iaddend.is selectively
engaged with deteriorated portions of the polishing pad with
accumulations of waste matter.
.Iadd.31. A pad refurbisher for refurbishing a polishing surface on
a polishing pad used in chemical-mechanical polishing of a
semiconductor wafer, comprising: a body adapted for attachment to a
wafer carrier of a chemical-mechanical polishing machine with the
body having a first ring and a second ring each with a face
positioned proximate to a perimeter portion of the wafer carrier
and facing the polishing surface of the polishing pad; and a first
refurbishment element connected to the face of the first ring and a
second refurbishment element connected to the face of the second
ring, the first ring operably coupled to a first linear actuator
configured to independently move the first ring downwardly to
selectively engage the first refurbishment element with the
polishing surface and upwardly with respect to the wafer carrier
and the second ring to selectively disengage the first
refurbishment element from the polishing surface and the second
ring operably coupled to a second linear actuator configured to
independently move the second ring downwardly to selectively engage
the second refurbishment element with the polishing surface and
upwardly with respect to the wafer carrier and the first ring to
selectively disengage the second refurbishment element from the
polishing surface, the first ring being positioned radially outward
from the perimeter of the wafer carrier and the second ring being
positioned radially outward from the first ring, the first and the
second refurbishing elements being adapted to engage the polishing
surface substantially adjacent to the perimeter portion of the
wafer carrier..Iaddend.
.Iadd.32. The pad refurbisher of claim 31 wherein the body is fixed
to the wafer carrier..Iaddend.
.Iadd.33. The pad refurbisher of claim 31 wherein the body is
slidably attached to the wafer carrier..Iaddend.
.Iadd.34. The pad refurbisher of claim 31 wherein the face is a
distal face of the body defining a ring positioned radially
outwardly from the perimeter of the wafer carrier..Iaddend.
.Iadd.35. The pad refurbisher of claim 31 wherein the first ring
and the second ring include a plurality of arcuate segments
positioned radially outwardly from the perimeter of the wafer
carrier, the arcuate segments being spaced apart from one another
around the wafer carrier and each arcuate segment having a distal
face facing generally towards the polishing surface of the
polishing pad..Iaddend.
.Iadd.36. The pad refurbisher of claim 31 wherein one of the
refurbishing elements is a brush comprising a plurality of bristles
extending downwardly from the face towards the polishing surface,
the bristles engaging the polishing surface to clean waste
particles from the pad..Iaddend.
.Iadd.37. The pad refurbisher of claim 31 wherein one of the
refurbishing elements is a pad conditioner that removes a layer of
pad material from polishing surface of the pad to form a new
polishing surface on the polishing pad..Iaddend.
.Iadd.38. The pad refurbisher of claim 37 wherein the pad
conditioner comprises a pad with a plurality of embedded diamonds,
the pad being connected to the distal surface of the
body..Iaddend.
.Iadd.39. The pad refurbisher of claim 31 wherein the first
refurbishing element is a pad cleaner and the second refurbishing
element is a pad conditioner..Iaddend.
.Iadd.40. The pad refurbisher of claim 31 wherein the body is
adapted to be symmetrically positioned about the center of the
wafer carrier..Iaddend.
.Iadd.41. A polishing machine for chemical-mechanical polishing of
a semiconductor wafer, comprising: a platen having an upper
surface; a polishing pad positioned on the upper surface of the
platen, the polishing pad having a polishing surface facing away
from the platen, a wafer carrier for carrying the wafer; and a pad
refurbisher having a body attached to the wafer carrier, the body
including a first ring having a first refurbishment element and a
second ring having a second refurbishment element, the first
operably coupled to a first linear actuator configured to
independently move the first ring downwardly to selectively engage
the first refurbishment element with the polishing surface and
upwardly with respect to the wafer carrier and the second ring to
selectively disengage the first refurbishment element from the
polishing surface and the second ring operably coupled to a second
linear actuator configured to independently move the second ring
downwardly to selectively engage the second refurbishment element
with the polishing surface and upwardly with respect to the wafer
carrier and the first ring to selectively disengage the second
refurbishment element from the polishing surface, the first ring
being positioned radially outward from the perimeter of the wafer
carrier and the second ring being positioned radially outward from
the first ring..Iaddend.
.Iadd.42. The polishing machine of claim 41 wherein the first and
the second ring each comprise a face positioned proximate to a
perimeter portion of the wafer carrier and facing generally towards
the polishing surface..Iaddend.
.Iadd.43. The polishing machine of claim 42 wherein the first
refurbishing element is connected to the face of the first ring and
the second refurbishment element is connected to the face of the
second ring, and wherein the body being attached to the wafer
carrier so that the body and each of the refurbishing elements
travel with the wafer carrier as the wafer carrier moves with
respect to the polishing pad, and wherein each of the refurbishing
elements engages the polishing surface substantially adjacent to
the perimeter portion of the wafer carrier while the wafer carrier
moves the wafer over the polishing surface..Iaddend.
.Iadd.44. The polishing machine of claim 41 wherein the body is
fixed to the wafer carrier..Iaddend.
.Iadd.45. A method for refurbishing a polishing pad, comprising the
steps of: providing a pad refurbisher attached to a wafer carrier,
the pad refurbisher having a first ring bearing a first
refurbishment element and a second ring bearing a second
refurbishment element, selectively engaging one of the first and
the second refurbishing elements with the polishing pad; and moving
at least one of the wafer carrier and the polishing pad with
respect to the other to pass at least one of the refurbishing
elements across the polishing pad..Iaddend.
.Iadd.46. The method of claim 45 wherein selectively engaging
comprises selectively lowering at least one of the refurbishing
elements towards the polishing pad while the wafer carrier presses
a wafer against the polishing pad and moves the wafer over the
polishing pad to polish the wafer..Iaddend.
.Iadd.47. The method of claim 45 further comprising selectively
disengaging the one of refurbishing elements from the polishing
pad..Iaddend.
.Iadd.48. The method of claim 47 wherein one of the refurbishing
elements is selectively disengaged from relatively unused portions
of the polishing pad not having accumulations of waste
matter..Iaddend.
.Iadd.49. The method of claim 45 wherein the selectively engaging
comprises lowering the wafer carrier until one of the refurbishing
elements and a wafer abut the polishing pad..Iaddend.
.Iadd.50. The method of claim 45 wherein one of the refurbishing
elements is selectively engaged with deteriorated portions of the
polishing pad with accumulations of waste matter..Iaddend.
.Iadd.51. The method of claim 45 wherein one of the refurbishing
elements is selectively engaged and disengaged from the polishing
pad as a function of the use of portions of the pad..Iaddend.
.Iadd.52. A pad refurbisher for refurbishing a polishing surface on
a polishing pad used in chemical-mechanical polishing of a
semiconductor wafer, comprising: a body adapted for attachment to a
wafer carrier of a chemical-mechanical polishing machine with the
body having a first ring and a second ring each with a face
positioned proximate to a perimeter portion of the wafer carrier
and facing the polishing surface of the polishing pad, the body
being moveably attached to the wafer carrier; and a first
refurbishment element connected to the face of the first ring and a
second refurbishment element connected to the face of the second
ring, the first ring operably coupled to a first linear actuator
configured to independently move the first ring downwardly to
selectively engage the first refurbishment element with the
polishing surface and upwardly with respect to the wafer carrier
and the second ring to selectively disengage the first
refurbishment element from the polishing surface and the second
ring operably coupled to a second linear actuator configured to
independently move the second ring downwardly to selectively engage
the second refurbishment element with the polishing surface and
upwardly with respect to the wafer carrier and the first ring to
selectively disengage the second refurbishment element from the
polishing surface, the first ring being positioned radially outward
from the perimeter of the wafer carrier and the second ring being
positioned radially outward from the first ring, the first and the
second refurbishing elements being adapted to engage the polishing
surface substantially adjacent to the perimeter portion of the
wafer carrier..Iaddend.
.Iadd.53. The pad refurbisher of claim 52 wherein the body is fixed
to the wafer carrier..Iaddend.
.Iadd.54. The pad refurbisher of claim 52 wherein the body is
slidably attached to the wafer carrier..Iaddend.
.Iadd.55. The pad refurbisher of claim 52 wherein the first ring
and the second ring include a plurality of arcuate segments
positioned radially outwardly from the perimeter of the wafer
carrier, the arcuate segments being spaced apart from one another
around the wafer carrier and each arcuate segment having a distal
face facing generally towards the polishing surface of the
polishing pad..Iaddend.
.Iadd.56. The pad refurbisher of claim 52 wherein one of the
refurbishing elements is a brush comprising a plurality of bristles
extending downwardly from the face towards the polishing surface,
the bristles engaging the polishing surface to clean waste
particles from the pad..Iaddend.
.Iadd.57. The pad refurbisher of claim 52 wherein one of the
refurbishing elements is a pad conditioner that removes a layer of
pad material from polishing surface of the pad to form a new
polishing surface on the polishing pad..Iaddend.
.Iadd.58. The pad refurbisher of claim 57 wherein the pad
conditioner comprises a pad with a plurality of embedded diamonds,
the pad being connected to the distal surface of the
body..Iaddend.
.Iadd.59. The pad refurbisher of claim 52 wherein the first
refurbishing element is a pad cleaner and the second refurbishing
element is a pad conditioner..Iaddend.
.Iadd.60. The pad refurbisher of claim 52 wherein the body is
adapted to be symmetrically positioned about the center of the
wafer carrier..Iaddend.
.Iadd.61. A polishing machine for chemical-mechanical polishing of
a semiconductor wafer, comprising: a platen having an upper
surface; a polishing pad positioned on the upper surface of the
platen, the polishing pad having a polishing surface facing away
from the platen; a wafer carrier for carrying the wafer; and a pad
refurbisher having a body including a first ring bearing a first
refurbishment element and a second ring bearing a second
refurbishment element, the body being movably attached to the wafer
carrier, the first ring operably coupled to a first linear actuator
configured to independently move the first ring downwardly to
selectively engage the first refurbishment element with the
polishing surface and upwardly with respect to the wafer carrier
and second ring to selectively disengage the first refurbishment
element from the polishing surface and the second ring operably
coupled to a second linear actuator configured to independently
move the second ring downwardly to selectively engage the second
refurbishment element with the polishing surface and upwardly with
respect to the wafer carrier and the first ring to selectively
disengage the second refurbishment element from the polishing
surface, the first ring being positioned radially outward from the
perimeter of the wafer carrier and the second ring being positioned
radially outward from the first ring..Iaddend.
.Iadd.62. The polishing machine of claim 61 wherein the first ring
comprises a face positioned proximate to a perimeter portion of the
wafer carrier and facing generally towards the polishing
surface..Iaddend.
.Iadd.63. The polishing machine of claim 62 wherein the first
refurbishing element is connected to the face, and wherein the body
being movably attached to the wafer carrier so that the body and
the first and the second refurbishing elements travel with the
wafer carrier as the wafer carrier moves with respect to the
polishing pad, and wherein at least one of the refurbishing
elements engages the polishing surface substantially adjacent to
the perimeter portion of the wafer carrier while the wafer carrier
moves the wafer over the polishing surface..Iaddend.
.Iadd.64. The polishing machine of claim 61 wherein the body is
fixed to the wafer carrier..Iaddend.
.Iadd.65. A method for refurbishing a polishing pad, comprising the
steps of: providing a pad refurbisher attached to a wafer carrier,
the pad refurbisher having a body including a first ring bearing a
first refurbishment element and a second ring bearing a second
refurbishment element, the body being movably attached to the wafer
carrier; selectively engaging one of the first and the second
refurbishing elements with the polishing pad; and moving at least
one of the wafer carrier and the polishing pad with respect to the
other to pass at least one of the refurbishing elements across the
polishing pad..Iaddend.
.Iadd.66. The method of claim 65 wherein selectively engaging
comprises selectively lowering at least one of the refurbishing
elements towards the polishing pad while the wafer carrier presses
a wafer against the polishing pad and moves the wafer over the
polishing pad to polish the wafer..Iaddend.
.Iadd.67. The method of claim 65 further comprising selectively
disengaging at least one of the refurbishing elements from the
pad..Iaddend.
.Iadd.68. The method of claim 67 wherein the at least one of the
refurbishing elements is selectively disengaged from relatively
unused portions of the polishing pad not having accumulations of
waste matter..Iaddend.
.Iadd.69. The method of claim 65 wherein the selectively engaging
comprises lowering the wafer carrier until one of the refurbishing
elements and a wafer abut the polishing pad..Iaddend.
.Iadd.70. The method of claim 65 wherein one of the refurbishing
elements is selectively engaged with deteriorated portions of the
polishing pad with accumulations of waste matter..Iaddend.
.Iadd.71. The method of claim 65 wherein one of the refurbishing
elements is selectively engaged and disengaged from the polishing
pad as a function of the use of portions of the pad..Iaddend.
Description
TECHNICAL FIELD
The present invention relates to an apparatus for selectively
cleaning and conditioning the surface of a polishing pad used in
chemical-mechanical polishing of semiconductor wafers and other
microelectronic substrates.
BACKGROUND OF THE INVENTION
Chemical-mechanical polishing ("CMP") processes remove material
from the surface of a wafer in the production of ultra-high density
integrated circuits. In a typical CMP process, a wafer is pressed
against a polishing pad in the presence of a slurry under
controlled chemical, pressure, velocity, and temperature
conditions. The slurry solution generally contains small, abrasive
particles that abrade the surface of the wafer, and chemicals that
etch and/or oxidize the surface of the wafer. The polishing pad is
generally a planar pad made from a relatively soft, porous material
such as blown polyurethane. Thus, when the pad and/or the wafer
moves with respect to the other, material is removed from the
surface of the wafer by the abrasive particles (mechanical removal)
and by the chemicals in the slurry (chemical removal).
FIG. 1 schematically illustrates a conventional CMP machine 10 with
a platen 20, a wafer carrier 30, a polishing pad 40, and a slurry
44 on the polishing pad. An under-pad 25 is typically attached to
the upper surface 22 of platen 20, and the polishing pad 40 is
positioned on the under-pad 25. A drive assembly 26 rotates the
platen 20 as indicated by arrow A, or in another existing CMP
machine the drive assembly 26 reciprocates the platen 20 back and
forth as indicated by arrow B. The motion of the platen 20 is
imparted to the pad 40 through the under-pad 25 because the
polishing pad 40 frictionally engages the under-pad 25. The wafer
carrier 30 has a lower surface 32 to which a wafer 12 may be
attached, or the wafer 12 may be attached to a resilient pad 34
positioned between the wafer 12 and the lower surface 32. The wafer
carrier 30 may be a weighted, free-floating wafer carrier, or an
actuator assembly 36 may be attached to the wafer carrier 30 to
impart axial and rotational motion, as indicated by arrows C and D,
respectively.
In the operation of the conventional planarizer 10, the wafer 12 is
positioned face-downward against the polishing pad 40, and then the
platen 20 and the wafer carrier 30 move relative to one another. As
the face of the wafer 12 moves across the planarizing surface 42 of
the polishing pad 40, the polishing pad 40 and the slurry 44 remove
material from the wafer 12.
In the competitive semiconductor industry, it is desirable to
maximize the throughput of the finished wafers and minimize the
number of defective or impaired devices on each wafer. The
throughput of CMP processes is a function of several factors, one
of which is the rate at which the thickness of the wafer decreases
as it is being planarized (the "polishing rate"). Because the
polishing period per wafer decreases with increasing polishing
rates, it is desirable to maximize the polishing rate within
controlled limits to increase the number of finished wafers that
are produced in a given period of time.
One problem with CMP processing is that the throughput may drop
because the condition of the polishing surface on the pad
deteriorates while polishing a wafer. The deterioration of the
polishing pad surface is caused by waste particles from the wafer,
pad, and slurry that accumulate on the polishing surface of the
polishing pad. Since the accumulations of waste particles alter the
condition of the polishing surface on the polishing pad, the
polishing rate tends to drift over time. For example, after
polishing a single wafer for only 4 minutes with a Rodel IC-1000
polishing pad and a Rodel ILD-1300 slurry (both of which are
manufactured by Rodel Corp. of Arizona), the polishing rate drops
and reduces the throughput for semiconductor wafers. Many
semiconductor manufacturers accordingly recondition the pad after
each wafer, but unless the reconditioning process is performed in
situ and in real-time, then the reconditioning of the pad also
causes down-time that reduces throughput. Thus, the waste particles
on the polishing surface reduce the throughput of the CMP
process.
CMP processes must also consistently and accurately produce a
uniform, planar surface on the wafer because it is important to
accurately focus the image of circuit patterns on the surface of
the wafer. As the density of integrated circuits increases, it is
often necessary to accurately focus the critical dimensions of the
circuit pattern to better than a tolerance of approximately 0.1
.mu.m. Focusing the circuit patterns to such small tolerances,
however, is very difficult when the distance between the emission
source and the surface of the wafer varies because the surface of
the wafer is not uniformly planar. In fact, several devices may be
defective on a wafer with a non-.[.uniformnly.]. .Iadd.uniformly
.Iaddend.planar surface. Thus, CMP processes must create a highly
uniform, planar surface.
Another problem with CMP processing is that the accumulations of
waste particles reduce the uniformity of the polished surface
because they do not accumulate uniformly across the polishing
surface of the pad. The polishing rate accordingly varies from one
region on the pad to another resulting in a nonuniform polished
surface on the wafer. Therefore, in light of the problems
associated with accumulations of waste particles on polishing pads,
it is necessary to periodically clean and condition the polishing
surface to remove such accumulations and bring the polishing pad
back to a desired condition.
Polishing surfaces on polishing pads are typically cleaned by
brushing the pad with a brush, or by flushing the pad with a fluid.
To perform the brushing and flushing processes, the wafer is
generally removed from the pad while the brush or fluid engages the
polishing surface of the polishing pad. One problem with the
brushing and flushing processes, therefore, is that a significant
amount of down-time is necessary to merely clean the polishing pad.
Thus, it would be desirable to develop a pad cleaner that
effectively cleans the pad in situ and in real-time.
Polishing surfaces of polishing pads are typically conditioned with
a diamond embedded plate mounted to a separate device that moves
the plate across the polishing pad to abrade the surface of the
pad. Some pad conditioners remove a portion of the upper layer of
the deteriorated polishing surface to form a new, clean polishing
surface. One problem with conventional pad conditioners is that
they condition the pad substantially uniformly across the polishing
surface. Since the wafers only polish on a well-defined area of the
pad (usually a concentric band spaced radially away from both the
center of the pad and the perimeter of the pad), the pad
conditioning needs to be performed proportionate to the pad surface
wear. Moreover, it is desirable to condition a pad in situ and in
real-time to avoid costly down-time associated with conditioning
processes that stop the polishing of the wafer. Thus, it would be
desirable to develop a device for selectively conditioning areas on
the pad that require conditioning in situ and in real-time.
SUMMARY OF THE INVENTION
The inventive pad refurbisher provides in situ, real-time
conditioning and/or cleaning of a polishing surface on a polishing
pad used in chemical-mechanical polishing of a semiconductor wafer.
The pad refurbisher has a body adapted for attachment to a wafer
carrier of a chemical-mechanical polishing machine, and a
refurbishing element connected to the body. The body has a face
positioned proximate to a perimeter portion of the wafer carrier
and facing generally toward the polishing surface of the polishing
pad. The body travels with the wafer carrier as the wafer carrier
moves over the polishing pad. The refurbishing element is connected
to the face of the body so that the refurbishing element can
operatively engage the polishing surface substantially adjacent to
the perimeter of the wafer carrier. The refurbishing element is a
pad conditioning device and/or a pad cleaning device that
conditions and/or cleans the polishing surface of the pad to remove
waste particles from the polishing surface of the polishing pad and
place the pad in a desired polishing condition. In operation, the
refurbishing element travels with the wafer carrier and is
selectively engaged with the polishing surface while the wafer
carrier presses the wafer against the polishing surface to
selectively condition and/or clean generally only the deteriorated
areas on the pad.
In one embodiment, the face of the body is a distal face defining a
ring positioned radially outwardly from the perimeter of the wafer
carrier, and the refurbishing element is either a diamond embedded
pad conditioner or a brush-like pad cleaner. In another embodiment,
the body has a first ring with a first refurbishing element and a
second ring with a second refurbishing element. The first ring is
positioned radially outwardly from the perimeter of the wafer
carrier, and the second ring is positioned radially outwardly from
the first ring. The first refurbishing element is preferably a
brush-like pad cleaner and the second refurbishing element is
preferably a diamond embedded pad conditioner.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view of a chemical-mechanical
polishing machine in accordance with the prior art.
FIG. 2 is a schematic cross-sectional view of a pad refurbisher in
accordance with the invention.
FIG. 3 is a bottom plan view of an embodiment of the pad
refurbisher of FIG. 2.
FIG. 4 is a bottom plan view of another embodiment of the pad
refurbisher of FIG. 2.
FIG. 5 is a schematic cross-sectional view of another pad
refurbisher in accordance with the invention.
FIG. 6 is a bottom plan view of the pad refurbisher of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a CMP polishing pad refurbisher that
selectively conditions and cleans generally only the deteriorated
regions of a polishing surface on a polishing pad in situ and in
real-time while a microelectronic substrate (e.g., a semiconductor
wafer) is polished. An important aspect of the invention is that
the pad refurbisher travels with the wafer carrier and positions a
refurbishing element proximate to the wafer carrier without
limiting the travel of the wafer carrier or over-conditioning
unused regions on the polishing surface of the polishing pad.
Another important aspect of the invention is that the refurbishing
element may have a pad conditioner and a pad cleaner to
simultaneously condition and clean the polishing surface in situ
and in real-time while a wafer is polished. The pad refurbisher of
the invention accordingly provides a clean and properly conditioned
polishing surface on the polishing pad that enhances the uniformity
of the finished surface on the wafer and the throughput of the CMP
process. FIGS. 2-6, in which like reference numbers refer to like
parts throughout the various views, illustrate pad refurbishers in
accordance with the invention.
FIG. 2 illustrates a pad refurbisher 50 in accordance with the
invention. The pad refurbisher 50 has a body 60 attached to a wafer
carrier 30 of a polishing machine, such as the polishing machine 10
shown in FIG. 1. The body 60 has a distal face 62 positioned
proximate to the perimeter of the wafer carrier 30 and facing
toward the polishing surface 42 of the polishing pad 40. A
refurbishing element 70 is attached to the distal face 62. The
refurbishing element 70 is preferably a pad conditioner or a pad
cleaner. In the case of a pad conditioner, the refurbishing element
70 is preferably a separate pad with a plurality of embedded
diamonds, or in other embodiments the diamonds may be embedded
directly into the distal face 62. In the case of a pad cleaner, the
refurbishing element 70 may be a brush or a number of fluid jets
attached to the distal face 62 of the body 60. Both the pad
conditioner and the pad cleaner are directed towards the polishing
surface 42 of the polishing pad 40 to be selectively engaged with
the polishing surface 42, as discussed in detail below.
The body 60 may be fixed to the wafer carrier 30, or as shown in
FIG. 2, the body 60 may be slidably attached to the wafer carrier
30 to move along a vertical axis substantially normal to the
polishing surface 42 of a polishing pad 40 (shown by axis Z--Z). A
vertical slot 64 extends along an inner wall of the body 60 facing
the wafer carrier 30 to slidably receive a key 66 protruding from
the perimeter of the wafer carrier 30. As the wafer carrier 30
rotates, the key 66 engages the side wall of the slot 64 to impart
the rotational movement of the wafer carrier 30 to the body 60. The
key 66 also slides within the slot 64 as the body 60 moves
vertically along the Z--Z axis with respect to the wafer carrier 30
to allow the distal face 62 of the body 60 to be selectively
positioned proximate to the polishing surface 42.
In a preferred embodiment, the body 60 is moved along the vertical
axis Z--Z with respect to the wafer carrier 30 by a number of
linear displacement actuators 80 positioned between a support
member 63 attached to the body 60 and the top surface of the wafer
carrier 30. The actuators 80 may be pneumatic cylinders, hydraulic
cylinders, servomotors, springs, or any other suitable device that
provides linear displacement between objects. The support member 63
may be a beam or plate connected to the body 60 (as shown in FIG.
2), or the support member may be made integrally with the body 60.
A hole 65 through the support member 63 is positioned to slidably
receive the shaft/actuator 36 of the wafer carrier 30 and allow the
support member 63 to move along the vertical axis Z--Z with respect
to the actuator 36. The actuators 80 preferably have a housing 82
attached to the wafer carrier 30 and an extensible rod 84 attached
to the support member 63. As the rods 84 push against or pull on
the support member 63, the body 60 moves upward or downward,
respectively, along the vertical axis Z--Z with respect to the
wafer carrier 30 to adjust the position of the distal face 62 with
respect to the pad 40.
In other embodiments, the actuators 80 may act directly against the
body 60 instead of the support member 63. For example, the actuator
may be a motor (not shown) that rotates a drive gear (not shown)
against a rack of teeth (not shown). The motor is connected to one
of the wafer carrier 30 or the body 60, and the rack of teeth is
positioned on the other of the wafer carrier 30 or the body 60. As
the motor rotates the drive gear against the teeth, the drive gear
moves the body 60 vertically with respect to the wafer carrier 30.
Importantly, the actuator acts against the wafer carrier 30 and
either the body 60 or a support member 63 connected to the body 60
to selectively move the body 60 vertically with respect to the
wafer carrier 30 along the vertical axis Z--Z.
The actuators may be controlled manually or by a processor to
selectively engage the refurbishing element 70 with the polishing
surface 42 of the pad 40. In general, the refurbishing element 70
is selectively engaged with the polishing pad 40 on the areas of
the planarizing surface 42 that contact the wafer 12. Since the
wafer 12 usually contacts the pad 40 in a concentric band at a
medial radial distance from the center of the pad 40, the actuators
80 are preferably controlled to lower the refurbishing element
against the polishing surface 42 in the area defined by the
concentric band. The actuators 80 may also control the pressure
between the refurbishing element 70 and the pad 40 to provide a
substantially constant pressure therebetween that does not affect
the pressure between the wafer 12 and the pad 40. In one
embodiment, the actuators 80 are manually set to position the body
60 so that the refurbishing element 70 engages the polishing
surface 42 when the wafer carrier 30 presses the wafer 12 against
the pad 40. To manually set the actuators, the wafer 12 is placed
against a reference surface and then the refurbishing element 70 is
lowered against the reference surface. The reference surface can be
either the polishing pad 40 or another platform (not shown). In
another embodiment, the actuators 80 are springs that bias the
refurbishing element 70 against the polishing surface 42 to provide
a substantially constant pressure between the refurbishing element
70 and the polishing pad 40. When the actuators are springs, the
refurbishing element 70 is preferably positioned slightly below the
face of the wafer 12 when the wafer 12 is off of the pad 40 so that
the refurbishing element 70 engages the polishing surface 42 as the
wafer carrier 30 presses the wafer 12 against the polishing pad
40.
In operation, the wafer carrier 30 is lowered to engage the wafer
12 with the polishing surface 42 of the polishing pad 40. As
discussed above with respect to FIG. 1, the platen 20 and polishing
pad 40 rotate in a direction R.sub.p while the wafer carrier 30
rotates the wafer 12 in a direction R.sub.w. The wafer carrier 30
also translates the wafer 12 in the direction T across the
polishing surface 42 of the polishing pad 40. As the wafer 12 is
polished on the polishing surface 42, the actuators 80 position the
body 60 with respect to the wafer carrier 30 to selectively engage
the refurbishing element 70 with the polishing surface 42. The
polishing surface 42 surrounding the wafer 12 is accordingly
conditioned (when the refurbishing element is a pad conditioner) or
cleaned (when the refurbishing element 70 is a cleaning element)
while the wafer 12 is polished. The actuators 80 selectively
disengage the refurbishing element 70 from the polishing surface 42
by extending the rods 84 against the support structure 63 to move
the body 60 upwardly along the vertical axis Z--Z. The refurbishing
element 70 is selectively removed from the polishing surface 42
over areas of the polishing pad 40 that do not need to be
conditioned or cleaned. Thus, by selectively engaging and
disengaging the refurbishing element 70 with the polishing surface
42, the pad refurbisher 50 can selectively condition or clean only
the deteriorated areas on the polishing surface 42 that need to be
brought back to an acceptable polishing condition.
The body 60 and the distal face 62 of the body 60 are shaped to
position the refurbishing element 70 proximate to the perimeter of
the wafer carrier 30 about at least a portion of the perimeter of
the wafer carrier 30. For example, the body 60 may be attached to
only a single side of the wafer carrier 30, and the body 60 may be
shaped so that the distal face 62 and refurbishing element 70 are
positioned asymmetrically about a fraction of the perimeter of the
wafer carrier 30. In some instances, however, an asymmetrical
mounting of the body 60 may impart asymmetrical forces on the wafer
carrier 30. In particular, as the wafer carrier 30 rotates an
asymmetrically positioned distal face 62 and refurbishing element
70 across the polishing pad 40, the centrifugal force of the
refurbishing element 70 may cause the wafer carrier 30 to wobble.
Also, since the polishing pad 40 will exert a force on the
refurbishing element 70, an asymmetrically positioned refurbishing
element 70 will cause the force between the wafer 12 and the
polishing pad 40 to be uneven across the surface of the wafer 12.
Accordingly, the body 60 is preferably shaped and attached to the
wafer carrier 30 to symmetrically position the distal face 62 and
refurbishing element 70 with respect to the center of the wafer
carrier 30, thus reducing or eliminating any uneven forces on the
wafer caused by an asymmetrical design.
FIGS. 3 and 4 illustrate two embodiments of the pad refurbisher 50
in which the body 60, the distal face 62, and the refurbishing
element 70 are symmetrically positioned with respect to the center
of the wafer carrier 30. It will be appreciated that the invention
is not limited to the embodiments illustrated in FIGS. 3 and 4, as
other symmetrical configurations are within the scope of the
invention. Referring to FIG. 3, the body 60 is a cylindrical sleeve
positioned adjacent to the perimeter of the wafer carrier 30, and
the distal face 62 is a continuous ring spaced radially apart from
the perimeter of the wafer carrier 30. The refurbishing element 70
substantially covers the complete surface area of the distal face
62, and not just a portion as shown in FIG. 3. Referring to FIG. 4,
the body 60 is a cylindrically shaped sleeve positioned adjacent to
the perimeter of the wafer carrier with a number of arcuate
segments 61 spaced radially apart from the perimeter of the wafer
carrier 30. The arcuate segments 61 are separated from one another
by a substantially equal angular distance with respect to the wafer
carrier 30. The distal face 62 of the body 60 is defined by the
bottom surface of each of the arcuate segments 61, and a
refurbishing element 70 is attached to the distal face 62 on each
of the arcuate segments 61 to condition or clean the polishing
surface 42, as discussed above. In another embodiment, pad
conditioners are attached to some of the arcuate segments 61 and
pad cleaners are attached to other arcuate segments 61 so that the
polishing surface 42 may be simultaneously cleaned and
conditioned.
FIG. 5 illustrates another embodiment of a pad refurbisher 150 in
which the body 60 has inner and outer rings 61(a) and 61(b),
respectively positioned proximate to the perimeter of the wafer
carrier 30. A first refurbishing element 70(a) is positioned on a
distal face 62(a) of the inner ring 61(a), and a second
refurbishing element 70(b) is positioned on a distal surface 62(b)
of the outer ring 61 (b). The first refurbishing element 70(a) is
either a pad conditioner or a pad cleaner, and the second
refurbishing element 70(b) is the other of the pad conditioner or
the pad cleaner so that the second refurbishing element 70(b) is
not the same as the first refurbishing element 70(a). In a
preferred embodiment, the first cleaning element 70(a) is a pad
cleaner and the second cleaning element 70(b) is a pad conditioner
to prevent large particles separated from the pad by the pad
conditioner 70(b) from engaging the surface of the wafer 12. In
this embodiment, therefore, the polishing pad 40 may be selectively
conditioned and cleaned in situ and in real-time with the same
apparatus. The pad refurbisher 150 illustrated in FIG. 5 operates
in the same manner as the pad refurbisher illustrated in FIG. 2,
and parts having the same reference numbers in FIGS. 2 and 5
perform the same functions.
In another embodiment, the inner and outer rings 61(a) and 61(b),
respectively, of pad refurbisher 150 illustrated in FIG. 5 operate
independently from one another. A first actuator (not shown) may be
operatively attached to only the inner ring 61(a) and a second
actuator (not shown) may be operatively attached to only the outer
ring 61(b). The inner and outer rings 61(a) and 61(b) are
accordingly separated from one another (not shown) so that they may
independently engage the polishing surface 42 of the polishing pad
40.
One advantage of the pad refurbishers 50 and 150 of the present
invention is that they selectively condition and/or clean generally
only the deteriorated areas on the polishing surface that need to
be brought back to an acceptable polishing condition. By attaching
the pad refurbisher to the wafer carrier so that the refurbishing
element travels with the wafer carrier, and by controlling the
vertical motion of the refurbishing element with respect to the
wafer carrier, the refurbishing element may be selectively engaged
with the deteriorated areas on the pad. Moreover, by positioning
the refurbishing element proximate to the wafer carrier, only a
slightly larger area than that of the wafer carrier is conditioned
or cleaned even when the refurbishing element continuously engages
the pad. Therefore, compared to conventional conditioners, the pad
refurbisher of the present invention reduces over-conditioning of
areas on the polishing surface that do not require conditioning or
cleaning.
Another advantage of the present invention is that the pad
refurbishers 50 and 150 condition and/or clean a polishing surface
of a polishing pad in situ and in real-time while a wafer is
planarized. Since the cleansing element 70 may be selectively
engaged and disengaged with the polishing pad from the wafer
carrier 30, the wafer 12 may be polished while the polishing
surface 42 of the pad 40 is conditioned and/or cleaned. Thus,
compared to some conditioning devices that cannot simultaneously
condition the pad and polish the wafer, the pad refurbisher 50
enhances the throughput of the CMP process because the down-time to
condition and clean the polishing pad is significantly reduced or
even eliminated.
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,
the apparatus and method may also be used in chemical-mechanical
polishing of other microelectronic substrates, such as field
emission displays, in addition to semiconductor wafers.
Accordingly, the invention is not limited except as by the appended
claims.
* * * * *