U.S. patent application number 10/851531 was filed with the patent office on 2005-11-24 for dynamic atomizer on conditioner assemblies using high velocity water.
Invention is credited to Rodriguez, Jose Omar, Seputro, Margareth, Storey, Charles A..
Application Number | 20050260936 10/851531 |
Document ID | / |
Family ID | 35375804 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050260936 |
Kind Code |
A1 |
Rodriguez, Jose Omar ; et
al. |
November 24, 2005 |
Dynamic atomizer on conditioner assemblies using high velocity
water
Abstract
A conditioner assembly is disclosed for conditioning a polishing
pad used in chemical mechanical polishing of planar semiconductor
wafer components. One embodiment of the conditioner assembly
comprises a plate-type conditioner plate comprising a circular
edge, having a first side and a second side, where on the first
side is provided one or more diamond-impregnated abrasive elements,
each comprising an abrasive surface disposed a distance from said
first side comprising diamond particles, and one or more jets
oriented to discharge fluid away from said first side. In operation
the jets dispense high velocity fluid that hits the surface of the
adjacent polishing pad with sufficient force to dislodge diamond
particles that have loosened or broken off from the
diamond-impregnated abrasive elements, thereby avoiding the
embedding of such particles into the polishing pad surface. Another
embodiment uses a ring-type conditioner plate assembly instead of a
plate type, and also comprises one or more diamond-impregnated
abrasive elements, each comprising an abrasive surface disposed a
distance from said first side comprising diamond particles, and one
or more jets oriented to discharge fluid away from said first
side.
Inventors: |
Rodriguez, Jose Omar;
(Orlando, FL) ; Seputro, Margareth; (Orlando,
FL) ; Storey, Charles A.; (Orlando, FL) |
Correspondence
Address: |
BEUSSE BROWNLEE WOLTER MORA & MAIRE, P. A.
390 NORTH ORANGE AVENUE
SUITE 2500
ORLANDO
FL
32801
US
|
Family ID: |
35375804 |
Appl. No.: |
10/851531 |
Filed: |
May 21, 2004 |
Current U.S.
Class: |
451/56 |
Current CPC
Class: |
B24B 53/12 20130101;
B24B 53/017 20130101 |
Class at
Publication: |
451/056 |
International
Class: |
B24B 001/00 |
Claims
What we claim in the invention is:
1. A conditioner assembly for conditioning a polishing pad used in
chemical mechanical polishing of semiconductor wafer comprising: a.
a polishing pad conditioner body comprising an abrasive surface
formed by a plurality of diamond particles embedded in the surface;
b. an apparatus for positioning said conditioner body in abrasive
relationship with a planar surface of the polishing pad and for
effective rotation of the conditioner body with the planar surface
of the polishing pad; and c. an apparatus for delivering a flow of
fluid into an interface between said conditioner body and said
planar surface of the polishing pad; wherein the flow of fluid is
sufficient to dislodge diamond particles which have become embedded
in the planar surface of the polishing pad.
2. The conditioner assembly of claim 1 wherein said apparatus for
delivering a flow of fluid is comprised of at least one jet.
3. The conditioner assembly of claim 1 wherein said abrasive
surface is comprised of an annular ring.
4. The conditioner assembly of claim 1 wherein said abrasive
surface is comprised of a plurality of sections separated by
channels.
5. The conditioner assembly of claim 1 wherein said conditioner
body is plate-shaped.
6. The conditioner assembly of claim 1 wherein said conditioner
body comprises a ring shape and comprises a central void within
said ring shape.
7. The conditioner assembly of claim 1 wherein said apparatus for
delivering a flow of fluid is comprised of a plurality of jets,
each said jet oriented at an angle less than 90 degrees, to direct
fluid through one of said channels.
8. The conditioner assembly of claim 2, apparatus for delivering a
flow of fluid comprises a rotary union adapted for rotation, and a
conduit attaching to said rotary union, fluidly communicating said
at least one jet with a supply of water in fluid communication with
said rotary union.
9. A conditioner sub-assembly employed in conditioning a polishing
pad used in chemical mechanical polishing of semiconductor wafer
comprising: a. a polishing pad conditioner body; b. an abrasive
surface formed by a plurality of diamond particles embedded in the
surface, on one side of said conditioner body; and c. one or more
jets in fixed communication with said conditioner body, positioned
to deliver a flow of fluid into an interface between said
conditioner body and said planar surface of the polishing pad,
wherein the flow of fluid is sufficient to dislodge diamond
particles which have become embedded in the planar surface of the
polishing pad.
10. A method of conditioning a polishing pad with a
diamond-impregnated conditioner body comprising the steps of: a.
contacting said polishing pad with an abrasive surface of said
conditioner body, of a conditioner plate assembly plate comprising:
i. said conditioner body comprising said abrasive surface formed by
a plurality of diamond particles embedded in the surface; ii. an
apparatus for positioning said conditioner body in abrasive
relationship with a planar surface of the polishing pad and for
effective rotation of the conditioner body with the planar surface
of the polishing pad; and iii. an apparatus for delivering a flow
of fluid into an interface between said conditioner body and said
planar surface of the polishing pad; b. effecting relative rotation
between said polishing pad and said conditioner body; and c.
supplying high velocity water through said apparatus for delivering
a flow of fluid, directed to the surface of said polishing pad;
wherein said high velocity water carries away diamond particles
loosened from said diamond-impregnated abrasive element during said
contacting.
11. The method of claim 10, wherein said diamond-impregnated
abrasive element additionally comprises at least one channel
communicating between an interior edge and an exterior edge of said
diamond-impregnated abrasive element, additionally comprising
flowing said high velocity water through said at least one
channel.
12. A method of assuring removal of particulate matter from a
surface of a polishing pad during conditioning, comprising the
steps of: a. positioning a conditioner body in abrasive
relationship with a planar surface of the polishing pad; b.
providing effective rotation of the conditioner body with the
planar surface of the polishing pad; and c. supplying high velocity
water through said conditioner body for delivering a flow of fluid,
directed to the surface of said polishing pad; wherein said high
velocity water carries away said particulate matter.
13. The method of claim 12, wherein said supplying directs water of
a force effective to loosen diamond particles embedded in said
surface of said polishing pad.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to integrated circuit
manufacture generally, and more specifically to abrading and
renewing a polishing pad using a conditioning assembly comprising a
forced-fluid particle-flushing feature.
BACKGROUND OF THE INVENTION
[0002] In semiconductor manufacture, semiconductor wafers need to
be processed to be flat both initially and at various stages of
manufacture. As device features become smaller and smaller, as in
the submicron size range, and as such features have increasingly
tight tolerances, the importance of achieving a desired level of
flatness increases. Without attaining a desired level of flatness,
other efforts toward obtaining consistent functionality in
submicron size chips tend to falter. Further, in achieving such
desired level of flatness, it is important to not impart any
undesirable characteristic to the wafer.
[0003] Toward achieving consistently flat wafers, specific
apparatuses and methods related to the process of chemical
mechanical planarization (CMP) have been developed. CMP, which
combines chemical etching and mechanical abrasion to produce a flat
surface, is used in wafer preparation and in wafer fabrication. A
polishing pad is used during CMP. In a typical CMP operation, this
pad is placed in abrading contact with a semiconductor wafer
surface, and a slurry is applied. The slurry typically contains a
polishing agent, for instance alumina or silica, and other
chemicals that etch or oxidize the wafer surface. Through such
abrading contact, including with application of a slurry, the wafer
surface is effectively polished and made more planar.
[0004] The typical polishing pad, comprised of material such as
polyurethane, is manufactured to have pores or grooves. The pore or
groove voids serve to carry the slurry into contact with the wafer
surface being abraded and polished. However, particularly for
uncoated polishing pads, these pores become filled with pad
material and slurry particles over time during the polishing
process. This can lead to what is known in the art as pad glazing
or pad clogging.
[0005] Glazed and/or clogged polishing pads are processed to
restore their functionality. This is done after a given period of
use of a polishing pad, or upon observation of decreased
performance. Typical processing involves abrading the polishing pad
itself by use of a conditioner assembly. A conditioner assembly
generally comprises a circular rigid conditioner body (also
referred to as a "plate" or "ring," or a "dresser") comprising one
or more abrasive elements on one side, and a drive mechanism
emanating from a central point on the other side. During operation
the drive mechanism positions and provides rotational force to turn
the body. Rotation of the conditioner body while the surface of the
abrasive elements contact the polishing pad provides a desired
removal of accumulated material from the polishing pad surface.
[0006] When diamond particles are in the abrasive material, the
conditioner body is known as a diamond conditioner body. Abrasive
elements of a diamond conditioner body may be prepared by any of a
number of methods using all electroplating, all brazing. Other
fabrication approaches include electroplating in the diamonds, and
sifting in powdered metal around the diamonds, then sintering at
high temperature to anchor the diamonds. For instance, in some
embodiments of a diamond conditioner body, an abrasive material is
comprised of diamonds embedded in a nickel plating (i.e.,
diamond-impregnated nickel). As to shapes, in some embodiments a
single abrasive element is an annular ring with its outer edge
along the periphery of a circular conditioner plate or ring. In
other embodiments there are breaks, or channels, formed between
discrete abrasive elements that are similarly arranged with their
outer edges along the periphery of a circular conditioner plate or
ring.
[0007] In use, the surface of the abrasive material is pressed
against the polishing pad in a manner to achieve an abrasion to
restore the polishing pad surface. This restoration involves
returning the polishing pad surface to a roughened but planar state
in which new clean depressions, such as pores or grooves, are
exposed.
[0008] An alternative to a diamond conditioner is a brush
conditioner. However, a brush conditioner provides a lower removal
rate, increasing the time to condition. Gas blowing and liquid
rinsing are other techniques employed to remove materials that have
become entrapped in the polishing pad.
[0009] Also known in the art is a fluid-based in-situ conditioning
system, as described in U.S. Pat. No. 6,517,416 B1 (issued Feb. 11,
2003 to Crevasse et al.). Also known in the art are various
apparatuses, methods and compositions are to increase the
effectiveness of conditioning a polishing pad, and/or decrease the
time to do this. For instance, the following references disclose
apparatuses, methods and compositions in this field: U.S. Pat. No.
6,234,868 B1 (issued May 22, 2001 to Easter et al.); U.S. Pat. No.
6,524,523 (issued Feb. 25, 2003 to Jeng et al.); and U.S. Pat. No.
6,679,761 B1 (issued Jan. 20, 2004 to Sunahara et al.). These
references, and all other references cited herein, whether patents,
patent application publications, scientific or technical
publications, or other publications, are hereby incorporated by
reference for their teachings. As indicated below where
appropriate, certain references are incorporated with particularity
for indicated teachings.
[0010] Although use of diamond conditioner bodies offer advantages,
a problem with such use has been recognized by the inventors.
Whereas it was known that during abrasion that a dust is formed
that requires removal, it was previously unknown that diamond
particles may loosen and break off from the surface of the abrasive
material. Once free on the surface of the polishing pad, these
particles may become embedded in the polishing pad, such as due to
the action and pressure of the conditioner assembly. When embedded,
the diamond can cause diamond scratching on one or more wafers
during subsequent polishing by the so-conditioned polishing pad.
Ultimately, during a subsequent conditioning of the polishing pad,
the embedded diamond may be removed, but not before having caused
wafer damage.
[0011] As disclosed and claimed herein, the present invention
provides apparatuses and methods directed to reduce and/or
eliminate the occurrence of, and/or dislodge undesired embedded
diamonds in a polishing pad during conditioning with a diamond
conditioner assembly. This solves the identified problem, and
improves the performance of conditioned polishing pads, and
decreases the defect rate of semiconductor wafers polished by such
pads.
SUMMARY OF THE INVENTION
[0012] In one embodiment of the present invention, a conditioner
assembly is comprised of one or more jets that direct a flow of
high velocity fluid, such as water, onto the surface of the
polishing pad. Typically, the jets are positioned within a boundary
formed by the interior border of the diamond-impregnated abrasive
material of the conditioner body. The shape of this
diamond-impregnated abrasive material, that is formed in or
attached to the conditioner body, may be selected from: an annular
ring; an annular ring broken by radially oriented channels; or
other shapes and configurations as known in the art.
[0013] The one or more jets are adapted to deliver high velocity
fluid, such as water, during a conditioning process. The high
velocity fluid washes away diamond particles that may have loosened
or broken off from the conditioner plate abrasive surface prior to
becoming embedded in the polishing pad. A driving arm around which
the conditioner body rotates is attached to the conditioner body,
such as at its center, to provide for rotation of the conditioner
body including the associated abrasive material. Fluid
communication is provided between a fluid supply and the one or
more jets wherein that fluid communication is maintainable during
the rotation, such as by use of a rotary union.
[0014] In another embodiment of the present invention, a method of
conditioning a polishing pad is comprised of contacting a
conditioner body (i.e., its abrasive material), having components
described above, with a polishing pad in need of polishing,
effecting relative rotation between the conditioner body and the
polishing pad, and supplying high velocity fluid during the
contacting, wherein the fluid dislodges and/or washes away diamond
particles that have loosened or broken off from the conditioner
plate. The fluid also washes away debris and/or dried slurry that
is being acted upon by the abrasive surface on the conditioner
plate.
[0015] Other aspects, advantages and objects of the present
invention are provided in the following description, which is to be
considered with the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] For a better understanding of the invention, reference is
made to the following detailed description taken in conjunction
with the accompanying drawings in which:
[0017] FIG. 1A provides a schematic cross-sectional side view of
one embodiment of a plate-type conditioner assembly of the present
invention having a continuous annular abrasive element. FIG. 1B
provides a schematic top view of the plate-type conditioner body
depicted in FIG. 1A.
[0018] FIGS. 2A and 2B provide bottom and top views, respectively,
of a plate-type conditioner body of the present invention. FIG. 2C
provides a close-up view of one abrasive element disposed on the
bottom edge of the plate-type conditioner body.
[0019] FIGS. 3A and 3B provide bottom and top views, respectively,
of a ring-type conditioner body of the present invention. FIG. 3C
provides a top view of one embodiment of a drive transfer frame
with central shaft. FIG. 3D provides a close-up view of one
abrasive element disposed on the bottom edge of the ring-type
conditioner body.
DETAILED DESCRIPTION OF THE INVENTION
[0020] For the figures described herein, unless otherwise indicated
like reference numerals refer to the same or similar structures
identified in previous figures.
[0021] As used herein, including the claims, the term "diamonds"
and "diamond particles" are taken to mean the grains, powders, and
dusts of diamonds, typically synthetic diamonds. Size-segregated
(i.e., sieved) diamond powders from synthetic diamond sources
commonly are used in the manufacture of abrasive elements used on
conditioner plates, because this source provides greater
uniformity. A representative particle size category for diamond
particles used in a conditioner plate abrasive element is 200 mesh
(i.e., particles passing through a mesh having 200 holes per linear
inch). Smaller and larger sizes of diamond particles are used,
depending on a particular purpose or preference.
[0022] As used herein, including the claims, an abrasive element
that contains diamonds is identified as a "diamond-impregnated
abrasive element" or, alternatively, as an "abrasive surface formed
by a plurality of diamond particles embedded in the surface." This
comprises diamond particles as defined above. When a
diamond-impregnated abrasive element is associated with a
conditioner body (i.e., plate-type or ring-type) of the present
invention, whether formed integrally with or attached thereto, this
combination is referred to herein variously as a "diamond
conditioner body," or as a "diamond-type conditioner" or a "diamond
conditioner" (the latter two terms optionally including other
components of a conditioner assembly). However, in that it is the
plate-type or ring-type conditioner body that is a standard
functional unit in the art, this combination also is referred to as
a conditioner body that comprises such abrasive element or
surface.
[0023] As described in the embodiments below, a diamond-impregnated
abrasive element may be shaped into an annular ring, with or
without channels, and into other shapes suitable for the purpose of
conditioning a polishing plate that is subsequently used to polish
and flatten semiconductor wafers at the start, or during, wafer
fabrication. Also as described herein, it is appreciated that a
conditioner body of the present invention, to which is attached (or
which is made integral with) a diamond-impregnated abrasive
element, may be of a plate-type or of a ring-type or ring shape. A
conditioner body of the present invention, when associated with one
or more other components for the purpose of conditioning (such as
an apparatus for positioning, etc.), is identified as a conditioner
assembly.
[0024] The diamond-impregnated abrasive element comprises an
abrasive surface that, during operation of a conditioner assembly,
is placed in intimate contact with a polishing plate to be
conditioned. The intimate contact over time has been found to
result in the release or break-off of diamond particles. The
diamond-impregnated abrasive element is formed by any means known
in the art, and is formed with or attached to the conditioner body
by any means known in the art. Without being limiting, examples of
creating and attaching a diamond-impregnated abrasive element are
taught in U.S. Pat. No. 6,524,523 (to Jeng et al.) which is
incorporated by reference with particularity for such teachings,
including the discussion of the prior art in that patent, and for
the designs of conditioner bodies.
[0025] FIGS. 1A and 1B provide side cross-sectional and top
schematic views of one embodiment of a plate-type conditioner
assembly of the present invention. A plate-type conditioner body
100 is disc-shaped (i.e., comprising a circular edge 101 with
substantially flattened opposing sides) and comprises on a bottom
side 102 two jets 104. The two jets 104 are disposed within a
peripherally located annular ring of abrasive 105. To rotate the
conditioner body 100, a rotating arm 106 attaches to the top side
103 of said conditioner body 100. The rotating arm 106 is adapted
for connection to a motor (not shown) to drive the conditioner body
100 in a rotating manner. More generally, any type of rotating arm
or drive as is known in the art may be employed, such as those
incorporating rotary unions to supply water to the conditioner body
100. Also, any means for attaching the conditioner body 100 to a
rotational driving shaft, such as rotating arm 106, may be employed
as is known in the art. For instance, not to be limiting, U.S. Pat.
No. 5,899,800 (to Shendon) teaches a rotary union associated with a
drive shaft (i.e., rotating arm), and is incorporated by reference
particularly for the teachings of a rotary union and of attachment
to the conditioner body.
[0026] The annular ring of abrasive 105 is attached to or formed
with the conditioner body 100, and is one shape of a
diamond-impregnated abrasive element of the present invention. When
not formed with the conditioner body 100, the annular ring of
abrasive 105 is secured to the conditioner body 100 by means known
in the art. The annular ring of abrasive 105 is comprised of
diamonds 107 mixed interspersed in the annular ring of abrasive
105, which may be otherwise comprised of a metal such as nickel.
The annular ring of abrasive 105 and has an exterior edge 108 and
interior edge 109. In that the annular ring of abrasive 105 has a
planar surface 110 that is disposed below bottom side 102 of
conditioner body 100 interior to interior edge 109, a recess 112 is
formed within the confines of the annular ring of abrasive 105.
[0027] As depicted in FIGS. 1A and 1B, the two jets 104 fluidly
communicate with recess 112. To the other end of each of the two
jets 104 is a connector housing 114, here shown disposed partially
within the conditioner body 100. The connector housing 114 receives
a connector (not shown) that fluidly connects with a supply of high
velocity water (not shown). Intervening fluid connections between
the supply and the jets 104 are adapted to provide water during
rotation of the conditioner body 100 by the rotating arm 106, such
as by any of various rotary unions known to those skilled in the
art.
[0028] Accordingly, during operation, when the annular ring of
abrasive 105 of conditioner 100 is disposed against a surface of
polishing pad (not shown), which is to be conditioned thereby, and
when the conditioner 100 is rotating to create an abrasive action,
high velocity water also is flowing from the supply, through the
connectors, and through the jets 104. The water flow from these
jets 104 is directed to the surface of the polishing pad (not
shown), thereby serving to loosen and/or wash away diamond
particles that are, respectively, embedded or lying on the surface
of the polishing pad beneath the flow of water from the jets 104.
Given the rotating motion of the conditioner 100 about the rotating
arm 106 (and, optionally, given the rotation of the polishing pad
and/or the lateral movement of the conditioner across the polishing
pad), the force of water from the jets 104 moves across a large
surface area of the polishing pad.
[0029] As water from the jets 104 flows into recess 112, it seeks a
path of least resistance to flow out. From the space defined by
recess 112 the water flows laterally to a lower pressure area, such
as that open space external to the annular ring of abrasive 105.
When no breaks, or channels, in the annular ring of abrasive 105
exist, the water passes across the active interface of the annular
ring of abrasive 105 rotating across the surface of the polishing
plate. While not being bound to a particular theory, this is
believed to provide additional cleaning action.
[0030] Also, regardless of the existence of breaks or channels in
the annular ring of abrasive 105, it is noted that the effects of
the water impacting the polishing pad surface from jets 104
additionally remove and/or wash away debris and/or dried slurry
from previous polish processes. Thus, one or more of the above
interactions and phenomenon results in better defect performance
and reduces or eliminates dried slurry scratches on a wafer later
polished by a polishing pad so conditioned.
[0031] FIG. 2A provides a perspective view a plate-type conditioner
body 200 having a circular edge 201, and showing features of the
bottom side 202. On the bottom side 202 along the circular edge 201
are disposed abrasive elements 205 separated by channels 215.
Disposed more centrally are two jets 204 that provide high velocity
water, as described herein, to flush away diamond particles.
[0032] FIG. 2B provides a perspective view of the top side 203 of
the plate-type conditioner body 200 of FIG. 2A. Disposed near the
circular edge are holes 212 for attachment of the conditioner body
200 to a drive mechanism (not shown). More centrally located are
holes 213 for alternative attachment of a drive mechanism (not
shown). Either set of holes 212 or 213 may be used for attachment
of a drive mechanism that includes a rotary union (not shown) for
supply of water during rotation. Also shown are two holes 216
through which water passes to supply jets 204.
[0033] FIG. 2C provides a perspective view of one abrasive element
205 of FIG. 2A. A plurality of diamond particles 207 are apparent
on the abrasive element surface 210. The shape of abrasive element
205 also is defined by an exterior edge 208, an interior edge 209,
and sides 211. Between opposing sides 211 of adjacent abrasive
elements 205 are channels 215.
[0034] FIG. 3A provides a perspective view a ring-type conditioner
body 300 having a circular edge 301, and showing features of the
bottom side 302 of the ring shape. On the bottom side 302 along the
circular edge 301 are disposed abrasive elements 305 separated by
channels 315. A large open span 317 exists in the middle of the
ring shape.
[0035] FIG. 3B provides a perspective view of the top side 303 of
the ring-type conditioner body 300 of FIG. 3A. Disposed near the
circular edge are holes 312 for attachment of the conditioner body
300 to a drive mechanism (not shown). More centrally located are
larger holes 313 for alternative attachment of a drive mechanism
(not shown). Either set of holes 312 or 313 may be used for
attachment of a drive mechanism that includes a rotary union (not
shown) for supply of water during rotation. Jet braces 319 are
attached to the top side of conditioner body 300 to hold jets 304
in desired positions. In other embodiments (not shown), the jets
may be positioned directly on drive transfer frame, such as 318 in
FIG. 3C. Drive transfer frame 318 depicts one embodiment by which a
drive shaft 306 attaches to body 300 (not shown) via six arms 330,
each bearing a hole 332 to align with holes 313. Jets may be placed
in or on such arms 330. Various arrangements for communicating a
water supply to jets, and for providing rotational force, will
become apparent to those skilled in the art.
[0036] During operation, as discussed above for other embodiments,
the two jets 304 provide high velocity water, as described herein,
to dislodge and/or flush away diamond particles, as well as other
particulates.
[0037] FIG. 3D provides a perspective view of abrasive elements 305
of FIG. 3A. A plurality of diamond particles 307 are apparent on
the abrasive element surface 310. The shape of abrasive element 305
also is defined by an exterior edge 308, an interior edge 309, and
sides 311. Between opposing sides 311 of adjacent abrasive elements
305 are channels 315.
[0038] It is appreciated that one general component of a
conditioner assembly of the present invention is an apparatus for
delivering a flow of fluid into an interface between said
conditioner body and said planar surface of the polishing pad. Any
approaches as known in the art for fluidly communicating a supply
of fluid to a rotating conditioner body may be employed, such as
the use of a rotary union. As to the outlets for such fluid, these
are generally referred to as "jets," however appreciating that a
range of outlets may be used so long as they fulfill the functional
requirement of supplying high velocity fluid against a surface of a
polishing pad that opposes the conditioner body surface comprising
the abrasive surface. Thus, a simple hole (as shown in FIG. 1A)
through which water passes may be used as an outlet, or,
alternatively, a separate jet nozzle may be attached to such a
hole, such as by threading the nozzle into such a hole.
[0039] As to the channels 215 and 315 of plate-type conditioner 200
and ring-type conditioner 300, respectively, these provide more
facile routes of exit than when water from jets 104 of conditioner
100 must pass through relatively small spaces between the
non-interrupted abrasive surface 105 and the opposing polishing pad
surface (not shown), as the latter are intimately contacting during
operation. Not being constrained by frictional loss as would be
higher through such small spaces, the flow through the channels is
more rapid and is suitable to carry away dislodged diamond
particles. As conditioner body 200 or 300 rotates, this exposes
different surface areas of the polishing pad to such washing
action. For a dislodged diamond particle (not shown) that is either
lying on or partially embedded in the surface of the polishing pad
(not shown), upon exposure to the transient flow of water through
channels 215 or 315 during rotation, such flow may by its force
carry away or dislodge and carry away such particle. Further, as
the effective velocity of the water is increased at a distance from
the impact area of the spray, along the polishing pad, the force
increases for carrying away a diamond particle from that non-impact
area. Thus, the optimization of the angling, positioning and flow
rate (at the impact and at non-impact areas) for each outlet, in
consideration of the exit pattern, can result in most or all
diamond particles being dislodged and removed with re-lodging into
the polishing pad surface.
[0040] Also, for any embodiment, the angle of the jet may be angled
to deviate from 90 degrees relative to the planar surface of the
polishing pad. For example, not to be limiting, in some embodiments
the jet is angled outwardly (relative to the inward geometric
center of the conditioner body, i.e., the centerline of the drive
mechanism). That is, the angle is less than 90 degrees relative to
degrees from the plane of said first side, and oriented toward the
circular edge, specifically directed to pass fluid through a
channel. Such outward angling provides an advantage of propelling
at a greater velocity dislodged diamond particles so that they have
a greater possibility of directly through a rotating channel
without becoming re-embedded due to action of the rotating abrasive
element(s). The degree of this directionality is balanced with the
loss of some force of impact against the surface, as occurs when
the angle is 90 degrees from the plane of the polishing pad.
[0041] Further as to the location and angling of jets, in certain
embodiments the jets are positioned near to the interior edges of
diamond-impregnated abrasive elements, and are angled outward and
positioned so the water spray strikes near or in the space of a
channel between two adjacent elements. This more directly directs
dislodged diamonds through the channel. In certain embodiments, a
jet is disposed to direct water near or in the space of each of the
channels. In other embodiments, to conserve water flow, only a
portion of the channels have a water spray outlet directing water
through the channel.
[0042] For plate-type conditioner embodiments such as the one
depicted in FIGS. 2A-C, during operation water flows outward
through the channels 215. For ring-type conditioner embodiments
such as the one depicted in FIGS. 3A-C, the water may flow outward
through the channels 315. However, water also may spray up and pass
through the open span 317. This will in part depend on the flow
rate and other factors, such as the style of opening of the jets
304, and their angles relative to the plane of the polishing
pad.
[0043] The compositional characteristics and design of the abrasive
surface, and the flow rate of the fluid, such as water, may be
varied to achieve a desired level of cleaning appropriate to a
particular polishing pad being conditioned. Without being limiting,
in an illustrative embodiment the range of total fluid flow rate is
about 1 to about 5 liters per minute for a total of two jets.
However, it is believed that a total fluid flow rate of about 1 to
about 3 liters per minute for the two jets is sufficient to achieve
the desired objectives of this invention. These rates are for a
conditioner (plate or ring type) having a diameter about 10 inches,
and provide water velocity and pressure sufficient to achieve the
dislodging of diamond particles that are embedded in the
conditioning pad. Higher flow rates may be used, depending on the
conditions and the priority of conserving fluid consumption (or the
cost of recycling it). Total flow rates increase or decrease as the
size of a plate increases or decreases. Also, total flow rates
increase as the total number of jets increases, to provide per jet
water velocity and pressure sufficient to achieve the dislodging of
diamond particles that are embedded in the conditioning pad.
[0044] Methods of operation using the conditioner assemblies of the
present invention are described as follows. In one embodiment, a
method of conditioning a polishing pad with a diamond-impregnated
conditioner assembly comprises the steps of:
[0045] 1. contacting a polishing pad surface with a surface of a
diamond-impregnated abrasive element of a diamond conditioner plate
assembly, said diamond conditioner plate assembly comprising a jet,
the jet in fluid communication with a supply of water or other
fluid;
[0046] 2. providing effective rotation of the conditioner plate
assembly with the planar surface of the polishing pad; and
[0047] 3. directing a flow of high velocity water through said jet
against the surface of the polishing pad;
[0048] wherein said high velocity water carries away diamond
particles loosened from said diamond-impregnated abrasive element
during said contacting.
[0049] In another method, in addition to the contacting and
supplying described above, there is a step of flowing the high
velocity water through one or more channels formed in the
diamond-impregnated abrasive element.
[0050] Although water is stated to flow through the jets in the
examples above, it is appreciated that any fluid may be utilized so
long as it is suitable for the purpose of washing away particulate
matter, and/or dislodging diamond particles, from the surface of a
polishing pad. Also, while it is appreciated that the force of the
high pressure water is the primary force to remove dislodged
diamond particles and other undesirable debris, the high velocity
water or other fluid may advantageously contain foaming agents,
surfactants, cleaners and the like. Such additions to the water or
other fluid aid in the removal, cleaning and reconditioning of the
polishing pad. Typically when such additives are used, prior to
completion of the conditioning, the source of high velocity water
is changed to provide a rinsing using water without such
additives.
[0051] In other embodiments of the present invention, the diamond
conditioner assembly comprising a jet directing water against a
polishing plate surface is provided in conjunction with a polishing
apparatus for wafers. An example of a polishing apparatus to which
this may be combined is found in U.S. Pat. No. 6,517,416, FIGS. 2A
and 2B, incorporated by reference specifically for this teaching.
The diamond conditioner plate and its associated abrasive elements
are disengaged from contact with the polishing plate when the
polishing plate is polishing a wafer. Then, when conditioning is
desired, the diamond conditioner plate is engaged so as to contact
the polishing pad. During such contacting a flow of high velocity
water passes through the jet(s) of the conditioner plate and serves
to flush away any of dislodged diamond particles, debris formed
from the abrading contacting, and, more particularly, dried
slurries from a previous polishing process.
[0052] While the preferred embodiments of the present invention
have been shown and described herein in the present context, such
embodiments are provided by way of example only, and not of
limitation. Numerous variations, changes and substitutions will
occur to those of skilled in the art without departing from the
invention herein. For example, the present invention need not be
limited to best mode disclosed herein, since other applications can
equally benefit from the teachings of the present invention.
Accordingly, it is intended that the invention be limited only by
the spirit and scope of the appended claims.
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