U.S. patent application number 10/799279 was filed with the patent office on 2005-09-15 for chemical mechanical polishing pad with grooves alternating between a larger groove size and a smaller groove size.
Invention is credited to Rodriguez, Jose Omar, Storey, Charles A., Thompson, John F..
Application Number | 20050202761 10/799279 |
Document ID | / |
Family ID | 34920479 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050202761 |
Kind Code |
A1 |
Rodriguez, Jose Omar ; et
al. |
September 15, 2005 |
CHEMICAL MECHANICAL POLISHING PAD WITH GROOVES ALTERNATING BETWEEN
A LARGER GROOVE SIZE AND A SMALLER GROOVE SIZE
Abstract
A chemical mechanical polishing (CMP) pad is provided. The CMP
pad includes a groove pattern disposed on a polishing surface of
the pad. The groove pattern is formed of an alternating sequence of
spaced apart grooves. The alternating sequence of grooves comprises
a groove of a first size and a groove of a second size, wherein the
first and second groove sizes are different relative to one
another.
Inventors: |
Rodriguez, Jose Omar;
(Orlando, FL) ; Storey, Charles A.; (Orlando,
FL) ; Thompson, John F.; (Orlando, FL) |
Correspondence
Address: |
BEUSSE BROWNLEE WOLTER MORA & MAIRE, P. A.
390 NORTH ORANGE AVENUE
SUITE 2500
ORLANDO
FL
32801
US
|
Family ID: |
34920479 |
Appl. No.: |
10/799279 |
Filed: |
March 12, 2004 |
Current U.S.
Class: |
451/56 |
Current CPC
Class: |
B24B 37/26 20130101 |
Class at
Publication: |
451/056 |
International
Class: |
B24B 001/00 |
Claims
1. A chemical mechanical polishing pad comprising: a groove pattern
disposed on a polishing surface of the pad, said groove pattern
comprising repetitive sequence of spaced apart groove pairs, each
of said groove pairs comprising a groove of a first size positioned
adjacent to a groove of a second size, wherein the first and second
groove sizes are different in size relative to one another, whereby
only grooves of different size are adjacent to one another in said
groove pattern.
2. The chemical mechanical polishing pad of claim 1 wherein a
groove of the first size comprises a width that ranges from about 5
mils to about 10 mils.
3. The chemical mechanical polishing pad of claim 1 wherein a
groove of the first size comprises a depth that ranges from about 1
mil to about 15 mils.
4. The chemical mechanical polishing pad of claim 1 wherein a
groove of the second size comprises a width that ranges from about
10 mils to about 60 mils.
5. The chemical mechanical polishing pad of claim 1 wherein a
groove of the second size comprises a depth that ranges from about
15 mils to about 60 mils.
6. The chemical mechanical polishing pad of claim 1 wherein said
alternating sequence of grooves comprises a pitch that ranges from
about 20 mils to about 80 mils.
7. The chemical mechanical polishing pad of claim 1 wherein said
groove pattern affects distribution of a slurry between the
polishing surface of the pad and a semiconductor wafer in
engagement with said polishing pad, said distribution resulting in
a relatively lesser amount of the slurry being used during a
chemical mechanical polishing process.
8. The chemical mechanical polishing pad of claim 1 wherein the
groove pattern is selected from the group consisting of a
concentric groove pattern, an X-Y groove pattern, a radially
extending groove pattern and a spiral groove pattern.
9. A chemical mechanical polishing system including a carrier for
holding and moving a semiconductor wafer during a chemical
mechanical polishing process, the polishing system comprising: a
rotatable platen; and a chemical mechanical polishing pad supported
by said platen, a groove pattern disposed on a polishing surface of
the pad, said groove pattern comprising repetitive sequence of
spaced apart concentric groove pairs, each of said concentric
groove is comprising a groove of a first size positioned adjacent
to a groove of a second size, wherein the first and second groove
sizes are different in size relative to one another, whereby only
grooves of different size are adjacent to one another in said
groove pattern.
10. The chemical mechanical polishing system of claim 9 wherein a
groove of the first size comprises a width that ranges from about 5
mils to about 10 mils.
11. The chemical mechanical polishing system of claim 9 wherein a
groove of the first size comprises a depth that ranges from about 1
mil to about 15 mils.
12. The chemical mechanical polishing system of claim 9 wherein a
groove of the second size comprises a width that ranges from about
10 mils to about 60 mils.
13. The chemical mechanical polishing system of claim 9 wherein a
groove of the second size comprises a depth that ranges from about
15 mils to about 60 mils.
14. The chemical mechanical polishing system of claim 9 wherein
said alternating sequence of concentric grooves comprises a pitch
that ranges from about 20 mils to about 80 mils.
15. The chemical mechanical polishing system of claim 9 wherein
said groove pattern affects distribution of a slurry between the
polishing surface of the pad and a semiconductor wafer in
engagement with said polishing pad, said distribution resulting in
a relatively lesser amount of the slurry being used during a
chemical mechanical polishing process.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to the field of
semiconductor device fabrication, and more particularly to the
field of chemical mechanical polishing of semiconductor wafers, and
specifically to an improved polishing pad for chemical mechanical
polishing of a semiconductor wafer.
BACKGROUND OF THE INVENTION
[0002] The fabrication of microelectronics devices involves the
deposition and removal of multiple layers of material on a
semiconductor substrate to form active semiconductor devices and
circuits. Device densities presently exceed 9 million transistors
per square centimeter, and they are expected to increase by an
order of magnitude within the next decade. Such devices utilize
multiple layers of metal and dielectric materials that can
selectively connect or isolate device elements within a layer and
between layers. Integrated circuits using up to six levels of
interconnects have been reported and even more complex circuits are
expected in the future. Device geometries have gone from 0.5 micron
to 0.12 micron and will soon be 0.08 micron. Multi-levels of
metallization are required in such devices to achieve the desired
speeds, and each inter-metal level must be planarized during the
manufacturing process. A known process with the ability to create a
sufficiently planar surface is chemical mechanical polishing (CMP).
CMP may be used to remove high topography and/or to remove defects,
scratches or embedded particles from the surface of a semiconductor
wafer as part of the manufacturing process.
[0003] The CMP process generally involves rubbing a surface of a
semiconductor wafer against a polishing pad under controlled
pressure, temperature and rotational speed in the presence of a
chemical slurry. An abrasive material is introduced between the
wafer and the polishing pad, either as particles affixed to the
polishing pad itself or in fluid suspension in the chemical slurry.
The abrasive particles may be, for example, alumina or silica. The
chemical slurry may contain selected chemicals, which function
together with the abrasive to remove a portion of the surface of
the wafer in a polishing action. The slurry also provides a
temperature control function and serves to flush the polishing
debris away from the wafer.
[0004] One important goal of CMP is achieving uniform planarity of
the substrate surface. Uniform planarity includes the uniform
removal of material from the surface of substrates as well as
removing non-uniform layers that have been deposited on the
substrate. Successful CMP also requires process repeatability from
one substrate to the next. Thus, uniformity must be achieved not
only for a single substrate, but also for a series of substrates
processed in a batch.
[0005] One factor that contributes to non-uniform polishing is
non-uniform distribution of the slurry at the interface of the
substrate and the polishing pad. One known technique to alleviate
the problem of poor slurry distribution has been to provide grooves
in the pad. The grooves are believed to control the distribution of
the slurry during operation by retaining a portion of the slurry in
the grooves. However, while such pad designs accommodate more
slurry volume than flat or planar pads, the pads have proved
somewhat ineffective in achieving uniformity in slurry distribution
because the inertia of the slurry causes the slurry to flow
radially outward and off of the pad during rotation of the pad.
[0006] In an attempt to achieve uniform distribution of fresh
slurry to all areas of the substrate, conventional techniques
generally rely on supplying a relatively large volume of slurry to
the pad during a polishing cycle. As a result, slurry becomes one
primary consumable in chemical mechanical polishing and a
significant source of the cost of operation. In order to reduce the
cost of operation, the volume of slurry used in a processing cycle
should be reduced. However, as noted above, conventional grooved
pads generally are not capable of efficiently retaining the slurry
between the pad and the substrate. As a result, the volume of
consumed slurry is higher than is desirable.
[0007] Another issue, due to the presence of grooves on the
polishing surface of a pad, can be mechanical effects that can
affect the polishing characteristics of the pad. For example, the
provision of grooves on the polishing surface can decrease the
stiffness of the pad to an unacceptably low level, resulting in
poor within-die uniformity.
[0008] Thus, it is desirable to provide a pad construction that
would allow for an appropriate balance between rigidity (or
stiffness) and compliance (or flexibility) of the polishing pad to
ensure within-die uniformity. Moreover, it is desirable to provide
a pad construction capable of reducing the cost of operation, such
as by reducing the volume of slurry used in a processing cycle, as
well as reducing a defect count, (e.g., number of scratches) that
can develop over the surface of a wafer subjected to a CMP
process.
BRIEF SUMMARY OF THE INVENTION
[0009] Generally, the present invention fulfills the foregoing
needs by providing in one aspect thereof, a chemical mechanical
polishing (CMP) pad. The CMP pad includes a groove pattern disposed
on a polishing surface of the pad. The groove pattern is formed of
an alternating sequence of spaced apart grooves. The alternating
sequence of grooves comprises a groove of a first size and a groove
of a second size, wherein the first and second groove sizes are
different relative to one another.
[0010] In another aspect thereof, the present invention further
fulfills the foregoing needs by providing a chemical mechanical
polishing system including a carrier for holding and moving a
semiconductor wafer during a chemical mechanical polishing process.
The polishing system includes a rotatable platen, and a chemical
mechanical polishing pad supported by the platen. A groove pattern
is disposed on a polishing surface of the pad. The groove pattern
may comprise an alternating sequence of spaced apart concentric
grooves. The alternating sequence of concentric grooves comprises a
groove of a first size and a groove of a second size, wherein the
first and second groove sizes are different relative to one
another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The features and advantages of the present invention will
become apparent from the following detailed description of the
invention when read with the accompanying drawings in which:
[0012] FIG. 1 illustrates a schematic representation of an
exemplary chemical mechanical polishing (CMP) system that may
benefit from aspects of the present invention.
[0013] FIG. 2 is a top view of a CMP pad embodying aspects of the
present invention.
[0014] FIG. 3 is a cross-sectional view along cutting plane 3-3 of
the polishing pad of FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[0015] A chemical mechanical polishing (CMP) system 10 may include
a carrier 12 for holding and moving a semiconductor wafer 14
against a polishing pad 16 embodying aspects of the present
invention, as described below. The polishing pad 16 may be
supported on a rotatable platen 18. A slurry 20 is used to provide
the desired chemical interaction and abrasion when the wafer 14 is
pressed and rotated against the polishing pad 16. As is known in
the art, the rate of material removal from the wafer 14 will depend
upon many variables, including the amount of force F exerted
between the wafer 14 and the polishing pad 16, the speed of
rotation R.sub.1 of the carrier, the speed of rotation R2 of the
platen, the transverse location of the carrier relative to the axis
of rotation of the platen, the chemical composition of the slurry,
the temperature, and the composition and history of use of the
polishing pad. Numerous configurations of CMP machines are known
and are available in the industry. One exemplary manufacturer of
such CMP machines is Applied Materials, Inc. of Santa Clara,
Calif.
[0016] A CMP pad is conventionally provided with grooves in its
polishing surface for slurry distribution and improved pad-wafer
contact. Aspects of the present invention allow providing a CMP pad
comprising a groove pattern configured to enhance positive effects
on the polishing characteristics of the pad while avoiding or
reducing potentially detrimental effects on the polishing
characteristics of the pad. Aspects of the present invention allow
for balancing various competing effects that can arise in a grooved
CMP pad. For example, grooves of increased size tend to decrease
the total area available for polishing the semiconductor wafer,
thereby decreasing the removal rate of material from the substrate.
However, grooves of increased size have been observed to provide
beneficial effects, such as providing a lower defect count over the
wafer surface, e.g., a lower number of scratches. Further, the
stiffness of the pad is affected by the configuration of the
grooves. In particular, an appropriate degree of stiffness is
needed to ensure within-die uniformity. This refers to the ability
of the CMP system to remove features on a local (or non-global)
scale across the diameter of the wafer regardless of wafer shape
and/or topography across its surface. It is noted, however, that an
appropriate degree of compliance (or flexibility) of the polishing
pad is desirable to meet planarity requirements across the entire
wafer. Accordingly, aspects of the present invention allow
providing in a single CMP pad a groove pattern configured to
balance various competing effects capable of influencing the
polishing characteristics of the pad.
[0017] The inventors of the present invention have observed that
improved within-die uniformity (WIDU) and lower defect count may be
achieved by providing a polishing pad 16 comprising a grooved
pattern 30 that, as illustrated in FIGS. 2 and 3, comprises two
distinct types of concentrically disposed grooves. A first of the
two groove types, referred to as "mini-grooves," comprises grooves
32 about 5 to 10 mils wide and 1 to 15 mils deep. A second of the
two groove types, referred to as "maxi-grooves" comprises grooves
34 about 15 to 60 mils deep by 10 to 60 mils wide. Aspects of the
present invention advantageously enhance positive effects
respectively provided by the mini-grooves and the maxi-grooves
while counter-acting effects that would be present if the
maxi-grooves or the mini-grooves were individually provided or not
appropriately arranged. For example, it has been observed that the
maxi-grooves, in addition to providing a lower-defect count, tend
to use relatively less slurry as compared to a grooved pattern just
comprising mini-grooves. Conversely, mini-grooves provide a
relatively stiffer CMP pad as compared to a grooved pattern just
comprising maxi-grooves. As noted above, a relatively stiffer CMP
pad provides improved within-die planarity. Accordingly, in one
exemplary embodiment, a grooved pattern embodying aspects of the
present invention comprises a circumferentially alternating
sequence of a mini-groove followed by a maxi-groove. This
concentric sequence of alternating maxi-grooves and mini-groves is
uniformly repeated as the concentric groves are spaced apart
relative to the center of the CMP pad.
[0018] In one exemplary embodiment groove pitch may range from
about 20 mils to about 80 mils depending on the requirements of the
specific application. Pitch of the grooved pattern may be
calculated as the average of mini-groove and maxi-groove pitch.
Depth of the grooved pattern may be calculated as the average of
mini- and maxi-groove depth. Width of the grooved pattern may be
calculated as the average of mini- and maxi-groove width.
[0019] In operation, a CMP pad comprising staggered mini- and
maxi-grooves, as described above, exhibits the type of superior
slurry transport normally associated with larger size grooves plus
the type of superior planarity normally associated with smaller
size grooves. The foregoing exemplary embodiments comprise
concentric grooves. It is contemplated, however, that CMP pads
comprising other groove geometrical arrangements or patterns may
benefit from a staggered arrangement of mini- and maxi-grooves.
Examples of such geometrical arrangements may include orthogonally
disposed grooves (X-Y oriented grooves), radially extending
grooves, and a spiral arrangement of grooves.
[0020] While the preferred embodiments of the present invention
have been shown and described herein, it will be obvious that such
embodiments are provided by way of example only. Numerous
variations, changes and substitutions will occur to those of skill
in the art without departing from the invention herein.
Accordingly, it is intended that the invention be limited only by
the spirit and scope of the appended claims.
* * * * *