U.S. patent application number 09/970689 was filed with the patent office on 2002-07-04 for multi characterized chemical mechanical polishing pad and method for fabricating the same.
Invention is credited to Moon, Jin-Ok.
Application Number | 20020086615 09/970689 |
Document ID | / |
Family ID | 19703748 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020086615 |
Kind Code |
A1 |
Moon, Jin-Ok |
July 4, 2002 |
Multi characterized chemical mechanical polishing pad and method
for fabricating the same
Abstract
A multi characterized CMP (Chemical Mechanical Polishing) pad
structure includes a lower pad and an upper pad. The lower pad
includes a lower central soft pad region and a lower peripheral
soft pad region formed outwardly of the lower central soft pad
region, with both the lower central soft pad region and the lower
peripheral soft pad region being located in a same plane of the
lower pad. The upper pad is disposed on the lower pad, and includes
an upper central hard pad region and an upper peripheral soft pad
region formed outwardly of the upper central hard pad region, both
the upper central hard pad region and the upper peripheral soft pad
region being located in the same plane of the upper pad. The lower
peripheral soft pad region has a lower hardness factor relative to
the lower central soft pad region, and the upper peripheral soft
pad region has substantially the same hardness factor as the lower
central soft pad region.
Inventors: |
Moon, Jin-Ok; (Seoul,
KR) |
Correspondence
Address: |
JONES VOLENTINE, P.L.L.C.
Suite 150
12200 Sunrise Valley Drive
Reston
VA
20191
US
|
Family ID: |
19703748 |
Appl. No.: |
09/970689 |
Filed: |
October 5, 2001 |
Current U.S.
Class: |
451/25 |
Current CPC
Class: |
B24B 37/22 20130101;
B24B 37/26 20130101 |
Class at
Publication: |
451/25 |
International
Class: |
B24B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2000 |
KR |
2000-83611 |
Claims
What is claimed is:
1. A multi characterized CMP (Chemical Mechanical Polishing) pad
structure, comprising: a lower pad comprising a lower central soft
pad region and a lower peripheral soft pad region formed outwardly
of the lower central soft pad region, both the lower central soft
pad region and the lower peripheral soft pad region being located
in a same plane of the lower pad; and an upper pad disposed on the
lower pad, the upper pad comprising an upper central hard pad
region and an upper peripheral soft pad region formed outwardly of
the upper central hard pad region, both the upper central hard pad
region and the upper peripheral soft pad region being located in
the same plane of the upper pad, wherein the lower peripheral soft
pad region has a lower hardness factor relative to the lower
central soft pad region, and the upper peripheral soft pad region
has substantially the same hardness factor as the lower central
soft pad region.
2. The CMP pad structure of claim 1, wherein the lower central soft
pad region has a first diameter, and the lower peripheral soft pad
region is a ring shaped region formed radially outward of the lower
central soft pad region, the lower peripheral soft pad region
having an outer diameter greater then the first diameter, and an
inner diameter equal to the first diameter.
3. The CMP pad structure of claim 2, wherein the upper central hard
pad region has a diameter equal to the first diameter, with the
upper central hard pad region lying on and being coextensive with
the lower central soft pad region, and the upper peripheral soft
pad region is a ring shaped region formed radially outward of the
upper central hard pad region, the upper peripheral soft pad region
having an outer diameter greater then the first diameter, and an
inner diameter equal to the first diameter.
4. The CMP pad structure of claim 3, further comprising an
attaching part formed on a lower surface of the lower pad, for
attaching the CMP pad to a table of a CMP apparatus.
5. The CMP pad structure of claim 4, further comprising an
attaching layer interposed between the upper pad and the lower
pad.
6. The CMP pad structure of claim 5, further comprising an adhesive
formed at an interface between the lower central soft pad region
and the lower peripheral soft pad region.
7. The CMP pad structure of claim 6, further comprising an adhesive
formed at an interface between the upper central hard pad region
and the upper peripheral soft pad region.
8. A multi characterized CMP (Chemical Mechanical Polishing) pad
structure, comprising: a lower pad comprising a lower homogeneous
soft pad region; and an upper pad disposed on the lower pad, the
upper pad comprising an upper central hard pad region and an upper
peripheral soft pad region formed outwardly of the upper central
hard pad region, both the upper central hard pad region and the
upper peripheral soft pad region being located in the same plane of
the upper pad, wherein the upper peripheral soft pad region has
substantially the same hardness factor as the lower homogeneous
soft pad region.
9. The CMP pad structure of claim 8, wherein the upper central hard
pad region has a first diameter, and the upper peripheral soft pad
region is a ring shaped region formed radially outward of the upper
central hard pad region, the upper peripheral soft pad region
having an outer diameter greater then the first diameter, and an
inner diameter equal to the first diameter.
10. The CMP pad structure of claim 9, wherein the lower homogeneous
soft pad region has a diameter substantially equal to the outer
diameter of the upper peripheral soft pad region.
11. The CMP pad structure of claim 10, further comprising an
attaching part formed on a lower surface of the lower pad, for
attaching the CMP pad to a table of a CMP apparatus.
12. The CMP pad structure of claim 11, further comprising an
attaching layer interposed between the upper pad and the lower
pad.
13. The CMP pad structure of claim 12, further comprising an
adhesive formed at an interface between the upper central hard pad
region and the upper peripheral soft pad region.
14. A method for fabricating a multi characterized CMP (Chemical
Mechanical Polishing) pad, comprising: preparing a first pad
mixture having a first hardness; injecting the first pad mixture
into a first mold; curing said first pad mixture within the first
mold to create a first cured ingot; removing the first cured ingot
from the first mold; preparing a second pad mixture having a second
hardness; injecting the second pad mixture into a second mold, the
second mold being peripherally formed around the first cured ingot,
wherein the second mold having an inner diameter equal to a
diameter of the first cured ingot, and an outer diameter greater
than the diameter of the first cured ingot; and integrally curing
the second pad mixture to the first cured ingot to create a multi
characterized ingot of a predetermined diameter.
15. The method of claim 14, further comprising cutting the multi
characterized ingot into a predetermined thickness.
16. The method of claim 14, wherein the first pad mixture has a
higher degree of hardness relative to the second pad mixture.
17. The method of claim 14, wherein the first pad mixture has a
lesser degree of hardness relative to the second pad mixture.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to equipment for fabricating a
semiconductor device, and more particularly, to a non-homogeneous
or multi characterized structure of a chemical mechanical polishing
(CMP) pad for use in CMP equipment, and a method for fabricating
the same.
[0003] 2. Description of the Related Art
[0004] Semiconductor devices are comprised of numerous integrated
circuits, which are produced by selectively and repeatedly
performing a series of photographic, etching, diffusive, metal
deposition, and other process steps. One particular process used on
mass produced semiconductor wafers is an etch-back or polishing
process to fully form device patterns that are pre-set on the
wafer.
[0005] A chemical mechanical polishing (CMP) process is widely used
in the semiconductor manufacturing field for horizontally
planarizing various kinds of layers, such as oxide layers, nitride
layers, metal layers and the like, which are sequentially deposited
on the semiconductor wafer to form the integrated circuits. The CMP
process is mostly used to polish metal or dielectric layers.
[0006] FIG. 1 is a typical CMP apparatus used to a polish a
semiconductor wafer that has completed a deposition process. In
FIG. 1, a polishing support, plate or table 2 is used for
supporting and rotating a CMP pad 4 positioned on the table 2. A
wafer 6 is fixed and rotated by a carrier 8, which moves vertically
to selectively contact the CMP pad 4, which CMP pad 4 is also
rotated at the same time by table 2. A slurry mixture, which
comprises a mixture of predetermined types of chemicals and other
ingredients, is provided at the central point of the CMP pad 4, and
then evenly distributed and coated on the upper surface of the CMP
pad 4 by the rotating force of the CMP pad 4. The semiconductor
wafer 6 attached to the wafer carrier 8 selectively contacts the
slurry covered CMP pad 4.
[0007] As a result of the relative rotation between the wafer 6 and
the CMP pad 4 and the slurry mixture on the surface of the CMP pad
4, both mechanical friction and chemical reactions take place, and
the material comprising the layer to be polished is gradually
removed from the surface of the wafer. As a result, a wafer is said
to be planarized to a certain pre-set thickness on the surface of
the wafer. It is well known that the ultimate quality of the
polished state of a thin wafer depends on several factors,
including, among others: (i) the mechanical friction between CMP
pad 4 and wafer 6, (ii) the material and state of the CMP pad 4,
(iii) the composition and distribution rate of the chemical slurry,
and (iv) the evenness or uniformity of the surface of the CMP pad
4.
[0008] With long-term utilization of the CMP equipment, the surface
of the CMP pad 4 will gradually show irregularities in uniformity,
making it difficult, if not impossible, to effectively polish the
surface of the wafer 6 to the desired degree of planarization.
[0009] Therefore, in an effort to ensure the desired degree of
evenness at the surface of the wafer 6 is maintained, a conditioner
9 is generally employed to uniformly grind the surface of the CMP
pad 4 at a predetermined time interval. The conditioner 9 includes
a grinding apparatus, such as artificial diamond structure, and the
grinding apparatus first moves vertically to contact the surface of
the CMP pad 4 and then rotates along the surface of the CMP pad 4
at a high speed. The conditioner 9 rotates and moves outwardly in a
radial direction along the rotating CMP pad 4, thereby performing a
conditioning process to remove a predetermined thickness of the
material along the entire surface of the CMP pad 4.
[0010] The CMP pad 4 is made of polyurethane based compound, with a
certain life cycle, so that it is impossible to use the CMP pad 4
for an unlimited amount of time by polishing with the conditioner
9. In other words, the CMP pad 4 must be replaced with a new CMP
pad after a certain period of time elapses.
[0011] As further shown in FIG. 1, the CMP pad 4 includes a lower
soft pad portion 20 contacting the table 2, and an upper hard pad
portion 10 which contacts the wafer 6. More particularly, as shown
in FIG. 2, the lower soft pad portion 20 is deposited on an
attaching part 25, which reinforces the bonding force with table 2
of the CMP equipment. The upper hard pad portion 10 is placed on
the lower soft pad portion 20, with another attaching layer 15
disposed therebetween. The attaching layer 15 functions to
integrate the soft and hard pads 20 and 10. For example, the "IC
1000" and "Suba IV" polishing pads produced by the RODEL Co. may be
used for the hard and soft pads 10 and 20, respectively. In another
embodiment as shown in FIG. 3, the lower soft pad 30 has a lower
degree of hardness relative to the hardness of the lower soft pad
20 of FIG. 2. The soft pad 30 may be a "Foam Pad" produced by the
RODEL Co.
[0012] The CMP pads shown in FIGS. 2 and 3 have been generally
constructed in the following manner. First, a mono-characterized or
homogeneous chemical ingot is formed, say from a polyurethane based
compound. The chemical ingot is then sliced into predetermined
sized pads, and then bonded together.
[0013] If a polishing process is performed with the conventional
CMP pads described above, CMP engineers face a problem in that
there may be a difference in the polishing rates at the center and
edge of a semiconductor wafer or chip. The difference in the
polishing rates leads to a dishing or recess being formed, which
produces an irregular surface on the polished semiconductor wafer.
To alleviate the dishing phenomenon, most engineers focus on the
non-uniformity of the slurry composition and the transfer rate of
the slurry, or changes in the speed of the wafer, as the main
causes of the problem to be corrected. They generally tend not to
focus on improving the quality of a CMP pad itself.
[0014] FIG. 4 is a graph illustrating various removal rates of soft
and hard pads at the center and edges of the wafer when a polishing
process is performed with a conventional mono-characterized CMP
pad. In FIG. 4, graphs 3a, 3b respectively indicate soft and hard
pads. As shown FIG. 4, the difference in the etching rates of the
hard pad at the center and edge of a wafer is more pronounced than
that of the soft pad. The level of uniformity is even lower in a
wafer having a large diameter of over 8 inches, as compared to a
smaller diameter wafer, thereby negatively affecting the yield of
products. For example, even if the amount of a interlayer
dielectric 4 (ILD4) to be removed by the aforementioned CMP pad
during the polishing step is very small, strong stresses may be
generated and concentrated at the edge of the wafer to damage a
semiconductor device pattern positioned at the edge of the
wafer.
[0015] Therefore, there has been a strong demand for development of
technology to improve polishing uniformity at the wafer level or
chip level of a wafer, to thereby prevent or minimize dishing or
recesses and any excessive damage caused to device patterns
positioned at the edge of the wafer.
SUMMARY OF THE INVENTION
[0016] It is an object of the present invention to provide an
improved structure of a CMP pad which can be adapted to presently
utilized CMP equipment, and a method for fabricating the same.
[0017] It is another object of the present invention to provide a
structure of a CMP pad to improve polishing uniformity of a wafer,
and a method for fabricating the same.
[0018] It is another object of the present invention to provide a
structure of a CMP pad to prevent or minimize dishing or recesses
from being formed during a CMP process, and a method for
fabricating the same.
[0019] It is another object of the present invention to provide a
structure of a CMP pad to prevent excessive damage to device
patterns at the edge of a wafer.
[0020] It is another object of the present invention to minimize
failures during a CMP process and stabilize the CMP process to
improve the yield of semiconductor device products.
[0021] To realize these and other objects, in a first aspect of the
present invention, there is provided a multi characterized CMP
(Chemical Mechanical Polishing) pad structure, which includes a
lower pad and an upper pad. The lower pad includes a lower central
soft pad region and a lower peripheral soft pad region formed
outwardly of the lower central soft pad region, with both the lower
central soft pad region and the lower peripheral soft pad region
being located in the plane of the lower pad. The upper pad is
disposed on the lower pad, and the upper pad includes an upper
central hard pad region and an upper peripheral soft pad region
formed outwardly of the upper central hard pad region, with both
the upper central hard pad region and the upper peripheral soft pad
region being located in the same plane of the upper pad. The lower
peripheral soft pad region has a lower hardness factor relative to
the lower central soft pad region, and the upper peripheral soft
pad region has substantially the same hardness factor as the lower
central soft pad region.
[0022] In another aspect, the present invention provides a lower
pad having a lower homogeneous soft pad region, combined with the
upper pad having an upper central hard pad region and an upper
peripheral soft pad region formed outwardly of the upper central
hard pad region. Both the upper central hard pad region and the
upper peripheral soft pad region are located in the same plane of
the upper pad. The upper peripheral soft pad region has
substantially the same hardness factor as the lower homogeneous
soft pad region.
[0023] In still another aspect, there is provided a method for
fabricating a multi characterized CMP (Chemical Mechanical
Polishing) pad, including preparing a first pad mixture having a
first hardness, and injecting the first pad mixture into a first
mold. The mixture is then cured to create a first cured ingot. A
second pad mixture is prepared and injected into a second mold,
peripherally formed around the first cured ingot. The second pad
mixture is integrally cured to the first cured ingot to create a
multi characterized ingot of a predetermined diameter. Preferably,
the hardness factors for the first and second pad mixtures are
different.
[0024] The multi characterized CMP pad structure and the method for
fabricating the same in the present invention are advantageous in
improving CMP process uniformity at the wafer level and chip level
of highly integrated semiconductor devices, while at the same time
stabilizing the process to increase product yields.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above objects and other advantages of the present
invention will become more apparent by describing in detail
preferred embodiments thereof with reference to the attached
drawings in which:
[0026] FIG. 1 is a schematic view illustrating the structure of
general CMP equipment;
[0027] FIG. 2 and FIG. 3 are cross-sectional views illustrating
structures of CMP pads in accordance with the conventional art;
[0028] FIG. 4 is a graph illustrating the removal rates of hard and
soft pads at the center and edge of a wafer;
[0029] FIG. 5 is a cross-sectional view illustrating a multi
characterized structure of a CMP pad in accordance with an
embodiment of the present invention;
[0030] FIG. 6 is a cross-sectional view illustrating a multi
characterized structure of a CMP pad in accordance with another
embodiment of the present invention;
[0031] FIG. 7 is a graph illustrating the relationship of hard pads
and soft pads relative to stress;
[0032] FIG. 8 is a flow diagram illustrating a sequence of steps to
fabricate a CMP pad in accordance with an embodiment of the present
invention; and
[0033] FIG. 9 is a schematic view illustrating a double mold used
to fabricate the CMP pad described with reference to FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The present invention will now be described more fully with
reference to the accompanying drawings, in which a preferred
embodiment of the invention is shown. This invention may, however,
be embodied in many different forms and should not be construed as
being limited to the embodiments set forth herein. Rather, the
embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey the concept of the invention to
those skilled in the art. In the drawings, the thickness of a layer
or region are exaggerated for clarity. It will also be understood
that when a layer is referred to as being "on " another layer or
substrate, it can be directly on the other layer or substrate, or
intervening layers may also be present.
[0035] FIG. 5 is a cross-sectional view illustrating the structure
of a CMP pad in accordance with an embodiment of the present
invention. As shown in FIG. 5, a lower pad 60 is constructed or
composed of two different soft pad regions, namely a lower central
soft pad region 20 and a lower peripheral soft pad region 30, both
of which are located in the same plane of the lower pad 60. The
lower central soft pad region 20 has a first diameter `x`, and the
lower peripheral soft pad region 30 is a ring shaped region formed
radially outward of the lower central soft pad region 20. The lower
peripheral soft pad region 30 has an inner diameter coexistent with
the first diameter `x`, and an outer diameter `y` larger than the
first diameter `x`. In other words, the lower peripheral soft pad
region has an outer diameter greater then the first diameter, and
an inner diameter equal to the first diameter. The lower peripheral
soft pad region 30 is softer (i.e., has a lower degree of
hardness), relative to the lower central soft pad region 20.
[0036] The upper pad 50 in FIG. 5 comprises an upper central hard
pad region 10 and an upper peripheral soft pad region 40, both of
which are located in the same plane of the upper pad 50. Upper
central hard pad region 10 has a diameter `x`, which is coextensive
with the lower central soft pad region 20, although it need not be.
In other words, the upper central hard pad region 10 can have a
diameter greater than or less than diameter `x`.
[0037] The upper peripheral soft pad region 40 is a ring shaped
region formed radially outward of the upper central hard pad region
10, and is coextensive with the lower peripheral soft pad region 30
in this embodiment. Here again, the upper peripheral soft pad
region 40 need not be coextensive with the lower peripheral soft
pad region 30. In this embodiment, the upper peripheral soft pad
region 40 has an inner diameter coexistent with the first diameter
`x`, and an outer diameter `y` larger than the first diameter `x`,
and corresponding to the lower soft pad region 30. The upper
peripheral soft pad region 40 is as soft (i.e., substantially the
same degree of hardness) as the lower central soft pad region 20.
For example, if the upper peripheral soft pad region 40 has a
hardness comparable to the "Suba IV" polishing pad made by RODEL
Co., the lower central soft pad region 20 would have a similar
hardness, and the lower peripheral soft pad region 30 would
correspond to that of the "Foam pad" made by RODEL Co. In this
example, the upper central hard pad 10 may be made of the "IC 1000"
polishing pad made by RODEL Co.
[0038] The lower pad 60 (comprising lower central soft pad region
20 and lower peripheral soft pad region 30) is secured to the
bonding table 2 via attaching part 25. The attaching layer 15
functions to integrate the upper pad 50 and lower pad 60.
[0039] The CMP pad structure shown in FIG. 5 is designed to achieve
reproducibility of CMP processes at the edge of a wafer.
Accordingly, the peripheral portion of the lower pad is composed of
a softer pad then the central portion of the lower pad. Also, the
peripheral portion of the upper pad is composed of a softer
material than the central portion of the upper pad. This CMP pad
design structure ensures the head pressure exerted by the CMP
equipment results in CMP pad uniformity during operation of the CMP
equipment.
[0040] FIG. 6 is a cross-sectional view illustrating a multi
characterized CMP pad structure in accordance with another
embodiment of the present invention. FIG. 6 differs from FIG. 5 in
that the lower pad 60 comprises a uniform or homogeneous lower soft
pad region 20' having a diameter `y`.
[0041] Similar to FIG. 5, the upper pad 50 in FIG. 6 comprises an
upper central hard pad region 10 and an upper peripheral soft pad
region 40, both of which are located in the same plane of the upper
pad 50. Upper central hard pad region 10 has a diameter `x`. The
upper peripheral soft pad region 40 is a ring shaped region formed
radially outward of the upper central hard pad region 10, and has
inner diameter coexistent with the first diameter `x`, and an outer
diameter `y` larger than the first diameter `x`. The upper
peripheral soft pad region 40 is as soft (i.e., substantially the
same hardness) as the lower central soft pad region 20. For
example, if the upper peripheral soft pad region 40 has a hardness
comparable to the "Suba IV" polishing pad made by RODEL Co., the
lower central soft pad region 20 would have a similar hardness. In
this example, the upper central hard pad 10 may be made of the "IC
1000" polishing pad made by RODEL Co.
[0042] The CMP pad structure shown in FIG. 6 is more suitable to
minimize stress at the edge of a wafer because the lower pad is
uniform and softer pads are applied to the peripheral portions of
the pad then the central portions of the pad. As a result, some
bending (elasticity) of the CMP pad occurs along the step coverage
characteristics at the part contacting the wafer to reduce stress
and optimally protect device patterns of the wafer.
[0043] This feature is better illustrated with reference to FIG. 7,
which is a graph showing the relationship of hard and soft pads
versus stress. In FIG. 7, intervals E1 and E2 respectively indicate
a device pattern portion with a small step coverage and another
device pattern portion with a large step coverage. Also, reference
symbols HP and SP respectively designate hard and soft pads. The
data for FIG. 7 was generated while the CMP pad was rotated at
about 150.about.200 rpm. From the data in FIG. 7, it can be seen
that the soft pad SP has a superior bending characteristic
(elasticity) relative to the hard pad HP, which means that that
soft pad is more appropriate to minimize stress on the edge
pattern.
[0044] With reference to FIGS. 8 and 9, we will now discuss a
method for fabricating a circular (or rotary) type CMP pad. An
important element of the method for fabricating the CMP pad in the
present invention is to form a multi-characterized pad within an
identical layer by using a double mold. Accordingly, a detailed
description of the slurry mixture or delivery rates thereof, as
used in a typical polishing process, is not undertaken in the
discussion of the method here, because they are well-known to the
molding related field and easily applied to the present
invention.
[0045] FIG. 8 is a flow diagram for illustrating a sequence of
processes to fabricate a CMP pad in accordance with an embodiment
of the present invention. FIG. 9 is a schematic view illustrating a
double mold to make the CMP pad described in FIG. 8.
[0046] First, a urethane polymer, a pore forming agent and a curing
agent prepared at steps 80, 81 and 82, respectively, are mixed by a
mixer in step 83. The urethane polymer is a type of resin,
comprising not just polyurethane, but at least one other material
selected from chemical groups such as isocyanate-capped
polyoxyethylene, polyester, vinyl-ester, acryl, ketone,
polytetrafluorethylene, polyprophylene, polyethylene, polyamide,
polyimide, phenolic, or the like. An organic polymer or silicon
based polymer is used as a pore forming agent to provide passage of
the slurry. The pore forming agent may be selected from one of the
group consisting of polyester, acrylic, acrylic ester co-polymer,
polyamide and polycarbonate.
[0047] This mixture of chemicals is cast into a mold at step 84,
more specifically, the mixture of chemicals is cast into an
internal mold 95 as shown in FIG. 9 to make the soft pad 20 in FIG.
5 or the hard pad 10 in FIGS. 5 and 6. At this time, an adhesive
may not be needed depending on the mixture materials of the pad,
but, if necessary, a suitable conventional adhesive should be
applied to the internal wall of the internal mold 95 prior to
casting the mixture in the mold.
[0048] The first pad mixture is then cured in the internal mold 95
at about 200.degree. F. for about 5 hours in step 85 to create the
inner ingot. After completion of step 85, the internal mold 95 is
removed. Then, a second pad mixture made in accordance with steps
80 through 83 is injected in the external mold 96 shown in FIG. 9,
which surrounds the previously cured inner ingot. The second pad
mixture is then cured in the external mold 96 at about 200.degree.
F. for about 5 hours (same as step 85 before). As a result, the
second pad mixture is cured and, at the same time, integrated with
the previously cured inner ingot. At this time, if pad ingot is
cured for forming the lower pad 60 shown in FIG. 5, the first and
second pad mixtures respectively are materials to form the lower
central soft pad region 20, and lower peripheral soft pad region
30.
[0049] After this multi-characterized pad ingot is completely
formed, the following conventional steps are carried out to
fabricate the CMP pad with a predetermined size and thickness. In
step 86, the ingot is cut or sliced into segments having a
predetermined thickness, perforated in step 87, grooved in step 88,
and pure sulfuric acid (PSA) is applied in step 89 to clean the
pad. In step 90, the base pad is laminated thereon, and in step 91,
the CMP pad is packaged.
[0050] In accordance with the aforementioned method for fabricating
the CMP pad, a chemical mixture of multi-characterized ingot is
made and cut into segments having a predetermined thickness.
Accordingly, the CMP pads shown in FIGS. 5 and 6 are made by
adequately attaching the segments of the multi-characterized pads
to correspond to the purpose for which they will be used.
[0051] When a polishing process is performed using the CMP pads
fabricated by the aforementioned method, the surface of the pad
will be detected with a sensor. The detection signal will be
transmitted to a controller so as to be monitored in a
three-dimensional profile. Accordingly, conditioning processes will
be periodically performed and a time to replace the CMP pad will be
determined by measurement of the degree of thickness reduced by
conditionings.
[0052] While the invention has been described in detail in terms of
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with various modifications or
changes within the spirit and scope of the appended claims. For
example, the present invention is not restricted to a rotary
polishing method. If a linear polishing method is performed, the
rotary pad structure described herein can be changed to a
multi-characterized belt type polishing pad.
[0053] As described above, there are advantages in the CMP pad
structure and the method for fabricating the same in that polishing
uniformity is improved, thereby preventing/minimizing dishing or
recesses, as well as preventing/minimizing excessive damage to
device patterns at the edge of a wafer. Thus, the prior drawbacks
and problems associated with conventional CMP processes are
minimized to improve uniformity of layers at the wafer or chip
level for highly integrated semiconductor devices, thereby
increasing the product yields.
* * * * *