U.S. patent application number 14/259646 was filed with the patent office on 2015-10-29 for chemical mechanical polishing pad.
This patent application is currently assigned to Taiwan Semiconductor Manufacturing Co., Ltd.. The applicant listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Chang-Sheng Lin.
Application Number | 20150306737 14/259646 |
Document ID | / |
Family ID | 54333930 |
Filed Date | 2015-10-29 |
United States Patent
Application |
20150306737 |
Kind Code |
A1 |
Lin; Chang-Sheng |
October 29, 2015 |
CHEMICAL MECHANICAL POLISHING PAD
Abstract
The present disclosure relates to a radiance decomposable CMP
pad, and an associated method to refresh the CMP pad. In some
embodiments, the CMP pad has a polymer layer and some macro pores
disposed therein. A monomer of the polymer layer has a photoactive
compound unit.
Inventors: |
Lin; Chang-Sheng; (Baoshan
Township, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsin-Chu |
|
TW |
|
|
Assignee: |
Taiwan Semiconductor Manufacturing
Co., Ltd.
Hsin-Chu
TW
|
Family ID: |
54333930 |
Appl. No.: |
14/259646 |
Filed: |
April 23, 2014 |
Current U.S.
Class: |
216/53 ;
156/345.12; 451/533 |
Current CPC
Class: |
B24D 3/346 20130101;
B24B 37/24 20130101 |
International
Class: |
B24D 3/34 20060101
B24D003/34; B24B 37/24 20060101 B24B037/24 |
Claims
1. A chemical mechanical polishing (CMP) pad comprising a polymer
layer and macro pores disposed therein, wherein a monomer of the
polymer layer comprises a photoactive compound (PAC) unit.
2. The CMP pad of claim 1, wherein the polymer layer is
decomposable through exposure to a radiance source.
3. The CMP pad of claim 2, wherein the radiance source is an
ultraviolet (UV) source.
4. The CMP pad of claim 1, wherein the PAC unit comprises
carboxylic of sulfonic acid with aromatic ring.
5. The CMP pad of claim 4, wherein the PAC unit comprises
9-anthracene carboxylic acid or
1,2-naphthoquinonediazide-5-sulfonic acid.
6. The CMP pad of claim 1, wherein the polymer layer comprises
polyurethane.
7. The CMP pad of claim 1, wherein the polymer layer comprises a
polyol unit (.OMEGA.) and a diisocyanate unit (.SIGMA.) wherein a
PAC unit is bonded to the polyol unit or the diisocyanate.
8. The CMP pad of claim 1, wherein a polymer chain of the polymer
layer comprises a structure of: ##STR00003## wherein x and y are
positive integers, PAC.sup.1 and PAC.sup.2 are same or different
units.
9. The CMP pad of claim 1, wherein the polymer layer comprises
polyol units (.OMEGA.), diisocyanate units (.SIGMA.) and PAC units
in order of: (.SIGMA.).sub.z-(.OMEGA.).sub.x-(PAC).sub.y or
(.SIGMA.).sub.z-(PAC).sub.y-(.OMEGA.).sub.x wherein x, y, z and n
are integers.
10. The CMP pad of claim 1, wherein the polymer layer comprises a
copolymer.
11. A chemical mechanical polishing (CMP) system, comprising: a
rotatable wafer carrier to hold a wafer face down to be processed;
a CMP pad disposed uniformly on a rotatable polishing platen
comprising a polymer layer; and a CMP dispenser to dispense a
slurry between the CMP pad and the wafer; wherein a monomer of the
polymer layer comprises a photoactive compound (PAC) unit.
12. The CMP system of claim 11 wherein the system is evidenced by
an absence of a pad conditioning disk.
13. The CMP system of claim 11, wherein a plurality of macro pores
are disposed in the polymer layer.
14. The CMP system of claim 11, further comprising a radiance
source disposed above the CMP pad.
15. The CMP system of claim 14, wherein the radiance source is an
ultraviolet source.
16. The CMP system of claim 15, wherein the ultraviolet source has
a wavelength range from approximately 100 nm to approximately 380
nm.
17. The CMP system of claim 15, wherein the ultraviolet source has
an energy range from approximately 10 mJ/cm.sup.2 to approximately
100 mJ/cm.sup.2.
18. A method of chemical mechanical polishing (CMP), the method
comprising: placing a wafer face down on a CMP pad; applying a
slurry between the wafer and the CMP pad; planarizing the wafer by
applying a pressure between the wafer and the CMP pad; wherein a
residue is formed on the CMP pad during the planarization;
irradiating the CMP pad by a radiance source, wherein a top portion
of the CMP pad is decomposed uniformly and removed together with
the residue; and cleaning the CMP pad by applying an aqueous
solution.
19. The method according to claim 18, wherein the CMP pad is
cleaned by applying high pressure deionized water.
20. The method according to claim 18, wherein the radiance source
is ultraviolet source and having an irradiation time in a range of
from approximately 5 seconds to approximately 40 seconds for an
irradiating cycle.
Description
BACKGROUND
[0001] In the manufacture of integrated circuits (ICs), devices are
formed on a wafer by forming various process layers, then
selectively removing or patterning portions of those layers and
depositing additional process layers thereon. An uppermost surface
after a deposition step is usually non-planar because of previous
selective patterning. A planarization process is performed in
succession to remove excess portions and prepare a flat surface for
the following process.
[0002] A chemical-mechanical polishing process (CMP process) is
utilized for the planarization. The wafer to be processed is held
upside down and forced against a rotating CMP pad. A slurry is
disposed between the CMP pad and wafer surface. Due to the applied
down force, this slurry, which includes chemicals that help
chemically dissolve the uppermost surface of the wafer and abrasive
particles that help physically wear away the uppermost surface,
provides for wafer surface planarization.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Aspects of the present disclosure are best understood from
the following detailed description when read with the accompanying
figures. It is noted that, in accordance with the standard practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
[0004] FIG. 1 shows a structural view of a CMP system in accordance
with some embodiments.
[0005] FIG. 2 shows a cross-sectional view of a CMP pad in
accordance with some embodiments.
[0006] FIG. 3 shows a flow diagram of a method of CMP in accordance
with some embodiments.
[0007] FIG. 4 shows a flow diagram illustrating a method of
polishing in accordance with some embodiments.
DETAILED DESCRIPTION
[0008] The following disclosure provides many different
embodiments, or examples, for implementing different features of
the provided subject matter. Specific examples of components and
arrangements are described below to simplify the present
disclosure. These are, of course, merely examples and are not
intended to be limiting. For example, the formation of a first
feature over or on a second feature in the description that follows
may include embodiments in which the first and second features are
formed in direct contact, and may also include embodiments in which
additional features may be formed between the first and second
features, such that the first and second features may not be in
direct contact. In addition, the present disclosure may repeat
reference numerals and/or letters in the various examples. This
repetition is for the purpose of simplicity and clarity and does
not in itself dictate a relationship between the various
embodiments and/or configurations discussed.
[0009] Further, spatially relative terms, such as "beneath,"
"below," "lower," "above," "upper" and the like, may be used herein
for ease of description to describe one element or feature's
relationship to another element(s) or feature(s) as illustrated in
the figures. The spatially relative terms are intended to encompass
different orientations of the device in use or operation in
addition to the orientation depicted in the figures. The apparatus
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
may likewise be interpreted accordingly.
[0010] Chemical-mechanical polishing (CMP) is a process utilized in
the semiconductor fabrication industry for planarization. In a CMP
process, a slurry including abrasive particles together with
chemicals is applied on a CMP pad to react with the uppermost layer
of a wafer and remove a non-planar portion thereof. The CMP pad
and/or asperities theron can become deformed during the wafer
polishing. Reaction residues, for example, or glazes adhering to
the CMP pad, may affect subsequent CMP processes by reducing
removal rates achieved by the CMP pad. For this reason, some CMP
systems use a conditioning disk, for example a diamond disk, to
remove such reaction residues. In some cases, the diamond disk may
introduce over-conditioning in which case a surface profile of the
CMP pad is damaged. In other cases, the diamond disk may introduce
under-conditioning in which case residues are not removed
completely. This over-conditioning or under-conditioning is
difficult to precisely control, making precise planarization with
diamond disks difficult to achieve. Also, to obtain the best
conditioning results, CMP systems go through a large number of
wafers, pads, and disks, as well as large amounts of slurry,
cleaning chemical, and tool time. Thus, a more efficient process to
remove residues and refresh the CMP pad properly is needed to keep
stable polish performance.
[0011] Accordingly, the present disclosure relates to apparatus and
methods which refresh CMP pads by irradiating UV decomposable CMP
pads with ultraviolet (UV) light. This UV light repairs or
reconditions a CMP pad surface that has been damaged or worn out by
previous CMP processing. For example, during previous CMP
processing, reaction residues can adhere to the CMP pad surface and
introduce an uneven surface which can damage the wafer during CMP
processing. The reaction residues can also cover portions of
grooves on the CMP pad surface, which are designed to retain
slurry. The reaction residues can comprise glazes generated by the
chemical reactions which occur during CMP processing, portions of
the processed wafer removed by the abrasive mechanical process, or
portions of the CMP pad removed during the CMP processing.
[0012] To remove the thin damaged surface region of the CMP pad
together with the reaction residues, if any, UV light is shone onto
the surface of the CMP pad to decompose a very thin top portion of
the CMP pads and thereby remove this thin top portion together with
any reaction residues in succession by some aqueous solution. In
this way, the CMP pad is refreshed for subsequent CMP processes.
This surface reconditioning by UV irradiation simplifies CMP
systems by removing or limiting the need for a conditioning disk.
Further, compared to conventional conditioning disks,
reconditioning by UV irradiation is more precise in that it can
decompose a only a very thin layer of a CMP pad. For example, some
embodiments of UV re-conditioning can remove a top portion of the
CMP pad with a thickness of less than about 0.001 mil, while
traditional mechanical removal of the CMP pad by the conditioning
disk removes about 0.05 mil to about 0.01 mil in every refreshment
cycle. Thus, the disclosed UV re-conditioning techniques for CMP
pads can increase the useful lifetime of CMP pads by approximately
5 to 20 times for a given pad thickness. Also, UV light has a more
precise control of the removal thickness which means a better
stability.
[0013] In some embodiments, the UV decomposable CMP pad is formed
by a polymer layer with photoactive units. These photoactive units
react with UV light, such that the CMP pad can be decomposed by the
UV light. In some embodiments, the method comprises placing a wafer
face down on a CMP pad, applying a slurry between the wafer and the
CMP pad and planarizing the wafer by applying a pressure between
the wafer and the CMP pad. The CMP pad is then exposed to a
radiance source, wherein a top portion of the CMP pad is decomposed
uniformly and removed together with a reaction residue. Then the
CMP pad is cleaned by applying an aqueous solution. By utilizing a
disclosed CMP pad and exposing the CMP pad to the radiance source,
the CMP pad is refreshed, thereby performing an optimized pad
conditioning.
[0014] FIG. 1 shows a structural view 100 of a CMP system in
accordance with some embodiments. The CMP system 100 can be
utilized to polish metal, semiconductor or insulator layers which
may include but are not limited to semiconductor thin films,
integrated circuit thin films and to polish any other films,
surfaces, and substrates where a CMP process is applied. A
rotatable wafer carrier 108 is disposed face to a rotatable
polishing platen 102. The rotatable wafer carrier 108 is utilized
to hold a wafer 106 upside down, for example with active device
structures face down and near the polishing platen 102. A CMP pad
104 is disposed on the rotatable polishing platen 102. The CMP pad
104 has a thickness of about 1 mm to about 4 mm. A CMP dispenser
110 is disposed above the CMP pad 104 to dispense a slurry 112
between the CMP pad 104 and the wafer 106. The slurry 112 can
comprise a chemical mechanical compositions and at least one
abrasive. The abrasive can be a metal oxide abrasive. Among other
proper materials, the metal oxide abrasive can be selected from the
group including Alumina, Zirconia, Germania, Silica, Cerium (IV)
oxide (Ceria) and mixtures thereof. A radiation source 114 is
disposed above the CMP pad 104. In some embodiments, the radiation
source 114 is an ultraviolet (UV) source having a wavelength range
from approximately 100 nm to approximately 380 nm. The UVsource may
have an energy range from approximately 10 mJ/cm.sup.2 to
approximately 100 mJ/cm.sup.2. The energy range of the UV source
corresponds to an irradiating time to the CMP pad 104 in a range of
several seconds to around one minute which is efficient and easy to
control.
[0015] FIG. 2 shows a cross-sectional view of the CMP pad 104 in
accordance with some embodiments. The CMP pad 104 comprises a first
polymer layer 204. In some embodiments, the CMP pad 104 can further
comprise macro pores 206 disposed in the polymer layer 204. The
macro pores 206 are utilized for holding and transporting slurry to
and from a surface (e.g. surface 212 or surface 214 after a
refreshing cycle) of the CMP pad 104. The macro pores 206 can be
distributed in all three dimensions of the polymer layer 204
randomly and uniformly. The macro pores 206 can have any suitable
density or void volume. In some other embodiments, the macro pores
206 can be replaced and/or supplemented by structures such as
grooves, channels, apertures or combinations thereof disposed in
the first polymer layer 204. The macro pores are disposed within a
significant depth of the first polymer layer 204 and help to retain
a slurry during a polishing process. Notably, the first polymer
layer 204 can be any CMP pad layer that comprises a suitable
polymer or can be prepared from any suitable polymer. For example,
the first polymer layer 204 may comprise polyurethane The first
polymer layer 204 may comprise a microporous urethane film. The
microporous urethane film can comprises a series of vertically
oriented cylindrical pores.
[0016] In some embodiments, the CMP pad 104 further comprises a
second polymer layer 202 can be disposed under the first polymer
layer 204. In some embodiments, the second polymer layer 202 can be
a polyester layer. The second polymer layer 202 may comprise
polyurethane impregnated into a polyester non-woven fabric. The
second polymer layer 202 can be used as a base material coated by
the microporous urethane film. The second polymer layer 202 has a
different hardness from the polymer layer 204, i.e., the second
polymer layer 202 can be either harder or softer than the first
polymer layer 204. The second polymer layer 202 can be a solid,
non-porous layer. The second polymer layer 202 is not typically
used as a polishing surface. The second polymer layer 202 helps to
support the polymer layer 204 and improve CMP performance.
[0017] In some embodiments, a thickness of the first polymer layer
204 can be from about 40 mil to about 150 mil. A hardness of the
first polymer layer 204 has a range of from approximately 5 shore A
to approximately 80 shore D. A density of the first polymer layer
204 has a range of from approximately 0.2 g/ml to approximately 1.2
g/ml. A compressibility of the first polymer layer 204 has a range
of from approximately 1% to approximately 30%.
[0018] In some embodiments, the first polymer layer 204 can
comprise a copolymer which is derived from at least two different
monomers. A photoactive compound (PAC) unit can be bonded to at
least one of the monomers of the first polymer layer 204's polymer
chain. For example, the PAC units can be bonded to a polyol monomer
or a diisocyanate monomer of the polymer layer 204. Or the PAC unit
can be an independent monomer bonded with other monomers of the
polymer layer to form a polymer chain. The PAC unit can be attached
to a terminal repeat unit or a non-terminal repeat unit of the
polymer chain. Thus, the polymer layer 204 can be decomposable by
exposing to the radiance source 114. A decomposed polymer layer can
be dissolved in an aqueous solution. The PAC unit can be any
suitable such unit. Existence of the PAC unit makes a top portion
208 of the polymer layer 204 decomposed with the exposure to the
radiance source. For example, the PAC unit can comprise carboxylic
of sulfonic acid with aromatic rings. For example, the PAC unit can
comprise 9-anthracene carboxylic acid or
1,2-naphthoquinonediazide-5-sulfonic acid. In some embodiments, the
PAC unit can comprise multi-aromatic rings, such as 2 to 7 aromatic
rings that are bonded together. Some example structures of the PAC
units are shown below:
##STR00001##
wherein x represents an oxygen, sulfur, or nitrogen atom.
[0019] In some embodiments, the PAC units can be bonded to a polyol
unit(.OMEGA.) or a diisocyanate unit (.SIGMA.) of a monomer of the
polymer layer 204. The monomer of the polymer chain of the polymer
layer 204 can be described by the following structures:
##STR00002##
wherein x and y are positive integers, and PAC.sup.1 and PAC.sup.2
can be same or different units.
[0020] In some other embodiments, the polymer layer 204 can
comprise a polyol unit(.OMEGA.) and a diisocyanate unit (.SIGMA.)
bonded together with the PAC unit. A monomer of the polymer chain
of the polymer layer 204 can be described by the following
structures:
(.SIGMA.).sub.z-(.OMEGA.).sub.x-(PAC).sub.y or
(.SIGMA.).sub.z-(PAC).sub.y-(.OMEGA.).sub.x
wherein x, y and z are positive integers.
[0021] Still referring to FIG. 2, when the CMP pad 104 is exposed
by the radiance source 114 for a selective period, the top portion
208 of a whole pad surface of the polymer layer 204 is decomposed
uniformly and can be removed by an aqueous solution. In this way, a
deformed or worn surface 212 is removed and replaced by a refreshed
surface 214. The refreshed surface 214 becomes flat with designed
asperities that can hold slurry well. Residues such as 210 are
removed together with the top portion 208 of the polymer layer 204.
In some embodiments, the top portion 208 of the polymer layer 204
has a thickness of from about 0.001 mil to 0.01 mil. The thickness
of the top portion 208 to be removed can be controlled by power
density and irradiation time of the radiance source 114.
[0022] FIG. 3 shows a flow diagram of a method 300 of CMP in
accordance with some embodiments. The CMP method 300 can be
configured to planarize a wide variety of wafer structures.
Exemplary wafer structures include, but are not limited to: Al
wiring, Cu wiring, W wiring, and the like.
[0023] At 302, a wafer is placed face down on a CMP pad. The wafer
can be held by a wafer carrier which can include a plurality of
variable-pressure chambers (not shown) for exerting either suction
or pressure onto backside of the wafer.
[0024] At 304, a slurry is applied between the wafer and the CMP
pad. The slurry comprises an abrasive to mechanically remove an
uppermost portion of the wafer and a chemical to dissolve the
uppermost portion of the wafer.
[0025] At 306, the wafer is planarized by applying a pressure
between the wafer and the CMP pad. A general-purpose controller
allows a variable down-force to be applied to the wafer carrier and
a polishing platen to be rotated at variable and independent rates,
and allows the slurry and/or other materials to be applied to the
polishing pad attached on the polishing platen.
[0026] During operation, the wafer carrier is preferably rotated
about spindle axis at a desired rate while the polishing platen is
preferably rotated around the platen axis at an independent desired
rate. In various embodiments, the slurry is comprised of slurry
particles present during polishing. In various embodiments, the
slurry particles are comprised of silica (SiO2) or alumina (Al2O3),
depending on the surface to be polished. The combined action of the
down-force of the wafer carrier, the respective rotations of the
wafer carrier and the polishing platen, and the chemical and
mechanical effects of the slurry combine to polish the surface of
the wafer to a desired planarity and thickness. A residue can be
formed on the CMP pad during the planarization, and the CMP pad can
be deformed during the polishing. For example, the residue can
introduce an uneven surface and cover the pores or grooves designed
to retain the slurry.
[0027] At 308, the CMP pad is irradiated by a radiance source. In
some embodiments, after polishing, the wafer carrier and the wafer
are lifted and can be removed from top of the polishing platen. The
deformed CMP pad can then be exposed to UV radiation from a UV
radiation source. A top portion of the CMP pad is decomposed
uniformly by the radiation. For example, in a refreshment cycle, a
UV radiation can be applied for about 5 seconds to about 40
seconds, a thickness of about 0.001 mil of the CMP pad can be
removed after a radiation scan. Notably, for traditional
refreshment approach, a worn portion of the CVD pad is removed
mechanically by a conditioning disk made of rigid material, for
example, diamond. Typical remove thickness every cycle is about
0.005 mil to 0.01 mil. The disclosed approaches extend the CMP pad
with a similar thickness about 5 to 10 times. Besides, more precise
control of the top portion removal of the CMP pad introduces higher
stability to the refreshment process. The disclosed approaches are
faster and improve efficiency. In some embodiments, the UV
radiation can be provided to the CMP pad intermittently or
continuously as an actual CMP operation is going on. Thus, UV
radiation can be provided to the CMP pad while the wafer and
polishing platen are rotating in the presence of slurry while
down-force is applied between wafer and polishing platen.
[0028] At 310, the CMP pad is cleaned by applying an aqueous
solution. The deformed pad is generally subjected to a
high-pressure spray of deionized water or other proper chemical
solutions to remove slurry residue and other particulate matter
from the pad. Other particulate matter may include wafer residue,
CMP slurry, oxides, organic contaminants, mobile ions and metallic
impurities.
[0029] By exposing the disclosed CMP pad to the radiation with
proper time and radiation energy after it had been deformed by a
polishing process, a thin top portion of the deformed CMP pad
becomes soluble to the aqueous solution, and is removed together
with reaction residues thereon. Method 300 refreshes the CMP pad
quickly (about one minute for a refresh cycle) and efficiently with
simplified CMP system configuration without a conditioning
disk.
[0030] The methods of the present invention may be implemented in
association with various types of monitoring components and
systems, and any such system or group of components, either
hardware and/or software, incorporating such a method is
contemplated as falling within the scope of the present
invention.
[0031] FIG. 4 shows a flow diagram illustrating a method of
polishing incorporating a CMP pad condition monitoring process in
accordance with some embodiments. The monitoring process for
example, can be realized by applying a pad probe or optical scan
over the CMP pad surface.
[0032] At 402, a CMP pad is forcefully pressed onto a wafer face
with slurry in place to planarize the wafer face. A wafer carrier
holding the wafer is preferably rotated about spindle axis at a
desired rate while a polishing platen supporting the CMP pad is
preferably rotated around platen axis at an independent desired
rate. In various embodiments, a slurry comprised of slurry
particles is present during polishing. The combined action of the
down-force of the wafer carrier, the respective rotations of the
wafer carrier and the polishing platen, and the chemical and
mechanical effects of the slurry combine to polish the surface of
the wafer to a desired planarity and thickness.
[0033] At 404, the processed wafer is unloaded. The wafer was held
by the wafer carrier which includes a plurality of
variable-pressure chambers (not shown) for exerting either suction
or pressure onto backside of the wafer. The wafer carrier is
removed from the top of the CMP pad and released the wafer after
planarization.
[0034] At 406, it is determined whether the CMP pad reached a worn
or spent conditionthrough the monitoring process. For example, in
some embodiments, this worn or spent condition can be met if groove
depths of the CMP pad are less than some predetermined groove
depth, or if a frictional constant of the CMP pad is less than some
predetermined frictional constant. In other embodiments, this worn
or spent condition can be met if a thickness of the CMP pad is less
than some predetermined thickness.
[0035] If the deformed CMP pad has not reached the worn or spent
condition, thenno pad refreshment is needed. A possible cleaning
process can be performed and a new wafer to be processed can be
loaded at 412. A repeated process of 402 to 406 will be performed.
Notably, "a new wafer" means another polishing cycle. It can be the
same wafer after some additional fabrication processes or a
different wafer.
[0036] If the deformed CMP pad has reached the worn or spent
condition, thena refreshment is performed at 408. The CMP pad is
irradiated by a radiance source, such as a UV light source. A top
deformed portion of the CMP pad is decomposed as a result.
[0037] At 410, the CMP pad is cleaned by applying an aqueous
solution. The deformed pad is generally subjected to a
high-pressure spray of deionized water or other proper chemical
solutions to remove slurry residue and other particulate matter
from the pad. Other particulate matter may include wafer residue,
CMP slurry, oxides, organic contaminants, mobile ions, and metallic
impurities. The refreshed CMP pad is ready for a next polishing
cycle started from loading a new wafer at 412.
[0038] The present disclosure is related to optimize CMP techniques
that refresh a CMP pad. A CMP pad comprises a polymer layer with a
PAC unit as part of its monomer such that it becomes soluble to
certain aqueous solution after certain time of exposure to a
radiance source. The CMP pad is refreshed by being exposed to the
radiance source and cleaned by the aqueous solution in succession.
As a result, better refreshment is achieved.
[0039] Thus, it will be appreciated that some embodiments relate to
a CMP pad. The CMP pad comprises a polymer layer and some macro
pores disposed therein. A monomer of the polymer comprises a
photoactive compound unit.
[0040] Other embodiments relate to a CMP system. The CMP system
comprises a rotatable wafer carrier to hold a wafer upside down to
be processed and a CMP pad disposed uniformly on a rotatable
polishing platen comprising a polymer layer. The CMP system further
comprises a CMP dispenser to dispense a slurry between the CMP pad
and the wafer. A monomer of the polymer layer comprises a
photoactive compound (PAC) unit.
[0041] Still other embodiments relate to a method of chemical
mechanical polishing. In this method, a wafer is placed face down
on a CMP pad. Then a slurry is applied between the wafer and the
CMP pad. Then the wafer is planarized by applying a pressure
between the wafer and the CMP pad. A residue is formed on the CMP
pad during the planarization. Then the CMP pad is irradiated by a
radiance source and a top portion of the CMP pad is decomposed
uniformly and removed together with the residue. At last, the CMP
pad is cleaned by applying an aqueous solution.
[0042] The foregoing outlines features of several embodiments so
that those skilled in the art may better understand the aspects of
the present disclosure. Those skilled in the art should appreciate
that they may readily use the present disclosure as a basis for
designing or modifying other processes and structures for carrying
out the same purposes and/or achieving the same advantages of the
embodiments introduced herein. Those skilled in the art should also
realize that such equivalent constructions do not depart from the
spirit and scope of the present disclosure, and that they may make
various changes, substitutions, and alterations herein without
departing from the spirit and scope of the present disclosure.
* * * * *