U.S. patent application number 15/638463 was filed with the patent office on 2019-01-03 for post-cmp cleaning apparatus and method with brush self-cleaning function.
The applicant listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Chun-Chieh CHAN, Chun-Jui CHU, Jen-Chieh LAI, Shih-Ho LIN, Yu-Chen WEI.
Application Number | 20190006204 15/638463 |
Document ID | / |
Family ID | 64739159 |
Filed Date | 2019-01-03 |
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United States Patent
Application |
20190006204 |
Kind Code |
A1 |
WEI; Yu-Chen ; et
al. |
January 3, 2019 |
POST-CMP CLEANING APPARATUS AND METHOD WITH BRUSH SELF-CLEANING
FUNCTION
Abstract
Apparatuses and methods for performing a post-CMP cleaning are
provided. The apparatus includes a chamber configured to receive a
wafer in need of having CMP residue removed. The apparatus also
includes a spray unit configured to apply a first cleaning solution
to at least one surface of the wafer. The apparatus further
includes a brush cleaner configured to scrub the at least one
surface of the wafer. In addition, the apparatus includes at least
one inner tank disposed in the chamber for storing a second
cleaning solution that is used to clean the brush cleaner.
Inventors: |
WEI; Yu-Chen; (New Taipei
City, TW) ; CHU; Chun-Jui; (Taoyuan City, TW)
; CHAN; Chun-Chieh; (Hsinchu City, TW) ; LAI;
Jen-Chieh; (Tainan City, TW) ; LIN; Shih-Ho;
(Jhubei City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsinchu |
|
TW |
|
|
Family ID: |
64739159 |
Appl. No.: |
15/638463 |
Filed: |
June 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/02096 20130101;
B24B 37/044 20130101; H01L 21/02052 20130101; H01L 21/67046
20130101; H01L 21/3212 20130101; H01L 21/30625 20130101; B08B 1/04
20130101; B24B 37/08 20130101; H01L 21/67051 20130101 |
International
Class: |
H01L 21/67 20060101
H01L021/67; B08B 1/04 20060101 B08B001/04; B24B 37/08 20060101
B24B037/08; B24B 37/04 20060101 B24B037/04 |
Claims
1. An apparatus for performing a post Chemical Mechanical Polish
(CMP) cleaning, the apparatus comprising: a chamber configured to
receive a wafer in need of having CMP residue removed; a spray unit
configured to apply a first cleaning solution to at least one
surface of the wafer; a brush cleaner configured to scrub the at
least one surface of the wafer; and at least one inner tank
disposed in the chamber for storing a second cleaning solution that
is used to clean the brush cleaner; wherein the at least one inner
tank comprises an inner compartment and an outer compartment,
wherein the inner compartment is configured to store the second
cleaning solution and receive the brush cleaner, and the outer
compartment is configured to receive the second cleaning solution
overflowing from the inner compartment.
2. The apparatus as claimed in claim 1, wherein the brush cleaner
is configured to be moved between a first position and a second
position, wherein the brush cleaner scrubs the at least one surface
of the wafer at the first position, and the brush cleaner is
submerged into the second cleaning solution in the at least one
inner tank at the second position.
3. The apparatus as claimed in claim 1, further comprising a liquid
delivery unit configured to supply the second cleaning solution
into the at least one inner tank.
4. The apparatus as claimed in claim 3, wherein the liquid delivery
unit comprises a heater that is used to heat the second cleaning
solution.
5. The apparatus as claimed in claim 1, wherein the at least one
inner tank has a high-frequency or megasonic vibrator therein.
6. The apparatus as claimed in claim 1, wherein the at least one
inner tank has a plurality of protruding structures formed on a
wall surface thereof and is configured to engage the brush
cleaner.
7. The apparatus as claimed in claim 6, wherein the brush cleaner
is configured to be pressed against and rotate over the plurality
of protruding structures.
8. (canceled)
9. The apparatus as claimed in claim 1, further comprising a drain
unit configured to drain the second cleaning solution from the
outer compartment.
10. An apparatus for performing a post-CMP cleaning, the apparatus
comprising: a chamber; a support mechanism comprising: a first
stage and a second stage positioned in the chamber, wherein the
support mechanism is operable in a first mode, in which a top
surface of the first stage faces upward and a top surface of the
second stage face a sidewall of the chamber, and a second mode, in
which the top surfaces of the first stage and the second stages
face each other; a spray unit configured to apply a first cleaning
solution to at least one top surfaces of the first stage; a brush
cleaner configured to move along the top surface of the first stage
in the first mode and move along the top surface of the second
stage in the second mode; and at least one inner tank disposed in
the chamber for storing a second cleaning solution, wherein the
brush cleaner is configured to be moved into the at least one inner
tank so that the brush cleaner is cleaned by the second cleaning
solution.
11. (canceled)
12. The apparatus as claimed in claim 10, wherein the first stage
is configured to support a wafer in a horizontal orientation in the
chamber so that a first surface of the wafer faces the brush
cleaner, and the second stage is configured to support the wafer in
a vertical orientation in the chamber so that a second surface of
the wafer faces the brush cleaner, the second surface being
opposite to the first surface.
13. The apparatus as claimed in claim 12, wherein one of the first
stage and the second stage is configured to tilt during the
transferring from the first mode to the second mode so as to
transfer the wafer thereon to the other one of the first stage and
the second stage.
14. The apparatus as claimed in claim 12, wherein at least one
sensor is mounted on at least one of the brush cleaner, the first
stage, and the second stage for detecting positions of the CMP
residue on the wafer.
15. The apparatus as claimed in claim 10, further comprising a
controller configured to control the brush cleaner to scrub over
the at least one surface of a wafer in a specific sweeping
profile.
16. A method for performing a post-CMP cleaning, the method
comprising: placing a wafer in need of having CMP residue removed
into a chamber; applying a first cleaning solution to at least one
surface of the wafer; scrubbing the at least one surface of the
wafer with a brush cleaner in the chamber; filling an inner
compartment of an inner tank in the chamber with a second cleaning
solution; moving the brush cleaner into the inner compartment of
the inner tank to clean the brush cleaner by the second cleaning
solution; and receiving the cleaning solution overflowing from the
inner compartment with an outer compartment of the inner tank.
17. The method as claimed in claim 16, further comprising
continuously supplying the second cleaning solution into the inner
tank when the brush cleaner is cleaned by the second cleaning
solution.
18. The method as claimed in claim 16, wherein the step of moving
the brush cleaner into the inner tank to clean the brush cleaner by
the second cleaning solution is performed either before or after
the at least one surface of the wafer is scrubbed by the brush
cleaner.
19. The method as claimed in claim 16, wherein the brush cleaner
comprises a pair of brushes configured to scrub both surfaces of
the wafer, and the brushes rub against each other after scrubbing
the surfaces of the wafer to perform a self-cleaning.
20. The method as claimed in claim 16, wherein the first cleaning
solution and the second cleaning solution are different types of
cleaning solutions.
21. The method as claimed in claim 16, further comprising draining
away the second cleaning solution from the outer compartment.
22. The apparatus as claimed in claim 10, wherein each of the first
stages and the second stages comprises an electrostatic chuck.
Description
BACKGROUND
[0001] Chemical Mechanical Polishing (CMP) processes are widely
used in the fabrication of integrated circuits. When an integrated
circuit is built up layer by layer on the surface of a
semiconductor wafer, CMP processes are used to planarize the
topmost layer to provide a planar surface for subsequent steps in
the fabrication process. CMP processes are carried out by polishing
the wafer surface against a polishing pad. A slurry containing both
abrasive particles and reactive chemicals is applied to the
polishing pad. The relative movement of the polishing pad and the
wafer surface coupled with the reactive chemicals in the slurry
allows the CMP process to planarize or polish the wafer surface by
means of both physical and chemical forces.
[0002] After a CMP process, the polished wafer surface is cleaned
to remove CMP residue, such as organic matter and abrasive slurry
particles, in order that the surface be made ready for subsequent
photolithography processes and other steps in the fabrication
process. In conventional post-CMP cleaning processes, brushes are
used to remove the residue on the polished wafers. The brushes are
typically formed of sponges.
[0003] Although existing apparatuses and methods for a post-CMP
cleaning process have been generally adequate for their intended
purposes, they have not been entirely satisfactory in all respects.
Consequently, it is desirable that a solution for performing a
post-CMP cleaning process be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] For a more complete understanding of the present disclosure,
and the advantages of the present disclosure, reference is now made
to the following descriptions taken in conjunction with the
accompanying drawings, in which:
[0005] FIG. 1 is a schematic view of partial elements of a post-CMP
cleaning apparatus in accordance with some embodiments.
[0006] FIG. 2 is a cross-sectional view of a nozzle in accordance
with some embodiments.
[0007] FIG. 3 is a schematic view of a spray bar equipped with a
filter in accordance with some embodiments.
[0008] FIG. 4A is a schematic view illustrating an intermediate
stage of a post-CMP cleaning process in accordance with some
embodiments.
[0009] FIG. 4B is a schematic view illustrating an intermediate
stage of a post-CMP cleaning process in accordance with some
embodiments.
[0010] FIG. 5 is a schematic view of an inner tank in accordance
with some embodiments.
[0011] FIG. 6 is a schematic view of an inner tank having inner and
outer compartments in accordance with some embodiments.
[0012] FIG. 7 is a schematic view of partial elements of a post-CMP
cleaning apparatus in accordance with some embodiments.
[0013] FIG. 8 is a schematic view illustrating that a first stage
tilts to transfer a wafer thereon to a second stage in accordance
with some embodiments.
[0014] FIG. 9 is a schematic view illustrating that the wafer's
backside surface is cleaned while the wafer is mounted on the
second stage in accordance with some embodiments.
[0015] FIG. 10 is a bottom view of a brush cleaner in accordance
with some embodiments.
[0016] FIG. 11 is a schematic view illustrating the brush cleaner
having a specific sweeping profile in accordance with some
embodiments.
[0017] FIG. 12 is a flow chart of a post-CMP cleaning method in
accordance with some embodiments.
[0018] FIG. 13 is a schematic view illustrating that the brushes of
the brush cleaner rub against each other to perform a self-cleaning
in accordance with some embodiments.
DETAILED DESCRIPTION
[0019] The following disclosure provides many different
embodiments, or examples, for implementing different features of
the invention. 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. Various features may be arbitrarily drawn in different
scales for the sake of simplicity and clarity.
[0020] Furthermore, spatially relative terms, such as "underlying,"
"below," "lower," "overlying," "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.
[0021] Apparatuses and methods for performing a post Chemical
Mechanical Polishing (CMP) cleaning are provided in accordance with
various exemplary embodiments. The variations of some embodiments
are discussed. Throughout the various views and illustrative
embodiments, like reference numbers are used to designate like
elements.
[0022] FIG. 1 schematically illustrates a perspective view of a
part of a post-CMP cleaning apparatus 1 in accordance with some
embodiments of the present disclosure. The post-CMP cleaning
apparatus 1 may be used to clean a wafer W after a CMP process.
More specifically, the post-CMP cleaning apparatus 1 may be used to
perform a post-CMP cleaning to remove CMP residue, such as organic
matter and abrasive slurry particles, from both surfaces (including
the polished wafer surface and backside surface) of the wafer W, in
order that the surfaces be made ready for subsequent steps in the
fabrication process. The wafer W may be a production wafer or a
test wafer made of silicon or other semiconductor materials.
[0023] As shown in FIG. 1, the post-CMP cleaning apparatus 1
includes a brush cleaner 10 including a pair of brushes 10A for
performing a scrubbing process onto both surfaces of the polished
wafer W. During the scrubbing process, the wafer W is supported by
several rollers 11 (support mechanism) in a vertical orientation in
a cleaning chamber 12 (see FIG. 4A) which encloses the brush
cleaner 10, and is rotatable by the rollers 11 as the arrow A1
indicated in FIG. 1.
[0024] The brushes 10A may, for example, be porous and/or sponge
like, and/or may be made of a resilient material such as polyvinyl
acetate (PVA). During the scrubbing process, each brush 10A is
rotatably (as the arrow A2 indicated in FIG. 1) mounted on the
respective spindle (not shown), and the two brushes 10A may be
driven by a drive mechanism 13 (for example a motor) or mechanisms
to move vertically (as the double-headed arrow A3 indicated in FIG.
1) along the diameter direction of the wafer W and rotate/scrub
over both surfaces of the wafer W. Also, the horizontal space D
between the two brushes 10A, related to the scrubbing force applied
to the wafer W, is adjustable by moving the brushes 10A via the
drive mechanism 13.
[0025] The post-CMP cleaning apparatus 1 also includes a fluid
delivery unit 14 for delivering a cleaning solution CS1 (first
cleaning solution) to the wafer W via a spray unit 15. The cleaning
solution CS1 may aid the scrubbing process performed by the brush
cleaner 10 by washing the CMP residue from the brushes 10A and/or
the surfaces of the wafer W.
[0026] The cleaning solution CS1 may include various types, wherein
different types of the cleaning solution CS1 may be used to clean
different CMP residue on the wafer W. In accordance with some
embodiments, the cleaning solution CS1 includes water with no
chemicals intentionally added. The cleaning solution CS1 may also
be deionized water. In alternative embodiments, the cleaning
solution CS1 includes an acid aqueous solution, which may include
an organic acid such as citric acid, an inorganic acid such as
HNO.sub.3, or the like. In yet alternative embodiments, the
cleaning solution CS1 includes an alkaline aqueous solution, which
may include an organic base such as NR.sub.3 (with R being alkyl),
an inorganic base such as NH.sub.4OH, or the like. Surfactants such
as sodium dodecyl sulfate may also be added into the cleaning
solution CS1 to reduce the surface tension thereof. The cleaning
solution CS1 may include water as a solvent. Alternatively, the
cleaning solution CS1 may use organic solvents such as methanol.
The cleaning solution CS1 may also be an aqueous solution including
peroxide. For example, the cleaning solution CS1 may include
H.sub.2O.sub.2 in water.
[0027] As shown in FIG. 1, the spray unit 15 includes a pair of
spray bars 15A fluidly connected to the fluid delivery unit 14. The
two spray bars 15A are respectively adjacent to both sides of the
wafer W. Several nozzles 15B are mounted on each spray bar 15A for
spraying the cleaning solution CS1 onto the wafer W. Although not
shown, during the scrubbing process, the two spray bars 15A may be
driven by a drive mechanism (for example a motor) or mechanisms to
rotate (to predetermined orientations) so that the cleaning
solution CS1 is accurately directed to both surfaces of the wafer W
via the nozzles 15B. The spray bars 15A may comprise a metal
material (such as stainless steel). The nozzles 15B may comprise
ceramics, quartz, or any other anti-corrosive materials (such as
plastic).
[0028] Various spray shapes of the cleaning solution CS1, including
a jet shape, a fan shape, a mist shape, or the like, may be
generated by the nozzles 15B. In accordance with some embodiments,
the nozzle 15B has a rounded nozzle hole O, a first inner path T1,
and a second inner path T2 surrounding the first inner path T1 as
shown in FIG. 2. The first inner path T1 is fluidly connected to a
gas source (not shown) which is used to supply N.sub.2 or other
inert gas, and the second inner path T2 is fluidly connected to the
spray bar 15A. With this configuration, the cleaning solution CS1
discharged from the nozzle hole O may have various spray shapes due
to the mixing of the inert gas in the first inner path T1 with the
cleaning solution CS1 in the second inner path T2. For example, the
nozzle 15B may spray the cleaning solution CS1 with a fan shape (as
shown in FIG. 2) if the gas source has a medium pressure such as 50
to 250 psi. Alternatively, the nozzle 15B may spray the cleaning
solution CS1 with a jet shape if the gas source has a higher
pressure such as 250 to 1000 psi, or spray the cleaning solution
CS1 with a mist shape if the gas source has a lower pressure such
as 10 to 50 psi. It should be appreciated that the nozzles 15B may
also include several configurations and are not limited to the
embodiments described above.
[0029] In accordance with some embodiments, the spray bar 15A may
have a filter 15C therein in order to prevent impurities such as
dust and organic material within the cleaning solution CS1 from
adhering onto the wafer W or blocking the nozzles 15B. For example,
the filter 15C may be mounted on the inlet end (i.e. the end
connected to the fluid delivery unit 14) of the spray bar 15A to
filter impurities X of the cleaning solution CS1 as shown in FIG.
3. The filter 15C may be a mesh filter with pore size in a range
from, for example, 1 nm to 1 .mu.m, and may be made of stainless
steel, plastic, nylon, or woven fiberglass. In accordance with some
embodiments, a cleaning pipe 15D may also be inserted into the
spray bar 15A through an hole (not shown) on the spray bar 15A to
wash the filter 15C via a cleaning fluid (such as deionized water
or other applicable chemical cleaning solutions) and take away the
impurities X from the filter 15C. Therefore, replacement of the
filter 15C may be reduced. The cleaning pipe 15D may comprise
rubber or any other anti-corrosive materials (such as plastic).
[0030] Referring back to FIG. 1, the post-CMP cleaning apparatus 1
also includes a controller 16 coupled to the fluid delivery unit 14
and the drive mechanism 13 and configured to control their
operation. For example, the controller 16 may comprise a
microprocessor, and the microprocessor may be programmed to active
and/or control the fluid delivery unit 14 so as to deliver the
cleaning solution CS1 to the spray unit 15 at predetermined times
and/or rates, and/or for a predetermined length of time. Similarly,
the microprocessor of the controller 16 may be programmed to active
and/or control the drive mechanism 13 so as to move and/or rotate
the brushes 10A of the brush cleaner 10 at predetermined times
and/or rates, and/or for a predetermined length of time. Although
not shown, the controller 16 may also be coupled to the rollers 11
and exert similar control over the rotation of the wafer W.
[0031] As the post-CMP cleaning apparatus 1 removes the CMP residue
from the surfaces of the wafer W during the scrubbing process, the
CMP residue may tend to adhere to and build up on the porous
surface of the brushes 10A, which eventually contaminates the
brushes 10A and render them ineffective. In addition, the CMP
residue accumulated on the brushes 10A is likely to re-adhere to
the wafer W, resulting in lower cleaning quality of the post-CMP
cleaning process. Because of cost pressures, the dirty brushes 10A
may also not be changed frequently.
[0032] The post-CMP cleaning apparatus 1 in accordance with some
embodiments further include a brush self-cleaning
function/mechanism for cleaning the dirty brushes 10A (prolonging
their life) and improving the cleaning quality of the post-CMP
cleaning process using the post-CMP cleaning apparatus 1, which
will be illustrated in FIGS. 4 to 6.
[0033] FIGS. 4A and 4B schematically illustrate two intermediate
stages of a post-CMP cleaning process using a post-CMP cleaning
apparatus (for example the post-CMP cleaning apparatus 1 described
above) in accordance with some embodiments. The brushes 10A in the
post-CMP cleaning apparatus 1 is configured to be moved between a
first position P1 shown in FIG. 4A and a second position P2 shown
in FIG. 4B.
[0034] At the first position P1, the brushes 10A may perform a
scrubbing process upon the polished wafer W after a CMP process.
More specifically, after the wafer W is vertically loaded into the
chamber 12, the brushes 10A may move vertically (as the
double-headed arrow A3 indicated in FIG. 4A) along the diameter
direction of the wafer W to rotate/scrub (as the arrows A2
indicated in FIG. 4A) over both surfaces of the wafer W while it is
rotated by several rollers (not shown). At the same time, a
cleaning solution CS1 (first cleaning solution) may be sprayed onto
both surfaces of the wafer W via the spray unit 15 described above.
Through cooperation of the scrubbing force from the brushes 10A and
the washing force of the cleaning solution CS1, the CMP residue on
the surfaces of the wafer W is removed.
[0035] Afterwards, the wafer W is retrieved out of the chamber 12,
and the brushes 10A are moved horizontally to the second position
P2 (FIG. 4B) and submerged into a cleaning solution CS2 (second
cleaning solution) stored in two inner tanks 17 in the chamber 12
so as to be cleaned by the cleaning solution CS2 (i.e. to perform a
brush cleaning process).
[0036] The position of the two inner tanks 17 (i.e. the second
position P2) may be close to opposite sidewalls of the chamber 12
and spaced from the first position P1 by a distance, which can
prevent the cleaning solution CS1 that have been used to clean the
wafer W falling from the wafer W and the brushes 10A from entering
the inner tanks 17 to contaminate the cleaning solution CS2.
Although not shown, the chamber 12 may also have a discharge
opening formed on the bottom surface thereof. A drain unit fluidly
connected to the discharge opening may be used to drain the
cleaning solution CS1 (and/or the cleaning solution CS2 overflowing
from the inner tanks 17) from the chamber 12.
[0037] In accordance with some embodiments, the inner tanks 17 are
independently disposed in the chamber 12 and comprise ceramics,
quartz, or any other anti-corrosive materials (such as plastic).
Alternatively, the inner tanks 17 and the chamber 12 are integrally
formed in one piece.
[0038] In accordance with some embodiments, the cleaning solution
CS2 includes an alkaline aqueous solution with pH value greater
than or equaling 7.5, such as NH.sub.4OH, NaOH, Tetramethyl Ammnium
Hydroxide (TMAH), or the like, in order for the CMP residue engaged
on the porous surface of the brushes 10A to be removed effectively.
In accordance with some embodiments, the first cleaning solution
CS1 and the second cleaning solution CS2 are different types of
cleaning solutions. Alternatively, the cleaning solution CS1 and
the cleaning solution CS2 are the same type of cleaning
solutions.
[0039] FIG. 5 schematically illustrates the internal configuration
of an inner tank 17 in accordance with some embodiments. As shown
in FIG. 5, the inner tank 17 has an inlet opening 17A formed on a
wall surface thereof for fluidly connecting a liquid delivery unit
18. The liquid delivery unit 18 is configured to supply the
cleaning solution CS2 into the inner tank 17. In some embodiments,
when the brush 10A is submerged into and cleaned by the cleaning
solution CS2, the liquid delivery unit 18 continuously supplies the
cleaning solution CS2 into the inner tank 17 to make the cleaning
solution CS2 in the inner tank 17 flow and overflow upwardly into
the chamber 12 (FIG. 4B). Therefore, the cleaning solution CS2
stored in the inner tanks 17 can be kept fresh and clean (i.e. the
cleaning solution CS2 containing the CMP residue from the brushes
10A may leave the inner tanks 17), improving the efficiency of
cleaning the brushes 10A.
[0040] In accordance with some embodiments, the liquid delivery
unit 18 may include a heater 18A for heating the cleaning solution
CS2 supplied to the inner tank 17 as shown in FIG. 5. For example,
the cleaning solution CS2 may be heated by the heater 18A to have a
temperature between about 15.quadrature. and about 25.quadrature..
The cleaning solution CS2 may also be heated by the heater 18A to a
temperature in the range between about 25.quadrature. and about
80.quadrature.. With the increased temperature, the efficiency of
cleaning the brush 10A may be improved. Alternatively, a
temperature higher than about 80.quadrature. or lower than about
15.quadrature. may also be used.
[0041] In accordance with some embodiments, the inner tank 17 may
also have a vibrator 19 therein as shown in FIG. 5, which is
configured to induce a vibration to the cleaning solution CS2,
thereby improving the efficiency of cleaning the brush 10A. The
vibrator 19, such as a high-frequency vibrator, a megasonic
vibrator, or the like, may be attached to one wall surface of the
inner tank 17.
[0042] In accordance with some embodiments, the inner tank 17 may
also have several protruding structures 17B formed on a wall
surface thereof as shown in FIG. 5. The protruding structures 17B
are configured to engage the brush 10A when the brush 10A is
submerged into and cleaned by the cleaning solution CS2 in the
inner tank 17. For example, while submerged into the cleaning
solution CS2 in the inner tank 17, the brush 10A may be driven by
the drive mechanism 13 (FIG. 13) to be pressed against and rotate
(as the arrow indicated in FIG. 5) over the protruding structures
17B. Therefore, the CMP residue engaged on the porous surface of
the brushes 10A can be effectively removed by friction between the
brush 10A and the protruding structures 17B of the inner tank
17.
[0043] The heater 18A, the vibrator 19, and the protruding
structures 17B may be used independently or together, according to
the actual requirements and the operation conditions. Although not
shown, the inner tank 17 may also have a discharge opening formed
on the bottom surface thereof. A drain unit fluidly connected to
the discharge opening may be used to drain the cleaning solution
CS2 from the inner tank 17.
[0044] FIG. 6 schematically illustrates an inner tank 17 having an
inner compartment 171 and an outer compartment 172 in accordance
with some embodiments. The inner compartment 171 is configured to
store cleaning solution CS2 and receive the brush 10A. In other
words, the brush 10A is submerged into the cleaning solution CS2
stored in the inner compartment 171 during the brush cleaning
process. Similar to the embodiments in FIG. 5, a liquid delivery
unit 18 is configured to supply the cleaning solution CS2 into the
inner compartment 171. Also, a heater 18A of the liquid delivery
unit 18 may be used to heat the cleaning solution CS2 supplied to
the inner compartment 171.
[0045] The outer compartment 172 is configured to receive the
cleaning solution CS2 overflowing from the inner compartment 171
(i.e. to provide a buffer tank outside the inner compartment 171).
Moreover, a drain unit 20 may be coupled to the outer compartment
172 to drain the cleaning solution CS2 from the outer compartment
172. With this configuration, the cleaning solution CS2 in the
inner tank 17 may not overflow into the chamber 12 (FIG. 4B), and
hence an interaction occurring between the cleaning solution CS2
and the cleaning solution CS1 remained in the chamber 12 may be
avoided. Also, the chemical solution handling at the downstream
ends of the drain unit coupled to the chamber 12 and the drain unit
20 coupled to the inner tank 17 may be simplified further.
[0046] By providing inner tanks 17 (such as the inner tanks 17 in
FIGS. 4 to 6) into the chamber 12 to store a cleaning solution CS2,
the brushes 10A (i.e. the brush cleaner 10) may be submerged into
and cleaned by the cleaning solution CS2 after the scrubbing
process. Alternatively, the brushes 10A may also be submerged into
and cleaned by the cleaning solution CS2 before the scrubbing
process in accordance with some embodiments. It is therefore a
brush self-cleaning function in the post-CMP cleaning apparatus 1
is achieved, resulting in the extended lifespan of the brush
cleaner 10. Furthermore, the cleaning quality of the post-CMP
cleaning process using the post-CMP cleaning apparatus 1 is also
improved because the brush cleaner 10 is maintained at consistent
levels of cleanliness for the wafers W from batch-to-batch and
job-to-job.
[0047] The above inner tanks 17 may also be used in various types
of post-CMP cleaning apparatuses. Referring to FIG. 7, which
schematically illustrates a perspective view of a part of another
post-CMP cleaning apparatus 1' in accordance with some embodiments
of the present disclosure. The post-CMP cleaning apparatus 1'
includes a chamber 12, a first stage 11A and a second stage 11B
(support mechanism), a spray unit 15, a brush cleaner 10, and an
inner tank 17. The configuration and function of the chamber 12 and
the inner tank 17 are the same or similar to those in the above
embodiments (FIGS. 1 to 6) and thus are not repeated here.
[0048] The first stage 11A is configured to support a polished
wafer W in a horizontal orientation in the chamber 12 so that a
first surface S1 (for example the polished wafer surface) of the
wafer W faces the brush cleaner 10 during a scrubbing process
(which will be illustrated later) as shown in FIG. 7. During the
scrubbing process, the wafer W can be held on top of the first
stage 11A using an electrostatic chuck (not shown) therein.
Alternatively, other clamping means may also be used.
[0049] Moreover, the first stage 11A connects to a spindle 111 as
shown in FIG. 7, and the first stage 11A and the wafer W thereon
can be rotated (as the arrow indicated in FIG. 7) by a drive
mechanism 21 coupled to the spindle 111 during the scrubbing
process. In accordance with some embodiments, the first stage 11A
is rotated in a speed range from 0 to 600 rpm. The drive mechanism
21 may also be used to drive first stage 11A to move along a
direction perpendicular to the surface of the wafer W. The drive
mechanism 21 may comprise a cylinder, a motor, a roller, a belt, or
a combination thereof.
[0050] The second stage 11B is configured to support the wafer W in
a vertical orientation in the chamber 12 so that a second surface
S2 (for example the backside surface opposite to the first surface
S1) of the wafer W faces the brush cleaner 10 during the scrubbing
process as shown in FIG. 9. The mechanisms for holding the wafer W
on the second stage 11B and rotating/moving the second stage 11B
are the same or similar to those for the first stage 11A and thus
are not repeated here.
[0051] In accordance with some embodiments, after the brush cleaner
10 scrubs/rotates over the first surface S1 of the wafer W held on
the first stage 11A to remove the CMP residue from the first
surface S1, the first stage 11A may also be driven by the drive
mechanism 21 to tilt so as to transfer the wafer W thereon to the
second stage 11B as shown in FIG. 8. The tilt angle .theta. of the
first stage 11A with respect to the bottom surface of the chamber
12 is between about 0 degree and about 90 degrees. Afterwards,
after the brush cleaner 10 scrubs/rotates over the second surface
S2 of the wafer held on the second stage 11B to remove the CMP
residue from the second surface S2 (FIG. 9), the second stage 11B
may also be driven by the drive mechanism 21 to tilt (not shown) so
as to transfer the wafer W thereon back to the first stage 11A for
subsequent steps (e.g. removing the wafer W from the chamber
12).
[0052] In accordance with some embodiments, a heater (not shown)
may also be mounted in the first stage 11A and/or the second stage
11B for heating the wafer W to have a temperature between about
25.quadrature. and about 85.quadrature., so that the CMP residue on
the wafer W can be removed more easily.
[0053] As shown in FIG. 7, the spray unit 15 includes a spray bar
15A and several nozzles 15B (only one nozzle 15B is depicted due to
the restricted viewing angle) mounted on the spray bar 15A. The
configuration and function of the spray bar 15A and nozzles 15B are
the same or similar to those in the above embodiments (FIGS. 1 to
3) and thus are not repeated here. It should only be noted that the
spray unit 15 is disposed adjacent to both the first stage 11A and
the second stage 11B and may be driven by a drive mechanism (for
example a motor (not shown)) to rotate so as to spray the cleaning
solution CS1 onto the first surface S1 or the second surface S2 of
the wafer W based on the location and/or movement of the brush
cleaner 10 during the scrubbing process.
[0054] As shown in FIGS. 7, 9, 10 and 11, the brush cleaner 10
includes a brush 10B which is configured as a disk shape. More
specifically, the brush 10B has a disk-shaped main body B1 and
several protrusions B2 formed on the bottom of the main body B1,
wherein the main body B1 may be of plastic material with enough
structural strength and the protrusions B2 may be made of a
resilient material such as PVA. The brush 10B scrubs and removes
the CMP residue on both surfaces S1 and S2 of the wafer W via the
resilient protrusions B2. In accordance with some embodiments, the
diameter of the main body B1 is in the range between about 2 inches
and about 6 inches. Alternatively, the diameter of the main body B1
may also be greater than about 6 inches.
[0055] In accordance with some embodiments, the top of the main
body B1 is coupled to a robotic arm 13' which is configured to
moving the brush 10B across over both surfaces S1 and S2 of the
wafer W to perform the scrubbing process. Moreover, the robotic arm
13' is electrically connected to a controller 16 (similar to the
controller 16 of the above embodiments) which may be programmed to
active and/or control the robotic arm 13' so as to move and/or
rotate (as the arrow indicated in FIG. 11) the brush 10B at
predetermined times and/or rates, and/or for a predetermined length
of time, and/or in a specific sweeping profile R (FIG. 11) above
both surfaces S1 and S2 of the wafer W. The specific sweeping
profile R includes various types which may be changed based on the
actual requirements for improving the cleaning efficiency of the
brush cleaner 10.
[0056] In accordance with some embodiments, a sensor B3 may also be
mounted on the brush cleaner 10, for example, mounted at the center
of the main body B1 (FIG. 10), for detecting the position of the
CMP residue on both surfaces S1 and S2 of the wafer W. Although it
is not shown, the sensor B3 is electrically connected to the
controller 16, and the controller 16 may control the operation of
the brush cleaner 10 based on a detection signal from the sensor
B3. For example, if the sensor B3 detects a CMP residue located at
a specific position on the wafer W and generates a detection
signal, the controller 16 may control the brush cleaner 10 based on
the detection signal to stay at the specific position for a longer
time and/or rotate at a higher speed so as to successfully remove
the CMP residue. Alternatively, the controller 16 may also control
to robotic arm 13' so as press the brush cleaner 10 against the
wafer W with a higher pressure based on the detection signal so as
to remove the CMP residue on the specific position of the wafer
W.
[0057] In accordance with some embodiments, one or more sensors B3
may also be mounted on the brush cleaner 10, the first stage 11A,
and/or the second stage 11B for detecting the position of the CMP
residue on both surfaces S1 and S2 of the wafer W. There are
various types of sensors B3, including optical sensors, infrared
sensors, motor torque sensors, and gas pressure sensors.
[0058] With the above configuration, the CMP residue on both
surfaces S1 and S2 of the wafer W can be removed by the scrubbing
force from the brush cleaner 10 in cooperation with the washing
force of the cleaning solution CS1.
[0059] It should also be noted that the brush cleaner 10 may be
submerged into and cleaned by a cleaning solution CS2 stored in the
inner tank 17 disposed in the chamber 12 before or after the above
scrubbing process. Therefore, a brush self-cleaning function in the
post-CMP cleaning apparatus 1' is achieved, resulting in the
extended lifespan of the brush cleaner 10. Furthermore, the
cleaning quality of the post-CMP cleaning process using the
post-CMP cleaning apparatus 1' is also improved because the brush
cleaner 10 is maintained at consistent levels of cleanliness for
the wafers W from batch-to-batch and job-to-job.
[0060] Although the post-CMP cleaning apparatuses 1 and 1' of
embodiments described above are used to clean both surfaces of the
polished wafer W, the invention is not limited thereto. That is to
say, the above design of providing at least one inner tank 17
(filled with a second cleaning solution CS2 that is used to clean
the brush cleaner 10) into the chamber 12 for achieving a brush
self-cleaning function may also be used in a post-CMP cleaning
apparatus for cleaning only the polished wafer surface of the wafer
W.
[0061] FIG. 12 is a flow chart of a post-CMP cleaning method 100 in
accordance with some embodiments. In operation 101, a wafer in need
of having CMP residue removed is placed into a chamber. The chamber
may be, for example, the cleaning chamber 12 of a post-CMP cleaning
apparatus 1 or 1' described above.
[0062] In operation 102, a first cleaning solution is applied to at
least one surface of the wafer. The first cleaning solution may be,
for example, the cleaning solution CS1 which is applied by the
spray unit 15 of the post-CMP cleaning apparatus 1 or 1' to the
polished wafer surface or both surfaces of the wafer.
[0063] In operation 103, the surface of the wafer is scrubbed with
a brush cleaner in the chamber. The brush cleaner may be, for
example, the brush cleaner 10 of the post-CMP cleaning apparatus 1
or 1' including a pair of brushes 10A or only single brush 10B. In
accordance with some embodiments, the brushes 10A and/or the brush
10B may be configured to have a cylindrical shape or a disk shape
and include porous or sponge like resilient protrusions for
scrubbing the surfaces of the wafer.
[0064] In operation 104, at least one inner tank in the chamber is
filled with a second cleaning solution. Inner tanks may, for
example, be inner tanks 17 of the post-CMP cleaning apparatus 1 or
1' for storing the (second) cleaning solution CS2. In accordance
with some embodiments, the inner tanks 17 may be independently
disposed in the chamber 12 or integrally formed with the chamber
12. In accordance with some embodiments, the second cleaning
solution CS2 and the above first cleaning solution CS1 may be the
same type or different types of cleaning solutions.
[0065] In operation 105, the brush cleaner is moved into the inner
tank to be cleaned by the second cleaning solution. In accordance
with some embodiments, when the brush cleaner 10 is submerged into
and cleaned by the second cleaning solution CS2, the second
cleaning solution CS2 is continuously supplied into the inner tank
17 so that the second cleaning solution CS2 in the inner tank 17
can be kept fresh and clean, thereby improving the efficiency of
cleaning the brush cleaner 10. In accordance with some embodiments,
the step of moving the brush cleaner 10 into the inner tank 17 to
clean the brush cleaner 10 by the second cleaning solution CS2 may
be performed either before or after the scrubbing process performed
by the brush cleaner 10.
[0066] It should be understood that the above post-CMP cleaning
method 100 is merely exemplary and may also have other steps and/or
other sequences of steps.
[0067] FIG. 13 schematically illustrates that the brushes 10A of
the brush cleaner 10 rub against each other to perform a
self-cleaning in accordance with some embodiments. Specifically,
after the brushes 10A remove the CMP residue on both surfaces of
the polished wafer W, the brushes 10A may be moved to close to each
other and rub against each other, in cooperation with the washing
force of the cleaning solution CS1, to allow some of the CMP
residue Z engaged on the porous surfaces of the brushes 10A to
separate from the brushes 10A, thereby performing a brush
self-cleaning. Afterwards, the brushes 10A may be moved into the
inner tanks 17 to be cleaned by the second cleaning solution CS2
(FIG. 4B). Accordingly, the efficiency of cleaning the brush
cleaner 10 may also be improved.
[0068] The embodiments of the present disclosure have some
advantageous features: During the post-CMP cleaning process, a
brush self-cleaning is performed by ex-situ cleaning the brush
cleaner in the inner tank in the cleaning chamber of the post-CMP
cleaning apparatus, either before or after the scrubbing process,
so that the CMP residue may be removed from and not accumulate on
the surface of the brush cleaner, leading to the extended lifespan
of the brush cleaner and a reduction in fabrication cost.
Furthermore, the cleaning quality of the post-CMP cleaning process
may also be improved because the brush cleaner is maintained at
consistent levels of cleanliness for the wafers from batch-to-batch
and job-to-job. Experiment results indicated that the CMP residue
having sizes between about 30 nm and about 50 nm have been
successfully removed from surfaces of the polished wafer.
[0069] In some embodiments, an apparatus for performing a post-CMP
cleaning is provided. The apparatus includes a chamber, a spray
unit, a brush cleaner, and at least one inner tank. The chamber is
configured to receive a wafer in need of having CMP residue
removed. The spray unit is configured to apply a first cleaning
solution to at least one surface of the wafer. The brush cleaner is
configured to scrub the surface of the wafer. The inner tank is
disposed in the chamber for storing a second cleaning solution that
is used to clean the brush cleaner.
[0070] In some embodiments, an apparatus for performing a post-CMP
cleaning is provided. The apparatus includes a chamber, a support
mechanism, a spray unit, a brush cleaner, and at least one inner
tank. The chamber is configured to receive a wafer in need of
having CMP residue removed. The support mechanism is configured to
support the wafer in the chamber. The spray unit is configured to
apply a first cleaning solution to at least one surface of the
wafer. The brush cleaner is configured to scrub the surface of the
wafer. The inner tank is disposed in the chamber for storing a
second cleaning solution, wherein the brush cleaner is configured
to be moved into the inner tank so that the brush cleaner is
submerged into and cleaned by the second cleaning solution.
[0071] In some embodiments, a method for performing a post-CMP
cleaning is provided. The method includes placing a wafer in need
of having CMP residue removed into a chamber. The method also
includes applying a first cleaning solution to at least one surface
of the wafer. The method also includes scrubbing the surface of the
wafer with a brush cleaner in the chamber. The method further
includes providing at least one inner tank into the chamber,
wherein the inner tank is filled with a second cleaning solution.
In addition, the method includes moving the brush cleaner into the
inner tank to clean the brush cleaner by the second cleaning
solution.
[0072] Although embodiments of the present disclosure and their
advantages have been described in detail, it should be understood
that various changes, substitutions and alterations can be made
herein without departing from the spirit and scope of the
disclosure as defined by the appended claims. For example, it will
be readily understood by those skilled in the art that many of the
features, functions, processes, and materials described herein may
be varied while remaining within the scope of the present
disclosure. Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, composition of matter, means,
methods and steps described in the specification. As one of
ordinary skill in the art will readily appreciate from the
disclosure of the present disclosure, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed, that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized according to the present disclosure. Accordingly, the
appended claims are intended to include within their scope such
processes, machines, manufacture, compositions of matter, means,
methods, or steps. In addition, each claim constitutes a separate
embodiment, and the combination of various claims and embodiments
are within the scope of the disclosure.
* * * * *