U.S. patent application number 17/068375 was filed with the patent office on 2021-01-28 for system and method of chemical mechanical polishing.
The applicant listed for this patent is Taiwan Semiconductor Manufacturing Co., Ltd.. Invention is credited to Kei-Wei Chen, Hao-Yun Cheng, Chih-Wen Liu, Che-Hao Tu.
Application Number | 20210023678 17/068375 |
Document ID | / |
Family ID | 1000005146971 |
Filed Date | 2021-01-28 |
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United States Patent
Application |
20210023678 |
Kind Code |
A1 |
Liu; Chih-Wen ; et
al. |
January 28, 2021 |
System and Method of Chemical Mechanical Polishing
Abstract
A system controls a flow of a chemical mechanical polish (CMP)
slurry into a chamber to form a slurry reservoir within the
chamber. Once the slurry reservoir has been formed within the
chamber, the system moves a polishing head to position and force a
surface of a wafer that is attached to the polishing head into
contact with a polishing pad attached to a platen within the
chamber. A wafer/pad interface is formed at the surface of the
wafer forced into contact with the polishing pad and the wafer/pad
interface is disposed below an upper surface of the slurry
reservoir. During CMP processing, the system controls one or more
of a level, a force, and a rotation of the platen, a position, a
force and a rotation of the polishing head to conduct the CMP
processing of the surface of the wafer at the wafer/pad
interface.
Inventors: |
Liu; Chih-Wen; (Taoyuan
City, TW) ; Cheng; Hao-Yun; (Keelung City, TW)
; Tu; Che-Hao; (Hsinchu, TW) ; Chen; Kei-Wei;
(Tainan City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiwan Semiconductor Manufacturing Co., Ltd. |
Hsinchu |
|
TW |
|
|
Family ID: |
1000005146971 |
Appl. No.: |
17/068375 |
Filed: |
October 12, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16252183 |
Jan 18, 2019 |
10800004 |
|
|
17068375 |
|
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|
|
62738732 |
Sep 28, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24B 37/30 20130101;
B24B 37/107 20130101; H01L 21/30625 20130101; B24B 57/02 20130101;
B24B 37/042 20130101 |
International
Class: |
B24B 57/02 20060101
B24B057/02; B24B 37/10 20060101 B24B037/10; H01L 21/306 20060101
H01L021/306; B24B 37/04 20060101 B24B037/04; B24B 37/30 20060101
B24B037/30 |
Claims
1. A system comprising: a platen within a chamber; a polishing
head; a first slurry input/output; and a second slurry
input/output, wherein both the first slurry input/output and the
second slurry input/output are located on an opposite side of the
platen than the polishing head.
2. The system of claim 1, further comprising a level sensor located
within the chamber.
3. The system of claim 2, wherein the level sensor is located at
least partially above a polishing pad located adjacent to the
platen.
4. The system of claim 1, further comprising a motor to physically
move the platen from a first distance away from a bottom of the
chamber to a second distance away from the bottom of the
chamber.
5. The system of claim 1, further comprising a slurry reservoir
within the chamber, wherein the platen is immersed within the
slurry reservoir.
6. The system of claim 1, further comprising a restoration system
connected to both the first slurry input/output and the second
slurry input/output.
7. A system, comprising: a chemical mechanical polishing chamber; a
first port and a second port both located at a first level within
the chemical mechanical polishing chamber; a platen located at a
second level within the chemical mechanical polishing chamber; and
a polishing head located at a third level within the chemical
mechanical polishing chamber, the second level being located
between the first level and the third level.
8. The system of claim 7, further comprising a polishing pad
attached to the platen.
9. The system of claim 8, further comprising a slurry reservoir
located within the chemical mechanical polishing chamber, wherein
each of the first port, the second port, and the polishing pad are
immersed within the slurry reservoir.
10. The system of claim 9, wherein the polishing pad is immersed to
a distance of at least 3 mm and about 7 mm.
11. The system of claim 7, further comprising a motor connected to
the platen to move the platen relative to a bottom surface of the
chemical mechanical polishing chamber.
12. The system of claim 7, further comprising: a filter connected
to the second port; and a restoration system.
13. The system of claim 7, further comprising a level sensor
located within the chemical mechanical polishing chamber.
14. The system of claim 13, wherein the level sensor is located at
least partially above a polishing pad over the platen.
15. A system, comprising: a chamber comprising a slurry intake; a
platen housed within the chamber; and a polishing pad housed within
the chamber, wherein an upper surface of the polishing pad is
located above a bottom surface of the chamber and wherein a
delivery orifice of the slurry intake is located below the upper
surface of the polishing pad.
16. The system of claim 15, further comprising a level sensor
located within the chamber.
17. The system of claim 16, wherein the level sensor is located at
least partially above the polishing pad.
18. The system of claim 15, further comprising a slurry reservoir
located within the chamber, the slurry reservoir covering the
polishing pad.
19. The system of claim 15, further comprising a motor located to
move the polishing pad in a first direction, the first direction
being perpendicular to a rotational motion of the polishing
pad.
20. The system of claim 15, further comprising: a filter connected
to an output of the chamber; and a restoration system.
Description
PRIORITY CLAIM AND CROSS-REFERENCE
[0001] This application is a divisional of U.S. patent application
Ser. No. 16/252,183, filed on Jan. 18, 2019, and entitled "System
and Method of Chemical Mechanical Polishing," which application
claims priority to and the benefit of U.S. Provisional Application
No. 62/738,732, filed on Sep. 28, 2018, and entitled "System and
Method of Chemical Mechanical Polishing," which applications are
incorporated herein by reference.
BACKGROUND
[0002] Chemical mechanical polish (CMP) processes can be used for
the fabrication of an integrated circuit. For example, CMP
processes may be used to planarize metal features, semiconductor
materials and inter-metal dielectrics of inter-level dielectric
layers that separate various circuit layers in an integrated
circuit. CMP processes are also commonly used in the formation of
the copper lines and/or contact plugs that interconnect components
of integrated circuits.
[0003] CMP processes are widely used in the fabrication of
integrated circuits. As 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 or layers to provide a leveled
surface for subsequent fabrication steps. However, improvements are
still desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The following 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.
[0005] FIG. 1 illustrates a CMP processing system and method, in
accordance with some embodiments.
[0006] FIG. 2 illustrates details of a chamber and method for
preparing for a CMP process, in accordance with some
embodiments.
[0007] FIG. 3 illustrates a method of performing a CMP processing
of a workpiece using the chamber of FIG. 2, in accordance with some
embodiments.
[0008] FIG. 4 illustrates a method of performing a CMP processing
of a workpiece using the chamber of FIG. 2, in accordance with some
embodiments.
[0009] FIG. 5 illustrates a purging of a slurry reservoir from the
chamber, in accordance with some embodiments.
[0010] FIG. 6 illustrates a method of performing a cleaning process
of a workpiece using the chamber of FIG. 2, in accordance with some
embodiments.
DETAILED DESCRIPTION
[0011] 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.
[0012] 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.
[0013] FIG. 1 illustrates a CMP processing system 100, according to
some embodiments. The CMP processing system 100 comprises a
plurality of various components including: a supply tank 107, a
chamber 113, a slurry filter 129, a slurry restoration system 150,
a control unit 101, a plurality of pumps P1-P5, a plurality of
valves V1-V4, and a plurality of sensors S1-S3. The various
components of the CMP processing system 100 are interconnected and
the control unit 101 controls the pumps P1-P5 and valves V1-V4 to
flow CMP slurries and/or solutions through the conduit 109 during
operation of the CMP processing system 100. (e.g., pipelines,
tubing, channels, feedlines, combinations thereof, and the like). A
general distribution and flow of a CMP slurry 103 within the CMP
processing system 100 is indicated by a set of directional arrows
in FIG. 1, according to some embodiments.
[0014] In preparation for performing a CMP process, the CMP
processing system 100 receives the CMP slurry 103 from a feedline
105 of a slurry distribution system 90 and delivers the CMP slurry
103 via a first inlet In1 to the supply tank 107. The CMP slurry
103 may be a slurry prepared, for example, according to a desired
CMP process recipe for use in a desired CMP processing of a
workpiece 123 (e.g., semiconductor substrate, semiconductor wafer,
etc.).
[0015] In some embodiments, the CMP slurry 103, in prepared form,
may comprise a base slurry (e.g., an undiluted stock slurry
comprising colloidal silica) that is mixed (e.g., in a mixing tank
of the slurry distribution system 90) with one or more slurry
diluents to dilute the base slurry and is mixed with one or more
slurry additives prior to being delivered to the supply tank 107.
In some embodiments, the supply tank 107 comprises an agitator 108
that provides a continuous stir of the components provided to the
supply tank 107 ensuring a thorough mixing of the base slurry, the
slurry diluents, and the slurry additives and ensuring a consistent
quality of the characteristics of the CMP slurry 103 that is drawn
out of the supply tank 107. Slurry diluents and slurry additives
may include, but are not limited to, one or more of: abrasives,
aqueous solutions (e.g., deionized water, ammonia), solvents,
oxidizing agents, pH adjusters, complexing agents, chelating
agents, corrosion inhibiting agents, and the like. All such slurry
diluents and slurry additives and combinations thereof that are
suited for the desired CMP process may be included without
limitation and are considered to be within scope of the embodiments
disclosed herein.
[0016] Initial steps in preparation for performing the desired CMP
processing of the workpiece 123, may include placing the workpiece
123 in the chamber 113 and forming a slurry reservoir 115 within
the chamber 113. In some embodiments, the control unit 101 controls
the first pump P1 and the first valve V1 to allow the CMP slurry
103 to flow through an intake 111 and pool at the bottom of the
chamber 113, thereby forming the slurry reservoir 115. The intake
111 is a point where the CMP slurry 103 enters the chamber 113 and
mixes with the ambient of the chamber 113, such as, via a
downstream port of the first valve V1 or an inlet main of the
chamber 113. For example, the CMP slurry 103 flows into and mixes
with the ambient of the chamber 113 via a delivery orifice 112 of
the intake 111. According to embodiments, the delivery orifice 112
of the intake 111 is arranged at or near a bottom surface of the
chamber 113. However, any suitable arrangement of the delivery
orifice 112 of the intake 111 within the chamber 113 may be used.
In some embodiments, the delivery orifice 112 provides a controlled
flow of CMP slurry 103 into the ambient of the chamber 113.
However, the delivery orifice 112 may allow for the CMP slurry 103
to freely flow into the ambient of the chamber 113. However, any
suitable arrangement of the delivery orifice 112 may be used.
[0017] In some embodiments, the control unit 101 controls the first
and second pumps P1-P2 and controls the first and second valves
V1-V2 to control the flow of the CMP slurry 103 into and out of the
chamber 113, according to the desired CMP process recipe. In some
embodiments, the control unit 101 controls the first and second
pumps P1-P2 and controls the first and second valves V1-V2 in order
to adjust a level of the slurry reservoir 115, according to the
desired CMP process recipe.
[0018] Once the slurry reservoir 115 has been formed, the desired
CMP processing of the workpiece 123 may begin to planarize the
surface of the workpiece 123. During the desired CMP processing,
surface materials of the workpiece 123 may react with one or more
slurry additives of the CMP slurry 103 and waste and impurities may
collect in the slurry reservoir 115. As such, desired concentration
levels of one or more slurry additives of the CMP slurry 103 in the
slurry reservoir 115 may become depleted, may become reduced to
ineffective levels, or may become imbalanced with respect to ratios
between the one or more slurry additives and another one of the
slurry additives. Consequently, the quality and characteristics of
the CMP slurry 103 of the slurry reservoir 115 may become
compromised such that concentration levels of one or more of the
slurry additives may sit outside a tolerance level as dictated by
the desired CMP process recipe. For example, the CMP slurry 103 of
the slurry reservoir 115 may become compromised due to chemical
reactions between components (e.g., an oxidizing agent) of the CMP
slurry 103 of the slurry reservoir 115 and materials of the
workpiece 123 consuming or otherwise altering the components of the
CMP slurry 103. Furthermore during CMP processing, the CMP slurry
103 of the slurry reservoir 115 may become contaminated due to
waste and impurities left behind during removal of surface
materials of the workpiece 123. As such, when the quality or
characteristics of the CMP slurry 103 of the slurry reservoir 115
has become compromised or has become contaminated (otherwise
referred herein as a "used slurry 127"), the control unit 101 may
initiate a purging of the slurry reservoir 115 to flow used slurry
127 out of the chamber 113.
[0019] In some embodiments, the control unit 101 may determine that
all or some of the used slurry 127 may be re-usable or recyclable
based on a degree of depletion, imbalance, compromise, or
contamination of the used slurry 127. The control unit 101 may also
determine when all or some of the used slurry 127 may be
compromised and no longer re-usable or recyclable for the desired
CMP process. Based on such determinations, the control unit 101 may
initiate a purging of all or some of the used slurry 127 from the
chamber 113.
[0020] Once purged from the chamber 113, the used slurry 127 may be
filtered, restored, and recycled to the original condition and/or
state of the CMP slurry 103, according to some embodiments. For
example, the control unit 101 may initiate a purging of the used
slurry 127 from the chamber 113 based on a concentration of waste
and impurities in the used slurry 127 of the slurry reservoir 115.
Once purging has been initiated, the control unit 101 controls the
second pump P2 and the third pump P3 to draw the used slurry 127
through the slurry filter 129 to remove waste and impurities from
the used slurry 127 and produce a filtered slurry 131 at an output
of the slurry filter 129. As such, the filtered slurry 131 may be
reused or recycled.
[0021] The slurry filter 129 removes oversized, large slurry
particles or agglomerated clusters or clumps of particles which
might otherwise scratch and damage the surface of the workpiece 123
during the CMP processing. In some embodiments, the slurry filter
129 may have pore sizes between about 0.02 .mu.m and about 0.10
.mu.m.
[0022] In some embodiments, based on a level of the concentration
of waste and impurities in the used slurry 127, the control unit
101 may determine that the used slurry 127 should be disposed. As
such, the control unit 101 initiates a purging of the used slurry
127 from the chamber 113 and directs the second valve V2 to open to
allow the used slurry 127 to flow through the disposal line 215 to
a Slurry Waste Disposal System 200 to discard the used slurry
127.
[0023] In some embodiments based on a level of the concentration of
waste and impurities in the used slurry 127, the control unit 101
may determine that a portion of the used slurry 127 can remain in
the slurry reservoir 115 as a remaining portion of the used slurry
127 and can be mixed with a supply of the filtered slurry 131. In
some embodiments, based on a concentration of the waste and
impurities in the used slurry 127, the control unit may determine
that the remaining portion of the used slurry 127 can be mixed with
a fresh supply of the CMP slurry 103 from the supply tank 107. In
still other embodiments, based on a concentration of the waste and
impurities in the used slurry 127, the control unit may determine
that the remaining portion of the used slurry 127 can be mixed with
a combination of the filtered slurry 131 and the fresh supply of
the CMP slurry 103 from the supply tank 107.
[0024] In some embodiments based on a degree of depletion of the
used slurry 127, the control unit 101 may determine that the used
slurry 127 should be restored and recycled. As such, the control
unit 101 initiates a purging of the used slurry 127 from the
chamber 113 and directs the second valve V2 to open to allow the
used slurry 127 to flow out of the chamber 113 and directs the
second pump P2 and the third pump P3 to draw the used slurry 127
through the slurry filter 129 to filter the used slurry 127. Once
filtered, the control unit 101 controls the third valve V3 and the
fourth pump P4 to transfer the filtered slurry 131 to a second
inlet In2 of the supply tank 107. As the filtered slurry 131 is
transferred to the supply tank 107, the filtered slurry 131 may be
restored by replenishing any depleted slurry diluent, replenishing
any depleted additives, correcting any corrupted concentration
levels, adjusting pH levels, or the like.
[0025] According to some embodiments, in order to restore the
filtered slurry 131 to a composition and a state consistent with an
original composition and an original state of the CMP slurry 103,
the control unit 101 directs a slurry restoration system 150 to
generate a make-up solution 133 to be mixed with the filtered
slurry 131. In an embodiment, the slurry restoration system 150
comprises a plurality of make-up tanks 151 respectively coupled via
a plurality of flow release valves 153 to a multi-input manifold
157. Each of the make-up tanks 151 contains a slurry diluent or a
slurry additive of the types used in the original composition of
the CMP slurry 103. According to some embodiments, the control unit
101 directs one or more of the flow release valves 153 to release
an appropriate amount of the slurry diluent or an appropriate
amount of the slurry additive contained in one or more respective
make-up tanks 151 based on the degree of depletion, the degree of
imbalance, or the degree of compromise of the used slurry 127. For
example, the slurry restoration system 150 may release a make-up
solution 133 including appropriate amounts of an acid solution or
an alkaline solution (e.g., acetic acid, KOH, NaOH) to adjust a pH
level of the used slurry 127 to restore the pH level of the used
slurry 127 to the pH level of the original composition of the CMP
slurry 103.
[0026] According to some embodiments, the multi-input manifold 157
may combine the released slurry diluents or the released slurry
additives to provide the make-up solution 133. In some embodiments,
the multi-input manifold 157 may individually provide each of the
released slurry diluents or the released slurry additives as a
series of solutions to be mixed with the used slurry 127, the
series of solutions forming the make-up solution 133. As such, the
control unit 101 directs the multi-input manifold 157, the fourth
valve V4 and the fifth pump P5 to deliver the make-up solution 133
to a third inlet In3 of the supply tank 107. Therefore, the used
slurry 127 purged from the chamber 113 may be recycled to restore
the used slurry 127 to its original composition and its original
state.
[0027] In some embodiments, the CMP processing system 100 may
provide a continuous flow system such that CMP slurry 103
continuously flows into the chamber 113 to continuously replenish
the slurry reservoir 115 and used slurry 127 continuously flows out
of the chamber 113, while the used slurry 127 is continuously
filtered and restored to the original composition and original
state of the CMP slurry 103 using the make-up solution 133.
Restoring the used slurry 127 allows for the used slurry 127 to be
reused in the slurry reservoir 115 while maintaining a quality of
the CMP slurry 103 during CMP processing of a single workpiece and
during a series of CMP processing of a batch of workpieces.
[0028] According to some embodiments, the make-up solution 133 is
mixed with the filtered slurry 131 that is released to the supply
tank 107 via the second inlet In2 and is mixed with any remaining
volume of the CMP slurry 103 directly in the supply tank 107. The
agitator 108 of the supply tank 107 continuously stirs the contents
of the supply tank 107 such that the used slurry 127 is restored to
its original composition and its original state when mixed with the
make-up solution 133. Therefore, a quality and consistency of the
CMP slurry 103 is maintained throughout the CMP processing of the
workpiece 123 and during the series of CMP processing of the batch
of workpieces.
[0029] According to other embodiments, the filtered slurry 131 and
the make-up solution 133 may be mixed prior to being released into
the supply tank 107. For example, the filtered slurry 131 and the
make-up solution 133 may be provided to a mixing tank to generate a
restored CMP slurry consistent with the original composition and
the original state of the CMP slurry 103. Once mixed, the restored
CMP slurry may be returned to the supply tank 107.
[0030] Furthermore, the control unit 101 may initiate a purging of
the slurry reservoir 115 at various times, as dictated by the
desired CMP process recipe. For example, the control unit 101 may
initiate a purging of the slurry reservoir 115 from the chamber 113
in preparation for a subsequent processing of the workpiece 123 or
prior to processing another workpiece. Examples of subsequent
processing steps may include, but are not limited to: a step of
changing slurry abrasives or changing abrasive concentrations
between CMP removal processes (e.g., between a bulk CMP removal and
a buffing CMP removal, or between a CMP removal of another
workpiece using another CMP slurry), a step of filtering the CMP
slurry 103, a step of cleaning the workpiece 123, and a step of
rinsing the chamber 113 (e.g., after CMP processing of the
workpiece 123 has been completed). However, the purging of the
slurry reservoir 115 may be initiated by the control unit 101 in
preparation for any suitable processing step.
[0031] FIG. 1 further illustrates that the plurality of sensors
S1-S3 may be arranged or integrally formed within one or more
elements of the CMP processing system 100 and may also be arranged
in-line of the conduit 109 between connected elements, according to
some embodiments. The plurality of sensors S1-S3 instantaneously
determine one or more conditions of the respective elements or
instantaneously determine characteristics of the CMP slurry 103 as
the CMP slurry 103 flows by a respective sensor of the plurality of
sensors S1-S3. The plurality of sensors S1-S3 may be
communicatively coupled to the control unit 101 to allow for the
determined conditions of the respective elements and the determined
characteristics of the CMP slurry 103 at the respective locations
of the plurality of sensors S1-S3 to be assessed by the control
unit 101.
[0032] Examples of the plurality of sensors S1-S3 include, but are
not limited to, flow meters, electro-acoustic sensors, ultra-sonic
abrasive concentration sensors, pH sensors, conductivity sensors,
temperature sensors, pressure sensors, combinations thereof, and
the like. However, any suitable sensor may be utilized. Examples of
conditions of the elements and characteristics of the CMP slurry
103 that may be determined by the plurality of sensors S1-S3
include, but are not limited to, pH levels, temperature levels,
volume levels, conductivity levels, ultrasonic attenuation
spectrums, particle size distributions, dynamic mobility spectrums,
particle zeta potentials, slurry pressures, abrasive particle
concentrations, and the like. However, any suitable characteristic
of the CMP slurry 103 may be determined by the plurality of sensors
S1-S3 and utilized by the control unit 101.
[0033] As such, the plurality of sensors S1-S3 instantaneously
detects conditions of the respective elements or characteristics of
the CMP slurry 103 at the respective locations of the sensors in
the CMP processing system 100. The instantaneously detected
conditions or characteristics may be provided to the control unit
101 for monitoring and analysis of each of the respective elements
and of the CMP slurry 103 at each of the respective locations of
the plurality of sensors S1-S3. Thus, the monitoring and analysis
performed by the control unit 101 may be performed in real-time or
in near real-time. According to some embodiments, the analysis
performed by the control unit 101 includes comparing relative
conditions of each of the respective elements (e.g., conditions
detected within the chamber 113) during CMP processing to certain
condition tolerances. The condition tolerances may be dictated, for
example, according to a desired CMP processing recipe. Furthermore,
the analysis performed by the control unit 101 may also include
comparing the instantaneous characteristics of the CMP slurry 103,
at each of the respective locations of the plurality of sensors
during CMP processing, to certain slurry characteristic tolerances.
The slurry characteristic tolerances may be dictated, for example,
according to the desired CMP processing recipe.
[0034] Based on the analysis of the instantaneous conditions of the
elements or the instantaneous characteristics of the CMP slurry
103, the control unit 101 may initiate one or more system
processes. The initiation of one or more system processes may
include, for example, one or more of: activating or deactivating
components of an element to modify one or more conditions of the
element, operating valves V1-V4 and activating pumps P1-P3 to allow
slurry to flow from one element to another element, and activating
the slurry restoration system 150 to provide the make-up solution
133.
[0035] As further illustrated in FIG. 1, a first sensor S1 may be
integrally formed with or arranged within the chamber 113 to
instantaneously determine conditions of the chamber 113 (e.g., a
chamber temperature, a chamber pressure, a level of the slurry
reservoir 115 within the chamber 113, etc.). In one embodiment the
first sensor S1 includes a level sensor which provides a
measurement of the depth of the slurry reservoir 115 within the
chamber 113. In such an embodiment the level sensor may comprise a
first portion which extends from a level below the polishing head
to a level above the polishing head in order to provide a suitable
reading for the level of the slurry reservoir 115.
[0036] The first sensor S1 may also instantaneously determine
characteristics of the CMP slurry 103 of the slurry reservoir 115
(e.g., a pH level, a temperature level, a particle zeta potential,
an abrasive particle concentration, a concentration of waste, a
concentration of impurities, etc.). Also illustrated in FIG. 1, a
second sensor S2 may be arranged, for example, in-line of the
conduit 109 connecting the second pump P2 and the slurry filter 129
to detect characteristics of the CMP slurry 103 at the location of
the second sensor S2. Also, a third sensor S3 may be arranged, for
example, in-line of the conduit 109 connecting the slurry filter
129 and the third pump P3 to detect characteristics of the CMP
slurry 103 at the location of the third sensor S3. As such, the
control unit 101 monitors and analyzes the instantaneous conditions
of the elements (e.g., the chamber 113) and characteristics of the
slurry at each of the respective locations of the first, second and
third sensors S1-S3 (e.g., the CMP slurry 103 within the slurry
reservoir 115, the used slurry 127 purged from the chamber 113, or
the filtered slurry 131 provided at the output of the slurry filter
129).
[0037] FIG. 2 illustrates details of the chamber 113 of FIG. 1 and
a method of preparing the chamber 113 for performing the desired
CMP processing of the workpiece 123. Along with the first sensor S1
and the slurry reservoir 115, the chamber 113 includes a polishing
head 203 and a platen 207 that are manipulated within the chamber
113 by the control unit 101 during the desired CMP processing of
the workpiece 123, according to the desired CMP recipe.
[0038] According to an embodiment, in order to prepare for the
desired CMP processing of the workpiece 123, the workpiece 123 is
attached by a wafer carrier 201 (e.g., a retaining ring) to the
polishing head 203. The wafer carrier 201 is adapted to retain the
workpiece 123 and to provide a down force of between about 2 psi
and about 3 psi in order to prevent the workpiece 123 from slipping
during the desired CMP processing. The polishing head 203 is
rotatable, adapted to move up and down, and may include a line,
hose, or tube for a vacuum which may be used for picking up and
retaining the workpiece 123 during the desired CMP process. The
workpiece 123 typically comprises a patterned layer of material
disposed on a semiconductor wafer that needs planarizing,
smoothing, or a reduction in thickness, for example. The workpiece
123 may be picked up by the polishing head 203, for example, by
using a vacuum of a load port of a CMP station within a CMP tool.
The vacuum may be used to lift the workpiece 123 as the polishing
head 203 moves the workpiece 123 up and down within the chamber
113, according to the desired CMP process recipe. After the CMP
process is complete, the workpiece 123 is lifted again by the
vacuum as the polishing head 203 moves the workpiece 123 up and
down within the chamber 113, and the workpiece 123 is returned, for
example, to the load port of the CMP station or to another station
within the CMP tool.
[0039] During preparation for the desired CMP processing, the
control unit 101 directs the flow of the CMP slurry 103 from the
supply tank 107 through the intake 111 and into the chamber 113
allowing the CMP slurry 103 to pool at the bottom of the chamber
113 and form the slurry reservoir 115, as discussed above. In some
embodiments, the intake 111 is arranged at or near a bottom surface
of the chamber 113. However, any suitable arrangement of the intake
111 within the chamber 113 may be used.
[0040] In some embodiments, the control unit 101 controls the first
pump P1 and the first valve V1 to continue flowing the CMP slurry
103 into the chamber 113 until an upper surface of the slurry
reservoir 115 has reached a desired level L1 within the chamber 113
or until a desired volume of the CMP slurry 103 has been flowed
into the chamber 113. According to an embodiment, the desired level
L1 of the slurry reservoir 115 may be between about 130 mm and
about 190 mm, such as about 160 mm. However, any suitable level may
be utilized for the desired level L1 of the slurry reservoir 115.
According to an embodiment, the desired volume of the of the slurry
reservoir 115 may be between about 32500 ml and about 47500 ml,
such as about 40000 ml. However, any suitable volume may be
utilized for the desired volume of the slurry reservoir 115.
[0041] The chamber 113 further comprises a platen 207 with a
polishing pad 205 secured to a top surface of the platen 207. The
platen 207 is adapted to rotate the polishing pad 205 during the
desired CMP processing of the workpiece 123. In some embodiments,
the platen 207 is adapted to raise and lower the polishing pad
within the chamber 113. When the polishing pad 205 is secured to
the platen 207, an upper surface of the polishing pad 205 may be
arranged at a first height H.sub.1 above the bottom surface of the
chamber 113. According to an embodiment, the first height H.sub.1
may be between about 200 mm and about 220 mm, such as about 210
mm.
[0042] The platen 207 may represent any of a high-rate platen,
low-rate platen, and a buffing platen. However, the platen 207 may
represent any suitable platen for performing the desired CMP
processing of the workpiece 123. The polishing pad 205 may
represent any type of polishing pad suitable for performing any of
a high-rate polishing, a low-rate polishing, and a buffing.
However, the polishing pad 205 may represent any suitable pad for
performing the desired CMP processing of the workpiece 123. In some
embodiments, the platen 207 may be a high-rate platen used for
polishing the workpiece 123 with a relatively high polishing rate
using the polishing pad 205 having a first coarseness suitable for
performing the high-rate polishing of the workpiece 123. According
to some embodiments, the platen 207 may be a low-rate platen used
for polishing the workpiece 123 with a relatively low polishing
rate using the polishing pad 205 having a second coarseness
suitable for performing the low-rate polishing of the workpiece
123. The platen 207, being the low-rate platen in some embodiments,
may also be used to detect whether a target thicknesses of the
workpiece 123 have been reached or not. Still in other embodiments,
the platen 207 may be a buffing platen used to buff (e.g., lightly
polish) the workpiece 123 using the polishing pad 205 having a
third coarseness suitable for performing the buffing of the
workpiece 123. The platen 207, being the buffing platen in some
embodiments, may also be used to fix defects and scratches, and to
further polish the workpiece 123 to achieve the final target
thickness of the workpiece 123.
[0043] The control unit 101 is communicatively coupled to the
platen 207, the polishing head 203, and the first sensor S1. During
CMP processing of the workpiece 123, the control unit 101 directs
the operations of the platen 207, directs the operations of the
polishing head 203, and monitors and analyzes the conditions of the
chamber 113 and the characteristics of the CMP slurry 103 of the
slurry reservoir 115 based on real-time feedback from the first
sensor S1.
[0044] During CMP processing of the workpiece 123, the polishing
pad 205 is secured to the platen 207 and the workpiece 123 is held
by the polishing head 203. Based on the desired CMP recipe, the
control unit 101 directs the polishing head 203 to manipulate the
workpiece 123 within the chamber 113. For example, the control unit
101 may direct the polishing head 203 to raise the workpiece 123,
to lower the workpiece 123, to rotate the workpiece 123, and to
move the workpiece 123 in horizontal directions within a plane of
the surface of the workpiece 123, according to the desired CMP
process recipe.
[0045] According to some embodiments, the platen 207 is directed by
the control unit 101 to manipulate the polishing pad 205 within the
chamber 113 according to the desired CMP process recipe. For
example, the control unit 101 may direct the platen 207 to rotate
the polishing pad 205 beneath the workpiece 123.
[0046] In some embodiments, an output 125 of the chamber 113 is
arranged at or near a bottom surface of the chamber 113. However,
any suitable arrangement of the output 125 within the chamber 113
may be used. The second valve V2 is arranged at the output 125 of
the chamber 113 and the second pump P2 is connected via the conduit
109 to the second valve V2. In order to control the flow of the CMP
slurry 103 from the slurry reservoir 115, the control unit 101
controls the second valve V2 to open and controls the second pump
P2 to begin drawing the CMP slurry 103 of the slurry reservoir 115
out of the chamber 113.
[0047] Based on one or more of the conditions and the
characteristics determined by the first sensor S1, the control unit
101 may control the components of the CMP processing system 100 to
perform one or more actions. For example, based on the determined
conditions of the chamber 113, the control unit 101 may direct the
chamber 113 (e.g., a heating element, a pressure valve, etc.) to
adjust one or more of the chamber temperature and the chamber
pressure, according to the desired CMP process recipe. As another
example, based on the determined characteristics of the CMP slurry
103 in the slurry reservoir 115 and according to the desired CMP
process recipe, the control unit 101 may direct the first and
second valves V1-V2 and the first and second pumps P1-P2 to
initiate one or more of: a purging of the CMP slurry 103 from the
chamber 113, a flowing of the CMP slurry 103 from the supply tank
107 into the chamber 113, a flowing of the CMP slurry 103 from the
slurry reservoir 115 out of the chamber 113, and an adjusting of a
level of the slurry reservoir 115 in the chamber 113.
[0048] During the desired CMP processing, the first sensor S1
instantaneously determines a concentration of one or more of the
slurry additives and a concentration of waste and impurities in the
slurry reservoir 115. The control unit 101 monitors and analyzes
the characteristics of the slurry reservoir 115, as determined by
the first sensor S1. Based on the analysis of the characteristics
of the slurry reservoir 115, the control unit 101 may determine a
degree to which the CMP slurry 103 in the slurry reservoir 115 has
become depleted, unbalanced, contaminated or otherwise corrupted
and may determine whether the CMP slurry 103 has become inadequate
to perform the desired CMP processing, as dictated by the CMP
process recipe. Once the control unit 101 has determined that the
CMP slurry 103 of the slurry reservoir 115 is deemed no longer
adequate or, otherwise referred herein as, "used slurry" 127, the
control unit 101 may initiate a purging of the used slurry 127 from
the chamber 113. In some embodiments, the control unit 101 may
determine to purge a portion of the used slurry 127 from the
chamber 113 with a remaining portion of the used slurry 127 staying
in the slurry reservoir 115. In other embodiments, the control unit
101 may determine to purge all of the used slurry 127 from the
chamber 113.
[0049] FIG. 3 illustrates a method of performing the CMP processing
of the workpiece 123, according to some embodiments. Once the
chamber 113 has been prepared as discussed above with regard to
FIG. 2, the control unit 101 may control a level of the slurry
reservoir 115 and may control one or more of manipulations of the
polishing head 203 and one or more manipulations of the platen 207,
according to some embodiments.
[0050] As illustrated in FIG. 3, the control unit 101 may initially
determine a second level L.sub.2 to which the surface of the slurry
reservoir 115 is to be raised during the CMP processing of the
workpiece 123. In some embodiments, the desired CMP recipe may
dictate a fixed level for the second level L2. In other
embodiments, the desired CMP recipe may dictate a fixed height
above the upper surface of the polishing pad 205 for the second
level L2. As discussed above with respect to FIG. 2, the height of
the upper surface of the polishing pad 205 is a first height H1.
The first height H1 may be at a fixed height within the chamber 113
and the first height H1, for example, may be set as a known
parameter within or otherwise provided to the control unit 101,
according to some embodiments. In other embodiments, the first
height H.sub.1 may be measured by the first sensor S1 and
communicated to the control unit 101.
[0051] The second level L.sub.2 may be determined based on the
first height H.sub.1 of the polishing pad 205. For example, the
desired CMP recipe may indicate that the upper surface of slurry
reservoir 115 is to be at least a second height H.sub.2 above the
upper surface of the polishing pad 205 during the desired CMP
processing of the workpiece 123. In some embodiments, the second
height H.sub.2 may be between about 3 mm and about 7 mm, such as
about 5 mm.
[0052] In an embodiment, once the second height H.sub.2 has been
determined, the control unit 101 may determine a supplemental
volume of the CMP slurry 103 to add to the slurry reservoir 115 in
order to raise the level of the slurry reservoir 115 from the first
level L.sub.1 to the second level L.sub.2. Based on the
supplemental volume, the control unit 101 may direct the first pump
P1 and the first valve V1 to flow an amount of the CMP slurry 103
from the supply tank 107 into the chamber 113 until the
supplemental volume has been added to the slurry reservoir 115. As
such, the platen 207 is submerged in the slurry reservoir 115 with
the upper surface of the polishing pad 205 being below the second
level L.sub.2 by at least the second height H.sub.2.
[0053] Once the platen 207 has been submerged in the slurry
reservoir 115, the control unit 101 begins the desired CMP
processing of the workpiece 123 by directing the polishing head 203
to lower the workpiece 123 into the slurry reservoir 115 and begin
rotating the workpiece 123 while pressing the surface of the
workpiece 123 into the upper surface of the polishing pad 205. The
polishing head 203 may also manipulate the workpiece 123 by moving
the workpiece 123 radially along the surface of the polishing pad
205 as the workpiece 123 is rotated by the polishing head 203 and
as the polishing pad 205 rotates beneath the workpiece 123. With
the polishing pad 205 submerged within the slurry reservoir 115 and
the surface of the workpiece 123 lowered into the slurry reservoir
115 and making contact with the polishing pad 205 during the
desired CMP processing, the CMP slurry 103 is uniformly distributed
at an interface (e.g., a wafer/pad interface) between the surface
of the workpiece 123 and the polishing pad 205. As such, no ramp up
time (e.g., 5 or more seconds) is spent to evenly distribute the
CMP slurry 103 as would be required in a chamber design that
dispenses the CMP slurry 103 from a slurry arm onto the polishing
pad at a slurry drop point. Therefore, a savings in process time
may be achieved during the desired CMP processing using the chamber
113 with the slurry reservoir 115.
[0054] As illustrated in FIG. 3, a wafer/pad interface 301 is
formed between the surface of the workpiece 123 and a portion of
the surface of the polishing pad 205 where the two surfaces are
pressed together below the upper surface of the slurry reservoir
115. As such, the CMP slurry 103 of the slurry reservoir 115 is
evenly distributed at the wafer/pad interface 301 during the
desired CMP processing of the workpiece 123. As the rotating
workpiece 123 is pressed into the surface of the polishing pad 205,
the wafer/pad interface 301 is maintained below the upper surface
of the slurry reservoir 115 thereby providing the even distribution
of the CMP slurry 103 during the CMP processing of the workpiece
123. The relative movements of the polishing pad 205 and the
surface of the workpiece 123 coupled with the one or more slurry
additives (e.g., abrasive particles and/or reactive chemicals) of
the CMP slurry 103 at the wafer/pad interface 301 allow the CMP
process to planarize the surface of the workpiece 123 by means of
both physical and chemical forces. With the CMP slurry 103 being
evenly distributed at the wafer/pad interface 301, a highly
controlled planarization of the workpiece 123 may be achieved
within short polishing times.
[0055] Furthermore, the polishing head 203 may apply a down force
to the workpiece 123 in order to force the workpiece 123 into the
polishing pad 205 to maintain the wafer/pad interface 301 while the
workpiece 123 is rotated, according to the desired CMP recipe. In
some embodiments, the down force applied is uniform across the
wafer/pad interface 301. In other embodiments, the polishing head
203 may apply local down forces corresponding to local thicknesses
of the workpiece 123, based on the desired CMP recipe. The applied
local down forces may be non-uniform across the wafer/pad interface
301.
[0056] According to some embodiments, the platen 207 applies a back
force to the workpiece 123 in order to force the polishing pad 205
against the workpiece 123 and to prevent bending of the workpiece
123 while maintaining the wafer/pad interface 301 as the polishing
pad 205 is rotated, according to the desired CMP recipe. In some
embodiments, the back force applied by the platen 207 to the
polishing pad may be between about 0.6 psi and about 6 psi, such as
about 3 psi.
[0057] In some embodiments, the polishing head 203 and the platen
207 may perform a high-rate polishing of the surface of the
workpiece 123 according to the desired CMP recipe. When performing
a high-rate polishing of the surface of the workpiece 123, the
polishing head 203 may rotate the workpiece 123 at speeds between
about 30 rpm and about 170 rpm, such as about 90 rpm and the platen
207 may rotate the polishing pad 205 at speeds between about 30 rpm
and about 170 rpm, such as about 90 rpm. As such, a high-rate
polishing of the surface of the workpiece 123 may be performed
within a polishing of time of between about 0 sec and about 180
sec, such as about 90 sec.
[0058] FIG. 4 illustrates another embodiment of performing the CMP
processing of the workpiece 123, according to some embodiments. In
this embodiment, rather than raising the level of the slurry
reservoir 115 within the chamber 113, the polishing pad 205 may be
lowered within the chamber 113. Such a movement relative to the
slurry reservoir 115 allows for another method of submerging the
surface of the polishing pad 205 into the slurry reservoir 115.
[0059] In this embodiment, once the chamber 113 has been prepared
as discussed above with regard to FIG. 2, the control unit 101 may
determine a second distance D.sub.2 to lower the polishing pad 205
from the first height H.sub.1 to a third height H.sub.3, the third
height H.sub.3 being the desired first distance D.sub.1 below the
surface of the slurry reservoir 115. According to some embodiments,
the first distance D.sub.1 may be determined based on the first
height H.sub.1, the first level L.sub.1 of the surface of the
slurry reservoir 115 and the desired first distance D.sub.1 below
first level L.sub.1, according to the desired CMP recipe.
[0060] Once the second distance D.sub.2 has been determined, the
control unit 101 may lower the polishing pad 205 by the second
distance D.sub.2 to the third height H.sub.3. Once lowered to the
third height H.sub.3, the polishing pad 205 is submerged within the
slurry reservoir 115 with the upper surface of the polishing pad
205 being arranged at the desired first distance D.sub.1 below the
surface of the slurry reservoir 115. In some embodiments, the third
height H.sub.3 may be between about 80 mm and about 120 mm, such as
about 100 mm. However, any suitable height for performing the
desired CMP processing of the workpiece 123 may be utilized as the
third height H.sub.3. In some embodiments, the second distance
D.sub.2 may be between about 60 mm and about 100 mm, such as about
80 mm. However, any suitable distance for performing the desired
CMP processing of the workpiece 123 may be utilized as the second
distance D.sub.2.
[0061] Once the platen 207 has been submerged in the slurry
reservoir 115, the control unit 101 begins the desired CMP
processing of the workpiece 123 by directing the polishing head 203
to lower the workpiece 123 into the slurry reservoir 115 and begins
rotating the workpiece 123 while pressing the surface of the
workpiece 123 into the upper surface of the polishing pad 205. The
polishing head 203 may also manipulate the workpiece 123 by moving
the workpiece 123 radially along the surface of the polishing pad
205 as the workpiece 123 is rotated by the polishing head 203 and
as the polishing pad 205 rotates beneath the workpiece 123,
according to the desired CMP recipe.
[0062] As further illustrated in FIG. 4, the wafer/pad interface
301 is formed between the surface of the workpiece 123 and a
portion of the surface of the polishing pad 205 where the two
surfaces are pressed together below the upper surface of the slurry
reservoir 115. As such, the CMP slurry 103 of the slurry reservoir
115 is evenly distributed at the wafer/pad interface 301 during the
desired CMP processing of the workpiece 123. As the rotating
workpiece 123 is pressed into the surface of the polishing pad 205,
the wafer/pad interface 301 is maintained below the upper surface
of the slurry reservoir 115 thereby providing the even distribution
of the CMP slurry 103 during the CMP processing of the workpiece
123. The relative movements of the polishing pad 205 and the
surface of the workpiece 123 coupled with the one or more slurry
additives (e.g., abrasive particles and/or reactive chemicals) of
the CMP slurry 103 at the wafer/pad interface 301 allow the CMP
process to planarize the surface of the workpiece 123 by means of
both physical and chemical forces. With the CMP slurry 103 being
evenly distributed at the wafer/pad interface 301, a highly
controlled planarization of the workpiece 123 may be achieved
within short polishing times.
[0063] In some embodiments, the control unit 101 monitors and
analyzes a level of the slurry reservoir 115. In order to maintain
the level of the slurry reservoir 115 and to keep the workpiece 123
submerged within the slurry reservoir 115 during CMP processing,
the control unit 101 may control one or more of the valve V1-V3 and
one or more of the pumps P1-P3 to adjust the flows of the CMP
slurry 103, the filtered slurry 131, and the used slurry 127 into
and out of the chamber 113. Keeping the workpiece 123 submerged
within the slurry reservoir 115 ensures that a uniform distribution
of the CMP slurry 103 is maintained at the wafer/pad interface 301
and avoids non-uniform slurry distribution during CMP processing
which allows for a highly controlled within wafer (WiW) leveling of
the surface of the workpiece 123. In some embodiments, the WiW
leveling may be controlled to within variances of between about 100
.ANG. and about 30 .ANG., such as about 50 .ANG..
[0064] Embodiments of the CMP processing system 100 and methods
described herein provide improved polish stability and improved WiW
thickness control, even when using short polish times (e.g., about
1-3 seconds). Furthermore, the space within the chamber 113 may be
minimized and material costs may be realized based on the design of
the chamber 113 allowing for the CMP slurry to flow into and out of
the chamber 113 via the intake 111 and the output 125 arranged at
or near the bottom of the chamber 113. Further space and cost
savings may be realized by performing the CMP processing of the
workpiece 123 below the surface of the slurry reservoir 115 instead
of using a slurry arm and nozzle to dispense the CMP slurry 103 to
a slurry drop point on the top surface of the polishing pad 205.
Furthermore, performing the CMP processing of the workpiece 123
below the surface of the slurry reservoir 115 allows for the
uniform distribution of the CMP slurry 103 at the wafer/pad
interface 301. Whereas, a non-uniform distribution of slurry at the
wafer/pad interface 301 occurs when dispensed from a slurry arm at
a drop point on a surface of the polishing pad 205. The non-uniform
distribution of the slurry dispensed from the slurry arm is caused
by the difference between the location of the slurry drop point and
the location of the wafer/pad interface 301. Further cost savings
and production efficiencies may also be realized by reusing and
recycling the CMP slurry 103 in the slurry reservoir 115.
[0065] The CMP processing system 100 provides a highly uniform
polish behavior with increased process stability, even in the
presence of varied topography of the wafer/pad interface 301 (e.g.,
due to coarseness of the polishing pad 205 and/or due to roughness
of within wafer (WiW) surfaces). Furthermore, the CMP processing
system 100 provides a highly uniform polish behavior with increased
process stability, even when using significant polishing down force
causing the polishing pad 205 to bend even when using short polish
times (e.g., about 1-2 seconds). Thus, improved WiW thickness
control is realized when using the chamber 113 with the slurry
reservoir 115, thereby further enhancing production yield.
[0066] FIG. 5 illustrates a purging of the slurry reservoir 115,
according to some embodiments. Once the desired CMP processing of
the workpiece 123 is completed, the CMP processing system 100
controls the polishing head 203 to raise the workpiece 123 away
from the polishing pad 205, thereby separating the workpiece 123
from contact with the polishing pad 205 and eliminating the
wafer/pad interface 301 as shown in FIG. 3 and in FIG. 4. Once the
workpiece 123 has been raised and separated from contact with the
polishing pad 205, the used slurry 127 of the slurry reservoir 115
may be purged from the chamber 113 via the output 125 of the
chamber 113, as discussed in detail above with regard to FIG.
1.
[0067] Embodiments disclosed herein relate to the CMP processing
system 100 and CMP polish method to improve within wafer (WiW)
performance via the chamber 113 including a slurry reservoir 115.
In some embodiments, the system includes the chamber 113 design
that allows for uniform distribution of the slurry at a wafer/pad
interface 301 during a CMP process and that avoids non-uniform
distribution of the slurry at the wafer/pad interface 301 due to
differences between a location of the pad/wafer interface and a
location of a slurry drop point. The CMP processing system 100
provides a highly uniform polish behavior with increased process
stability, even in the presence of varied topography of wafer/pad
roughness and/or varied topographies of wafer-to-wafer (WtW)
surfaces, even when using significant polish down forces causing
the polishing pad 205 to bend, and even when using short polish
times (e.g., about 1-2 seconds). As the CMP processing system 100
provides the highly uniform polish behavior with increased process
stability, improved control of a WiW thickness profile may be
realized.
[0068] FIG. 6 illustrates a method of performing a cleaning process
of a workpiece using the chamber of FIG. 2, in accordance with some
embodiments. Once the chamber 113 has been purged of all slurry, as
discussed above with regard to FIG. 5, the control unit 101 may
control a cleaning process for the workpiece 123. As such, the
control unit 101 may direct the valves V1-V4 and pumps P1-P5 to
supply a cleaning solution 603 from the supply tank 107 or, for
example, from a cleaning supply tank 600 of the slurry distribution
system 90. According to some embodiments, the cleaning solution 603
may comprise one or more of de-ionized water, SC-1, NH.sub.4OH, HF,
citric acid, or other chemicals, for example.
[0069] The cleaning solution 603 may be provided via a cleaning
solution feedline 609 connected between a second multi-port
manifold 657 of the slurry distribution system 90 to flow through
the intake 111 of the chamber 113. As the cleaning solution 603
continues to flow into the chamber 113, a cleaning solution
reservoir 615 is formed therein. The control unit 101 may control a
level of the cleaning solution reservoir 615 and may control one or
more of manipulations of the polishing head 203 and one or more
manipulations of the platen 207 during the cleaning process of the
workpiece 123, according to some embodiments.
[0070] As illustrated in FIG. 6, the control unit 101 may initially
determine a third level L.sub.3 to which the surface of the
cleaning solution reservoir 615 is to be raised during the cleaning
processing of the workpiece 123. In some embodiments, the desired
recipe may dictate a fixed level for the third level L.sub.3, a
fixed height above the upper surface of a cleaning pad 605 for the
third level L.sub.3. The height of the upper surface of the
cleaning pad 605 and the level of the surface of the cleaning
solution reservoir 615 may be determined by the control unit 101
using the methods described above for determining the height of the
upper surface of the polishing pad 205 and the surface of the
slurry reservoir 115.
[0071] Once the platen 207 has been submerged in the cleaning
solution reservoir 615, the control unit 101 begins the desired
cleaning processing of the workpiece 123 by directing the polishing
head 203 to lower the workpiece 123 into the cleaning solution
reservoir 615 and begin rotating the workpiece 123 while pressing
the surface of the workpiece 123 into the upper surface of the
cleaning pad 605. The polishing head 203 may also manipulate the
workpiece 123 by moving the workpiece 123 radially along the
surface of the cleaning pad 605 as the workpiece 123 is rotated by
the polishing head 203 and as the cleaning pad 605 rotates beneath
the workpiece 123. With the cleaning pad 605 submerged within the
cleaning solution reservoir 615 and the surface of the workpiece
123 lowered into the cleaning solution reservoir 615 and making
contact with the cleaning pad 605 during the desired cleaning
processing, the cleaning solution 603 is uniformly distributed at a
wafer/pad cleaning interface (e.g., a wafer/pad interface 601)
between the surface of the workpiece 123 and the cleaning pad
605.
[0072] As illustrated in FIG. 6, a wafer/pad cleaning interface 601
is formed between the surface of the workpiece 123 and a portion of
the surface of the cleaning pad 605 where the two surfaces are
pressed together below the upper surface of the cleaning solution
reservoir 615. As such, the cleaning solution 603 of the cleaning
solution reservoir 615 is evenly distributed at the wafer/pad
cleaning interface 601 during the desired cleaning processing of
the workpiece 123. As the rotating workpiece 123 is pressed into
the surface of the cleaning pad 605, the wafer/pad cleaning
interface 601 is maintained below the upper surface of the cleaning
solution reservoir 615 thereby providing the even distribution of
the cleaning solution 603 during the cleaning processing of the
workpiece 123. The relative movements of the cleaning pad 605 and
the surface of the workpiece 123 coupled with the cleaning solution
603 at the wafer/pad cleaning interface 601 allow the cleaning
process to remove waste and impurities from the surface of the
workpiece 123 by means of both physical and chemical forces. With
the cleaning solution 603 being evenly distributed at the wafer/pad
cleaning interface 601, a highly controlled cleaning of the
workpiece 123 may be achieved within short cleaning times.
[0073] In accordance with an embodiment, a method includes
attaching a semiconductor wafer to a polishing head within a
chamber; placing a polishing pad on a platen within the chamber;
flowing a slurry into the chamber to form a slurry reservoir; and
performing a chemical mechanical polishing process at an interface
between a surface of the semiconductor wafer and the polishing pad,
the interface being below an upper surface of the slurry reservoir.
In an embodiment, the method further includes raising the surface
of the slurry reservoir to cover a surface of the polishing pad
prior to the performing the chemical mechanical polishing process.
In an embodiment, the method further includes lowering the
polishing head into the slurry reservoir to form the interface. In
an embodiment, the method further includes lowering the polishing
head to cover a surface of the polishing pad with the slurry prior
to the performing the chemical mechanical polishing process. In an
embodiment, the method further includes lowering the polishing head
into the slurry reservoir to form the interface. In an embodiment,
the method further includes purging the slurry from the chamber;
and flowing a cleaning solution into the chamber to create a
cleaning reservoir.
[0074] In accordance with another embodiment, a method includes
securing a substrate to a wafer carrier of a polishing head within
a chamber; attaching a polishing pad to a platen within the
chamber, an upper surface of the polishing pad being at a first
height; forming a slurry reservoir within the chamber, an upper
surface of the slurry reservoir being at a level below the first
height; lowering the platen to submerge the polishing pad in the
slurry reservoir; and performing a chemical mechanical polishing
process on a surface of the substrate below the upper surface of
the slurry reservoir. In an embodiment the forming the slurry
reservoir comprises flowing a slurry into the chamber at a point
below the platen. In an embodiment the method further includes
purging a first slurry of the slurry reservoir from the chamber;
flowing a second slurry into the chamber to form a second slurry
reservoir in the chamber; and performing a second chemical
mechanical polishing process below an upper surface of the a second
slurry reservoir. In an embodiment the second slurry is different
from the first slurry. In an embodiment the method further includes
filtering the first slurry that is purged from the chamber to
provide a filtered slurry; and using at least a portion of the
filtered slurry as the second slurry. In an embodiment the method
further includes filtering the first slurry that is purged from the
chamber to provide a filtered slurry; mixing a make-up solution to
restore depleted slurry additives in the filtered slurry to form a
recycled slurry; and using the recycled slurry as the second
slurry. In an embodiment the performing the chemical mechanical
polishing process comprises lowering the substrate into the slurry
reservoir. In an embodiment the method further includes purging a
slurry of the slurry reservoir from the chamber; and flowing a
cleaning solution into the chamber to form a cleaning reservoir in
the chamber; and performing a cleaning process below an upper
surface of the cleaning reservoir.
[0075] In accordance with yet another embodiment a system includes
a chamber comprising a slurry intake; a platen housed within the
chamber; and a polishing pad housed within the chamber, wherein a
delivery orifice of the slurry intake is located below an upper
surface of the polishing pad. In an embodiment the system further
includes a level sensor located within the chamber. In an
embodiment the level sensor is located at least partially above the
polishing pad. In an embodiment the system further includes a
slurry reservoir located within the chamber, the slurry reservoir
covering the polishing pad. In an embodiment the system further
includes a motor located to move the polishing pad in a first
direction, the first direction being perpendicular to a rotational
motion of the polishing pad. In an embodiment the system further
includes a filter connected to an output of the chamber; and a
restoration system.
[0076] 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.
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