8:30 – 9:00Research and Educational Objectives / Spanos
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Transcript of 8:30 – 9:00Research and Educational Objectives / Spanos
8:30 – 9:00 Research and Educational Objectives / Spanos
9:00 – 9:45 9:00 – 9:45 CMP / CMP / Doyle,Doyle, Dornfeld, Talbot, SpanosDornfeld, Talbot, Spanos
9:45 – 10:30 Plasma & Diffusion / Graves, Lieberman, Cheung, Haller
10:30 – 10:45 break10:45 – 12:00 Poster Session / Education, CMP, Plasma, Diffusion
12:00 – 1:00 lunch 1:00 – 1:45 Lithography / Spanos, Neureuther, Bokor 1:45 – 2:30 Sensors & Controls /Aydil, Poolla, Smith, Dunn, Cheung, Spanos
2:30 – 2:45 Break 2:40 – 4:30 Poster Session / all subjects 3:30 – 4:30 Steering Committee Meeting in room 373 Soda 4:30 – 5:30 Feedback Session
3rd Annual SFR Workshop & Review, May 24, 2001
5/24/2001
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Chemical Mechanical Planarization
SFR Workshop & Review
May 24, 2001
David Dornfeld, Fiona Doyle, Costas Spanos, Jan Talbot
Berkeley, CA
5/24/2001
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CMP Milestones
• September 30th, 2001– Build integrated CMP model for basic mechanical and chemical
elements. Develop periodic grating metrology (Dornfeld, Doyle, Spanos ,Talbot). Model Outline Progressing- initial Chemical and Mechanical Modules in Development
• September 30th, 2002– Integrate initial chemical models into basic CMP model. Validate
predicted pattern development. (Dornfeld, Doyle, Spanos ,Talbot) .
• September 30th, 2003– Develop comprehensive chemical and mechanical model. Perform
experimental and metrological validation. (Dornfeld, Doyle, Spanos, Talbot)
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Abstract2002 Milestone: Integrate initial chemical models into basic
CMP model. Validate predicted pattern development.
Key areas involved in this are:• Chemical Aspects of CMP (Talbot and Gopal)• Glycine effects on CMP & chemical effect on abrasion (Doyle and Asku)• Material Removal in CM P: Effects of Abrasive Size Distribution and
Wafer-Pad Contact Area (Dornfeld and Luo) • Fluid/Slurry Flow Analysis for CMP Model (Dornfeld and Mao)• Fixed Abrasive Design for C MP (Dornfeld and Hwang)• CMP Process Monitoring using Acoustic Emission (Dornfeld and Chang)• Establishing full-profile metrology for CMP modeling (Spanos and Chang)
Recent activities in yellow will be reviewed here
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OverviewModel Structure & Development Basic
Process Mechanism
Model Validation
Metrology, Process Control, &
OptimizationChem Mech
Chemical Aspects X X XMechanical Aspects X X XFluid Aspects X X XPad Surface Effects XProcess Monitoring X XGrating Metrology XProcess control X
X
X
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Model development scenario
• Identify key influences of chemical and mechanical activity
• Experimental analysis of influences in parallel with model formulation for “module” development
• Identification of “coupling” elements of mechanical and chemical activity
• Build “coupling” elements into integrated model• Full scale model verification by simulation and test• Strategies for model-based process optimization
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Focus of this presentation
• Review of progress in understanding the role of chemistry in CMP
• Update on process monitoring activity• Full-profile metrology for CMP modeling
• Details of these and other key areas in posters
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Contact Pressure
ModelModel of
Active Abrasive
Number N
Model of Material
Removal VOL
by a Single Abrasive
Physical Mechanism; MRR: N´VOL
Slurry Concentration,
Abrasive Shape, Density,
Size and Distribution
Slurry Chemicals
Chemical Reaction
Model (RR0)chem
Pad Roughness
Pad Hardness
Wafer, Pattern,Pad and
Polishing Head Geometry
and Material
Pressure and Velocity
Distribution Model
(FEA and Dynamics)
Down Pressure
Relative Velocity
Wafer Hardness
Dishing &
Erosion
Preston’s Coefficient Ke (RR0 )mech
WIWNUSurface
Damage WIDNU
WIWNU
MRR
Fluid Model
Review - Overview of Integrated Model
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Chemical Aspects of CMP Role of Chemistry
• Chemical and electrochemical reactions between material (metal, glass) and constituents of the slurry (oxidizers, complexing agents, pH) – Dissolution and passivation
• Solubility• Adsorption of dissolved species on the abrasive
particles• Colloidal effects• Change of mechanical properties by diffusion &
reaction of surface
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Modeling of Chemical Effects
• Electrochemical/chemical dissolution and passivation of surface constituents
• Colloidal effects (adsorption of dissolved surface to particles or re-adsorption)
• Solubility changes • Change of mechanical properties (hardness, stress)
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Copper Interconnection using Chemical Mechanical Planarization (CMP)
Fiona Doyle and Serdar Asku
How Glycine Changes Electrochemistry of Copper? Comparison of Cu Behavior in Aqueous Solutions with and without Glycine in terms of Potential-pH Diagrams Polarization Experiments
How Electrochemical Behavior Changes under Abrasion In-situ Electrochemical Experiments during Polishing using Slurries/ Solutions with or without Glycine In-situ Polarization Experiments In-situ Monitoring of Open Circuit Potential (EOC)
Conclusions Experimental Results and Their Comparison with the Theoretical Diagrams
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Copper Interconnection with CMP
ALUMINA PARTICLES w/
Average Size ~ 120 nm From EKC Tech.
CHEMICAL MECHANICAL PLANARIZATION
Cross-sectional View ofSUBA 500 Pad, RodelCorp. (Taken from Y.Moon’s PhD Thesis)
SLURRY • Abrasive particles • ChemicalsWafe
r
Carrier
Slurry feeder
Polishing Plate
POLISHING PAD
Pressure
Rotation
Trench
Via
Etch SiO2
Deposit Barrier Copper Fill CMP
DUAL DAMASCENE PROCESS
SiN
Polishing padPad
asperities
Patterned wafer
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Objective and Methods In Copper CMP,
Electrochemical and Mechanical Mechanisms are not Well Understood
Slurries are formulated empirically at present
Develop a Fundamental Basis for the Behavior ofSlurries with Complexing Agents
Tertiary Potential-pH Diagrams Polarization Experiments using Cu Rotating Disk Electrode In-situ Electrochemical Experiments during Polishing
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Experimental Techniques
Magnetic stirrer
Rotating DiskElectrode
In-situ Electrochemical Experiments
Pt Counter Electrodes
Luggin Probe & Reference Electrode
Polish pad
Copper Working Electrode
Slurry pool P
Rotator Frame
Fritted glassgas bubbler
Rotating CuDisk electrode
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Cu
T=
10-5
Cu-H2O System
-0.8-0.6-0.4-0.20.00.20.40.60.8
0 2 4 6 8 10 12 14 16pH
E, V
vs.
SH
E
Cu2+
Cu
O2
2-
Cu
Cu2O
CuO
RDE
200 rpm
Scan Rate
2 mV/sec
2.17x10-624 12, No Buffer
3.23x10-6102 9, With Carbonate Buffer + 10-2 M Na2SO4
4.43x10-6196 4, With Acetate Buffer + 10-2 M Na2SO4
iOC (A/cm2)EOC (mV vs. SHE)
pH and
pH Buffer System
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
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Cu T
=10
-5 ;
LT=
10-2
Cu-H2O-Glycine System
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
0 2 4 6 8 10 12 14 16pH
E,
V v
s. S
HE
Cu2+
CuL2Cu
L+
Cu
O2
2-
Cu
O
Cu2OCu
RDE
200 rpm
Scan Rate
2 mV/sec
10-2 M Glycine
1.21x10-5-65 12, No Buffer
1.04x10-5-26 9, No Buffer + 10-2 M Na2SO4
6.41x10-6186 4, With Acetate Buffer + 10-2 M Na2SO4
iOC (A/cm2)
EOC (mV vs. SHE)
pH and
pH Buffer System
-800
-600
-400
-200
0
200
400600
800
1000
1200
1400
1600
1800
1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03
i, A/cm 2
E, m
V v
s. S
HE
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Cu-H2O-Glycine System (De-aerated)
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
0 2 4 6 8 10 12 14 16pH
E,
V v
s. S
HE Cu2+
CuL2
CuL+
CuO
22-
Cu Cu2O
CuO
CuHL2+
CuL2-
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
0 2 4 6 8 10 12 14 16pH
E,
V
vs.
SH
E
Cu2+
CuL2CuL
+
CuO
22-
CuO
Cu2OCu
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
Cu T
=10
-5 ;
LT=
10-2
Cu T
=10
-4 ;
LT=
10-1
pH=9
pH=11
pH=12
pH=10
pH=9
pH=11
pH=12
pH=10
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In-Situ Polarization at pH=4
RDE/
IN-SITU
200 rpm
27.6 kPa
Scan Rate
2 mV/s 1.16x10-5181Polishing w/ pad + 5wt % Al2O3
7.33x10-6183Polishing w/ pad only
6.41x10-6186No abrasionAcetate Buffer
10-2 M Na2SO4
10-2 M glycine
6.18x10-6188Polishing w/ pad + 5wt % Al2O3
4.69x10-6191Polishing w/ pad only
4.43x10-6196No abrasion (RDE)Acetate Buffer
10-2 M Na2SO4
No Glycine
iOC
(A/cm2)
EOC
(mV vs. SHE)Abrasion Type
Chemical Composition
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V S
HE
-800-600-400-200
0200400600800
10001200140016001800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
No Glycine 10-2 M Glycine
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In-Situ Polarization at pH=9
RDE/
IN-SITU
200 rpm
27.6 kPa
Scan Rate
2 mV/s 2.87x10-5-33Polishing w/ pad + 5wt % Al2O3
1.28x10-5-32Polishing w/ pad only
1.04x10-5-26No abrasionNo Buffer
10-2 Na2SO4
10-2 M glycine
4.09x10-546Polishing w/ pad + 5wt % Al2O3
5.18x10-692Polishing w/ pad only
3.23x10-6102No abrasion (RDE)Carbonate Buffer
10-2 M Na2SO4
No Glycine
iOC
(A/cm2)
EOC
(mV vs. SHE)Abrasion TypeChemical
Composition
-800
-600
-400
-200
0
200
400600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm2
E, m
V v
s. S
HE
No Glycine 10-2 M Glycine
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In-Situ Polarization at pH=12
RDE/
IN-SITU
200 rpm
27.6 kPa
Scan Rate
2 mV/s8.62x10-5-163Polishing w/ pad + 5wt % Al2O3
3.42x10-5-75Polishing w/ pad only
1.21x10-5-68No abrasionNo Buffer
No Na2SO4
10-2 M glycine
9.72x10-6-140Polishing w/ pad + 5wt % Al2O3
4.83x10-612Polishing w/ pad only
2.17x10-623No abrasion (RDE)No Buffer/Na2SO4
DD Water with
No Glycine
iOC
(A/cm2)
EOC
(mV vs. SHE)Abrasion Type
Chemical Composition
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
1600
1800
1E-08 1E-07 1E-06 1E-05 1E-04 1E-03 1E-02 1E-01
i, A/cm 2
E, m
V v
s. S
HE
No Glycine 10-2 M Glycine
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In-Situ OC Potential Measurements
Without Glycine With 10-2 M Glycine
-300
-250
-200
-150
-100
-50
0
50
100
150
200
250
300
0 60 120 180 240 300 360 420 480 540 600
Time, s
EO
C,
mV
vs.
SH
E
Polishingstarted
Polishingstopped
Polishingre-started
pH 4
pH 12
pH 9
-300
-250
-200
-150
-100
-50
0
50
100
150
200
250
300
0 60 120 180 240 300 360 420 480 540 600
Time, s
EO
C,
mV
vs.
SH
EPolishingstarted
Polishingstopped
Polishingre-started
pH 4
pH 12
pH 9
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Conclusions
•Polarization results well correlated with potential-pH diagrams
•No significant changes in in-situ polarization for active behavior
•Mechanical components significantly affected in-situ polarization for active-passive behavior
•Kaufman’s tungsten CMP model is also valid for Cu CMP
•Glycine (complexing agents) may enhance the polishing efficiency.
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Future Work-I Determination of Chemical (Electrochemical) and
Mechanical Contributions
Maintain a Constant Level Of In-Situ Polarization, Measure Current CHEMICAL CONTRIBUTION from Time-Averaged Current POLISH RATE from Weight Loss MECHANICAL CONTRIBUTION from the Difference
Generation of Chemical,Mechanical and Total Removal Rate versus Polarization Plots at Different pH’s.
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Future Work-IIIn-Situ Electrochemical
Experiments using “Patterned” Cu Electrodes
In-Situ Polarization Experiments Polishing at a Constant Level of Polarization Surface Examination of Passive Films XPS, Auger Spectroscopy
Verification of Kaufman’s Model using “Patterned”Cu Electrodes
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Process Monitoring of CMP using Acoustic EmissionAndrew Chang UCB
Motivation
• Endpoint Detection
- The characteristics of the acoustic emission signal from various materials can be easily discernable during the polishing process.
- Outside noise sources, once characterized, can be minimized and filtered from disturbing the process signal.
• Scratch Detection
- Scratches and/or other mechanically induced flaws (large agglomeration of particles, contaminants on the pad, etc.) can be detected and used as feedback for purposes of real-time process control.
• Abrasive Slurry Design
- Energy of the AE signal can be correlated to the active number of abrasive particles during polishing for slurry concentration optimization
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Acoustic Emission Propagation in the WaferSchematic view of abrasive particles during polishing
(exaggerated view)
Oil film couplantSensor
Carrier ringWafer carrier
Wafer
Pad
Polishing plate
Abrasives in slurry
Individual burst emission waves generated by abrasive particles contacting wafer produce a continuous acoustic emission source.
Wafer
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Experimental Setup
Pressure = ~ 1 psiTable Speed = 50 RPMWafer Carrier Speed = Stationary Slurry flowrate = 150 ml/min
Polishing Conditions
IC 1000/Suba IV stacked padPad type
ILD 1300, abrasive size (~100 nm)Alumina slurry, abrasive size (~100 nm)
Slurry type
Bare silicon & copper blanket wafersTest Wafers
Toyoda Float Polishing MachineCMP Tool
PC Data Acquisition
Raw Sampling Rate = 2 MHz
Raw AE
Signal Conditioning(60-100 dB)
Pre-amplification &Primary amplification
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Raw Acoustic Emission from CMP Process
Low frequency noise due vibrations from table motor, pad pattern effects, etc.
Filtered raw signal containing high frequency AE content
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Establishing full-profile metrology for CMP modeling
Costas Spanos & Tiger Chang UCB
SubstrateOxide
• Use scatterometry to monitor the profile evolution• The results can be used for better CMP modeling
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Mask Designed to explore Profile as a function of pattern density
• The size of the metrology cell is 250m by 250m
• Periodic pattern has 2m pitch with 50% pattern density
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Sensitivity of Scatterometry (GTK simulation)
0 500 1000 1500 20000
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5Profile Evolution during CMP
Oxide (nm)
pro
file
(m
icro
n)
• We simulated 1 m feature size, 2 m pitch and 500nm initial step height, as it polishes.
• The simulation shows that the response difference was fairly strong and detectable.
Tan PSI Response to Profile Evolution
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
240
280
320
360
400
440
480
520
560
600
640
680
720
760
Wavelength(nm)
tan
PS
I
tan PSI 500nm
tan PSI 400nm
tan PSI 300nm
tan PSI 200nm
tan PSI 100nm
tan PSI Flat Surface
Cos DEL Response to Profile Evolution
-1.5
-1
-0.5
0
0.5
1
1.5
240
280
320
360
400
440
480
520
560
600
640
680
720
760
Wavelength(nm)
cos
DE
L
cos DEL 500nm
cos DEL 400nm
cos DEL 300nm
cos DEL 200nm
cos DEL 100nm
cos DEL Flat Surface
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Characterization Experiments Completed
• Three one-minute polishing steps were done using the DOE parameters
Initial profilesSopra/AFM
CMP NanospecThickness
measurement
SopraSpectroscopicellipsometer
AFM(AMD/SDC)
Wafer cleaning
10060611
10060610
1006069
1508048
1508087
508046
508085
1504084
1504043
504082
504041
Slurry Flow
(ml/min)
Table Speed (rpm)
Down Force
(psi)
Wafer #
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Library-based Full-profile CMP Metrology
Reference: X. Niu, N. Jakatdar, J. Bao, C. Spanos, S. Yedur, “Specular spectroscopic scatterometry in DUV lithography”, Proceedings of the SPIE, vol.3677, pt.1-2, March 1999.
Five variables were used in to generate the response library: bottom oxide height (A), bottom width (B), slope 1 (C), slope 2 (D) and top oxide height (E).
Substrate
AB
CD
E
oxide
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-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2
x 104
0
2000
4000
6000
-2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3
x 104
-5000
0
5000
-3 -2 -1 0 1 2 3
x 104
0.9
1
1.1x 10
4
AFM
Full Profile CMP Results, so far
• Extracted profiles match SEM pictures within 10nm• Scatterometry is non-destructive, faster and more descriptive than
competing methods.• Next challenge: explore application in wet samples.
SEM Scatterometry
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Conclusions
• Chemical effects model and synergy with mechanical effects being developed and validated
• Mechanical effects model validated for abrasive size and activity and wafer-pad contract area
• Fabrication technique for micro-scale abrasive design experiments
• Sensing system for process monitoring and basic process studies being validated
• Scatterometry metrology sensitivity study indicates suitability for observing profile evolution
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2002 & 2003 Goals
Develop comprehensive chemical and mechanical model. Perform experimental and metrological validation, by 9/30/2003.
•Simulation of Integrated CMP model
•Experimental verification of integrated CMP model (role of chemistry elements, mechanical elements in mechanical material removal)