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

2

Chemical Mechanical Planarization

SFR Workshop & Review

May 24, 2001

David Dornfeld, Fiona Doyle, Costas Spanos, Jan Talbot

Berkeley, CA

5/24/2001

3

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)

5/24/2001

4

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

5/24/2001

5

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

5/24/2001

6

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

5/24/2001

7

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

5/24/2001

8

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

5/24/2001

9

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

5/24/2001

10

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)

5/24/2001

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

5/24/2001

12

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

5/24/2001

13

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

5/24/2001

14

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

5/24/2001

15

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

5/24/2001

16

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

5/24/2001

17

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

5/24/2001

18

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


4.43x10-6196No 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

5/24/2001

19


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


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


5/24/2001

20


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


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


5/24/2001

21

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

5/24/2001

22

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.

5/24/2001

23

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.

5/24/2001

24

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

5/24/2001

25

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

5/24/2001

26

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

5/24/2001

27

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

5/24/2001

28

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

5/24/2001

29

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

5/24/2001

30

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

5/24/2001

31

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

5/24/2001

32

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 #

5/24/2001

33

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

5/24/2001

34

-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

5/24/2001

35

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

5/24/2001

36

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)

Documents

8:30 – 9:00Research and Educational Objectives / Spanos