advances in sti process and consumable design...aslawing nccavs cmpug 6/2005 zeta...

ASLawing NCCAVS CMPUG 6/2005

Advances in STI Process and Advances in STI Process and Consumable DesignConsumable Design

A. Scott LawingJune 1, 2005


Outline

Nanophase ceria particle technologyConsistency

CMP Technologies slurry technologyCelexis™CX94S single component highly selective ceria slurryColloidal stabilityLow defectivityEase of use

CMP Technologies process technologyRobust process designLeverage entire consumable set

Next Generation performance


Particle Technology

Celexis™ slurries use a unique ceria particle produced by Nanophase Technologies via a patented gas-phase plasma technologyNanoArc™ Synthesis (NAS) process creates a unique discrete, single ceria crystal:

Stable dispersion due to in situ created high particle surface charge Tight particle control to eliminate large, defect causing particles.Non- milling process (eliminates media contamination)

Other Benefits:Simplified process for consistent and repeatable particle outputEnhanced filtration compatibility

Final product is filtered to 1.0 µm absolutePOU filtration capability


Nanophase NAS Process

Precursor Feed

Plasma EnergyApplied

Precursor Evaporated

Quench/Reactive GasAdded

Condensation andSolidification

Cooling Gas Added

NanoparticlesCollected

NanoArc™ Synthesis (NAS)Patented gas-phase plasma processNon-porous, discrete single

crystalsMean particle size: 50 nmHigh chemical purityHigh zeta potential via in situ

surface treatment


Ceria Dispersion

Final milling

Wet dispersion

(formsagglomerates)

CalciningMillingParticle precipitation

Cerium solution Drying

NAS ProcessDispersionto primaryparticles

Truncate particle size distribution

Typical ceria process

Nanophase ceria process

Ceria Raw Stock

Ceria Raw Stock

Final ceriadispersion

FormCrystals

DispersionStep

Final Sizing

1 2 3 4 5 6 7

1 2 3Final ceriadispersion


Particle Size/Low Defectivity

Celexis ceria particle distributions matches state-of-the-art low defectivity silica products.

Tail ends <200 nm

Colloidal SilicaFumed Silica

Ceria STI slurry

Tail ends <200 nm

Colloidal SilicaFumed Silica

Ceria STI slurry


Zeta Potential

-50

-40

-30

-20

-10

0

10

20

30

40

50

1 2 3 4 5 6 7 8 9 10 11

pH

Zeta

Pot

entia

l (m

V)

Raw Ceria

Raw Ceria treated with non-ionicdispersant

Celexis CX2000 (Ceria particle slurry)

Celexis CX94S (Single Component Slurry)

Isoelectric point of Raw Ceria: pH = 6.8

Zeta Potential as a Function of pH

Optimized dispersion of ceria particle provide stable ceria particle slurry and enhanced single component slurry stability


Chemistry OptimizationCelexis CX94 slurry chemistry has been optimized to hit target polish rate, while minimizing range across active density and maximizing the thickness remaining in the widest trenchNote that rate and planarization metrics are coupled

Planarization metrics are tied to the rate inhibiting nature of the chemistry

CX94S chemistry does not have significant stop-on-planar or deceleration characteristics

1

0

Desirability

0 1

Lo Hi

Lo Hi

Hi

1

0

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

Opt

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

OptDesirability

0 1

Lo Hi

Lo Hi

Lo

Hi

Lo

Hi

Lo

1

0

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

Opt

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

OptDesirability

0 1

Lo Hi

Lo Hi

TEO

S R

R Hi

Tren

ch T

IR(1

0-90

% R

ange

)La

rge

Tren

ch

Thic

knes

sD

esira

bilit

y 1

0

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

Opt

Parameter A

Lo Hi

Opt

Parameter B

Opt

Parameter C

OptDesirability

0 1

Lo Hi

Lo Hi

Lo

Hi

Lo

Hi

Lo


Slurry Stability

Time (Hours)

0 0.5 2 2.5 3 3.5 4 5 6 7 8 9

Nor

mal

ized

Per

cent

Sol

ids

0

0.5

1

1.5

CelexisTMShutdown Study

Bottom of drum

Top of drum

Celexis™ CX94S slurry has excellent ceria particle suspension and stability


Defectivity Performance

Nor

mal

ized

Cha

tter M

arks

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Celexis™ CX94S Silica

Slurry Type

Each Pair

Student's t

0.05

Oneway Analysis of Normalized Chatter Marks By Slurry Type

Celexis™ STI slurry outperforms low defectivity ILD slurry for micro-scratch defectivity


Defectivity Performance

Cha

tterm

arks

0

10

20

30

40

50

60

70

80

90

Celexis™ 1st Generation

Process Improvements

Each Pair

Student's t

0.05

Oneway Analysis of Norm Chattermarks By Filtration

Celexis CX94S slurry Defectivity ImprovementsMicroscratch count determined by 100% defect review using SEM Vision™. (after 300 angstrom HF decoration)


Step Height and Motor Current Response

-0.3

0

0.5

1

0 20 40 60 80 100 120 140 160

Polish Time (sec)

Nor

mal

ized

Ste

p H

eigh

t

5

5.5

Most significant features of the friction endpoint trace seem to correlate with planarization, not clearing

6

6.5

7

7.5

8

8.5

9

9.5

10

Fric

tion

EP V

alue90%

70%50%30%10%50% 5 µm50% 50 µm50% 500 µm

This characteristic “hump” in the friction trace corresponds to planarization across the entire range of pattern density

This more subtle feature indicates clearing of the nitride

“MIT” mask:10-90 % features on 100 µm pitch [i.e. 10 µm line 90 µm space (10 %) – 90 µm line 10 µm space (90 %)]. Sizes on 50% % density structures refer to the trench depth.


Effect of Overfill on Motor Current

0 20 40 60 80 100 120 140

Polish Time (s)

Endp

oint

Sig

nal (

arb.

uni

ts)

0 nm

50 nm

100 nm

0 50 100 150 200

Polish Time (s)En

dpoi

nt S

igna

l (ar

b. u

nits

)

0 nm

50 nm

100 nm

Design A Design B

Onset of planarization

Planarizationachieved

Polishing on planar surface

Onset of clearing

Clearingachieved

Both devices exhibit the same qualitative behavior5 stages of polishing evident:

I – pre-planarization, II – planarization, III polishing on planar surface, IV – clearing, V - overpolish


Stages of Polishing & Endpoint Trace

Length of stage III and height of the feature at the end of stage II affected by overfillHeight of feature saturated with complete planarization (50 & 100 nm overfill reach same height), 0 nm overfill probably not completely planarized

Stage I –Pre-planarization. Polishing on surface with significant step height

Stage II –Planarization. Steps removed in some areas. Substantial planarization as stage II proceeds.

Stage III –Polishing on planar surface. Length of stage III dependent on overfill thickness.

Stage IV –Clearing. Wafer clear at end of stage IV

0 20 40 60 80 100 120 140

Polish Time (s)

Endp

oint

Sig

nal (

arb.

uni

ts)

0 nm

50 nm

100 nm

III III

IV V

Stage V –Wafer clear. Nitride thickness decreases and dishing increases.


Motor Current - ISRM Comparison

Both signals show a similar response of the “trigger" featurePeak at 160 - 175 s in ISRM trace increases with increasing overfillMaximum in optical traces does not signal endpoint directly, but can be used as a reliable trigger for the end of the polish step

Motor Current

ISRM

Endpoint Trigger

100 nm Overfill0 nm Overfill 50 nm Overfill


Effect of Downforce on Dishing

Medium down-force process Low down-force process

260 Å 120 Å

Dishing performance improved at low down-force


Subpad Type and Dishing

Step height is combination of dishing and erosion withoverpolishDishing improved with SP2150 subpad vs. Suba™ IV

-0.5

0

0.5

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Normalized Polish Time (1.0 = Just Clear)

Nor

mal

ized

Ste

p H

eigh

t

90% 70%50% 30%10% 50% 50 um50% 5 um 50% 500 um

IC1010™/SP2150

-0.5

0

0.5

1

0 0.2 0.4 0.6 0.8 1 1.2 1.4


Ste

p H

eigh

t (A

)

90% 70%50% 30%10% 50% 50 um50% 5 um 50% 500 um

IC1010™/Suba™IV


Effect of Conditioning on Rate

These data from the AMAT Mirra™ using CX94 slurry formulation, IC1010™/Suba™ IV pad, 100 % in situconditioning30-40% higher polish rate with low aggressive conditioning compared to medium/high

0

500

1000

1500

2000

2500

3000

Low Med/High Low Med/High

Conditioning Aggressiveness

Polis

h R

ate

(A/m

in)

Low DF, High Speed

High DF, Low Speed


Conditioning and Polish Rate

0

500

1000

1500

2000

2500

3000

3500

0

0A0 -+- --+ 0

A00 a00 0 0

0a0

Run #

Polis

h R

ate

(A/m

in)

Low Medium/High High

0

500

1000

1500

2000

2500

3000

3500

0

0A0 -+- --+ 0

A00 a00 0 0

0a0

Run #

Polis

h R

ate

(A/m

in)

Low Medium/High High

Experimental Solid Pad IC1000™ k-groove Pad

Identical DOE’s with developmental formulation (not CX94S) and various levels of conditioning aggressiveness on the Ipec472Highest polish rates obtained with low aggressive conditioning

On IC series pads, higher aggressiveness conditioners exhibit extremely low polish rates


Effect of Conditioning on Selectivity

0

5

10

15

20

25

30

35

40

0 Low

Wafer Down-Force (relative)

Sele

ctiv

ity (O

x/N

itrid

e) Low Aggressive

Medium/High Aggressive

High

POR conditionSelectivity = 20

Selectivity increases with increasing down forceSelectivity decreases with increasing conditioning aggressiveness

Data from Mirra™ tool with 100% in situ conditioning


Effect of Conditioning on Dishing

Low aggressive conditioning results in significantly less dishingMore truncated asperity structure penetrates less deeply into low lying areasData from EBARA EPO222

-0.5

0

0.5

1

0 0.3 0.6 0.9 1.2 1.5

Fractional Polish Time

Nor

mal

ized

Ste

p H

eigh

t

0 0.3 0.6 0.9 1.2 1.5

Fractional Polish Time

90%

10%

50% 5 µm

50% 50 µm

50% 500 µm

Over-polish

Dishing

Medium/High Aggressive Low Aggressive


IC1000 Pad Break-in Characteristics

10001100120013001400150016001700180019002000

0 50 100 150 200 250 300Break-In Time (equivalent minutes @ 5 lb CDF, 99 rpm PS)

Polis

h R

ate

(A/m

in)

012345678910

% S

td D

ev o

f Rat

e

Polish RateUniformity

Medium cut-rate conditioner~75 minutes equivalent break-in time @ 5 lbs CDF, 99 rpm PSRate is unstable until pad is sufficiently broken-in

Ceria-based STI is particularly sensitive to break-in effectsBreak-in can be reduced to 30 minutes with process adjustments


Performance Comparison - MIT Wafers

Ste

p H

eigh

t (A

)

-0.4

-0.3

-0.2

-0.1

0

0.1

1 1.1 1.2 1.3 1.4 1.5


90% 70%50% 30%10% 50% 50 um50% 5 um 50% 500 um

Nex Gen Process Celexis™ CX94S Process

-0.4

-0.3

-0.2

-0.1

0

0.1

1 1.1 1.2 1.3 1.4 1.5


Ste

p H

eigh

t (A

)

90% 70%50% 30%10% 50% 50 um50% 5 um 50% 500 um

Endpoint 30% OverpolishEndpoint 30% Overpolish

Next generation process incorporates stop-on-planar chemistryPlanarization performance rivals fixed abrasiveRobust clearing with excellent planarization and wide overpolish window


Conclusions

Rohm and Haas Electronic Materials CMP Technologies has developed the Celexis™ series of STI slurries

Nanophase ceria particle technology forms the backbone of the slurry lineCMP Technologies slurry design and manufacturing expertise ensure consistent, repeatable performanceCMP Technologies process expertise provides solid process and consumable design guidance and support in the fieldCelexis™ CX94S slurry provides consistent, predictable performance with excellent defectivity, robust clearing behavior and high planarization efficiency in a single component packageNext generation polish performance rivals fixed abrasive planarization levels


Acknowledgements

Rohm and Haas Electronic Materials CMP TechnologiesKerry Lindemann, Asa Yamada, Brian Mueller, Pat Flanagan, Charlie Yu, Sarah Lane, Mike Collins, Josh Ruple, Nichole Bishop

Nanophase

Kinik

Celexis, IC1000, IC1010 and Suba are trademarks of Rohm and Haas Company or its affiliates. NanoArc is a trademark of NanophaseTechnologies. Mirra, SEM Vision and AMAT are trademarks of Applied Materials, Inc

advances in sti process and consumable design...aslawing nccavs cmpug 6/2005 zeta...

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