Slurry Handling, Troubleshooting and FiltrationSlurry Handling, Troubleshooting and Filtration

Levitronix CMPUG SymposiumBudge Johl – Phoenix, AZ

February 17, 2005

Key CMP Issues & Their Causes

Three key CMP issues encountered in field:High defects/microscatches on wafersChange in polishing performance (removal rate, nonuniformity)Short filter lifetime or reduction in lifetime

Associated causes of these three key issues:Large particles in slurryChange in slurry particle size distributionHigh gel content in slurry

Particles MicrogelAggregate AgglomerateRef.: R. Iler, Chapter One , “The Chemistry of Silica”,

John Wiley & Sons, 1979

Terminology of Particles Observed with SEM, ESEM & Light Microscope

Particle: single solid sphere or other geometryAggregate: multiple particles chemically attached to each other (chain), primarily via siloxane bonds“Agglomerate”: particles and aggregates come together into close-packed clumps due to entanglement, drying, and coagulation, denser than the surrounding solution Microgels: aggregates link together and form three dimensional network with water trapped within; same density and refractive index as the surrounding solution (Filter Plugging Problem)

Potential Defect Causing Agglomerates & Large Particles

Silica slurry was diluted with pH adjusted water,then filtered through a 3 micron Isopore membrane.

Membrane with Wet Gel & Particles Same Membrane with Dry Gel & Particles

WetGels

DryGels

LargeParticles

Gels

Possible Sources of Large Particles & Gels:

AgglomerationLocal drying in shipping container, tank, and fittingsSettlingpH shock during dilutionTemperature fluctuation during shipping and storageShearing (i.e. certain valves, pumps, piping design)Improper MixingLarge # of TurnoversLack of PM’s on Distribution SystemLack of proper slurry conversion protocols from one slurry type to another, including flushing and system sterilization protocols.

Oxide Defects “Large Particles” in Slurry Create Micro-Scratches & Embedded Particles on Wafers

Typical defects in oxide CMPRef.:C. Dennison, KLA-Tencor, Micro, February 1998

W-CMP Defects

Nine types of tungsten CMP defects

Ref.: C. Dennison, KLA-Tencor, Micro, February 1998

Large ScratchLarge Scratch

Cu-CMP Defects

Large Chatter Marks

Optical image (Compass®) SEM images (SEMVision™)

AFM (Veeco)

Cu-CMP Defects

Gouge

AFM (Veeco)

Cu-CMP DefectsOptical image (Compass) SEM images (SEMVision)

Micro ScratchMicro Scratch

AFM (Veeco)

Cu-CMP DefectsOptical image (Compass) SEM images (SEMVision)

Slurry Troubleshooting Takes Detective Work

Slurry Trouble Shooting Methods

• Delta p measurement• SEM analysis of usedfilter

•ESEM analysis of slurry

Gel Content of SlurryShort or Reduced Filter Lifetime

• Mean Particle Analyzer• % Solids Measurement• Density• pH• Conductivity• % Assay• Viscosity• Zeta Potential

Change in Mean Particle Size Distribution or other parameter

Change in Polishing Performance

• Particle Counting Eq.• SEM Analysis• EDX (Elemental Signature)

Large Particles in SlurryDefects including Microscratches (LPD’s on Wafers)

Troubleshooting MethodAssociated Cause of ProblemTypical Problem Encountered

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.0930N500

50

100

150

200

250

Analytical Labs Play Key Role for Slurry Handling, Troubleshooting and Filtration

� Total % Solids� Density / Specific Gravity� pH� Conductivity� Viscosity� Mean Particle Size� Large Particle Size� Filtration Testing & Optimization (Source, Post Mix, Global Loop & POU)� Zeta Potential� Percent Assay & Assay Development� Slurry Characterization, Distribution & Handling Evaluations, Slurry Conversion Protocols

Drum Contamination

Clean drum surface to remove dust particles before openingWhen removing lids bung holes should be carefully cleaned before pouring out slurry.Carefully clean the slurry container lids & bung holes before closing left over slurry pails or drums to prevent introducing dry slurry particles.Dip tubes should be clean before introducing into new slurry container.

Some MixingFactors

� Size of Tote� Age of Slurry� Number of Propellers� Type of Mixer and Propeller� Direction of Mixing � RPM� Propeller Scraping Side of Drum

CUS1201A Mixing Time @ 500 RPM

2929.5

3030.5

3131.5

3232.5

33

0 5 10 15 20 25

Time (minutes)

Tota

l Per

cent

Sol

ids

Top Bottom

Note: Slurry allowed to remain undisturbed for several weeks for Time 0 sample.

Proper Mixing of Slurry

Minimizing Particle GrowthHumidificationNeed to humidify the air pockets that come in contact with the slurry with >95% humidity.Need to avoid drying of the slurry which can result in formation of agglomerations and aggregates.

Non-Humidified

Effect of Humidification in CDM’s

Effect of CDM’s on Slurry Health

Large Particle Population Distribution

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

0.5 1 1.5 2 2.5

Particle Diameter (µm) ->

Counts

ControlCDM-I

CDM-II

CDM-III

Levitronix Pump Study

Magnetic Levitation Technology

Dynamic Levitronix Pump Study

Time (Hours)

0 50 100 150 200 250 300 350

Tota

l Per

cent

Sol

ids

22.5

25.0

27.5

30.0

32.5

Vis

cosi

ty (c

P),

Den

sity

(g/m

L)

0

1

2

3

4

5

6

Storage Tank Turnovers

0 250 500 750 1000 1250 1500 1750

Viscosity (cP)

Density (g/mL)

Total Percent Solids

Klebosol® 1501-50

HOURS

0 50 100 150 200 250 300 350

Zeta

Pot

entia

l (m

V)

-75

-50

-25

0

Days

0 2 4 6 8 10 12 14

Dynamic Levitronix Pump

Klebosol 1501-50

HOURS

0 50 100 150 200 250 300 350

Mea

n PS

D (n

m)

0

25

50

75

100

125

150

Days

0 2 4 6 8 10 12 14

Dynamic Levitronix Pump

Klebosol 1501-50

Klebosol 1501-50 Dynamic Levitronix Pump Study

0

1000

2000

3000

4000

5000

6000

0 5 10 15 20 25 30 35 40 45 50

Particle Diameter (microns)

Cum

ulat

ive

Num

ber

(# P

art

> D

iam

eter

)

T0hrs T24hrs (122 TO) T144hrs (730 TO) T336hrs (1700 TO)

Klebosol 1501-50 Dynamic Levitronix Wafer Removal Rate Response

0.0

0.5

1.0

1.5

2.0

1 2 3

Polisher Head #

Nor

mal

ized

RR

Dat

a

STANDARD (0 Turnovers) RRLEVITRONIX (1700 Turnovers) RR

Klebosol 1501-50 Dynamic Levitronix Pump Defectivity Response

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Head 1 Head 2 Head 3

Polisher Head #

Nor

mal

ized

Def

ect D

ata

( >

0.1

µm ) STANDARD (0 Turnovers)

LEVITRONIX (1700 Turnovers)

Filtration

Wonder if this filter will work?

Possible Filter Locations

DIFiltration

ShippingContainer

Dilution Day Tank

PolishingTool

Water Track

CleaningChemicalFiltration

RecirculatedDI

Filtration

POUFiltration

RecirculationLoop

Filtration

PostDilutionFiltration

IntakeFiltration

Post CMP Cleaning

Filter Retention Curves

� Filter Ratings Are Not All Created Equal� Filter Retention Curves are Very Useful to Determine

Effective Micron Size of the Filter at various Percent Retentions

Retention Efficiency Curves for Planargard CMP Filters

0

20

40

60

80

100

0 5 10 15 20 25 30

Particle Size (microns)

Perc

ent R

eten

tion

CMP1

CMP3

CMP5

CMP7

CMP9

CM11

CM13

CM16

Defectivity Improvement

Large Defectivity Improvement Seen with Global Loop and POU filters.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Nor

mal

ized

Def

ect D

ata

Res

pect

to D

ay 0

(>0.

1 µµ µµ m

)

0 24 72 144 192Time (Hours)

EPL2362 Defectivity Response

Dynamic 3 µms Global Loop Filtered

Unfiltered (Static)

Point-of-Use 1.5 µms Filtered (Static)

If the filter is optimized for the slurry, there is noRR loss.

Loop filter : no RR loss

Filter : Mykrolis Corp., Planargard CMP3 10”

Foreign Materials Found On Filter

Foreign Materials� Can Decrease Filter Life� Such as Plastic Shavings/Misc.� Some Foreign Materials Statically� Attracted to PFA Tubing

� Some Other Possible Sources� Unclean Source Container� Mixing Blade Improperly Adjusted & � Scrapes Side of Drum� Dirty Dip Tubes� Unclean Environment where Drum Opened� Improperly Cleaned Delivery System

Filtration Summary

CMP slurry filtration may reduce defects and improve process consistency

POU slurry filtration allows the use of more retentive filters

Higher retention provides better defect reduction

Filtration in slurry delivery systems will extend POU filter’s lifetime

Filter lifetime is highly slurry and process dependent

Lifetime can be monitored by pressure drop and/or flow rate

Conclusion

Understanding slurry characteristics, handling properties and filtration is key for maintaining distribution systems, troubleshooting and minimizing large defect causing particles.

Rohm and Haas Electronic Materials actively seeks to collaborate with distribution system suppliers, filter companies & others to provide the best solutions for the customer.

Together as suppliers we can achieve optimized solutions to fit customer needs and to keep them on target.

� BOC Edwards and FSI International Publications (John Bare & Budge Johl)

� Mykrolis (Millipore) Ken Adrian, Budge Johl, Geanne Vasilopoulos & Gregg Conner

� Rohm and Haas Electronic Materials (Team)

Acknowledgements

Compass and SEMVision are trademarks of Applied Materials, Inc. Klebosol is a trademark of AZ Electronic Materials.Planargard is a trademark of Mykrolis Corp.

� Levitronix® – Provided Pump for Evaluation