CMP Pump Effects on Filter Lifecmpconsulting.org/wa_files/rakesh_singh.pdf · Development of...

Levitronix 2005 CMP Users’ Conference, February 17, 2005, Santa Clara, CAMykrolis Corporation, Rakesh K. Singh 1

CMP Pump Effects on Filter LifeCMP Pump Effects on Filter Life

Rakesh K. Singh, Ph.D., P.E.Rakesh K. Singh, Ph.D., P.E.Mykrolis CorporationMykrolis Corporation


AcknowledgmentsAcknowledgments

Slurry manufacturers for providing CMP slurry and

abrasive dispersion samples for various studies

Beckman Coulter for making available a LS™ 230

analyzer for Particle Size Distribution Measurements

Levitronix GmbH for providing a magnetically levitated

centrifugal pump for slurry handling studies

Christopher Wargo, Craig Lazinsky, Dr. Bipin Parekh and

Dr. Ben Roberts for their contributions to this work


OverviewOverview

Motivation

CMP Slurry Metrology, Handling and Filtration Challenges

Slurry Filtration Methodologies and Design Considerations

Slurry Filtration Physics - Future Directions

Effects of Extensive Pump Handling on CMP Slurries

Results of Large Particle Concentration and Filter Lifetime

Summary and Conclusions


MotivationMotivationCMP processes and consumables must continue to improve

Decreasing feature size and increasing number of metal layersIntroduction of larger wafer, copper, ultra low-k and noble metalsLower defectivity, higher yield and reduced cost of ownership

Important to maintain slurry blend consistency and quality over timeAchieve more uniform and efficient global and local wafer planarizationReal-time CMP slurry blend quality monitoring and control requirementsSubsystems and filtration may help with slurry pot-life and time sensitivity

Significantly different handling and filtration demands of newer slurriesMuch lower abrasive content and mean particle sizes of new slurriesStringent specifications of point-of-use and global loop slurry filtration More efficient handling, flow and large particle management of slurries


Slurry Metrology, Handling and Filtration ChallengesSlurry Metrology, Handling and Filtration ChallengesChallenges:

Tighter blend accuracy and control requirements Quick settling characteristics and limited post-blend useful lifeVariability in the slurry and chemical properties of different lotsUncertainties of oxidizer decay and adjustments with time Strict particle counts, size distribution and filtration requirementsDetection and removal of hard large particles at very small concentrationsDevelopment of end-pointing technique to control dishing and erosion

Slurry health or quality and mix ratio monitoring parameters:Large (> 0.56 or 1.01 micron) particle counts (LPC)Particle size distribution (PSD) and zeta potentialpH, ORP, conductivity, viscosity and refractive indexTotal dissolved solids, wt % solids and density or specific gravityOxidizer concentration and ionic contaminationOxide slurries: agglomeration, filtration, density, PSD and LPCTungsten and copper slurries: settling, oxidizer level, density and LPC


CMP Slurry Filtration: Defect Reduction and CMP Slurry Filtration: Defect Reduction and Process ImprovementProcess Improvement

There are “large particles” (>10x of d50) in CMP slurries that can cause defects (microscratches) and yield losses Slurry suppliers have implemented filtration to eliminate those particles in manufacturingLarge particles tend to slowly reform due to instabilities in chemistry and handling & distributionObjective of CMP Slurry Filtration

To remove large particles and agglomerates from slurry that can cause defects, without changing slurry polishing performance

Gel

“Particles”

0

10

20

30

40

50

60

70

80

90

100

0 200 400 600 800 1000 1200 1400 1600Particle Size (nm)

Rel

ativ

e N

umbe

r of P

artic

les

Defect-Causing“Large Particles”

10 to 10 Particles/ml4 6

>10 Particles/ml15Bulk Particle Concentration


CMP Slurry Filtration: Changed Process Needs CMP Slurry Filtration: Changed Process Needs and Slurry Mean Particle Sizesand Slurry Mean Particle Sizes

• New generation slurries filtration targets tighter retention of large particles at much smaller large-particle cut-off (e.g., 0.5 or 0.3 µm)

• More consistent flow and pressure drop behavior, and longer filter lifetime

• Minimal effects on the mean working particles for better local and global planarity, and repeatability in CMP processing

D50(mean

size)

D99

Earlier 0.20 µm 1 µm

NewTarget

0.16 µm 0.5 µm

NextTarget

0.06 µm 0.3 µm


CMP Slurry Filtration Methodology and MechanismsCMP Slurry Filtration Methodology and MechanismsSlurry Filtration Process

•CMP filtration is actually a separation process•Filters have difficulty separating particles that are less than 1 order of magnitude different in size•Don’t think of filters as strainers working only by size exclusion, there are other important mechanisms

•Inertial impaction, Interception, Adsorption/Adhesion, Diffusion, Gravitational settling

•There are also effects tied to how the media is arranged in the filterIdeal filter with sharp cut-off

100%

Retention Typical retention curve

0Particle Size


Filter Design and Particle RetentionFilter Design and Particle RetentionFilter Design

•Filter design is set by the needs of the fluid challenge: particle size distribution affects the optimum design

•Goal is to fill the available cylindrical volume uniformly with particles

•As the particle concentration increases in an area the flow ratedecreases in that area

•Capture of particle in a narrow particle size range calls for use of pleated cartridge designs

•Capture of particle in a wide particle size range calls for depth of media accommodated by wrapped or layered designs


Filter Media and ConfigurationsFilter Media and ConfigurationsFilter Media

Tighter filter media

Core

Wraps

Flow

More open mediaFlow In

Flow OutVent

Drain

Cartridgeelement

Tighter filtermedia

More openmedia

Typical graded density depth media for CMP slurry filtration Typical depth filter housing arrangement and a pleated depth filter configuration


Filtration Physics Filtration Physics -- Extending Filter LifetimeExtending Filter Lifetime

100%

0

Retention

Particle Size

Ideal filter with sharp cut-off

Effect of each new layer

Flow In

Tighterfiltermedia

Moreopenmedia

Flow Out

(a) (b)

Filter Retention

•Each layer improves the probability of capture at the larger sizes faster than it does for the smaller particle sizes

•Sharper curves improve separation and increase life•As a filter loads the compression of the media will change the filtration performance making it more retentive

•Designs that prevent this in-use compression will also have longer life


Filtration Physics Filtration Physics -- Extending Filter Lifetime (Cont...)Extending Filter Lifetime (Cont...)•Layering of media also provides far greater depth than traditional designs

0%

20%

40%

60%

80%

100%

0 1 10 100Particle Size (mm)

Ret

entio

n

2 3 4 5.1

CMP5 & CMP3 Solaris SLR03

Planargard® CMP3 & CMP5 are typical graded-density wrapped depth media filtersSolaris is a multiple layered design providing extreme depth for extended lifetime

Flow In

Tighter filtermedia

More openmedia

Flow Out


Slurry Filtration Physics Slurry Filtration Physics -- Future DirectionsFuture Directions•Multiple layered designs can be optimized further:

•Conduct more experiments with layering to improve performance•Employ designs with lower face velocities and shapes that fit into equipment more easily

•Pursue better media: Filter theory shows that finer fibers provide better retention at a constant pressure drop

•Currently the smallest diameter fibers used in CMP are meltblownnonwovens •Other technologies exist that can provide finer fibers (non-glass), but for now they are not cost effective/practical

•Consider other filtration models: With significantly more dilute slurries, it may be possible to consider TFF designs

•With more chemically aggressive slurries: There may be better designs for both ease of use and elimination of stainless steel from wetted flow paths


Slurry Filtration CharacterizationSlurry Filtration CharacterizationRetention/Flow and Pressure Drop Test

Retention test conducted with PSL beads solution and CMP slurries and pressure drop tests at 0, 1, 2, 3, 4 GPM using a differential pressure unit

Lifetime Test Testing with CMP slurries and pressure drop and flow rate measurements till pressure drop reaches a specified limit

Recirculation Loop TestEvaluation of global loop and POU filters using a vacuum-pressure dispense system as well as bellows, diaphragm, a magnetically levitated centrifugal pumps

Collaborative Testing with Slurry Vendors and CustomersField returned filter analysis and troubleshootingExtent of filter plugging/remaining lifetime by ∆p and weight gainSEM and ESEM (environmental SEM, for wet sample imaging) analysis

Filter Related Troubleshooting at Site


Test SetTest Set--up for Single Pass POU Operationup for Single Pass POU Operation

PumpDepth Filter

Slurry Supply Tank

PressureGauge, P1

PressureGauge, P2

Weight Scale


Slurry and Filter Characterization in a Slurry and Filter Characterization in a Simulated Recirculation LoopSimulated Recirculation Loop

Pump

DischargeDampener

Supply Tank

25 Foot Long PFATubing Coil

Pinch Valve

Schematic of Recirculation Loop Test Set-Up

Chiller

DI Water

POUFilter

DistributionLoop Filter

In CentrifugalPump Test Only

Collection Tank


Filter Lifetime MonitoringFilter Lifetime Monitoring

Filter lifetime can be monitored byDifferential pressure across the filterFlowrate through the filter under a given system pressure

Pres

sure

Dro

p A

cros

s the

Filt

er

Given Filter’s lifetime depends on

Gel concentration and particle loading in slurryBatch-to-batch variabilityFlowrateDelivery system pressure characteristics

Filter change-out region

Time or Volume


Effects of Extensive Pump Handling Effects of Extensive Pump Handling on CMP Slurrieson CMP Slurries


PSD and LPC data for silica slurry 1 under extensive PSD and LPC data for silica slurry 1 under extensive handling in a bellows pump loop at 36 turnovers/hrhandling in a bellows pump loop at 36 turnovers/hr

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1 10 100Particle Diameter (microns)

Nor

mal

ized

# o

f Par

ticle

s(>

= D

iam

eter

)

s o urce

20 ho urs

69.5 ho urs

21 3 ho urs

31 0 ho urs

334 ho urs

0

2

4

6

8

10

12

0.01 0.1 1

Particle Diameter (microns)

Diff

eren

tial V

olum

e (%

)

0 ho ur, s o urce1 5 minutes2 ho urs8 ho urs

20 ho urs31 0 ho urs361 ho urs

Ho urs in pump lo o p

(Courtesy of BOC Edwards: Singh & Roberts, ASMC 2001)


PSD and LPC data for silica slurry 1 during handling in a PSD and LPC data for silica slurry 1 during handling in a vacuumvacuum--pressure dispense pump loop at 36 turnovers/hrpressure dispense pump loop at 36 turnovers/hr

0

2

4

6

8

10

12

0.01 0.1 1Particle Diameter (microns)

Diff

eren

tial V

olum

e (%

)

0 ho ur, s o urce1 5 minutes2 ho urs8 ho urs21 ho urs70 ho urs1 20.5 ho urs1 65 ho urs

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1 10 100

Particle Diameter (microns)N

orm

aliz

ed #

of P

artic

les

(> =

Dia

met

er)

s o urce

1 ho ur

21 ho urs

70 ho urs

1 20.5 ho urs

1 93 ho urs



PSD and LPC data for alumina slurry 1 under extensive PSD and LPC data for alumina slurry 1 under extensive handling in a bellows pump loop at 14.5 turnovers/hrhandling in a bellows pump loop at 14.5 turnovers/hr

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1 10Particle Diameter (microns)

Nor

mal

ized

# o

f Par

ticle

s(>

= D

iam

eter

) 0 ho ur

2 minutes

1 ho ur

65.5 ho urs

90 ho urs


0

2

4

6

8

10

12

14

0.01 0.1 1 10 100Particle Diameter (microns)

Diff

eren

tial V

olum

e (%

)

s o urce5 minutes5 ho urs42.5 ho urs90 ho urs



PSD and LPC data for alumina slurry 2 under extensive PSD and LPC data for alumina slurry 2 under extensive handling in a bellows pump loop at 37.5 turnovers/hrhandling in a bellows pump loop at 37.5 turnovers/hr

0.0

0.2

0.4

0.6

0.8

1.0

1.2


Nor

mal

ized

# o

f Par

ticle

s(>

= D

iam

eter

)

0 ho ur1.5 ho ur3 ho urs21 ho urs39 ho urs51 ho urs64 ho urs1 28 ho urs


0

2

4

6

8

10

12

0.01 0.1 1 10

Particle Diameter (microns)

Diff

eren

tial V

olum

e (%

)

s o urce

5 minutes1 ho ur

64 ho urs1 28 ho urs



LPC and PSD data for ceria slurry 1 and silica slurry 2 under LPC and PSD data for ceria slurry 1 and silica slurry 2 under extensive handling in bellows pump loopextensive handling in bellows pump loop

LPC data for ceria slurry 1 in bellows pump LPC data for ceria slurry 1 in bellows pump loop at 41.3 turnovers/hr

PSD data for silica slurry 2 in bellows pump PSD data for silica slurry 2 in bellows pump loop at 85 turnovers/hrloop at 41.3 turnovers/hr loop at 85 turnovers/hr

0.0

0.2

0.4

0.6

0.8

1.0

1.2


Nor

mal

ized

# o

f Par

ticle

s(>

= D

iam

eter

)

So urce , 0 ho urs5 minutes1 ho ur7 ho urs31 ho urs54 ho urs1 1 6 ho urs1 88.5 ho urs

0

2

4

6

8

10

0.01 0.1 1 10Particle Diameter (microns)

Diff

eren

tial V

olum

e (%

)

s o urce

6 ho urs

69 ho urs

1 45.5 ho urs



LPC data for silica slurry 3 under extensive handling in a LPC data for silica slurry 3 under extensive handling in a vacuumvacuum--pressure dispense system and bellows pump looppressure dispense system and bellows pump loop

LPC data for silica slurry 3 a vacuumLPC data for silica slurry 3 a vacuum--pressure pressure dispense system at 17.1 turnovers/hr

LPC data for silica slurry 3 in bellows pump LPC data for silica slurry 3 in bellows pump recirculation loop at 60 turnovers/hrdispense system at 17.1 turnovers/hr recirculation loop at 60 turnovers/hr

0

20000

40000

60000

80000

100000


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 hour5 minutes24 hours72 hours140 hours162 hours

0

20000

40000

60000

80000

100000


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 hour5 minutes2 hours18 hours24 hours42 hours

(Ref: Singh, Conner and Roberts, SST 2004)


LPC data for silica slurry 4 under extensive handling tests LPC data for silica slurry 4 under extensive handling tests in BPSin BPS--3 magnetically levitated centrifugal pump loop3 magnetically levitated centrifugal pump loop

Test 1: 8000 rpm, 28 psi back pressure, 31.7 Test 1: 8000 rpm, 28 psi back pressure, 31.7 turnovers/hr, 8 lpm, up to 45 hr samplesturnovers/hr, 8 lpm, up to 45 hr samples

(0.05 ml slurry added in 30 ml Accusizer flask)

Test 1: 8000 rpm, 28 psi back pressure, 31.7 Test 1: 8000 rpm, 28 psi back pressure, 31.7 turnovers/hr, up to 4.5 hr samplesturnovers/hr, up to 4.5 hr samples

(0.05 ml slurry added in 30 ml Accusizer flask)(0.05 ml slurry added in 30 ml Accusizer flask) (0.05 ml slurry added in 30 ml Accusizer flask)

0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

0.1 1 10Particle Diameter (microns)

Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers63.4 Tunovers143 Turnovers523 Turnovers761 Turnovers1427 Turnovers

0.0E+00

2.0E+03

4.0E+03

6.0E+03

8.0E+03

1.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers63.4 Tunovers143 Turnovers



Test 1: 8000 rpm, 28 psi back pressure, Test 1: 8000 rpm, 28 psi back pressure, 31.7 turnovers/hr, 8 lpm, up to 330 hr samples31.7 turnovers/hr, 8 lpm, up to 330 hr samples




0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers143 Tunovers2156 Turnovers2948 Turnovers10461 Turnovers

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers31.7 Tunovers63.4 Turnovers127 Turnovers1270 Turnovers



Test 1: 8000 rpm, 28 psi back pressure, Test 1: 8000 rpm, 28 psi back pressure, 31.7 turnovers/hr, 8 lpm, up to 4.5 hr samples

Test 2: 8000 rpm, 28 psi back pressure, 63.4 Test 2: 8000 rpm, 28 psi back pressure, 63.4 turnovers/hr, 8 lpm, up to 2 hr samples31.7 turnovers/hr, 8 lpm, up to 4.5 hr samples turnovers/hr, 8 lpm, up to 2 hr samples

0.0E+00

1.0E+03

2.0E+03

3.0E+03

4.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers143 Tunovers

0.0E+00

1.0E+03

2.0E+03

3.0E+03

4.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers31.7 Tunovers63.4 Turnovers127 Turnovers





Test 3: 5000 rpm, 10 psi back pressure, Test 3: 5000 rpm, 10 psi back pressure, 39.6 turnovers/hr, 5 lpm, up to 24 hr samples39.6 turnovers/hr, 5 lpm, up to 24 hr samples


0.0E+00

1.0E+04

2.0E+04

3.0E+04

4.0E+04

5.0E+04

6.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)


0.0E+00

1.0E+04

2.0E+04

3.0E+04

4.0E+04

5.0E+04

6.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)


0.0E+00

5.0E+02

1.0E+03

1.5E+03

2.0E+03

2.5E+03

3.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)


0.0E+00

5.0E+02

1.0E+03

1.5E+03

2.0E+03

2.5E+03

3.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)



LPC data for silica slurry 4 under extensive handling tests LPC data for silica slurry 4 under extensive handling tests in BPSin BPS--3 centrifugal pump and diaphragm pump 13 centrifugal pump and diaphragm pump 1

Test 2: 8000 rpm, 28 psi back pressure, 8 lpm, Test 2: 8000 rpm, 28 psi back pressure, 8 lpm, 63.4 turnovers/hr, 20 hr test, BPS63.4 turnovers/hr, 20 hr test, BPS--3 pump3 pump


Test 4: 28 psi back pressure, 8 lpm, 63.4 Test 4: 28 psi back pressure, 8 lpm, 63.4 turnovers/hr, 24 hr test, diaphragm pump 1turnovers/hr, 24 hr test, diaphragm pump 1


0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)


0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers31.7 Tunovers63.4 Turnovers127 Turnovers380 Turnovers1395 Turnovers


LPC data for silica slurry 4 under extensive handling tests LPC data for silica slurry 4 under extensive handling tests in diaphragm pump 1 at different turnover ratesin diaphragm pump 1 at different turnover rates

Test 5: 28 psi back pressure, 31.7 turnovers/hr, Test 5: 28 psi back pressure, 31.7 turnovers/hr, 8 lpm, diaphragm pump 1, up to 184 hr samples

Test 4: 28 psi back pressure, 63.4 turnovers/hr, Test 4: 28 psi back pressure, 63.4 turnovers/hr, 8 lpm, diaphragm pump 1, 24 hr test8 lpm, diaphragm pump 1, up to 184 hr samples 8 lpm, diaphragm pump 1, 24 hr test

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers31.7 Tunovers143 Turnovers761 Turnovers1427 Turnovers5833 Turnovers

0.0E+00

5.0E+04

1.0E+05

1.5E+05

2.0E+05

2.5E+05


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

0 Turnovers31.7 Tunovers63.4 Turnovers380 Turnovers1395 Turnovers1522 Turnovers


LPC data for silica slurry 4 under extensive handling tests LPC data for silica slurry 4 under extensive handling tests in diaphragm pumps 1 and 2 at same turnover ratesin diaphragm pumps 1 and 2 at same turnover rates

Test 4: 28 psi back pressure, 63.4 turnovers/hr, Test 4: 28 psi back pressure, 63.4 turnovers/hr, 8 lpm, diaphragm pump 1, 6 hr samples

Test 6: 28 psi back pressure, 63.4 turnovers/hr, Test 6: 28 psi back pressure, 63.4 turnovers/hr, 8 lpm, diaphragm pump 2, 6 hr samples8 lpm, diaphragm pump 1, 6 hr samples 8 lpm, diaphragm pump 2, 6 hr samples

0.0E+00

1.0E+04

2.0E+04

3.0E+04

4.0E+04

5.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)


0.0E+00

1.0E+04

2.0E+04

3.0E+04

4.0E+04

5.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)



LPC data for silica slurry 4 in singleLPC data for silica slurry 4 in single--pass POU filtration pass POU filtration tests with fresh and extensively handled slurrytests with fresh and extensively handled slurry

Test 7: Fresh silica slurry 4 feed and fltrate Test 7: Fresh silica slurry 4 feed and fltrate LPC for Planargard CMP3 and CMP5 filters

Test 8: Slurry feed and fltrate LPC for CMP3 Test 8: Slurry feed and fltrate LPC for CMP3 and CMP5 filters (6 hour diaph pump 2 Test 6: and CMP5 filters (6 hour diaph pump 2 Test 6:

63.4 turnovers/hr handling of silica slurry 4) LPC for Planargard CMP3 and CMP5 filters

63.4 turnovers/hr handling of silica slurry 4)

0.0E+00

1.0E+03

2.0E+03

3.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

Feed

CMP5 Filtrate

CMP3 Filtrate

0.0E+00

1.0E+04

2.0E+04

3.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

Feed Test 6

CMP5 Filtrate

CMP3 Filtrate

0.0E+00

1.0E+04

2.0E+04

3.0E+04


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

Feed

CMP5 Filtrate

CMP3 Filtrate

Test 8: ∆ p at ~ 542 ml/min, CMP5 ~ 1.8 psi, CMP3 ~ 4.1 psi

Test 7: ∆ p at ~ 557 ml/min, CMP5 ~ 1.8 psi, CMP3 ~ 4.4 psi


LPC data for silica slurry 4 in singleLPC data for silica slurry 4 in single--pass POU filtration tests pass POU filtration tests with BPSwith BPS--3 pump (2 speeds) extensively handled slurry3 pump (2 speeds) extensively handled slurry

Test 10: Slurry feed and fltrate LPC for CMP3 Test 10: Slurry feed and fltrate LPC for CMP3 and CMP5 filters (24 hour Test 3: 5000 rpm, and CMP5 filters (24 hour Test 3: 5000 rpm, 39.6 turnovers/hr handling of silica slurry 4)

Test 9: Slurry feed and fltrate LPC for CMP3 Test 9: Slurry feed and fltrate LPC for CMP3 and CMP5 filters (20 hour Test 2: 8000 rpm, and CMP5 filters (20 hour Test 2: 8000 rpm, 63.7 turnovers/hr handling of silica slurry 4) 39.6 turnovers/hr handling of silica slurry 4)63.7 turnovers/hr handling of silica slurry 4)

0.0E+00

1.0E+03

2.0E+03

3.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

Feed Test 2

CMP5 Filtrate

CMP3 Filtrate

0.0E+00

1.0E+03

2.0E+03

3.0E+03


Cum

ulat

ive

Num

ber

(# P

art >

= D

iam

eter

)

Feed Test 3

CMP5 Filtrate

CMP3 Filtrate

Test 9: ∆ p at ~ 529 ml/min, CMP5 ~ 1.7 psi, CMP3 ~ 3.9 psi Test 10: ∆ p at ~ 548 ml/min, CMP5 ~ 1.9 psi, CMP3 ~ 4.1 psi


LPC data for silica slurry 4 under extensive handling tests LPC data for silica slurry 4 under extensive handling tests in BPSin BPS--3 and diaphragm pump 13 and diaphragm pump 1

Test 11: Slurry feed and fltrate LPC for CMP3 Test 11: Slurry feed and fltrate LPC for CMP3 and CMP5 filters (24 hour diaphragm pump 1 and CMP5 filters (24 hour diaphragm pump 1

Test 4: 63.4 turnovers/hr of silica slurry 4)

Test 9: Slurry feed and fltrate LPC for CMP3 Test 9: Slurry feed and fltrate LPC for CMP3 and CMP5 filters (20 hour BPSand CMP5 filters (20 hour BPS--3 Test 2: 8000 3 Test 2: 8000

rpm, 63.4 turnovers/hr of silica slurry 4) Test 4: 63.4 turnovers/hr of silica slurry 4)rpm, 63.4 turnovers/hr of silica slurry 4)

0.0E+00

1.0E+03

2.0E+03

3.0E+03


Cum

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ive

Num

ber

(# P

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= D

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eter

)

Feed Test 2CMP5 FiltrateCMP3 Filtrate

0.0E+00

1.0E+03

2.0E+03

3.0E+03

0.1 1 10 100 1000Particle Diameter (microns)

Cum

ulat

ive

Num

ber

(# P

art >

= D

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eter

)

Feed Test 4CMP5 FiltrateCMP3 Filtrate

Test 9: ∆ p at ~ 529 ml/min, CMP5 ~ 1.7 psi, CMP3 ~ 3.9 psi Test 11: ∆ p at ~ 546 ml/min, CMP5 ~ 2.3 psi, CMP3 ~ 4.3 psi


Summary and ConclusionsSummary and Conclusions

• Current and next generation CMP slurries target tighter retention of large particles at much smaller large-particle cut-off (e.g., 0.5 or 0.3 µm) and well-characterized graded density depth filters can effectively manage large particles in these slurries.

• Optimum slurry delivery and filtration should consider slurry abrasive type and composition, chemical additives, LPC, PSD, wt % solids, viscosity, abrasive settling, target retention level, pressure-drop, flow rate, filter lifetime, and the distribution system “pump” characteristics.

• Bellows and diaphragm pump recirculation tests show that silica-based (shear-sensitive) CMP slurries generate significant large particles, whereas alumina and ceria-based STI CMP slurries do not generate large agglomerates under extensive shearing/handling. A vacuum-pressure dispense technology pump was found to generate fewer large particles as compared to a bellows pump in a silica slurry handling test.

• A magnetically levitated centrifugal pump (Levitronix BPS-3) was found to generate far fewer large particles (> 1 micron) as compared to diaphragm and bellows pumps in silica slurry tests for the comparable turnovers. Almost no increase in large particle was seen for this pumps at moderate speed and back pressure in a silica slurry extensive handling test.


Summary and Conclusions (Cont...)Summary and Conclusions (Cont...)• As expected, in extreme repeated handling situations with limited slurry in the system

and very high pump speeds, large growth in particles > 0.5 and < 1 micron was noticed in the BPS-3 tests. It is important to note that such handling conditions are not likely to occur in most practical applications. The above behavior of LPC may be attributed to the cumulative effects of low-intensity uniform shear application at very high pump speeds.

• Since, BPS-3 pump generated far fewer >1 micron particles in shear sensitive slurry, the filter lifetime for this pump based slurry delivery systems should be longer than other approaches, when relatively open filters are used in global distribution loop. However, more extensive fab based studies would be needed to confirm this behavior.

• Results of present study demonstrate the significant advantages of magnetically levitated centrifugal pumps in handling shear sensitive CMP slurries under normal turnovers expected in a typical fab operation. This pump can provide stable low-pulsation slurry delivery with limited large particle growth when used in optimally designed systems.

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Isopore is a trademark of Millipore Corporation

Levitronix is a registered trademark of Levitronix GmbH

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LS 230 is a trademark of Beckman Coulter, Inc.


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