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Treatment of CMP Waste Streams. B.M. Belongia, Y. Sun Dr. J.C. Baygents, Dr. S. Raghavan The University of Arizona Joe O’Sullivan Pall Corp.  1999 Arizona Board of Regents for The University of Arizona. Outline. Background Treatment Strategies

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treatment of cmp waste streams
Treatment of CMP Waste Streams

B.M. Belongia, Y. Sun

Dr. J.C. Baygents, Dr. S. Raghavan

The University of Arizona

Joe O’Sullivan

Pall Corp.

 1999 Arizona Board of Regents for The University of Arizona

outline
Outline
  • Background
  • Treatment Strategies
  • Electrocoagulation/Electrodecantation Studies
    • pH Effects & Electrode Compartments
    • Solid/Liquid Separation
    • Copper Removal
  • Cross-flow filtration
    • MicrozaTM UF Systems
  • Summary
significance
Significance
  • Large quantities of waste slurry generated from CMP
    • ~ 6 L of waste slurry generated per wafer
    • 0.1 - 0.5 % solids and ~ 40 ppm copper ions
  • Efficient disposal or recycle strategies need to be developed to comply with environmental regulations.
  • Recycling would require that the dilute waste slurry be concentrated to the initial slurry solids content and the particle size remain unchanged.
slurry types
Slurry Types
  • Oxide slurry
    • Silica is the abrasive material
    • Suspension is stabilized with either NH4OH or KOH; pH = 10 - 11
    • Used to polish oxide layers
    • Particle size: 50-100 nm
slurry types cont d
Slurry Types (cont’d)
  • Metal
    • Abrasive is primarily aluminum oxide, but some contain silica
    • Contains an oxidizer, either ferric nitirate, potassium iodate or hydrogen peroxide
    • pH = 3 - 5
    • Used to polish tungsten and copper (recently popular) interconnects
    • Particle size: 100 - 300 nm
why treat cmp wastewater
Why Treat CMP Wastewater?
  • Suspended solids too high to discharge to sewer
  • Traditional flocculation and clarification requires large tanks and lots of chemical addition
  • A need to reclaim water at the individual facility
slide7

NEW SLURRY

6–10wt% solids

WATER TO

POLISHING

LOOP

RINSE

WATER

SLURRY

POLISHING

TOOL

WATER

USED

SLURRY

MIRACULOUS PROCESS!

0.02–0.5wt% solids

2 –40ppm Cu

SOLIDS

WASTE

SOLIDS

treatment objective
Treatment Objective
  • To develop a generic methodology for the treatment of CMP waste streams.

e.g. a copper CMP waste may contain:

  • 0.02 – 0.5% solids
  • 2 – 40ppm copper ions
  • An organic complexant (e.g. EDTA, Citric Acid)
  • A corrosion inhibitor (e.g. BTA)
treatment strategies
Treatment Strategies
  • 1. Electrocoagulation/Electrodecantation (EC/ED)
  • University of Arizona research
  • Possible follow on to ultrafiltration
  • 2. Cross-flow filtration
  • Pall MicrozaTM ultrafiltration system
ec ed
EC/ED
  • Electrocoagulation
    • used to treat waste steams; electric field applied for a short period, suspension allowed to settle in absence of field — rate of settling was found to be enhanced
  • Electrodecantation
    • used to concentration proteins, viruses, natural rubber latex, and various inorganic sols
ec ed apparatus

Cathode (-)

(Stainless Steel)

Sample Port

Suspension

Membrane

Anode (+)

(Stainless Steel)

Water

EC/ED Apparatus
electrode reactions
Electrode Reactions

Membrane

(-) Electrode

2H+ + 2e- H2

(+) Electrode

2H20 

4H+ + 4e- + O2

or

2H2O + 2e-

H2 + 2OH-

Suspension

pH increases

Water

pH decreases

ph changes

3.5V/cm

pH

Cathode Chamber

Anode Chamber

Time (min)

pH Changes

Electrophoretic Mobility of Al2O3

cm2/V·s  10-4

1mM KNO3

pH

ec ed of al 2 o 3

Membrane

Liquid

Level

Clarified

Liquid

(Sample Zone)

c/c0

Cathode

Anode

Solids

 1.75V/cm

 3.50V/cm

 7.00V/cm

 14.00V/cm

Time (min)

EC/ED of Al2O3

Initial Cond.  1300 mS/cm

Initial pH  6.0

copper removal during ec ed

cCu/c0Cu

Time (min)

Copper Removal during EC/ED

Initial Cond.  1300 mS/cm

Initial pH  6.0

 1.75V/cm

 3.50V/cm

 7.00V/cm

 14.00V/cm

copper distribution
Copper Distribution

Initial Suspension

220ml @ 34ppm Cu

Membrane

165 ml

4.2ppm Cu (9.7%)

97 ml

16.0ppm Cu (20.5%)

Cathode

Plated Cu (16.3%)

Anode

44ml

68.0ppm Cu (39.4%)

effect of edta and cu on al 2 o 3 particle charge

EDTA

EDTA

Cu2+

Cu2+

Al2O3

Al2O3

Effect of EDTA and Cu on Al2O3 Particle Charge

pH  6

+

-

+

-

-

+

-

+

-

-

+

-

+

+

Electrophoretic Mobility

cm2/V·s  10-4

+

+

 Al2O3

Al2O3 + 184ppm EDTA

 Al2O3 + 40ppm Cu

+ 184ppm EDTA

pH

copper distribution18

Cu2+

(EDTA)2-

[(EDTA)Cu]-

Cu(OH)2

OH

OH

OH

OH

OH

OH

Anode

OH

OH

OH

OH

OH

OH

Cathode

Copper Distribution

Membrane

pH  6

ec ed of concentrated al 2 o 3 wastes

Membrane

Clarified

Liquid

0.5% solids

Cathode

Anode

Solids 29%

EC/ED of Concentrated Al2O3 Wastes

c0 12% solids

c/c0

Initial pH  6.0

Initial Cond.  1300 mS/cm

Time (min)

3.50V/cm

filtration and ec ed in tandem

Highly Concentrated

Suspension

Recirculated

Suspension

Water

Cross-flow

filtration

Electrocoagulation

Apparatus

Waste

Permeate

Solids

Filtration and EC/ED in Tandem

 Pall Corp. patented technology to treat CMP waste.

summary of ec ed method
Summary of EC/ED Method
  • Alumina suspension can be dewatered by EC/ED.
  • Copper can be simultaneously removed from the clarified layer.
    • plating out onto the cathode
    • in situ precipitation?
  • pH changes are critical to the success of the EC/ED process.
cost and power consumption
Cost and Power Consumption

(Using $0.05/kWhr)

For 7.0V/cm, 90mins

Cost: $0.014/l

$0.08/wafer

@ 6 l/wafer

For 3.5V/cm, 90mins

Cost: $0.002/l

$0.01/wafer

@ 6 l/wafer

 1.75V/cm

 3.50V/cm

 7.00V/cm

Work (kW·hr/l)  10-3

Time (min)

what is ultrafiltration

Feed

Retentate

Membrane

Solute A

Solute B

Permeate

What is Ultrafiltration?
factors affecting separations

10

MICROFILTERS

1

1

10

0.1

100

0.01

1000

0.001

0.0001

Micron (µm)

Factors Affecting Separations

SIZE

DIFFUSIVITY

IONIC CHARGE

DENSITY

cross section of microza tm hollow fiber membrane
Cross Section of MicrozaTM Hollow Fiber Membrane

Uniform outer surface skin further improves mechanical properties, facilitates design and provides extra assurance of removal efficiency

Macroporous regions allow low pressure differential and enhanced flow rate.

Uniform skinned membrane with narrow pore range for highly efficient separation characteristics.

Dense porous layer provides exceptional mechanical strength and fiber reliability.

microza tm uf systems
MicrozaTM UF Systems
  • Process dilute CMP wastewater
    • 0.02% to 0.1% total suspended solids
  • Treat oxide, metal or mixture of waste
  • Concentrate all suspended solids
    • up to 15-17%
  • Permeate is free of suspended solids
    • can pretreat to remove ferric ion and soluble silica
    • can use as RO makeup water
challenges of treating cmp wastewater
Challenges of Treating CMP Wastewater
  • Abrasive material
    • expect 18-24 months service life on UF modules
  • Broad pH range
    • oxide, metal or mixed waste
    • polyacrylonitrile membrane, pH 2-10
  • Prevention of membrane fouling
    • high linear velocity
    • reverse filtration
chemical treatment for removal of soluble silica
Chemical Treatment for Removal of Soluble Silica
  • Formation of silicate
  • Precipitation of magnesium/iron silicate
    • iron silicates pH 8-9
    • magnesium silicates pH 10.5-11
silica solubility vs ph
Silica Solubility vs. pH

1000

900

,

800

700

600

500

Silica Solubility (mg/L)

400

,

300

200

,

,

,

,

,

,

,

100

0

0

0

2

4

6

8

10

12

pH

chemical treatment for removal of soluble silica cont d
Chemical Treatment for Removal of Soluble Silica (cont’d)
  • Holding tank upstream of UF system
  • Typical reaction time of 30 minutes

-

+

SiO

+ 2KOH SiO

(silicate) + 2K

2

3

NaOH + MgCl Mg (OH)

2

Mg (OH)

+ H

SiO

MgSiO

(s) + 2H

O

2

2

3

3

2

Magnesium

Silicate

chemical treatment for the removal of ferric ion
Chemical Treatment for the Removal of Ferric Ion
  • Form hydroxy complexes in acidic media
    • yellow-orange in color
  • Neutralization results in hydrous ferric oxide
    • reddish-brown precipitate
chemical treatment for the removal of ferric ion cont d
Chemical Treatment for the Removal of Ferric Ion (cont’d)
  • Caustic injection upstream of UF system
  • Instantaneous reaction

2+

-

2 Fe (H

O)

(OH)

+ 4 OH

Fe

O

. 13 H

O

2

5

2

3

2

hydrous ferric oxide

yellow-orange in color

reddish-brown

precipitate

copper cmp waste
Copper CMP Waste
  • Abrasive is primarily aluminum oxide
  • Contains an oxidizer, typically hydrogen peroxide
  • pH = 3
  • Used to polish copper interconnects
  • particle size: 100-300 nm
treatment of copper cmp waste
Treatment of Copper CMP Waste
  • Soluble copper
    • Assuming 5000 wafer starts per week with five levels of copper results in 6 kg of copper per week
    • Classified as both metal finishing waste and semiconductor waste
removal of soluble copper
Removal of Soluble Copper
  • Precipitation of Cu(OH)2 by Addition of Caustic
  • Removal of Copper by I/E
    • Conventional treatment method in Printed Circuit Board Industry and Plating Industry
    • Achievable Effluent Levels of < 0.1 ppm of copper
    • 10K Gallons of Water per cubic foot of resin at a influent level of 10 ppm copper
    • Electrowinning of copper
slide37

Turn-key System for Treatment of Copper CMP Waste

  • Removal of suspended solids by UF
  • Removal of Soluble copper by I/E and possibly electrowinning
  • Further treatment required to generate RO-ready water
slide38

Schematic of a Water Reclamation System from CMP Waste Slurry

CMP WASTE

SLURRIES

from

POLISHERS

RECLAIMED

WATER

RECLAIMED

WATER

REVERSE

OSMOSIS

and/or

ION EXCHANGE

PERMEATE

MICROZA

UF System

BUFFER

TANK

TO WASTE

TREATMENT

REJECT

CONCENTRATION

FILTRATE

FILTER

PRESS

CONCENTRATE

PRE-TREATMENT

slide39

Dewatering of UF Concentrate

  • UF Concentrate
    • Maximum of 17% Total Suspended Solids
  • Dewatering Via a Filter Press for Landfill Disposal
    • Treat with Fluoride Waste
    • Treat Separately
      • RCRA Paint Filter Test
      • Non-Hazardous Material
  • pH Adjustment
  • Addition of coagulant
  • Addition of flocculant
flux profile for uf system typical for mixed cmp slurry waste

Flux vs. Concentration Factor (X)

90

45.0

80

40.0

Flux

X (2ndY)

70

35.0

60

30.0

50

25.0

Flux, lmh

Conc Factor

40

20.0

30

15.0

20

10.0

10

5.0

0

0.0

0

1

2

3

4

5

6

7

Time, hr

Flux Profile for UF SystemTypical for Mixed CMP Slurry Waste
typical microza tm cmp waste slurry concentrating installation single uf module skid

WASTE SLURRY FEED

FROM CMP TOOLS

PERMEATE

RF PERMEATE

UF RINSE

FORWARD

PREFILTER

PROCESS PERMEATE

TRANSFER

F-1

BUFFER

FEED

TANK

RETENTATE

UF RACK

UF RACK

No.1

No.2

FEED/BATCH

REVERSE

TANK

FILTRATION

TANK

RECIRCULATION

FEED

TRANSFER

RF/PERMEATE

PUMP

PUMP

PUMP

PUMP

DRAIN

CONCENTRATE

DRAIN

PUMP

Typical MicrozaTM CMP Waste Slurry Concentrating Installation (Single UF Module Skid)
microza uf system sizing oxide cmp waste

Percent

Initial Conc

VCF

Flowrate (GPM)

# of Modules

Recovery

0.1 %

10X

90

20

5

0.1%

50X

98

20

6

0.2%

10X

90

20

5

0.1%

10X

90

50

13

0.1%

50X

98

50

16

Microza UF System SizingOxide CMP Waste
microza uf system sizing mixed oxide and mixed metal cmp waste
Microza UF System SizingMixed Oxide and Mixed Metal CMP Waste

# of

Modules

Percent

Initial Conc

VCF

Flowrate (GPM)

Recovery

0.1 %

10X

90

20

7

0.1%

50X

98

20

8

0.1%

10X

90

50

18

0.1%

50X

98

50

21