water: a key process fluid and an environmental bottleneck in semiconductor manufacturing

Shadman

1

Water: A Key Process Fluid and an Environmental Bottleneck in

Semiconductor Manufacturing

Farhang ShadmanUniversity of Arizona

1999 Arizona Board of Regents for The University of Arizona

NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

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2

Water Usage In Semiconductor Plants

0.0

10.0

20.0

30.0

40.0

50.0

UP

W U

sage (

gallons p

er

square

inch)

10

15

20

25Approximate Mask Levels (+/-2)

Wafer Diameter (in)

56

8

Source: Sematech, 1996

Shadman 148

Goal: Significant reduction in water use for the next three years: 2-3 fold reduction in UPW usage per in2 of Si for the 300 mm wafers.


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3

WATER AND ENERGY

TECHNOLOGY REQUIREMENTS

1997250 nm

2000180 nm

2003130 nm

2006100 nm

200970 nm

201250 nm

Decrease net feed water use

Gal/in2

30 10 6 5 2 2

Decrease UPW use

Gal/in222 10 7 6 5 5

Lower water purification cost

X 90%X 80%X 70%X 60%X 50%X

Decrease energy consumption

KWh/in2

9 8 7 5 5 4

300MM energy

consumption KWh/in2

4 4 4 3

Solutions Exist

SolutionsBeing Pursued

No Known Solutions

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4

Strategies to Achieve the UPW Goals

• Replace wet processes:

– The environmental gain is not obvious or guaranteed• Reduce water usage:

– Emphasis on FEOL and rinse processes for FEOL and post-CMP

• Reuse and recycle


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5

Drivers for Water Conservation Strategies

Improve process and products performance

Lower cost

Insure sustainability in operation and growth

• The three drivers are interdependent

• The three drivers are not contradictory

• Insuring sustainable growth is the primary environmental justification


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Recycle and Reuse Which one is preferred

What are the determining factors?

UPW Plant Rinse Operation

Cooling / Gas Scrubbing

Feed Water


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7

Determining Factors:• Purity at the POU• Purification cost• System & installation cost• Real risk• Perceived risk

UPW Plant Rinse Operations

Cooling/Scrubbing


Cooling/Scrubbing

Reuse

Recycle

• Match the flow rates for supply and demand (water balance)• Match the water quality for supply and demand (optimization)

Guidelines:


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8

Polishing

UVIEx

S

SecondaryTreatment

Reverse Osmosis UV/Ion Exchange

PrimaryTreatment

Point-Of-Use

Feed

Treatment

Recycle

Polishing Loop

20,000 20,000 20,000

10,000

(400 gpm)

(700 gpm)

(200 gpm)

(130 gpm)

(100 gpm)

(40 gpm)

(160 gpm)

Humic Acid @ 3 ppm

270 gpm with recycle430 gpm without recycle

Recycle/Feed Ratio(R/F)

Point of Use TOCConc. (ppb)

0 4.1

0.30 3.6

0.60 2.1

UPW Quality at POU

0.0

2.0

4.0

0 300 600 900 1200 1500

Time (min)

Co

nce

ntr

atio

n (

pp

b)

TOC


Effect of Recycle on POU Purity

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9

Time

Q *

C

Rinse A (QA)

Rinse B (QB)

Area A = Area B

Rinse and Reuse Inter-dependence


Q


C

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10

(50)

500 UPW Plant Rinse

1000(30)

500(10)

P500

(100)

500S

(160)

(50)

1000 1000

(150)UPW Plant RinsePresent operation:

(50)

200 200

(550)UPW Plant RinseOption 1: Reduce the rinse flow

Option 2: Keep the rinse flow; add moderate recycle


Rinse and Recycle Inter-dependence

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11

(50)

1000 1000


Option 3: Keep the rinse flow; add aggressive recycle

(50)

50 UPW Plant Rinse

1000(10)

950

(~8)P

950

(~108)

50S

(150)



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12

(50)

50 500(214)

UPW Plant Rinse500(14)

450

(10)P

450

(~205)

50S

(300)

Option 4: Decrease the rinse flow, combine with recycle

(50)

1000 1000




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13

Support Processes(e.g. Cooling,

Gas Scrubbing)

Purification

SegregationSensor/Control

WaferCleaning

UPW Plant

Recycle

ReclaimWaste

Evaporation

Makeup

FeedMakeup

Water Use and Reuse in Semiconductor Manufacturing(Role of Integration in the Design for Environment)


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14

Adverse Effects of Concentrating the Recycled or Reused Wastewater Stream

• Lowering TOC removal efficiency

• Lowering ion exchange utilization factor

• Being out of range for some of the purification unit processes

• Triggering fouling mechanism

– Biofouling and biofilm

– Corrosion


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15

UPW Strategic Research Needs for 2003 and Beyond

1. Low water, high performance FEOL and post-CMP rinse

2. Low energy, robust purification processes

3. Advance waste segregation and collection

4. Simulator-based metrology and control

5. Matched supply and demand purity

6. Advanced design tools to facilitate low-cost, low risk, high performance preparation and distribution of UPW

7. Special UPW sub-system for CMP

8. On-line rapid-response multi-component sensors for 3,4,5,7


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16

Issues and Technology Gaps Related to Water and Wastewater Purification

• Low-energy and low-chemical new purification processes

• Multi-component interactions of process-generated impurities

• Robust purification methods with tolerance to system upsets and transience

• Improved removal of recalcitrant compounds, particularly organic impurities


Shadman

17NSF/SRC Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Shadman

18Shadman p173

1997250 nm / 200 mm

2003130 nm / 300 mm

2006100 nm / 300 mm

200970 nm / 450 mm

201250 nm / 450 mm

1999, 2001180 nm / 300 mm150 nm / 300 mm

Recycle New PurificationMetrologyAdvancedControl

RecycleConservation

RecycleConservationMetrology

10

20

30

10

20

Net

Fee

d (

gal

/ in

2 )

UP

W U

se (

gal

/ in

2 )

YearTechnology

Trends and Technology Gaps for Water Usage

Strategic SolutionsResearch Gaps

Tactical Solutions


Shadman

19

FeedTank

Pre-Treatment

PrimaryStorage

Tank

Primary Treatment

UPWPolishingStorage Tank

PolishingTreatment

FABProcessTools

SRWStorage

Tank

UP

W R

etur

n

UP

W S

uppl

y

MunicipalFeed

2nd RO Reject

1st ROReject

UF Reject

UPW System with Recycle Options

Monitoring/Purification

Recycle

Sensor/Divertor

Sensor/Divertor

IWW IWW

Reject

RejectReject


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20

Structure of the UPW Recycle Simulator


Water Balance Model (Flow Balance Equations)

Main Program: Simultaneous PDE’s for Species Balance

Rinse Module

Treatment Modules

IEx UV AC

Loop Solver

Dynamic Link

ParameterDatabase

Flow SheetSpecifications

- Impurity concentration (time and location)- Water balance

Input Output User-FriendlyLevel

LinkageLevel

MainCode Level

RO

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Effect of Recycle on POU Impurity Concentration

Polishing

UVIEx

S

SecondaryTreatment

Reverse Osmosis UV/Ion Exchange

PrimaryTreatment

Point-Of-Use

Feed

TreatmentRecycle

Polishing Loop

20,000 20,000 20,000

10,000

(400 gpm)

(700 gpm)

(200 gpm)

(130 gpm)

(100 gpm)

(40 gpm)

(160 gpm)

Humic Acid @ 3 ppm

270 gpm with recycle430 gpm without recycle

UPW Quality at POU

0.0

1.0

2.0

3.0

4.0

0 300 600 900 1200 1500

Time (min)

Co

nce

ntr

atio

n (

pp

b)

Ionic Impurities at POU

0.000

0.005

0.010

0.015

0.020

0.025

0 300 600 900 1200 1500

Time (min)

Co

ncen

trati

on

(p

pb

)

Calcium

Sulfate

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22

Importance of Multi-Component Interactions

• A critical technology gap in approaching risk-free recycling.

• Potentials for chemical interactions caused by process- generated reactive compounds; formation of problematic impurities.

• Change in the efficiencies of purification processes.

• Re-entrainment of impurities due to multi-component effect.

• Effect on metrology and control.


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23

Key Questions

What are the important impurities?

Which impurities are trouble makers in UPW systems with recycle?

How can we remove these harmful impurities?

How should we collect the waste water: mixed or segregated; diluted or concentrated?

What are the treatment options?

Given the above information, how do we design a recycle system, optimize it, or control its operation? Issues: effectiveness, cost and reliability.


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24

Organic Impurities

Problems:

• Proven detrimental effect on yield Wide variety of impurities with different properties Conversions and reactions Recalcitrant impurities

Removal Method:

• Separation by membranes and filters Adsorption Degasification Chemical reactions (oxidation, decomposition)


Shadman


Experimental Setup for Adsorption Studies(Ion Exchange and Activated Carbon Application)

UPW

System

Impurity

Source

Adsorption M

ediaColumn Wall

Cup Filter

TOC Analyzer Ion

ChromatographUPW Stream

Impurity Stream

Bypass Line

Stainless Steel

Filters

Mixing Tee

Metering Pump

3-Way Valve

Metering Valve

To Drain

Sample Ports

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26

XI X I: ReactionLocal

ii

i

idi

iiai

isa1

sk

sa1sck

ts

:onConservati PhaseAdsorbed

2i

2iii

zc

Dzc

Uts

1tc

:onConservati PhaseFluid

i

iosss

:onConservati Sites

U

Z

S = unoccupied site

Si = solid phase impurity

Ci = fluid phase impurity

Activated carbon particle

Competitive adsorption

Dispersion

Convection

Dynamics of Multicomponent Impurity Removal by Adsorption


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27

Secondary Contamination due to Desorption of IPA from Activated Carbon

0

100

200

300

400

500

600

700

800

900

0 50 100 150 200 250 300 350 400 450

Time (min)

TO

C (

ppb

) 15" column

9" column

6" column

UPW

Start 100 ml/min of 10 ppm HCl thru column

Start 100 ml/min of UPW thru column

Secondary Contamination


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28

0

100

200

300

400

500

600

700

800

900

0 50 100 150 200 250 300

Impurity Release due to Multicomponent Interactions(Adsorption on Activated Carbon)

Flu

id P

hase

Con

cent

ratio

n (p

pb)

Time (min)

Inlet Concentration for Component A 700 ppb

Component A Multicomponent

Component A Single Component

Component B Multicomponent

Component A onlyBoth components

A and B

Net impurity release from the column


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29

0

100

200

300

400

500

600

700

0 100 200 300 400 500

6” Test column

9” Test Column

12” Test Column

15” Test Column

Model Fit

Model Deviation due to Fluid Retention in Pores

Flu

id P

hase

Con

cent

ratio

n (p

pb)

Desorption of IPA from Activated Carbon

Time (min)


Shadman

30

0

100

200

300

400

500

600

700

0 100 200 300 400 500 600

Start 150 ml/min of 150 ppb IPA thru column

6” Test column

9” Test Column

12” Test Column

15” Test Column

Model Fit

Adsorption of IPA on Activated CarbonF

luid

Pha

se C

once

ntra

tion

(ppb

)

Time (min)


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31

Water Softener

AC Prefilter

Ion Exchange

RO TankRO #1

Ion Exchange

10 gal Tank

100 GalTank

185 nm UV

Degassifier

Ion Exchange

Ion Exchange

Ultra Filter

Recycle Tank To Drain

RO #2

Polish Loop

Recycle Loop

Primary TreatmentPre-Treatment

Bypass

Bench-Scale UPW Testbed

Feed

Pump


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32

HP Recycle System with IPA

Carbon Bed

Cation Exchange

Anion Exchange

254 nm UV

3000 gal.

Bypass Bypass

Return

RO Storage

Tank

Spent Rinse Water


0

50

100

150

200

250

300

0 20 40 60 80 100 120 140 160

Con

cent

rati

on (

ppb)

Time (min)

Data

Model

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33

Trends and Technology Gap for Energy Usage

0

5

10

1997 1999 2003 2006 2009 2012

Year of Production

KW

h /

in2

200400600800

10001200

1997 1999 2003 2006 2009 2012

Year of Production

KW

h /

wa

fer Tactical Solutions

Strategic SolutionsResearch Gap


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34

Organics

Organics

Water

Water

UV

Membrane Support

Catalytic sites

Flow-through configuration(oxidation and filtration)

Tangential configuration(oxidation and degasification)

Two Configurations Under Development


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35

Catalytic Membrane Experimental Setup

UV Source

Gas In Gas Out

Quartz Window

Reactive Membrane

MembraneSupport

Catalytic Packing

Water

Water Tank

NDIRCO/CO2MS

Capillary

Vacuum Chamber

GC

TOCAnalyzer

UV

Multi-portValve

Purge gas


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36

Effect of Adsorption on Photocatalytic TOC Removal (Response to 30 ppb IPA in the feed)

0

5

10

15

20

25

30

0 10 20 30 40

Time (min)

IPA

Co

nc

en

tra

tio

n (

pp

b)

Non-catalytic

Photocatalytic

Adsorption

Reaction


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37

Catalytic Oxidation of IPA Initial IPA Concentration: 2.2 ppm

0

500

1000

1500

2000

2500

0 50 100 150 200 250 300

Time (min)

IPA

Oxi

datio

n (p

pb)

IPA Oxidized

CO2 Dissolved in Water

UV offUV on

CO2 Degasified through Membrane


water: a key process fluid and an environmental bottleneck in semiconductor manufacturing

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