Sustainability Opportunities and Challenges in the next · PDF fileSustainability...

Engineering Research Center for Environmentally Benign Semiconductor Manufacturing

Sustainability Opportunities and Challenges in the next decade

Prof. Farhang Shadman, DirectorThe Engineering Research Center for

Environmentally Benign Semiconductor Manufacturing

Leo T Kenny


Overview• Background/history• Challenges in EHS and sustainability• Technology opportunities and challenges

– Nano‐processing– Additive processing– Computer‐aided process simulation– Value of green chemistry & engineering concepts

• Conclusions• Backup

2


Background/History• NSF/SRC Engineering Research Center (ERC) for

Environmentally Benign Semiconductor Manufacturing was created as a result of a joint initiative between Arizona, MIT, Cal and Stanford; sponsored by NSF and SRC

Goals:• Develop novel strategic solutions to existing (ESH) problems in

semiconductor manufacturing.• Create new and effective environmentally benign

manufacturing processes.• Demonstrate the positive impact of design for environment

on all aspects of semiconductor manufacturing• Develop innovative education programs in which

environmental factors are integral parts of the curriculum.3


NSF/SRC Engineering Research Center A University-Industry Collaborative Program

Other University members• Arizona State U (1998 - )• Columbia (2006 - 2009)• Cornell (1998 - )• Georgia Inst. of Tech. (2009 - )• U Maryland (1999-2003)• U Massachusetts (2006 - 2009)• U North Carolina (2009 - )• Purdue (2003 - 2008 )• U Texas - Dallas (2009 - )• Tufts (2005 - 2008 )• U Washington (2008-) • U Wisconsin (2009- )• UCLA (2011 - )• North Carolina A&T (2012 - )• Johns Hopkins (2012 - )• Colorado School of Mines (2012 - )

18 years of Experience

Founding Universities (1996) U Arizona U California – Berkeley MIT Stanford


SRC ERC overview• Nearly 20 year track record of value added research,

education and innovation• Flexible framework, adaptable to rapidly changing business,

technology and regulatory drivers• Demonstrated success and commitment to collaborative

approach to R&D, from near term industry sponsored projects to long term basic research investigations

• Expansive, multidisciplinary initiatives may have potential value beyond direct semiconductor industry applications

• One of the best, most effective working institutional examples of ‘green chemistry and green engineering’ principles in action

5


Challenges in EHS & Sustainability

• Ongoing regulatory volume, variations and complexity across the world

• A more diverse and broader industry• Precautionary approach toward materials use• Differing regional drivers and challenges• Natural resource constraints• Support challenges for consortia and industry associations (esp. proactive and technical)

• Driving the integrated, long term view• 3 key elements: equipment/materials/process

6


Global Regulatory Landscape

CIS


ESH Aspects of Nano-Manufacturing

1. Nano-Particles in Manufacturing• Workers exposure to nano-particles in the fabs• Emission of nano-particles through fab waste streams

2. Impact on Resource Utilization• Increase is water, energy, and chemical usage

3. Introduction of New Materials • New device materials, new processing fluids, etc.

4. Positive Environmental Impact • Opportunities for major ESH gain

8


Trends in Feature Size

High Volume Manufacturing Date

Min

imum

Fea

ture

Siz

e (n

m)

10

100

1000

1990 1995 2000 2005 2010 2015

Nano-Technology

9


Introduction of New Materials

11 Elements

15 Elements

>60 Elements

10

Engineering Research Center for Environmentally Benign Semiconductor Manufacturing 11

“The number of transistors per chip will double every 18 months”

Gordon Moore, 1967

Question: Is this trend sustainable? What is the impact of further shift to

nano-scale manufacturing?- Challenges- Opportunities

Is this Growth Sustainable?


Sustainability Factors

1. Product performance 2. Cost and economic factors3. Environmental impact

Safety and Health Social factors and

compatibility Resource utilization and

availability

Factors that determine the sustainability of a product, a process, a manufacturing operation, or an industry:

CostESH Impact

Performance Obstacles

Upper LevelConstraint

Area of Triangle = Manufacturing Burden

To be Minimized

CostESH Impact

Performance Obstacles

Upper LevelConstraint

Area of Triangle = Manufacturing Burden

To be Minimized

12


Chemical Mechanical Planarization (CMP)

Slurry45%

Equipment22%

Labor8%

Other9%

Pad16%

Slurry45%

Equipment22%

Labor8%

Other9%

Pad16%

Total slurry input

Amount of slurry that never reaches the wafer

Amount of slurry that reaches the wafer but does not get underneath

Amount of slurry that does the actual polishing is often less than 10%

• Fastest growing process segment• Major source of nano particle emission in S/C

fabs.• Costly and wasteful operation: For a typical

200-mm factory:– 6,000,000 liters of slurry ($20M) per year– 300 metric tons of solid waste per year

CMP Cost


What is Unique About Nano-Particles?

• Nano-particles cannot be effectively removed by conventional separation methods such as agglomeration, settling, and filtration.

• Active surface• Selective adsorption• Pore condensation (Kelvin Effect)

Shell

Adsorbedcontaminants

Treatment problem:

Core

o Concentrationo Facilitated transporto Enhanced life-time

Consequence

Synergistic ESH impact of nano-particles:

14


Toxicity of Nano-Particles

Attachment


0

0.5

1

1.5

2

2.5

3

1.5 2 2.5 3 3.5

SiO2

HfO2

ZrO2

VO

C a

dsor

ptio

n ca

paci

ty

(1014

mol

ecul

es/c

m2 )

1000/T (K-1)

Toxicity Enhancement in Nano-Particles

a) Nano-particles in the gas phase15ppb VOC; 40 nm particles

• 10 ppb of Cu++ in CMP wastewater results in 3x106 ppb of adsorbed copper on 90 nm CeO2nano-particles

• 10 ppb of PFOS in wastewater results in 2.8x104 ppb of contaminated 10 nm carbon nano-particles

b) Nano-particles in the wastewater

15


Trench Depth (m)

0.001

0.01

0.1

1

10

0 1 2 3 4 5

Cle

anin

g Ti

me

(min

)

1

10

100

1 10 100 1000 10000 100000

Node 1

Req

uire

d D

ryin

g E

nerg

y (k

J / g

)Feature Width, w (nm)

Node 2

Node 3H (enthalpy) of

H2O evaporation

0.01

0.1

1

10

100

1 10 100 100010000Trench Width (nm)

Cle

anin

g Ti

me

(min

)

Trend: Large increase in water, chemicals, and energy usage as feature size decreases and wafer size increases.

Use of Natural ResourcesWater and Energy

17


Examples of New Materials with ESH Issues

Strontium bismuth tantalate (SrBi2Ta2O9) high thermal budgetLead zirconium titanate (PbZrTiO3) low thermal budget

Shadman P278b

Material Stable with Si k ValueTantalum pentoxide (Ta2O5) no (forms SiO2) k ~ 25Strontium titanate (SrTiO3) no (e.g. Pt electrodes) k ~ 150Barium strontium titanate (BaSrTiO3) no (e.g. Pt electrodes) k ~ 300

High-k Dielectrics for DRAM

Ferroelectric Dielectrics for Nonvolatile Memory (FeRAM)


Environ. Sci. Technol. 2001, 35, 1339. Environ. Health Perspect. 2005, 113, 539.

Global Distribution of PFOS in Wildlife

• PFOS banned for most application is the US and EU.

• PFOS listed as chemical for regulation within the Stockholm Convention on Persistent Organic Pollutants (POPs)

• EPA Provisional Health Advisory Levels for PFOS 200 ng L-1

Example: Challenge of Replacing PFOS

PFOS in human blood PFOS in drinking water

PFOS and other PFCs detected in drinking water resources worldwide

19


aliphatic or aryl unit perfluorinated unit

acid size,miscibility, thermal stability, absorption, outgassing.

acid strength,absorption

photosensitivity,absorption,thermal stability.

acidhead chromophore

Sugar based “Sweet” PAG

Natural molecules Biocompatible/

Biodegradable PAG

Hydrophilic

Hydrophobic

Aromatic

Aliphatic

Polar

Nonpolar

Linearbranch

ring

Molecular Design of PFOS-Free PAGS

20


ESH Issues

Precursors, HAPs, wastes

VOCs, radiation

VOCs, waste

VOCs, HAPs

HAPs, PFCs

A/B chemicals, solvents

A/B chemicals, UPW

ConventionalLithographyConventionalLithography

development inaqueous base

spin-onimaging layer

dielectricdeposition

selectiveirradiation

dielectricpatterning

imaginglayer strip

resiststrip

An Example of Subtractive ProcessingDeposition and Patterning of Dielectrics

21








imaginglayer strip

resiststrip

All-Dry, ResistlessLithography

All-Dry, ResistlessLithographyVS.

CVD of patternable dielectric layer

selective irradiation

development in supercritical CO2

wet chemistry eliminated

wet chemistry eliminated

step eliminated

step eliminated

Deposition and Patterning of DielectricsKaren Gleason (MIT), Chris Ober (Cornell)









imaginglayer strip


wet chemistry eliminated(CVD)

wet chemistry eliminated(supercritical CO2)

Photo initiated CVD

Selective Dielectric Deposition

Selective Dielectric Deposition

ESHGainESHGain

ProcessGain

ProcessGain

win/win

Cost Reduction

Cost Reduction

Deposition and Patterning of DielectricsKaren Gleason (MIT), Chris Ober (Cornell)


TiCl4H2O TiO2

+

Conventional Subtractive ProcessingDeposition

24


Conventional Subtractive ProcessingPlanarization

TiCl4H2O TiO2

+

Waste

25


TiCl4H2O TiO2

+

Waste

Conventional Subtractive ProcessingPhoto-Resist

26


TiCl4H2O TiO2

+

hv

Conventional Subtractive ProcessingLithography

Waste

27


TiCl4H2O TiO2

+

Etch

Conventional Subtractive ProcessingEtch

Waste

28


TiCl4H2O TiO2

+

A lot ofwater and chemical

waste

Conventional Subtractive ProcessingCleaning

29


Additive Processing:

Patterning and Selective Passivation

hvSelective passivation

30


H2O


Selective Atomic Layer Deposition (ALD)

31




32


TiCl4TiO2



33




34




35


Proc

essi

ng T

ime

(min

)

Material Utilization (%)

0.1

1.0

10.0

100.0

1,000.0

10,000.0

10 30 50 70 90

10 nm

200 nm800 nm

Al2O3

Ta2O5HfO2

Metals

Feasibility of Additive Processing in Nano-ScaleSelective Atomic Layer Deposition (ALD)


Computer-Aided Process SimulationExamples of Development and Application

37

Water and Energy Use Reduction


Mechanism Time Scale Flow Effect

Boundary Diffusion d2/D ~ 10 s Indirect, mildConvection d/u ~ 1-3 s Direct, strongDesorption 1/kd ~ 0 - 105 s No effect

Des

orpt

ion

Con

vect

ion/

Diff

usio

nConvection

Des

orpt

ion

Convection

Cleaning of Nano-Structures

Lowering water and energy usageBetter metrology and process controlNeeds:

38


A Novel Metrology Technology:Electro-Chemical Residue Sensor (ECRS)

0

0.2

0.4

0.6

0.8

1

0 5 10 15 20 25 30

HCl

H2SO4

0

0.2

0.4

0.6

0.8

1.0

Solution (pH)

(ppt)

UPW (pH=7) HCl (pH=6) HCl (pH=5)

185

2.3

300.23400Resolution

Time (min)

Sens

or O

utpu

t (%

full

scal

e)

0

0.2

0.4

0.6

1.0

Resistivity (MΩ)

Unique Characteristics:• In-situ• Real time• On-line• High sensitivity for small feature sizes• Very short response time• Total integration

39


Convection

Diff

usio

n

wafer

water

Extent of Cleaning

Time

Diff

usio

n

wafer

water

Des

orpt

ion

Dominant Operation Parameters:• Temperature• Time• Water Purity• Additives

Dominant Operation Parameters:

• Flow• Mixing

Purge Transition Final Surface Cleaning

A Novel Staged Rinse Process


Integrated Metrology and Control for Water Systems with Reclaim and Recycle

T

S

S

CMP

Other Uses

Secondary

Primary

Polishing

Main Factory

CMP Sub-System

Recycle Reuse

ReuseS

Clean Water 1

Clean Water 2

Process Simulator

Sensors and Control Signals

PSC Module

P

PP P

P

PP

T

TT

TP

Clean Clean

PSC PSC

PSC

PSC


Effect of Recycle on Product Water Purity

Polishing

UVIEx

S

SecondaryTreatment

Reverse Osmosis UV/Ion Exchange

PrimaryTreatment

Factory

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

0.0

1.0

2.0

3.0

4.0

0 300 600 900 1200 1500Con

cent

ratio

n (p

pb)

Time (min)

UPW Quality at POU

0.000

0.005

0.010

0.015

0.020

0.025

0 300 600 900 1200 1500

Conc

entra

tion

(ppb

)

Time (min)

Ionic Impurities at POU

Calcium

Sulfate

TOC


Computer Aided Process SimulationExamples of Development and Application

43

Pressure Cyclic Purge (PCP)

for Purging Tool Chambers


Point A

Point B

Conventional Steady State Purge (SSP)SSP Flow Pattern Point B

Point A

Darker regions: High concentration


Pressure Cyclic Purge (PCP)

Velocity vectors during PCP

depressurization

PCP-inducedconvection in dead

spaces

Valve B

Valve A

Phigh

Plow

A openB closed

A closedB closed

A closedB open

A closedB closed


Surface Cleaning: PCP vs SSP

A

B

PCP SSPB A

AB

Point APoint B

1.19E15 molecules/cm2

(Equilibrium gas-phase concentration = 15ppb)

Time (min)


0

1

2

3

4

5

6

7

5.66E+15 4.72E+15 3.46E+15 2.20E+15 1.19E+15

Rat

io o

f SSP

to P

CP

Pur

ge T

imes

Surface Concentration (molecules/cm^2)

Point A Point B

Purge Time Saving by PCPTarget concentration: 1.19E15 molecules/cm2

AB

Point APoint B


Application of Green Chemistry

Definition: The design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances; applicable across the life cycle of a chemical product, including its design, manufacture, and use.

Application: • Green as the preferred (ideal) end state• Create a sustainable framework/process across the

technology life cycle (maximizing the viability of the materials used and addressing ESH mitigation at the outset of chemical design)


ResearchExploration

Pathfinding, ArchitectureDevelopment

HVM, Production

Process, ProductDevelopment

World Semiconductor Council

ITRS

Reg influencing:•CA Safe Product Law•TSCA•Nano materials

Chemical Registration:EU REACh, GHS

Con

cept

de

velo

pmen

t In

tern

al o

r ext

erna

l

Chemical Replacement

PFOS/PFAS

DfE (TD thru tech Transfer/ramp)

Today

Materials Riskassessment

+15 yrs 2-3 yrs4-6 yrs

Sponsored Research, consortia

Suppliers

Waste treatment, Air emissions abatement

Auditing, Risk AssessmentsEICC, extractives

Up front evaluation =lower COO

Green Chemistry methodology

Green Chemistry Methodology through the technology process: a continuum of proactive engagement


Nano-manufacturing is not a simple extension of

manufacturing in larger scales.

Sustainability issues are related to new materials, new

tools, and new methods for process development.

A shift to additive processing would revolutionize nano-

manufacturing feasibility and sustainability.

Computer-aided process simulation is a critical tool for

development of sustainable nano-manufacturing processes.

Developing proactive, integrated evaluation of process,

equipment and material design for EHSS/P is critical50

Summary and Conclusions

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Sustainability Opportunities and Challenges in the next · PDF fileSustainability...

Documents