PFOS USE IN THE SEMICONDUCTOR INDUSTRY LRTAP Review Process

1
PFOS USE IN THE SEMICONDUCTOR INDUSTRY LRTAP
Review Process

• June 2005

2
Addition of Chemicals to LRTAP Information
Elements

• Executive Body Decision 1998/2, Paragraph 1 lays
  out information required for evaluating proposed
  additions
• Data elements include
• Production/uses/emissions
• Socio-economic factors, including
• Alternatives and their efficacy
• Known adverse environmental or health effects of
  alternatives
• Process changes, controls, prevention techniques
  which can reduce emissions of the substance

3
Key Messages

• Semiconductor sector is a strategic industry
  enables economic productivity growth, sustainable
  development, etc.
• PFOS is used in very small quantities in s/c
  photolithography, playing a critical role in
  several applications no current substitutes
• PFOS carefully managed in s/c manufacturing to
  yield de minimis emissions and exposure
• This fact recognized by EU SCHER Committee and US
  EPA
• Semiconductor industry committed to finding
  substitutes for current critical uses of PFOS
• No drop-in or one-size-fits-all substitutes
  available substitution process will take time
  and millions of Dollars/Euros of research
• Most likely PFOS alternatives are PFASs they are
  not PBTs

4
Presentation Outline

• Background
• Overview of semiconductor industry
• Semiconductors and the economy
• PFOS definitions
• Production/uses/emissions
• Basic steps in semiconductor manufacturing
• The semiconductor technology development cycle
• How and why semiconductors used in
  photolithography
• PFOS carefully managed in photolithography
• US regulatory action on PFOS
• EU SCHER report conclusions re PFOS in
  semiconductor industry

5
Presentation Outline

• Alternatives
• Critical vs. Non-critical
• The PFOS substitution process
• Progress in eliminating non-critical PFOS uses
• Known health effects of alternatives
• Industry Voluntary Commitment

6

• BACKGROUND

7
Semiconductors at the Heart of the Modern Economy
8
Overview of the Semiconductor Industry

• Value Added
• Semiconductor companies
• 213 billion worldwide sales in 2004
• SEMI
• 28 billion worldwide chemicals/materials sales
  in 2004
• Jobs created in semiconductor industry
• 226,000 in US
• 80,000 in EU
• Semiconductor industry at the heart of recent
  productivity growth gains in US economy

9
Semiconductors and the Economy

• A consensus has emerged that the development
  and deployment of information technology (IT) is
  the foundation of the American growth resurgence.
  The mantra of the new economy faster,
  better, cheaper characterizes the speed of
  technological change and product improvement in
  semiconductors, the key enabling technology.
• Source Harvard Economics Professor Dale
  Jorgenson, 2005 Semiconductor Industry
  Association Annual Report (Emphasis added)

10
Semiconductors and the Economy

• "Semiconductors are for the Information Society,
  what grain was for the agrarian society and iron
  and steel were for the industrial society."
• Source Adapted from the Shanghai Museum for
  Urban Development 2004

11
Definitions
Lower MW PFAS Homologues
Higher MW PFAS Homologues
C1 C4
C5 C7
C8
C9 Cn
PFOS
MW Molecular Weight

• PFAS is.
• PFOS is

• PFOS Chemical Structure

12

• PRODUCTION/USES/EMISSIONS

13
Oxidation
Basic Steps in Semiconductor Manufacturing
Photolithography
Doping (Ion Implantation/diffusion)
15-30 Iterations
Thin Film Deposition
Etching
Metallization
CMP
14
Typical Photolithography Process Life Cycle
Typical Photolithography ProcessLife Cycle
BARC applied via Spin Coating
EBR/RER applied via Spin Coating
TARC applied
Pre-expose Bake
Expose
Post-expose Bake
Develop
Polyimides
BARC, Resist Wastes and EBR/RER To Solvent Waste
Tank ? Disposed via Fuel Blend/Incineration
Developer and TARC Wastes to IW Drain
15
The Semiconductor TechnologyDevelopment Cycle

• The semiconductor manufacturing process is highly
  complex
• As circuit features get ever smaller, specialty
  chemicals like PFOS become ever more important
• Chemicals and materials must work precisely with
  advanced equipment (tools) to accomplish
  high-yield, high-volume manufacturing
• The process for developing new chemicals, new
  tools, and ensuring that the two work together in
  a manufacturing environment can take 10-15 years
  to complete
• Substitution of new materials into an existing
  process cannot happen quickly

16
The Semiconductor TechnologyDevelopment Cycle
Too close for change
Supplier RD
Toxicity Evaluation
10
8
6
4
2
0
Years
Ramp to High Volume Manufacturing
17
How PFOS is Used in Photolithography

• Photoacid Generators (PAGs)
• Anti-Reflective Coatings (ARCs)
• Top Anti-Reflective Coatings (TARCs)
• Bottom Anti-Reflective Coatings (BARCs)
• PFOS-based Surfactants

18
Why is PFOS in Photoacid Generators?

• Photoacid Generators (PAGs)
• Photoresists for 248nm and shorter wavelengths
  rely on chemical amplification
• During exposure the photoacid generator forms an
  acid catalyst which aids in creating the desired
  image
• PAGs control diffussion which results in better
  resolved features and smaller scale roughness
• Reduced roughness translates into reduced risk of
  semiconductor failure during critical
  applications
• Photo-acid generators used for this purpose are
  typically sulfonic acids
• PFOS is currently the ONLY chemical that can
  provide the necessary acidity

19
Photoacid Generator Example
PAGs give a 21 resistpolymer chain
destructionfor each photon of light - CHEMICAL
AMPLIFICATION
20
Photoacid Diffusion Control
65 nm
Long Diffusion
Short Diffusion
Path of catalyst
Resist morphology
Feature Foot
Well resolved features Smaller scale
roughness(exemplary of PFOS PAG)
Poorly resolved features Larger scale
roughness(exemplary of non-PFOS PAG)
Feature roughness can cause failure in critical
applications
21
Why is PFOS in ARCs and Surfactants?

• Anti-Reflective Coatings (ARCs)
• Refractive index (RI) must be as close as
  possible to the square root of the photoresist RI
  
• Only fluorinated materials can meet this
  requirement
• PFOS-based Surfactants
• Surface tension can produce thickness variations
  that emanate from the wafer center during spin-on
  photoresist application
• PFOS-based surfactants are particularly effective
  in
• Lowering the surface tension
• Reducing thickness variation
• Creating more uniform films

22
Anti-Reflective Coating Example
Metal substrates can reflect photons back from
the surface into areas of the resist not to be
exposed.
ARCs absorb the photons and prevent them from
reflecting back the composition and
capabilities of the ARC must be matched to the
resist and the light source.
23
PFOS Carefully Managed inSemiconductor
Manufacturing

• Small quantities of PFOS in critical
  applications
• PFOS stringently managed in photolithography
  process to minimize emissions and exposure
• End result de minimis emissions and exposure

Data Source ESIA-SEMI 2002 PFOS Mass Balance
24
Photolithography Equipment
Coater Bowl Cabinet
Coater Bowl
25
Semiconductor IndustryPFOS Use in Perspective
EU Case
Industry Sector 2003 EU Use kg/year
Photographic Industry 1000
Semiconductor Related Photolithography 470
Hydraulic Fluids (Aviation) 730
Metal Plating 10000


Data source RPA/BRE RRS August 2004
26
Generic Semiconductor PFOS Mass Balance Flow
Diagram
27
ESIA-SEMI PFOS Mass Balance Example

• 2002 Summary
• Total PFOS incinerated 196.5 kg
• Total PFOS released to wastewater 238.4 kg
• Total amount of PFOS used annually 435.9 kg
• of PFOS incinerated 45
• Example in event of no PFOS use in developer
• PFOS in EBR 85.3 kg
• PFOS in photoresist PAG Surfactant 44.9
  kg
• PFOS in TARC 104.1 kg
• PFOS in BARC 6.6 kg
• Total amount of PFOS used annually 240.9 kg
• Total estimated PFOS released to wastewater
  43.38 kg
• PFOS incinerated 82

28
US Regulatory Action on PFOS

• Following 3M action phasing out their PFOS
  products, USEPA issued rule essentially banning
  future uses of PFOS without new chemical approval
• USEPA provided for three limited exemptions from
  the ban, including one for critical
  photolithography uses in the semiconductor
  industry photoresists, ARCs, and surfactants
• Exemption was based on showing by industry that
• These chemicals are critical to semiconductor
  manufacturing
• Their use in semiconductor manufacturing is
  tightly controlled
• Releases to the environment are de minimis

29
EU SCHER Conclusions onSemiconductor PFOS Use

• Scientific Committee on Health and Environment
  (SCHER) advises EU Commission on chemical risk
  management issues
• Recent review of PFOS uses in Europe concluded
• The contribution of the confirmed on-going
  industrial/professional uses to the overall risks
  for the environment and for the general public
  are probably negligible with regard to the
  sectorsincluding semiconductor industry
• Source SCHER report, February 2005 (Emphasis
  added)

30

• ALTERNATIVES

31
Critical vs. Non-Critical PFOS Uses

• The distinction between critical and
  non-critical revolves around the availability,
  or expected availability, of technically-adequate
  substitutes where PFOS makes a unique
  contribution to the manufacturing process
• The semiconductor industry has eliminated
  non-critical uses, substituting other chemicals
  that can serve the same purpose
• Remaining PFOS uses are those for which there are
  no readily available substitutes (e.g., PAGs and
  ARCs)
• .
• Finding substitutes for all critical PFOS uses
  will take many years of research and
  qualification in high-volume manufacturing
• Among the issues to be faced
• Highly competitive industry
• Confidentiality issues
• Information not readily available and
• Because of low volumes, supplier interest is
  mixed

32
The PFOS Substitution Process

• Considerable engineering required to make the
  PFOS-free alternatives work in manufacturing
• A semiconductor manufacturing is a combination of
  100-400 steps that are all partly dependent on
  each other
• Each technology is unique
• Any or all of the steps may be different, as well
  as their processing parameters (e.g. feature
  size)
• A photolithography step in one technology is not
  equivalent to another technology, although
  sometimes they are similar
• Introducing a new resist requires an extensive
  qualification for each technology use
• Up to 20 different resist uses could exist in one
  technology
• This qualification is costly and involves many
  engineers
• Development engineers working primarily on legacy
  resists cannot work on the newest technologies
• Total technology development timeline impacted

PFOS alternatives are not drop-in replacements
33
Semiconductor Industry Progress inEliminating
Non-Critical PFOS Uses

• Developers
• Industry is in the process of phasing out
  PFOS-containing developers because alternatives
  exist with same performance
• Etchants
• Alternatives with same performance exist and are
  used
• Emission controls
• PFOS containing solvent waste from semiconductor
  manufacturing is incinerated at high temperatures
• Wastewater treatment
• Wastewater point of use abatement technology
  under evaluation (ISMT) Concentration in ng/l ?
  ALARA principle

34
Semiconductor Industry Progress inEliminating
Non-Critical PFOS Uses

• PFOS Consumption
• Total use of PFOS continues to decline as the
  industry goes from 200 mm to 300 mm wafer size
• Wafer area increases 125
• Amount of resist used drops from 3 ml to 1 ml per
  wafer ? 85 less resist used on a per wafer
  basis
• Voluntary Commitment
• Industry is working on an INTERNATIONAL voluntary
  approach to reduce emissions from PFOS use
  because the semiconductor manufacturing industry
  is truly a global industry

35
Known Health Effects of Alternatives

• Lower homologues of Perfluoroalkyl sulfonates
  (PFAS) are thought be the most likely
  replacements for PFOS
• Currently these are the only known potential
  alternatives
• Effectiveness is unknown
• Studies suggest that lower homologues of PFASs
  are not PBTs
• Low bioaccumulation factor (lt1)
• Lower environmental persistence
• Nearly non-toxic to mammals
• Not acutely eco-toxic
• See 3Ms information at
• http//multimedia.mmm.com/mws/mediawebserver.dyn?T
  TTTTTB_LdgTmwUTfwUTTTj7zDsssssr

36
Industry Voluntary Commitment

• Voluntary Commitment being developed by World
  Semiconductor Council member associations (SIA,
  ESIA, JSIA, etc.)
• Proposed elements include
• Stop non-critical uses
• Incineration of solvents containing PFOS
• Equipment effluent optimization research
• Work towards critical use phase-out
• Research for alternatives to perfluorinated
  chemistry
• Wastewater effluent evaluations of control
  technology
• Reporting activity

37

• BACKUP

38
SIA-SEMI U.S. PFAS Mass Balance
39
ESIA-SEMI PFOS Mass Balance