Projecting PFC Emissions Using EPAs PFC Emissions Vintage Model

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Projecting PFC Emissions Using EPAs PFC
Emissions Vintage Model

• Presented at
• 9th Annual ISESH Conference
• June 9 13, 2002
• San Diego, CA

C. Shepherd Burton Scott Bartos
Consultant U. S. Environmental 2047
Huckleberry Rd. Protection Agency San Rafael,
CA 1200 Pennsylvania
Ave. Washington, DC
2
Outline

• Introduction
• Some considerations
• PEVM Formulation and structure
• Results 2010 Projections
• Key Uncertainties, limitations and caveats
• Summary of findings

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Introduction

• Semiconductor manufacturing At threshold of low
  to zero emissions future
• Path to threshold well documented
• Recognition of environmental risks of PFC
  emissions
• Broad industry cooperation
• International government-industry cooperation
• Challenge ahead Achieving aggressive WSC
  reduction goal by 2010
• What to do?
• Our aim Contribute to collective sense of what
  can be done using emissions modeling

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Some Considerations

• IPCC vs. PEVM Bottoms-up and top-down methods
• Are PFC emissions correlated with Si consumption?
• Si demand Historical and projected patterns
• Trends in complexity and effect of copper on
  interconnects on emissions

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IPCC vs. PEVM Bottoms-up and top-down methods

• IPCC estimation method
• Bottoms-up Company inventories
• Q(MMTCE) usage x (1 UF) x (1 DE)
• Tiered Rigor varies
• Arguably impractical for projecting industry
  emissions

• Si - consumption method
• Top-down Not now used
• ltQ(MMTCE)gt Si x gas-process EF
• Global EF to be developed
• Partner reports and public information
• Arguably practical for projecting PFC emissions

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Partner Reported 99 MMTCEs vs. MSI Si-Layers
(2000 WFW SEMI)(Values not shown to preserve
Partner confidentiality)
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Correlating Partner PFC Emissions Totals (MMTCE)
and MSI Silicon x Nominal Number of Layers
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Historical and Projected Si Demand by Linewidth,
1988 - 2010
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Process Complexity Trend
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Reducing metal layers by switching from Al to Cu
How many?
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Model Formulation, Structure and
Operationalization

• Formulation
• Structure, sources of information and
  operationalization
• Comparison of emissions factors

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PEVM Formulation and Structure

• ltPFC Emissions(y)gt gas-process avg. PFC
  emissions in year, y
• ltPFC Emissions(y)gt E(y) x S(y)
• Definition of E(y), an emissions factor for
  uncontrolled emissions, MMTCE per unit area of Si
  consumed
• ltPFC Emissions(y)gt, from Partner emission reports
• S(y),from SEMI WFW database and VLSI Research,
  Inc. world Si consumption figures
• Result Estimate of E(y), does NOT account for
  complexity

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PEVM Formulation and Structure Accounting for
Complexity

• ltPFC Emissions(y)gt E(y) S(y)
• Si ?i(y) si(y) e(y)
• ?i(y) nominal no. of layers for technology
  node
• i and year y (from ITRS)
• si(y) Si consumed (from VLSI Res., Inc.)
  for node i
• e(y) avg. gas-process emissions per unit of
  area
• of Si consumed per average layer
• e(y) E(y)/lt?(y)gt lt?(y)gt (1/ S(y)) Si ?i(y)
  si(y)
• Result Est. of gas-process average uncontrolled
  emission factor

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PEVM Formulation and StructureIntegrating
Concept and Mathematics

• ltPFC Emissions(y)gt E(y) x S(y)
• Si ?i(y) si(y) e(y)
• Si ltPFC Emissions(y)gti
• Result Project uncontrolled gas-process average
  (BAU) emissions using ltegt Avg(e(y)) and
  projected si(y) and ?i(y)

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Projecting Emissions
Sources Types of Information
Method for Estimating PFC-Process Average
Emission Factors
Projecting Si Demand to 2010
Annual PFC Emissions Totals, 95-99
Partners
U. S. share of world layer-weighted capacity, ,
1995 - 2000
U. S. Si demand by linewidth, in2 Si, 1988 - 2010
World Fab Watch databases ownership, location,
capacity, geometry, etc. 95-99
SEMI
Partner PFC-Process average emission factors
(MMTCE/in2 Si) 1995, 96,
97, 98 99
U. S. PFC emissions by linewidth 1988 2010 MMTCE
World CAGR for Si demand, 1988 - 2005
World Si demand (in2) by linewidth, 1988 - 2010
World Si Demand, wafer size, in2 , 83-05

Partner per-average-layer emission factors
(MMTCE/in2Silayer) 1995, 96, 97, 98, 99
Linewidth-specific emission factors (MMTCE/in2
Si), Avg. 95-99
World PFC emissions by linewidth 1988- 2005 MMTCE
Adj. for full- process test wafers
VLSI Research, Inc.
World Si Demand, device type, 83-05
Analysis Adoption/decay profiles for future
technology nodes
World Si Demand, linewidth, in2, 83-05
Compare calc. Partner avg. utilization with
available world reports.
Avg. number of layers/node
Specs outlook for industry
ITRS
Effect of Cu interconnect on number of wiring
levels (layers)
Test wafers full processed, Cu effect on layers,
industry capacity utilization, etc.
Industry Reports
Schematic of EPAs PFC Vintage Model (v.2.14) for
Projecting US PFC Emissions from Semiconductor
Manufacturing
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Avg. PFC-Process Emission Factors Formation of
E(y) , e(y) and ltegt
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Some Results Application of PEVM

• Projected U. S. emissions without and with Cu
• Comparison of PEVM and IPCC-like Method

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Projected PEVM PFC U. S. Emissions With Cu, No
Reduction Technology
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Projected PEVM PFC U. S. Emissions Without Cu,
No Reduction Technology
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Comparing PEVM and IPCC-like Method

• IPCC-like Method Extrap. DataQuest 90 96
  survey figures
• 18 MMTCEs cf. 15 and 16 MMTCEs PEVM with and
  without Cu, respectively
• CAGR 20, 95 10 period, IPCC-like
• Partnership CAGR 13, 95 99 period

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Key Assumptions, Uncertainties and Limitations

• Emission factors reflect process-gas average
• Silicon projections changes by wafer size and
  technology generation metal layers across
  markets (MPUs, memory, logic, etc.)
• Disaggregating avg. process-gas, node-specific
  emissions factors, ltegt?i(y) formation of
  process/gas-specific emission factors
• Reduction cases Selecting technology DEs and
  penetration rates for alternative control
  strategies
• Estimating U. S. share of world emissions

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Findings

• Avg.emissions per unit of Si consumed per average
  layer appears a robust concept
• BAU projections PEVM PFC emissions estimates
  compare favorably with bottoms-up IPCC-like
  method
• BAU 2010 projections with Cu PEVM gives 8 times
  corresponding 1995 emissions
• PFC reduction technologies On average gt90 DE
  implemented at 200 mm and 300 mm fabs