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Global Warming Science Status and Statistics
Phyllis Pei Walter Worth Sematech ? 1999
Arizona Board of Regents for The University of
Arizona
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Perfluorocompounds (NF3, SF6, C2F6, CF4, CHF3)

• Have long atmospheric lifetimes
• Stable, non-toxic
• Strong infrared absorbers
• Continuing emissions will likely accumulate with
  unknown consequences
• Some, such as C2F6, are made solely for use in
  semiconductor manufacturing
• Most PFC gas is not consumed in the etch and
  CVD processes

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Key Greenhouse Gases Affected by Human Activity
ATMOSPHERIC CONCENTRATION
NOTE H2O has largest greenhouse effect, but is
not affected by human sources and sinks
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PFC Lifetimes and GWPs
GWP Global Warming Potential _at_ 100 year time
horizon Source IPCC
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Global Warming Potential (GWP)
The following equation is used to calculate GWP
t
?
a i c i dt
0
GWPt
t
a c dt
?
co2 co2
0
where a1 the instantaneous radiative forcing
resulting from a unit increase in the atmospheric
concentration of trace gas, i c1 concentration
of trace gas, i, remaining in the atmosphere at
time, t, after release of unit mass at t0 t
number of years over which the calculation is
performed
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Million Metric Tons Of Carbon
Equivalents (MMTCE)
MMTCE 12 x Kg x GWP100
44 109
GWP100 global warming potential at 100 yr. time
horizon
Kg weight of PFC emitted
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Global Warming Calculations
Wavelength Molecular Size Lifetime

Rad. Forcing Conc. Time

GWPt Mass


Million
Metric Tons Carbon Equivalent

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U.S. Greenhouse Gas Emissions
Each source, although small, contributes to
the whole
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PFC Emissions/Use Chart
Data Source EPA Dataquest
Tons/year
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1993 PFC Purchases
(U.S. Semiconductor Industry)
1993 Purchases of PFCs (metric tons)
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Chronology - PFC Technology Development
1994 - Tested first commercial PFC
thermal destruction device (Delatechs
CDO) - Alzeta develops and installs first
inwardly-fired burner at SEMATECH - MIT starts
screening PFC alternative chemicals 1995 - Alzeta
licenses burner technology to Edwards - IBM
demonstrates 50 C2F6 reduction by process
optimization
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Chronology - PFC Technology Development (Contd)

• - Edwards develops and SEMATECH tests prototype
  burnbox
• - MIT successfully destroys destruction of PFCs
  in microwave reactor
• - Novellus and 3M develop C3F8 as C2F6
  replacement
• 1996 - Beta testing of PFC capture technologies
• Air Products/Radian at TI
• Air Liquide at TI
• BOC at IMEC

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Chronology - PFC Technology Development (Contd)
- Schumacher unveils potential PFC alternative
(TFAA) - C3F8 is being evaluated in fabs at TI
and AMD as drop-in replacement for
C2F6 - Edwards improves burnbox to destroy CF4,
tested at Motorola - DuPont announces PFC
replacement studies