Chapter 6: Electronics Industry Emissions

CHAPTER 6

ELECTRONICS INDUSTRY EMISSIONS

2006 IPCC Guidelines for National Greenhouse Gas Inventories

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Volume 3: Industrial Processes and Product Use

Authors
Scott Bartos (USA)
Laurie S. Beu (USA), C. Shepherd Burton (USA), Charles L. Fraust (USA), Francesca Illuzzi (Italy), Michael T.
Mocella (USA) and Sebastien Raoux (France/USA)

Contributing Authors
Guido Agostinelli (Italy), Erik Alsema (Netherlands), Seung-Ki Chae (Republic of Korea), Vasilis M. Fthenakis(USA) , Joseph Van Gompel (USA) , Hideki Nishida (Japan), Takayuki Oogoshi (Japan) and Kurt T. Werner
(USA)

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Chapter 6: Electronics Industry Emissions

Contents
6

Electronics Industry Emissions .....................................................................................................................6.5
6.1

Introduction ...........................................................................................................................................6.5

6.2

Methodological issues ...........................................................................................................................6.6

6.2.1

Choice of method ..........................................................................................................................6.6

6.2.1.1

Etching and CVD cleaning for semiconductors, liquid crystal displays, and photovoltaics....6.6

6.2.1.2

Heat transfer fluids ................................................................................................................6.13

6.2.2

Choice of emission factors ..........................................................................................................6.15

6.2.2.1

Etching and CVD cleaning for semiconductors, liquid crystal displays, and photovoltaics..6.15

6.2.2.2

Heat transfer fluids ................................................................................................................6.22

6.2.3

Choice of activity data.................................................................................................................6.22

6.2.4

Completeness ..............................................................................................................................6.24

6.2.5

Developing a consistent time series.............................................................................................6.25

6.3

Uncertainty assessment .......................................................................................................................6.25

6.3.1

Emission factor uncertainties ......................................................................................................6.25

6.3.2

Activity data uncertainties...........................................................................................................6.26

6.4

Quality Assurance/Quality Control (QA/QC), Reporting and Documentation ...................................6.29

6.4.1

Quality Assurance/Quality Control (QA/QC) .............................................................................6.29

6.4.2

Reporting and Documentation.....................................................................................................6.29

References.....................................................................................................................................................6.31

Equations
Equation 6.1

Tier 1 method for estimation of the set of FC emissions.......................................................6.9

Equation 6.2

Tier 2a method for estimation of FC emissions...................................................................6.10

Equation 6.3

By-product emissions of CF4 ...............................................................................................6.10

Equation 6.4

By-product emissions of C2F6 .............................................................................................6.10

Equation 6.5

By-product emissions of chf3...............................................................................................6.10

Equation 6.6

By-product emissions of C3F8 .............................................................................................6.10

Equation 6.7

Tier 2b method for estimation of FC emissions ..................................................................6.11

Equation 6.8

By-product emissions of CF4 ...............................................................................................6.12

Equation 6.9

By-product emissions of C2F6 .............................................................................................6.12

Equation 6.10 By-product emissions of CHF3 ............................................................................................6.12
Equation 6.11 By-product emissions of C3F8 .............................................................................................6.12
Equation 6.12 Tier 1 method for estimation of total FC emissions from heat transfer fluids .....................6.14
Equation 6.13 Tier 2 method for estimation of FC emissions from heat transfer fluids .............................6.14

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FiguresFigure 6.1

Decision tree for estimation of FC emissions from electronics manufacturing.....................6.8

Figure 6.2

Decision tree for estimation of FC emissions from HT fluid loss from electronics
manufacturing......................................................................................................................6.15

TablesTable 6.1

Information sources necessary for completing the tiered emission estimating methods forelectronics manufacturing......................................................................................................6.7

Table 6.2

Tier 1 Gas-specific emission factors for FC emissions from electronics manufacturing ....6.16

Table 6.3

Tier 2 Default emission factors for FC emissions from semiconductor manufacturing ......6.17

Table 6.4

Tier 2 Default emission factors for FC emissions from LCD manufacturing......................6.18

Table 6.5

Tier 2 Default emission factors for FC emissions from PV manufacturing ........................6.19

Table 6.6

Tier 2a & 2b Default efficiency parameters for electronics industry FC emission reduction
technologies.........................................................................................................................6.20

Table 6.7

Country total silicon (Si) and glass design capacities (Mm2) for 2003, 2004 and 2005 ......6.23

Table 6.8

Country total PV production capacitya for 2003, Mm2 ........................................................6.24

Table 6.9

Tier 2 default estimates of relative errors (%) for emission factor for FC emissions fromsemiconductor manufacturing, 95 percent confidence intervals..........................................6.27

Table 6.10

Tier 2 default estimates of relative errors (%) for emission factor for FC emissions from LCD
manufacturing, 95 percent confidence intervals ..................................................................6.28

Table 6.11

Information necessary for full transparency of estimates of emissions from electronics
manufacturing......................................................................................................................6.30

Box
Box 6.1

6.4

Example for semiconductor manufacture ............................................................................6.13

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

6 ELECTRONICS INDUSTRY EMISSIONS
6.1

INTRODUCTION

Several advanced electronics manufacturing processes utilise fluorinated compounds (FCs) for plasma etching
intricate patterns, cleaning reactor chambers, and temperature control. The specific electronic industry sectors
discussed in this chapter include semiconductor, thin-film-transistor flat panel display (TFT-FPD), andphotovoltaic (PV) manufacturing (collectively termed ‘electronics industry’).1
The electronics industry currently emits both FCs that are gases at room temperature and FCs that are liquids atroom temperature. The gases include CF4, C2F6, C3F8, c-C4F8, c-C4F8O, C4F6, C5F8, CHF3, CH2F2, nitrogen
trifluoride (NF3), and sulfur hexafluoride (SF6), and are used in two important steps of electronics manufacturing:(i) plasma etching silicon containing materials and (ii) cleaning chemical vapour deposition (CVD) toolchamber-walls where silicon has deposited. 2 The majority of FC emissions results from limited utilisation
efficiency (i.e., consumption) of the FC precursors during the etching or the cleaning process. In addition, afraction of the fluorinated compounds used in the production process can be converted into by-product CF4 andin some instances into C2F6, CHF3 and C3F8.3 Also, formation of CF4 as a by-product of etching or cleaning
carbon-containing low dielectric constant (low k) materials (or carbide) must be taken into account.4 In addition,
F2, COF2, and ClF3 use may increase. These gases, although not in themselves contributors to global warming
may lead to CF4 formation under some conditions.
Electronics manufacturers use FCs for temperature control during certain processes. Also known as heat transfer
fluids, these FCs are liquids at room temperature and have appreciable vapour pressures. Evaporative losses
contribute to the total FC emissions. These evaporative losses occur during cooling of certain process equipment,
during testing of packaged semiconductor devices and during vapour phase reflow soldering of electronic
components to circuit boards. Evaporative losses do not appear to occur when liquid FCs are used to coolelectronic components or systems during operation. In this application, the liquid FCs are contained in closed
systems throughout the life of the product or system. More than 20 different liquid FCs are marketed, often as
mixtures of fully fluorinated compounds, to the electronic sector.5 Because the CO2 equivalents of each liquid
differ, each should be tracked and reported separately. The precise value of this conversion will be determinedby the specific applicable reporting requirements.6,7 In addition, liquid FCs are occasionally used to clean TFTFPD panels during manufacture.

1

Recent comprehensive surveys of European and US PV manufacturers indicate that 40 to 50 percent of PV-manufacturers
use relatively small quantities of FCs (predominantly CF4 during etching of crystalline silicon wafers and C2F6 during
chamber cleaning after deposition of SiNx films). Global usage, according to these surveys for 2004, was approximately 30
Mtonnes CF4. While global FC use appears low in 2004, credible growth-forecasts of the PV industry are approximately 30
percent per year (and higher) for the foreseeable future. Morevoer, several reports extol the virtues of FC use as a means toincrease manufacturing productivity and lower costs for silicon-based technologies (Shah et al., 2004; Maycock, 2005;
Agostinelli et al., 2004 and Rentsch et al., 2005), Such expected growth rates and prospects for increase FC use motivate
inclusion of FC emissions from PV manufacture in this chapter.

2

Although C5F8 does not currently have a global warming potential (GWP) recognized by the IPCC, C5F8 emissions are
discussed in this chapter. C5F8 is a direct greenhouse gas and emissions can be estimated using methods and data describedin this chapter. C5F8’s atmospheric lifetime is approximately 1 year, resulting in a relatively low GWP (Sekiya, 2003).

3

Emissions of C2F6 by-products have been observed from the decomposition of C4F6 molecules and may occur for other FC
molecules with greater than two carbon atoms. Note that for most FC precursors, C2F6 formation as a by-product has notbeen observed. CHF3 formation has been reported when c-C4F8 is used as an etchant in TFT-FPD manufacture and C3F8
by-product emissions have been reported when C4F8O is used in chamber cleaning.

4

Low dielectric constant (low k) materials were first used as insulators for the interconnect structure of semiconductor chips
at the 0.25μm node and below. Many low k materials contain carbon that may be removed as CF4 during etching of thinfilms or the cleaning of the CVD reactors used for low k deposition. CF4 may also be formed during cleaning of CVD
reactors used for carbide deposition.

5

A relatively recent review summarises the uses of liquid FCs (heat transfer fluids), their chemical composition, GWPs,
among other things. See Burton (2004a).

6

These materials are marketed under the trade names Fluorinert™ and Galden®. The Fluorinert™ materials are selected fromfully fluorinated alkanes, ethers, tertiary amines and aminoethers and mixtures thereof to obtain the desired properties. The
Galden® fluids span a range of fully fluorinated polyethers, called perfluoropolyethers (PFPEs), also selected for thedesired properties.

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6.2

METHODOLOGICAL ISSUES

6.2.1

Choice of method

6.2.1.1

E TCHING AND CVD CLEANING FOR SEMICONDUCTORS ,LIQUID CRYSTAL DISPLAYS , AND PHOTOVOLTAICS

Emissions vary according to the gases used in manufacturing different types of electronic devices, the processused (or more roughly, process type (e.g., CVD or etch)), the brand of process tool used, and the implementationof emission reduction technology.
The choice of methods will depend on data availability and is outlined in the decision tree, see Figure 6.1,
Decision Tree for Estimation of FC Emissions from Electronics Manufacturing. Emissions from liquid FCs are
estimated using Tier 1, 2 and 3 approaches and are described separately in this section.8
Continuous (in-situ) emissions monitoring is currently considered a technically and economically unviablemeans to estimate emissions from this industry. FC emissions are periodically measured, however, during thedevelopment of new processes and tools, and after the establishment of commercial-ready process conditions(also known as centreline process conditions).9 The industry seeks, prior to the introduction of high-volume
manufacturing, centreline process designs that minimize FC emissions. However, it must be noted that FCemissions can be affected by changes in process variables (e.g., pressure, temperature, plasma power, FC gas
flow, processing time). Thus, the accuracy of the methods used for estimating emissions will be affected byeventual differences between the process used in production and the reference centreline process. In addition, theefficacy of FC emission control equipment depends on operating and maintaining the equipment according to the
manufacturer’s specifications: Increased gas flows, improper temperature settings, and failure to perform
required maintenance will individually and collectively negatively impact performance.
The accuracy of estimated emissions depends on the method used. The Tier 1 method uses default values for allparameters and does not account for the use of emission control technology. The Tier 2a method uses companyspecific data on the proportion of gas used in processes with and without emission control technology, but does
not distinguish between etching and cleaning, and uses default values for the other parameters. The Tier 2b
method uses company-specific data on the proportion of gas used in etching versus cleaning and the proportionof gas used in processes with emission control technology, but relies on default values for some or all of theother parameters. The most rigorous method, Tier 3 method, requires a complete set of process-specific values
rather than defaults.
Table 6.1 summarises the data requirements for the tiered emissions estimating methods for electronics
manufacturing.

7

Where a commercial mixture is used inventory compilers will need to ensure that the conversion of the mass of the mixture
to CO2 equivalents uses the appropriate conversion factors.

8

The logic depicted in Figure 6.1 does not show the possibility of combining tiers to improve estimates of emissions. For
example, improved estimates of emissions might be achieved by using Tier 3 for a specific gas and process and Tier 2b forother gases and processes instead of using only the Tier 2b method. Similarly, the Tier 2a and 2b methods might be
combined to produce an improved estimate compared to using only Tier 2a. However, the Tier 1 method should not be
combined with any other method.

9

Centreline conditions refer to the conditions under which equipment manufacturers standardise their equipment for sale.
These are nominal specifications for gas flows, chamber pressure, processing time, plasma power, etc. It is common for
semiconductor manufacturers to modify these conditions to optimise for particular needs.

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Chapter 6: Electronics Industry Emissions

TABLE 6.1
INFORMATION SOURCES NECESSARY FOR COMPLETING THE TIERED EMISSION ESTIMATING METHODS FOR
ELECTRONICS MANUFACTURING

Annual
Production
Capacity

Downstream FC Emission
Control

Process Gas
Reactions and
Destruction in
Tool

Process Gas Entering
Tool

Data

Tier 1

Tier 2aTier 2b

Tier 3

FCi,p = kg of gas i fed into specific process
p or small set of common process tools(e.g., silicon nitride etch).

M

FCi,p = kg of gas i fed into broad process
category (e.g., etching or CVD chambercleaning).

M

M(etch) &M(CVD)

h = Fraction of gas remaining in shipping
container after use (heel).

D

D

M

Ui,p = Use rate (fraction destroyed ortransformed) for each gas i and process p.

D

D(etch) &D(CVD) aM

BCF4,i,p, BC2F6,i,p, BCHF3,i,p and BC3F8,i,p =Emission factor for by-product emissionsof CF4, C2F6, CHF3 and C3F8 respectively
for gas i for each process.

D

D(etch) &D(CVD) aMai,p = Fraction of gas i volume fed into
processes with certified FC emission
control technologies.

M

M

M

di,p = Fraction of gas i destroyed by theemission control technology.

D

Da

M

dCF4,p, dC2F6,p, dCHF3,p and dC3F8,p = Fractionof CF4, C2F6, CHF3 and C3F8 by-products
respectively destroyed by the emission
control technology.bM

Cd = Annual manufacturing design
capacity in surface area of substrate
processed (e.g., silicon, glass).

M

Cu = Fraction of annual capacity utilisation

D/M

M = measure or acquire these values.
D = Use default factors from guidance.
aWhen available and supportable, M values may be substituted for D values for Tier 2a and 2b. See conditions in Table 6.6.

b

There are no default values for Tier 2a and Tier 2b because the effect of by-products has been incorporated into the D-values fordi,p for gas i.

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Volume 3: Industrial Processes and Product Use

Figure 6.1

Decision tree for estimation of FC emissions from electronics manufacturing
Start

Are FC
activity data available
from electronics
companies?

Do
companies thatreport use process-specificemission factors?

Yes

Yes

Estimate emissions
using the Tier 3
method.
Box 4: Tier 3

No

Collect activity andemissions data fromelectronics companies.

Is
Electronics
Industry a key category1 and is
this subcategorysinificant?

No

Do
reporting companies
track FC gas usage by process
type (i.e., CVD clean
and etch)?

Yes

Yes

Estimate emissions
using the Tier 2b
method.
Box 3: Tier 2b

No
No
Are
national data available
on annual electronics production
capacities by substrate area
(e.g., silicon or
glass)?

Yes

No

Develop or obtaindata on annual
production capacity
by substrate area foreach sector.

Estimate emissions
using the Tier 2amethod.
Box 2: Tier 2a

Estimate emissions
using the Tier 1
method.
Box 1: Tier 1

Note:
1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for
discussion of key categories and use of decision trees.

TIER 1 METHOD – DEFAULTThe Tier 1 method is the least accurate estimation method and should be used only in cases where companyspecific data are not available. The Tier 1 method, unlike the Tier 2 or 3 methods, is designed to give an
aggregated estimate of FC emissions although its methodology appears to produce gas-specific emissions.
Estimates are made simultaneously for all gases as listed in Table 6.2 and can only be used if reported as acomplete set.
The calculation of emissions relies on a fixed set of generic emissions factors. The members of the set differ
depending on the sector (or class) of electronic products being manufactured (semiconductors, TFT-FPDs or PVcells). Each member of a set, which is a gas-specific emission factor, expresses an average emissions per unit ofsubstrate area (e.g., silicon, TFT-FPD panel or PV-cell) consumed during manufacture. For any class ofelectronic products, the factors (members of the set) are multiplied by the annual capacity utilisation (Cu, afraction) and the annual manufacturing design capacity (Cd, in units of giga square meters (Gm2)) of substrate
processes. The product (Cu • Cd) is an estimate of the quantity of substrate consumed during electronics
manufacture. The result is a set of annual emissions expressed in kg of the gases that comprise the set for eachclass of electronic products. Because the use of FCs varies widely during PV manufacture, a third factor to

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Chapter 6: Electronics Industry Emissions

account for the proportion of PV manufacture that employs FC is needed to estimate FC emissions from the PV
cells manufacturing. The Tier 1 formula is shown in Equation 6.1.
EQUATION 6.1
TIER 1 METHOD FOR ESTIMATION OF THE SET OF FC EMISSIONS{FCi }n = {EFi • Cu • Cd • [CPV • δ + (1 − δ )]}n (i = 1, K, n )Where:{FCi}n = emissions of FC gas i, mass of gas iNote: { }n denotes the set for each class of products (semiconductors, TFT-FPD or PV-cells) and ndenotes the number of gases included in each set (six for semiconductors, three for TFT-FPD
manufacture and two for PV-cells. See Table 6.2.). The estimates are only valid if made and reported
for all members of the set using this Tier 1 methodology.
EFi = FC emission factor for gas i expressed as annual mass of emissions per square meters of substratesurface area for the product class, (mass of gas i)/m2
Cu = fraction of annual plant production capacity utilisation, fraction
Cd = annual manufacturing design capacity, Gm2of substrate processed, except for PV manufacturing
which is Mm2
CPV = fraction of PV manufacture that uses FCs, fraction

δ = 1 when Equation 6.1 is applied to PV industry and zero when Equation 6.1 is applied to either
semiconductor or TFT-FPD industries, dimensionlessThis method does not account for differences among process types (etching versus cleaning), individual
processes, or tools. It also does not account for the possible use of atmospheric emission-control devices.
In using Tier 1, inventory compilers should not modify, in any way, the set of the FCs assumed in Table 6.2.
Inventory compilers should not combine emissions estimated using Tier 1 method with emissions estimatedusing the Tier 2 or 3 methods. Neither may inventory compilers use, for example, the Tier 1 factor for CF4 toestimate the emissions of CF4 from semiconductors and combine it with the results of other FC gases from a Tier
2 or Tier 3 method. (See also Section 6.2.2.1.)

TIER 2a METHOD – PROCESS GAS-SPECIFIC PARAMETERS
This method calculates emissions for each FC used on the basis of company-specific data on gas consumption
and on emission control technologies. It uses industry-wide default values for the ‘heel’ or fraction of thepurchased gas remaining in the shipping container after use (h), the fraction of the gas ‘used’ (destroyed ortransformed) in the semiconductor or TFT-FPD manufacturing process, and the fraction of the gas converted into
CF4 or C2F6 during the process. To use the Tier 2a method inventory compilers must have direct communication
with industry (e.g., annual emissions reporting) to gather data and ensure that emission control technologies are
installed and in use.
Total emissions are equal to the sum of emissions from the gas FCi used in the production process plus theemissions of by-product CF4, C2F6, CHF3 and C3F8 resulting from use of the gas FCi., as shown in Equations 6.2,
6.3, 6.4, 6.5 and 6.6. Unlike the Tier 3 and 2b methods that are explained later in this section, the Tier 2amethod does not distinguish between processes or process types (etching versus cleaning), individual processes
or tools. The default emission factors represent weighted averages (based on expert judgments of weights),
formed separately for each gas, over all etch and CVD processes.
As discussed below in the section on emission factors, the Tier 2a method uses the emission factor for theprocess type (CVD or etch) in which the individual FC is most frequently used in the particular electronics sector.
This method reflects a current trend where individual FCs tend to be used predominantly in particular process
types (CVD or etch) throughout each industry. However, in countries with companies or plants that departsignificantly from the industry-wide pattern of usage (e.g., by using a gas primarily in etch while others
primarily use it in CVD), inventory compilers should evaluate the potential to introduce error by using the Tier
2a method rather than the Tier 2b method.

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EQUATION 6.2
TIER 2a METHOD FOR ESTIMATION OF FC EMISSIONS
Ei = (1 − h ) • FCi • (1 − U i ) • (1 − ai • d i )Where:
Ei = emissions of gas i, kg
FCi = consumption of gas i,(e.g., CF4, C2F6, C3F8, c-C4F8, c-C4F8O, C4F6, C5F8, CHF3, CH2F2, NF3, SF6),kg
h = fraction of gas remaining in shipping container (heel) after use, fraction
Ui = use rate of gas i (fraction destroyed or transformed in process), fraction
ai = fraction of gas i volume used in processes with emission control technologies (company- or plantspecific), fraction
di = fraction of gas i destroyed by the emission control technology, fraction

EQUATION 6.3
BY-PRODUCT EMISSIONS OF CF4
BPECF 4, i = (1 − h ) • BCF 4, i • FCi • (1 − ai • d CF 4 )Where:BPECF4,i = by-product emissions of CF4 from the gas i used, kg
BCF4,i = emission factor, kg CF4 created/kg gas i used
dCF4 = fraction of CF4 by-product destroyed by the emission control technology, fraction

EQUATION 6.4
BY-PRODUCT EMISSIONS OF C2F6BPEC 2 F 6, i = (1 − h ) • BC 2 F 6, i • FCi • (1 − ai • d C 2 F 6 )Where:
BPEC2F6,i = by-product emissions of C2F6 from the gas i used, kg
BC2F6,i = emission factor, kg C2F6 created/kg gas i used
dC2F6 = fraction of C2F6 by-product destroyed by the emission control technology, fraction

EQUATION 6.5
BY-PRODUCT EMISSIONS OF CHF3
BPECHF 3, i = (1 − h ) • BCHF 3, i • FCi • (1 − ai • d CHF 3 )Where:BPECHF3,i = by-product emissions of CHF3 from the gas i used, kg
BCHF3,i = emission factor, kg CHF3 created/kg gas i useddCHF3 = fraction of CHF3 by-product destroyed by the emission control technology, fraction

EQUATION 6.6
BY-PRODUCT EMISSIONS OF C3F8BPEC 3 F 8, i = (1 − h ) • BC 3 F 8,i • FCi • (1 − ai • d C 3F 8 )Where:

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Chapter 6: Electronics Industry Emissions

BPEC3F8,i = by-product emissions of C3F8 from the gas i used, kg
BC3F8,i = emission factor, kg C3F8 created/kg gas i used
dC3F8 = fraction of C3F8 by-product destroyed by the emission control technology, fraction
After estimating the emission of gas i (Ei) and the CF4, C2F6, CHF3 and C3F8 by-product emissions for each gas(BPECF4,i, BPEC2F6,i, BPECHF3,i and BPEC3F8,i), inventory compilers or companies should sum these emissions
across all gases to estimate the total aggregate FC emissions.

TIER 2b METHOD – PROCESS TYPE-SPECIFIC PARAMETERS
The Tier 2b method requires data on the aggregate quantities of each gas fed into all etching processes and all
cleaning processes (FCi,p). Thus, it distinguishes only between broad process types (etching vs. CVD chambercleaning), but it does not distinguish among the many possible individual processes or small sets of processes.
Industry-wide default values can be used for any or all of the following:•

the fraction of the gas remaining in the shipping container after use termed the ‘heel’ (h);•the fraction of the gas ‘used’ (destroyed or transformed) per process type (Ui,p);•the emission factor for CF4 by-product emissions in the process type (BCF4,i,p);•the emission factor for C2F6 by-product emissions in the process type (BC2F6,i,p);•the emission factor for CHF3 by-product emissions in the process type (BCHF3,i,p)); and•the emission factor for C3F8 by-product emissions in the process type (BC3F8,i,p).

Defaults are also presented (see Table 6.6) for the fraction of the gas destroyed by the emissions control
technology by process type (di,p, dCF4,p, dC2F6,p, dCHF3,p and dC3F8,p). Unless emission control technologies are
installed, the default value for ai,p, the fraction of gas volume fed into processes with emission control
technologies, is zero. The default values for Ui,p, BCF4,i,p, BC2F6,i,p, BCHF3,i,p and BC3F8,i,p represent simple
unweighted averages, formed separately for each gas, over all etch processes and over all CVD processes.
Company or plant-specific emission factors may be substituted for default values when available. The equations
account for the plant-specific use of emission-control devices, but do not account for differences amongindividual processes or tools or among manufacturing plants in their mix of processes and tools. Thus, Tier 2b
estimates will be less accurate than Tier 3 estimates. Also, note that the Tier 2b method is applicable tosemiconductor and TFT-FPD manufacture.
Emissions resulting from the use of a specific FC (FCi) consist of emissions of FCi itself plus emissions of CF4,
C2F6, CHF3 and C3F8 created as by-products during use of FCi. The following calculation should be repeated foreach gas for each process type:
EQUATION 6.7
TIER 2b METHOD FOR ESTIMATION OF FC EMISSIONS

[

(

) (

Ei = (1 − h ) • ∑ FCi , p • 1 − U i , p • 1 − ai , p • d i , pp)]Where:
Ei = emissions of gas i, kg
p = process type (etching vs. CVD chamber cleaning)
FCi,p = mass of gas i fed into process type p (e.g., CF4, C2F6, C3F8, c-C4F8, c-C4F8O, C4F6, C5F8, CHF3,
CH2F2, NF3, SF6), kg
h = fraction of gas remaining in shipping container (heel) after use, fraction
Ui,p= use rate for each gas i and process type p (fraction destroyed or transformed), fraction
ai,p = fraction of gas i volume fed into process type p with emission control technologies (company-or
plant-specific), fraction
di,p = fraction of gas i destroyed by the emission control technology used in process type p (If more than
one emission control technology is used in process type p, this is the average of the fraction
destroyed by those emission control technologies, where each fraction is weighted by the quantity ofgas fed into tools using that technology), fraction

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EQUATION 6.8
BY-PRODUCT EMISSIONS OF CF4[(

BPECF 4, i = (1 − h ) • ∑ BCF 4, i , p • FCi , p • 1 − ai , p • d CF 4, pp)]

Where:BPECF4,i = by-product emissions of CF4 converted from the gas i used, kg
BCF4,i,p = emission factor for by-product emissions of CF4 converted from gas i in process type p, kg CF4
created/kg gas i used
dCF4,p = fraction of CF4 by-product destroyed by the emission control technology used in process type p(e.g., control technology type listed in Table 6.6), fraction

EQUATION 6.9
BY-PRODUCT EMISSIONS OF C2F6[(BPEC 2 F 6, i = (1 − h ) • ∑ BC 2 F 6, i , p • FCi , p • 1 − ai , p • d C 2 F 6, pp)]

Where:
BPEC2F6,i = by-product emissions of C2F6 converted from the gas i used, kg
BC2F6,i,p = emission factor for by-product emissions of C2F6 converted from gas i in process type p, kg
C2F6 created/kg gas i used
dC2F6,p = fraction of C2F6 by-product destroyed by the emission control technology used in process type p(e.g., control technology type listed in Table 6.6), fraction

EQUATION 6.10
BY-PRODUCT EMISSIONS OF CHF3[(

BPECHF 3, i = (1 − h ) • ∑ BCHF 3, i , p • FCi , p • 1 − ai , p • d CHF 3, pp)]

Where:BPECHF3,i = by-product emissions of CHF3 converted from the gas i used, kg
BCHF3,i,p = emission factor for by-product emissions of CHF3 converted from gas i in process type p, kg
CHF3 created/kg gas i useddCHF3,p = fraction of CHF3 by-product destroyed by the emission control technology used in process type p(e.g., control technology type listed in Table 6.6), fraction

EQUATION 6.11
BY-PRODUCT EMISSIONS OF C3F8[(BPEC 3 F 8, i = (1 − h ) • ∑ BC 3F 8, i , p • FCi , p • 1 − ai , p • d C 3F 8, pp)]

Where:
BPEC3F8,i = by-product emissions of C3F8 from the gas i used, kg
BC3F8,i,p = emission factor for by-product emissions of C3F8 converted from gas i in process type p, kg
C3F8 created/kg gas i used
dC3F8,p = fraction of C3F8 by-product destroyed by the emission control technology used in process type p(e.g., control technology type listed in Table 6.6), fraction

6.12

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

Note that in certain etching or cleaning recipes, multiple FC precursors can be used concurrently and emissionsof CF4, C2F6, CHF3 or C3F8 as by-products may originate from each of the individual FC precursor
decomposition. In such cases, emissions of CF4, C2F6, CHF3 or C3F8 by-products should be reported asoriginating from the FC gas with the largest mass flow.

TIER 3 METHOD – PROCESS-SPECIFIC PARAMETERS
The Tier 3 method also uses Equations 6.7, 6.8, 6.9, 6.10 and 6.11. However, this method requires companyspecific or plant-specific values for all the parameters used in these equations for each individual process or foreach of small sets of processes (e.g., silicon nitride etching or plasma enhanced chemical vapour deposition(PECVD) tool chamber cleaning). Therefore, when using Equations 6.7, 6.8, 6.9, 6.10 and 6.11, inventory
compilers need to interpret ‘p’ in these equations as a specific ‘Process’ (e.g., silicon nitride etching or plasma
enhanced chemical vapour deposition (PECVD) tool chamber cleaning), not as ‘Process type’.
For purposes of transparency and comparability, the values used for these emission parameters should be well
documented (see Section 6.2.2).

CF 4 formation from C-containing films during semiconductor manufacturing
The Tier 2a, Tier 2b and Tier 3 methods account for CF4 emissions formed during removal via etching ofcarbon-containing low dielectric constant (k) materials or cleaning CVD reactors containing low k or carbide
films during semiconductor manufacture. CF4 may be formed even if the FC precursor does not contain carbon
or if the FC precursor is not a greenhouse gas.
For example, cleaning low k CVD reactors with NF3 will produce CF4 as a by-product. In these cases, Equation
6.7 should be used to report NF3 emissions and the result of Equation 6.8 should be used to reflect emissions of
CF4 from the process. In those situations where F2, COF2, or ClF3 is used in chamber cleaning, CF4 may also be
formed. In this case, CF4 emissions are estimated using Equation 6.8 and the results added to the total CF4emissions obtained from Equation 6.7. In both cases, BCF4,i,p should be measured as the fraction of the mass of
CF4 produced over the mass of clean or etch gas introduced in the reactor.
After estimating emissions of each FC gas and emissions of CF4, C2F6, CHF3 and C3F8 as by-products, inventory
compilers or companies should sum these emissions across all gases to arrive at an estimate of aggregate FC
emissions from a particular process.
BOX 6.1
EXAMPLE FOR SEMICONDUCTOR MANUFACTURE

For example, if a source used NF3 (for chamber cleaning and etch), CHF3 (etch) and CF4 (etch),
the total emissions, if low k films were used, are estimated using Equation 6.7 for NF3, CHF3 andCF4 and Equation 6.8 for the formation of CF4 formed when removing low k films with NF3. In
equation form, the total is:
Total FC emissions = ENF3 + ECHF3 + ECF4 + BPECF4,NF3

6.2.1.2

H EAT TRANSFER FLUIDS

There are two methods for estimating emissions from the use of heat transfer fluids. The choice of methods will
depend on the availability of activity data on the use of heat transfer fluids, and is outlined in the decision tree(see Figure 6.2, Decision Tree for Estimation of FC Emissions from Heat Transfer Fluids, and see Section 1.5 ofChapter 1, Choosing between the Mass-Balance and Emission-Factor Approach).

TIER 1 – HEAT TRANSFER FLUIDS
Tier 1 is appropriate when company-specific data are not available on heat transfer fluids. It is the less accurateof the two methods for estimating emissions from losses of heat transfer fluids. The method, unlike the Tier 2
method, gives an estimate of aggregate emissions - a weighted average emission across all liquid FCs that isexpressed as the mass of C6F1410. The calculation relies on a generic emission factor that expresses the average

10

In the absence of GWP estimates, the appropriate GWP for C6F14 has been used as a proxy (to derive the default emission
factor). (See the Inventory of U.S. Greenhouse Gas and Sinks: 1990-2003, the footnote to Table 4-58, page 166. (U.S. EPA,
2005))

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.13

Volume 3: Industrial Processes and Product Use

aggregate emissions per unit of silicon consumed during semiconductor manufacturing. The formula is shown inEquation 6.12.
EQUATION 6.12
TIER 1 METHOD FOR ESTIMATION OF TOTAL FC EMISSIONS FROM HEAT TRANSFER FLUIDS
FCliquid , total = EFl • Cu • Cd

Where:
FCliquid, total = total FC emissions as expressed as the mass of C6F14, Mt C6F14
EFl = emission factor (aggregate FC emissions per Gm2 of silicon consumed during the period expressedas the mass of C6F14 (See Table 6.2.)), Mt C6F14/Gm2
Cu = average capacity utilisation for all semiconductor manufacturing facilities in the country during theperiod, fraction
Cd = design capacity of semiconductor manufacturing facilities in the country, Gm2

TIER 2 METHOD – HEAT TRANSFER FLUIDS
There is one Tier 2 method for estimating actual emissions from the use of each FC fluid. This method is a massbalance approach that accounts for liquid FC usage over an annual period. It is appropriate when companyspecific data are available. Over the course of a year, liquid FCs are used to fill newly purchased equipment andto replace FC fluid loss from equipment operation through evaporation. The Tier 2 method neglects fluid losses
during filling new or existing equipment or when decommissioning old equipment (which is reasonable for thesecostly fluids).11 Inventory compilers should obtain from companies the chemical composition of the fluid(s) for
which emissions are estimated. The method is expressed in Equation 6.13.
EQUATION 6.13
TIER 2 METHOD FOR ESTIMATION OF FC EMISSIONS FROM HEAT TRANSFER FLUIDS
FCi = ρ i • I i , t −1 (l ) + Pi , t (l ) − N i , t (l ) + Ri ,t (l ) − I i , t (l ) − Di ,t (l )[]Where:
FCi = emissions of FCi, kg

ρ i = density of liquid FCi, kg/litre
Ii,t-1(l) = the inventory of liquid FCi at the end of the previous period, litres
Pi,t(l) = net purchases of liquid FCi during the period (net of purchases and any returns), litresNi,t(l) = total charge (or nameplate capacity) of new installed, litres
Ri,t(l) = total charge (or nameplate capacity) of retired or sold equipment, litresIi,t(l) = inventory of liquid FCi at end of the period, litres
Di,t(l) = amount of FCi recovered and sent offsite from retired equipment during the period, litres

11

Prices for heat transfer fluids vary from $55 – 130/litre. 3M, a manufacturer of a popular heat transfer fluid estimates that a
vintage 2 000 manufacturing plant may loose 1 900 litres/year via evaporation. Manufactures of testing equipment that use
heat transfer fluids report loss rates of approximately 30 litres/year/system for newer designs that reduce evaporative losses
and 50 litres/year/system for older designs.

6.14

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

Figure 6.2

Decision tree for estimation of FC emissions from HT fluid loss fromelectronics manufacturingStart

Are heat transfer fluid
loss data available from electronics
manufacturing companies?

Yes

Estimate emissions using
the Tier 2 method.
Box 2: Tier 2

No

Is Electronics
Industry a key category and is
this subcategory
significant? 1

Yes

Collect liquid FC use
data from companies.

No
Estimate emissions using theTier 1 method.
Box 1: Tier 1
Note:
1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited
resources), for discussion of key categories and use of decision trees

6.2.2
6.2.2.1

Choice of emission factors12
E TCHING AND CVD CLEANING FOR SEMICONDUCTORS ,LIQUID CRYSTAL DISPLAYS , AND PHOTOVOLTAICS

TIER 1The default emission factors for the Tier 1 method is presented in Table 6.2 below.
In using Tier 1, it is not good practice to modify, in any way, the set of the FCs or the values of the emission
factors assumed in Table 6.2. Inventory compilers should not combine emissions estimated using Tier 1 methodwith emissions estimated using the Tier 2 or 3 methods. For example, inventory compilers may not use the Tier 1
factor for CF4 to estimate the emissions of CF4 from semiconductors and combine it with the results of other FC
gases from a Tier 2 or Tier 3 method. It should be also noted that the Tier 1 FC emission factors presented inTable 6.2 should not be used for any purpose other than estimating annual FC-aggregate emissions fromsemiconductor, TFT-FPD or PV manufacturing for compilation of the national greenhouse gas inventory.

12

Sources and methods for developing emissions factors, if not explicitly provided in Chapter 6, can be found in Burton(2006).

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.15

Volume 3: Industrial Processes and Product Use

TABLE 6.2
TIER 1 GAS-SPECIFIC EMISSION FACTORS FOR FC EMISSIONS FROM ELECTRONICS MANUFACTURING
Emission Factor (EF) (Mass per Unit Area of Substrate Processed)

Electronics Industry Sector
Semiconductors, kg/m2
2

TFT-FPDs, g/m
a

CF4

C2F6

CHF3

C3F8

NF3

SF6

C6F14

0.9

1.

0.04

0.05

0.04

0.2

NA

0.5

NA

NA

NA

0.9

4.

NA

5

0.2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

0.3

2

PV-cells , g/mb

2Heat Transfer Fluids , kg/ma

EFs adapted from unpublished work of Fthenakis, Alsema and Agostinelli. (Fthenakis ,2005) Note that factor is applicable only tosilicon-specific technologies and is applied for abatement.

b

EF assumes HTFs have the same GWP and C6F14 represents a suitable proxy. The origin of this factor is described in Burton, 2004,
and is based in part on the work of Tuma and Tousignant (2001).

TIER 2
As discussed above, emissions factors based on simple electronics production variables are not adequate toaccount for all of the factors that influence emissions. Data for each of the following parameters are necessary to
prepare a reliable estimate:•

The gases used;•

The process type (CVD or etch) used;•

The brand of process tool used;•

Emission reduction technology.

Default values have been developed for the parameters used in Tier 2a and 2b methods (See Figure 6.1) on thebasis of direct measurements, literature, and expert judgement (see Tables 6.3, 6.4, and 6.5 Tier 2 Default
Emission Factors for FCs Emissions from Semiconductor12, TFT-FPD13, and PV12 Manufacturing respectively).
Given the difficulty in representing the diverse production conditions within the electronics industry, default
emission parameters are inherently uncertain. While accuracy can be improved with larger sets of measured data
and where factors are applied to similar processes using similar or identical chemical recipes, developing default
factors necessarily involves some form of averaging across all of the data.
Electronics industry specialists expect that rapid technical innovation by chemical and equipment suppliers andelectronics manufacturers will result in major emission reductions in the future (i.e., 2006 onwards). As a result,emission factors for these categories should evolve to reflect these changes. The semiconductor and TFT-FPD
industries have established mechanisms through the World Semiconductor Council and the World LCD Industry
Cooperation Committee, respectively, to evaluate global emission factors. The PV industry may be considering
establishing a mechanism for tracking its PFC emissions during PV manufacture. (Fthenakis, 2006)
FC-use during PV manufacture may or may not increase. Existing evidence suggests that, should FC-use in thisindustry grow, efforts will be made to control their emissions (Agostinelli et al., 2004; Rentsch et al., 2005).
Inventory compilers may wish to periodically consult with the industry to better understand global and national
circumstances.
Tables 6.3 and 6.4 include two entries for NF3: Remote-NF3 and NF3. The first refers to a cleaning method inwhich the film cleaning-agents formed from NF3 (F-atoms) are produced in a plasma upstream (remote) from thechamber being cleaned. The last, denoted as simply NF3, refers to an in-situ NF3 cleaning process that is
analogous to the process for other cleaning gases like C2F6 and C3F8.
The default value for the fraction of gas remaining in the shipping container (heel) is 0.10.

13The emissions factors (EFs) for TFT-FPD manufacturing are simple (unweighted) averages developed from gas- andprocess-specific values published by Nishida et al. (2005).

6.16

2006 IPCC Guidelines for National Greenhouse Gas Inventories

0.2
NA
NA

NA

NA

NA

BCF4

BC2F6

BC3F8

*

0.6
*

0.4
NA
0.1
NA
NA

0.9

NA

NA

NA

NA

NA

CVD 1-Ui

Etch BCF4

Etch BC2F6CVD BCF4

CVD BC2F6CVD BC3F8

NA

NA

NA

NA

0.08

*

NA

0.06*

NA

NA

0.08

0.1

CH2F2

NA

NA

0.1

NA

NA

0.4

NA

NA

NA

0.1

0.4

C3F8

NA

NA

0.1

0.2

0.2

0.1

0.2*

NA

0.1

0.1

0.1

c-C4F82006 IPCC Guidelines for National Greenhouse Gas Inventories

Estimate reflects presence of low-k, carbide and multi-gas etch processes that may contain a C-containing FC additive

†

NA

NA

The default emission factors for F2 and COF2 may be applied to cleaning low-k CVD reactors with ClF3.

NA

NA

NA

NA

0.1

0.2

0.2*
NA

0.2

0.3

0.1

0.2

NA

0.04

0.1

0.1

C5F8

*

NA

0.1

NA

0.2

0.3

0.1

C4F6

Estimate includes multi-gas etch processes

NA

NA

NA

NA

NA

NA

0.2

NA

NA

NA

0.2

SF6

*

NA

NA

0.1

†

†

0.02

NA

NA

0.2

0.2

NA

NA

NA

0.02

NA

NA

NA

NA

0.09

0.02

0.2

†

NF3

0.02

NF3
Remote

0.04

NA

0.1

NA

NA

0.1

NA

0.04

NA

0.1

0.1

C4F8O

Greenhouse Gases
without TAR GWP‡

Notes: NA denotes not applicable based on currently available information

NA

NA

NA

NA

0.07

NA

0.4*

0.7*

0.4*

NA

NA

0.07

0.4

CHF3

Etch 1-Ui

Tier 2b

0.6

C2F6

0.9

CF4

1-Ui

Tier 2aProcess Gas(i)

Greenhouse Gases with TAR GWP

TABLE 6.3
TIER 2 DEFAULT EMISSION FACTORS FOR FC EMISSIONS FROM SEMICONDUCTOR MANUFACTURING

NA

NA

0.02

†

NA

NA

NA

NA

NA

NA

0.02

†

NA

F2

NA

NA

0.02†

NA

NA

NA

NA

NA

NA

0.02†

NA

COF2

Non-GHGs
Producing FC
By-products‡

6.17

Chapter 6: Electronics Industry Emissions

NA
NA
NA
NA

NA

NA

NA

NA

BCF4

BCHF3

BC2F6

BC3F8

NA
NA
NA
NA
NA
NA
NA

NA

NA

NA

NA

NA

NA

NA

CVD 1-Ui

Etch BCF4

Etch BCHF3

Etch BC2F6CVD BCF4

CVD BC2F6CVD BC3F8

NA

NA

NA

0.05

NA

0.07

NA

0.2

NA

0.05

NA

0.07

0.2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

CH2F2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C3F8

NA

NA

NA

NA

0.02

0.009

NA

0.1

NA

NA

0.02

0.009

0.1

c-C4F82006 IPCC Guidelines for National Greenhouse Gas Inventories

Notes: NA denotes not applicable based on currently available information

NA

0.6

Etch 1-Ui

Tier 2b

NA

CHF3

NA

NA

NA

NA

NA

NA

0.03

NA

NA

NA

NA

NA

0.03

NF3
RemoteGreenhouse Gases with TAR GWP

NA

NA

NA

NA

NA

NA

0.3

NA

NA

NA

NA

NA

0.3

NF3

NA

NA

NA

NA

NA

NA

0.9

0.3

NA

NA

NA

NA

0.6

SF6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C5F8

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F8O

Greenhouse Gases
without TAR GWP

TABLE 6.4
TIER 2 DEFAULT EMISSION FACTORS FOR FC EMISSIONS FROM LCD MANUFACTURING

C2F6

0.6

CF4

1-Ui

Tier 2aProcess Gas(i)

Volume 3: Industrial Processes and Product Use

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

F2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

COF2

Non-GHGs
Producing FC
By-products

6.18

0.2
NA
NA

NA

NA

NA

BCF4

BC2F6

BC3F8

0.6
0.2
NA
0.2
NA
NA

NA

NA

NA

NA

NA

NA

CVD 1-Ui

Etch BCF4

Etch BC2F6CVD BCF4

CVD BC2F6CVD BC3F8

NA

NA

NA

NA

NA

NA

0.4

NA

NA

NA

0.4

CHF3

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

CH2F2

NA

NA

0.2

NA

NA

0.1

NA

NA

NA

0.2

0.4

C3F8

NA

NA

0.1

0.1

0.1

0.1

0.2

NA

0.1

0.1

0.2

c-C4F82006 IPCC Guidelines for National Greenhouse Gas Inventories

Notes: NA denotes not applicable based on currently available information

0.4

0.7

Etch 1-Ui

Tier 2b

0.6

C2F6

0.7

CF4

1-Ui

Tier 2aProcessGas (i)

NA
NA

NA

NA

NA

NA

0.3

NA

NA

NA

0.05

0.2

NF3

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NF3
RemoteGreenhouse Gases with TAR GWP

NA

NA

NA

NA

NA

0.4

0.4

NA

NA

NA

0.4

SF6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C5F8

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F8O

Greenhouse Gases without
TAR GWPTABLE 6.5
TIER 2 DEFAULT EMISSION FACTORS FOR FC EMISSIONS FROM PV MANUFACTURING

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

F2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

COF2

Non-GHGs
Producing FC
By-products

6.19

Chapter 6: Electronics Industry Emissions

Volume 3: Industrial Processes and Product Use

TABLE 6.6
TIER 2a & 2b DEFAULT EFFICIENCY PARAMETERS FOR ELECTRONICS INDUSTRY FC EMISSION REDUCTION
a,b,e

TECHNOLOGIES

CF4

C2F6

CHF3

C3F8

c-C4F8NF3f

SF6

Destruction

0.9

0.9

0.9

0.9

0.9

0.95

0.9

Capture/Recoveryd

0.75

0.9

0.9

NT

NT

NT

0.9

Emission Control TechnologycaValues are simple (unweighted) averages of destruction efficiencies for all abatement technologies. Emission factors do not apply toemission control technologies which cannot abate CF4 at destruction or removal efficiency (DRE) ≥ 85 percent when CF4 is present as
an input gas or by-product and all other FC gases at DRE ≥ 90 percent. If manufacturers use any other type of emission control
technology, its destruction efficiency is 0 percent when using the Tier 2 methods.
bTier 2 emission control technology factors are applicable only to electrically heated, fuelled-combustion, plasma, and catalytic devices
that•are specifically designed to abate FCs,•
are used within the manufacturer’s specified process window and in accordance with specified maintenance schedules and•have been measured and has been confirmed under actual process conditions, using a technically sound protocol, which
accounts for known measurement errors including, for example, CF4 by-product formation during C2F6 as well as the effectof dilution, the use of oxygen or both in combustion abatement systemscAverage values for fuelled combustion, plasma, and catalytic abatement technologies.
d
Average values for cryogenic and membrane capture and recovery technologies.
e
Vendor data verified by semiconductor manufacturers. Factors should only be used when an emission control technology is being
utilised and maintained in accordance with abatement manufacturer specifications.
f
Use of NF3 in the etch process is typically small compared to CVD. The aggregate emissions of NF3 from etch and CVD under Tier 2bwill usually not be greater than estimates made with Tier 2a or Tier 1 methods.
NT = not tested.

Process tool emission factors
The procedures for calculating process tool emission factors for Tier 2a and Tier 2b methods are identical.
Process tool emission factors are defined as the amount of greenhouse gas emitted divided by the amount ofgreenhouse gas used in the process. The emission factors correspond to the ‘(1 – Ui)’ term in the Tier 2 formulas.
For example, the emission factor of 0.9 for CF4 (see Table 6.3 above, Tier 2a value) means that 90 percent of theCF4 used in the process is emitted as CF4.
By-product emission factors were also calculated. The major by-product emission of significance is CF4. While
it is generally held that the only gases that emit significant amounts of CF4 as a by-product are C2F6 and C3F8,
the data provided by tool manufacturers and chemical suppliers showed that CF4 is also formed from mixtures ofgases (e.g., that contain CHF3 or CH2F2) and c-C4F8. As a result of this discussion, CF4 by-product emission
factors were calculated for CHF3, CH2F2, C2F6, C3F8, c-C4F8 and C4F8O. For example, a value of 0.1for C3F8
(taken from Table 6.3 above, Tier 2a value) means that 10 percent of the C3F8 used is converted into CF4.
However, C2F6 may also be emitted from the decomposition of molecules such as C4F6. As described previously,
CF4 may also be formed when etching or cleaning chambers where carbon-containing films are present.
In order to calculate the Tier 2b process tool emission factors, data were collected from process equipment andgas manufacturers. The data were collected according to process type (either Chemical Vapour Deposition (CVD)or etch) and also by type of gas (e.g. C2F6, CF4). The methods used to conduct the emissions testing were realtime Quadrupole Mass Spectrometry (QMS) and Fourier Transform Infrared Spectroscopy (FTIR), the best
known methods for measuring process tool emissions. Calibration standards (usually 1 percent mixtures with abalance of N2) were used to quantify the results. The measurement protocol and quality control requirements thatwere followed are outlined in the ‘Guidelines for Environmental Characterisation of Semiconductor Equipment.’(Meyers et al., 2001) 14 The emission factors for Tier 2b (see Tables 6.3 and 6.4 above) are the simple(unweighted) average of the data collected for each gas for etch and CVD, rounded to one significant figure.12, 16
In order to determine the Tier 2a process tool emission factors, knowledge of the amounts of gas used in typical
semiconductor manufacturing processes is required. The Tier 2a emission factors were obtained using weights
provided by industry experts for the proportion of each gas used in etching and cleaning processes. For example,
the Tier 2b emission factors for C2F6 (Table 6.3) are 0.5 (etch) and 0.6 (CVD). The distribution of C2F6 usage
between etching and CVD chamber cleaning processes during semiconductor manufacture is 20:80. Applying
these weights to each of the emission factors gives 0.6 for the Tier 2a factor for C2F6 to one significant figure.

14

These guidelines have also been adopted by flat panel display manufacturers for measuring FC-emissions during flat panel
device manufacture.

6.20

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

The corresponding distribution of SF6 usage in TFT-FPD manufacture is 50:50, which gives 0.6 forcorresponding Tier 2a emission factor (Table 6.4).15
For Tier 3 emission factors, semiconductor manufacturers use company or plant-specific values rather than using
default values as listed in Table 6.1 above. In order to assure the quality of emission factors, emission testingshould be conducted in accordance with accredited methods.16 If a third-party supplier conducts the emissions
testing, the semiconductor manufacturer should make sure that the third-party supplier is capable of meeting allof the requirements outlined in Revision 3.0 of the Equipment Environmental Characterisation Guidelines (SIA,
2000). Semiconductor manufacturers who use emission factors provided by the process tool equipment suppliershould make sure that the emission factors are applicable to their specific manufacturing process. Manufacturingmethods with process parameters (e.g., pressure, flow rate) that deviate from centreline conditions may havedifferent emission factors than those provided by the tool manufacturer.

Emission control technology factors for Tier 2 methods
Emissions control technologies are developing at a rapid pace along with electronics manufacturing technology.
Default control technology emission factors in Table 6.6 are based on tests of control devices that have been
optimised for specific processes and tools. Results are expected to vary across tools and gas flow rates. Emission
factors are not applicable to all tools or processes in semiconductor, liquid crystal display, or photovoltaic
manufacturing facilities. The Tier 2 default destruction efficiency parameters presented in Table 6.6 are only
applicable when the inventory compiler can demonstrate through communication with facility managers andsubsequent documentation that emissions control technologies are operated and maintained in accordance with
manufacturer specifications. If companies use any other type of abatement device, they should assume that its
destruction efficiency is 0 percent under the Tier 2 a and b methods.
Assumptions for the emissions control technology emission factors for the Tier 2 (a & b) methods include:(i) Specific emissions control technologies are not listed; emission factors for each chemical were
established based on results achieved during testing of emissions control technologies insemiconductor manufacturing applications;(ii) Emission factors should only be used when abatement is applied to emissions that fall within theoperating range specified by the abatement manufacturer to meet or exceed the factors listed in Table
6.6;(iii) Emission factors apply only to that portion of emissions that pass through a properly operating andmaintained control device; emission factors should not be applied when control device is bypassed,
not operating according to manufacturer specifications, or not maintained in accordance withspecifications.
(iv) Emission factors do not apply to emission control technologies which cannot abate CF4 at a destruction
removal efficiency (DRE) ≥ 85 percent when CF4 is present as an input gas or by-product and all otherFC gases at DRE ≥ 90 percent. If manufacturers use any other type of emission control technology, its
destruction efficiency is 0 percent when using the Tier 2 methods.
The default Tier 2 emission control factors in Table 6.6, Default Efficiency Parameters for Electronics Industry
FC Emission Reduction Technologies were calculated from data received from equipment suppliers, abatement
technology suppliers and electronic device manufacturers. It should be noted that only data from abatement
devices that were specifically designed to abate FCs were used in the calculation. Data were received fromcombustion abatement devices (all of which used some type of fuel), plasma abatement devices, electricallyheated abatement devices, and catalytic abatement devices.
The values presented in Table 6.6, Default Efficiency Parameters for Electronics Industry FC Emission
Reduction Technologies, are the results of all of the data received for optimized technologies and for each input
gas, rounded down to the next 5 percent (e.g., an average of 98 percent would be rounded down to 0.95). The
averages were rounded down to reflect that (i) emissions control devices vary in their efficacy depending upon
what gas they are optimised to destroy, and (ii) the efficacy of emission control devices depends on the type oftool they are installed on (150, 200 or 300mm wafers) and the amount of FC gas flown through that particulartool, and total exhaust flow through the emissions control device. An emission control device that can destroy 99
percent of a FC when it is optimised to destroy that FC on a certain tool may destroy less than 95 percent of that
FC when it is optimised to destroy something else or when it is used on a tool for which it was not designed, or if
the FC or total exhaust flow exceeds a certain limit. Electronics manufacturers and abatement tool manufacturers
15

The 50:50 SF6 usage rates represent an average for the leading TFT-FPD manufacturing regions of Japan, Republic ofKorea and Taiwan. That proportion was provided by Nishida (2006) and Kim (2006).

16

One example of an internationally accredited testing method is Meyers et al. (2001).

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.21

Volume 3: Industrial Processes and Product Useshould ensure that the abatement system installed is properly sized and maintained and that the emission control
device can meet or exceed the default emission factor highlighted in Table 6.6.

6.2.2.2

H EAT TRANSFER FLUIDS

The emission factor for the Tier 1 method is presented in Table 6.2. There is no emission factor for the Tier 2
method for estimating emissions from evaporation of heat transfer fluids.

6.2.3

Choice of activity data

Activity data for the electronics industry consists of data on gas sales and use or the annual amount of electronics
substrate processed (e.g., m2 of silicon processed for semiconductors). For the more data-intensive Tier 2
methods, gas purchase data at the company or plant-level are necessary. For the Tier 1 methods, inventory
compilers will need to determine the total surface area of electronic substrates processed for a given year. Siliconconsumption may be estimated using an appropriate edition of the World Fab Watch (WFW) database, publishedquarterly by Semiconductor Equipment & Materials International (SEMI)17 . The database contains a list ofplants (production as well as R&D, pilot plants, etc.) worldwide, with information about location, design
capacity, wafer size and much more. Similarly, SEMI’s ‘Flat Panel Display Fabs on Disk’ database provides anestimate of glass consumption for global TFT-FPD manufacturing.
The activity data in Table 6.7 reflect design capacity figures. Semiconductor and TFT-FPD manufacturing plants
are not operated at design capacities for sustained periods, such as a full year. Instead, the capacity fluctuates
depending on product demand. For semiconductor manufacturing, publicly available industry statistics show thatthe global annual average capacity utilisation during the period 1991 – 2000 varied between 76 and 91 percent,with an average value of 82 percent and most probable value of 80 percent. When country-specific capacity
utilisation data are not available, the suggested capacity utilisation for semiconductor manufacturing is 80
percent. This should be used consistently for a time series of estimates. For TFT-FPD manufacturing, publicly
available capacity utilisation data are not available. The TFT-FPD manufacturing industry, like thesemiconductor manufacturing industry, lowers product prices to maintain the highest practical plant capacity
utilisation. By analogy, therefore, it is suggested to use 80 percent to estimate substrate glass consumption using
the design capacities provided in Table 6.7 for country TFT-FPD manufacturers. For PV manufacturing,
published capacity utilisation data ranges between 77 – 92 percent, with the average for the years 2003 and 2004of 86 percent. Therefore, 86 percent is the recommended default figure for Cu (see Equation 6.1) to use.
When estimating emissions during PV manufacture, one should account for the fraction of the industry that
actually employs FCs (CPV in Equation 6.1). Because recent surveys indicate that between 40 – 50 percent of PV
manufacture actually uses FC, and the usage trend may be increasing, the recommended default value for CPV is
0.5.
Table 6.7 summarises the capacity for 2003, 2004 and 2005 for countries, which in total, account for more than90 percent of world capacity in 2003.

17

The term ‘fab’ is synonymous with clean room/manufacturing facility. Semiconductor and flat panel display manufacturing
plants are often called fabrication plants, from which the abbreviation ‘fab’ follows.

6.22

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

TABLE 6.7
COUNTRY TOTAL SILICON (Si) AND GLASS DESIGN CAPACITIES (Mm2) FOR 2003, 2004 AND 2005
Annual Si design capacities, Mm2

Annual Glass design capacities, Mm2

Country Totals

20031

20042

20052

20031

20042

20052

Australia

0.00080.00080.0008NA

NA

NA

Austria0.02010.02010.0201

NA

NA

NA

Belgium

0.00400.00400.0040NA

NA

NA

Canada0.00410.00410.0041

NA

NA

NA

China

0.1436

0.19820.32430.04320.04320.8154

Czech Republic

0.00570.00570.0057NA

NA

NA

France0.06530.06740.0674

NA

NA

NA

Germany

0.16220.16220.1622

NA

NA

NA

China, Hong Kong

0.00590.00590.0059NANA

NA

Hungary

0.00060.00060.0006

NA

NA

NA

India

0.01280.01280.0128NA

NA

NA

Ireland0.01750.04300.0430NA

NA

NA

Israel

0.03100.03100.0564

NA

NA

NA

Italy

0.0431

0.04310.0609

NA

NA

NA

Japan

0.9091

0.92350.96394.57465.32566.9201

Latvia0.00190.00190.0019NA

NA

NA

Malaysia

0.02840.02840.0284NA

NA

NA

Netherlands

0.03010.03010.03010.02090.02090.0209Republic of Belarus

0.00770.00770.0077NA

NA

NA

Russia0.02500.02500.0325NA

NA

NASouth Korea

0.35890.3742

0.39375.87899.467912.4857

Singapore

0.17300.17300.19850.28210.28210.2821

Slovakia

0.00430.00430.0043NA

NA

NASouth Africa

0.00210.00210.0021

NA

NA

NA

Sweden0.00190.00190.0019NA

NA

NA

Switzerland

0.00980.00980.0098NA

NA

NA

Thailand

0.00000.00000.0094NA

NA

NA

Turkey0.00000.00000.0000NA

NA

NA

United Kingdom

0.05970.0597

0.0936NA

NA

NA

United States of America

0.6732

0.69210.71900.00000.00000.0000Vietnam

0.00000.00000.0000NA

NA

NA

Global Total

3.32063.49723.884915.0572

23.9959

33.7459

1Country totals include fab in production

2

Country totals include fabs under construction and announced.

NA = not applicable.
Sources: Extractions from World Fab Watch Database, January 2004 Edition for Semiconductor Manufacturing and Flat Panel
Display Fabs on Disk Database (Strategic Marketing Associates, 2004a), October 2004 Edition for TFT-FPD Manufacturing(Strategic Marketing Associates, 2004b).

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.23

Volume 3: Industrial Processes and Product Use

TABLE 6.8
COUNTRY TOTAL PV PRODUCTION CAPACITYa FOR 2003, Mm2
Australia

0.135

Austria0.0307

Canada0.0154

Denmark

0.00254

France0.162

Germany

0.817

Italy

0.100

Japan

3.72

Norway0.0138

Portugal

0.115

S. Korea

0.462

Spain

0.715

Sweden0.377

Switzerland

0.00238

United Kingdom

0.0269

United States

1.02

a

Capacities for all PV manufacturing technologies, includes
those that may not use FCs during PV manufacture; Worldaverage capacity utilisation for 2003 = 86%.
Source: IEA, 2004. PV participating survey countries.

6.2.4

CompletenessComplete accounting of emissions from the semiconductor industry should be achievable in most countries
because there are a limited number of companies and plants. There are four issues related to completeness thatshould be addressed:•

Other by-products: A number of transformation by-products are generated as a result of FC use forchamber cleaning and etching. As highlighted above, formation of CF4 and C2F6 can result from thedecomposition of other FC gases. Also, CF4 formation has been observed in the cleaning of low k CVD
chambers. In this case, the Tier 3 method should be used to accurately estimate emissions.

•

New chemicals: Completeness will be an issue in the future as the industry evaluates and adopts new
chemical processes to improve its products. Industry-wide efforts to reduce FC emissions are also
accelerating the review of new chemicals. Consequently, good practice for this industry is to incorporate amechanism that accounts for greenhouse gases not listed in the IPCC Third Assessment Report (e.g., C4F6,
C5F8, Fluorinerts™, and Galdens®). These new FC materials have high GWPs or may produce high GWP byproduct emissions.

•

Other sources: A small amount of FCs may be released during gas handling (e.g. distribution) and bysources such as research and development (e.g. university) scale plants and tool suppliers. These emissions
are not believed to be significant (e.g., less than 1 percent of this industry’s total emissions).

•

Other products or processes: FC use has been identified in the electronics industry in emissive
applications including: micro-electro-mechanical systems (MEMS),18 hard disk drive manufacturing, device
testing (FC liquids), vapour phase reflow soldering,19 and precision cleaning.20

18

Emissions from micro-electro-mechanical systems (MEMS) manufacturing may be estimated using methods similar to
those used for the other electronic sub sectors. Company-specific emission and abatement factors are required. Very small
amounts of FCs are also used in and research and development laboratories/facilities.

6.24

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

6.2.5

Developing a consistent time series

Use of FCs by the semiconductor industry began in the late 1970s and accelerated significantly beginning in theearly 1990s. Determining a base year emissions level may present difficulties because few data are available foremissions occurring before 1995. If historical emissions estimates were based on simple assumptions (e.g., use
equals emissions), then these estimates could be improved by applying the methods described above. If historical
data are not available to permit use of a Tier 3 or 2 method, then the Tier 1 method using default emission
parameters can be used retrospectively. Both Tier 1 and Tier 2 could then be applied simultaneously for the years
in which more data become available to provide a comparison or benchmark. This should be done according to
the guidance provided in Volume 1, Chapter 5.
In order to ensure a consistent emissions record over time, an inventory compiler should recalculate FC
emissions for all years reported whenever emissions calculation procedures are changed (e.g., if an inventory
compiler changes from the use of default values to actual values determined at the plant level). If plant-specificdata are not available for all years in the time series, the inventory compiler will need to consider how current
plant data can be used to recalculate emissions for these years. It may be possible to apply current plant-specificemission parameters to sales data from previous years, provided that plant operations have not changed
substantially. Such a recalculation is required to ensure that any changes in emission trends are real and not anartefact of changes in procedure.

6.3

UNCERTAINTY ASSESSMENT

Use of the Tier 3 method will result in the least uncertain inventory. Given the limited number of plants and theclose monitoring of production processes at the plant level, collection of data for use in Tier 2b or Tier 3
methods should be technically feasible. Inventory compilers should seek the advice of the industry on
uncertainties, using the approaches to obtaining expert judgement outlined in Volume 1, Chapter 3.
Of all the methods, Tier 1 is the most uncertain. Using a single factor to account for the FC emissions from thediversity of semiconductor products is a glaring simplification. The factors presented in Table 6.2 are heavily
weighted toward the manufacture of advanced vintage-late-1990s memory and logic products, having 3 to 5
layers, respectively, manufactured on the silicon wafer. The factors for countries that are currently
manufacturing products at the leading-edge of technology (and are not using measures to reduce FC emissions)would be larger, while countries that manufacture products that use older technologies or manufacture simpler
devices would use the same or an even smaller factor.
The Tier 1 emissions factors for TFT-FPD manufacturing represents a weighted average of the estimatedaggregate PFC emissions per unit area of substrate glass consumed during TFT-FPD manufacture for the area
where data were available (Burton, 2004b). The estimated emissions reported for Japan used Tier 2b factors forsemiconductor manufacturing from Good Practice Guidance and Uncertainty Management in National
Greenhouse Gas Inventories (IPCC, 2000) in semiconductor manufacturing (Nishida et al., 2004). For emissions
from Taiwan’s TFT-FPD manufacturers, the method for estimating emissions was not reported (Leu et al., 2004).
However, subsequently Leu (2004) reported an aggregate emission factor having a similar magnitude to thatdeveloped by Burton (2004b). The uncertainty in the Tier 1 emissions factor for TFT-FPD manufacture is
probably large, but not known at this time.
When using Tier 3 method for semiconductor and TFT-FPD manufacturing, the resulting estimates of emissions
will be more accurate than the Tier 2a, 2b or Tier 1 methods, on the order of ± 30 percent (95 percent confidence
interval). Uncertainty in the efficacy of emission control technology appears to contribute most to thisuncertainty, especially the variability in the uptime of emission control devices and in flow rates to emission
control devices that may exceed device design limits.
Estimates of emissions from using heat transfer fluids using the Tier 2 method will be more accurate than Tier 1
method, of the order of ± 20 percent (95 percent confidence interval).

6.3.1

Emission factor uncertainties

The uncertainties in the emission factors suggested for the Tier 2b and 2a methods are shown in Table 6.9 forsemiconductor manufacturing and Table 6.10 for TFT-FPD manufacturing. The factors were developed
19

Emissions from vapour phase reflow soldering may be estimated to equal annual net FC purchases for maintaining vapour
phase reflow soldering equipment.

20

Emissions from precision cleaning are to be accounted for in Section 7.2 (Solvents) of this Volume.

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.25

Volume 3: Industrial Processes and Product Use

specifically for this guidance. For Tier 2b, relative errors for each entry (process and gas in the case of Tier 2b)
were estimated as the standard deviation of the factors provided by an expert group, normalised to the simple(unweighted) average, rounded to one significant figure.12 The estimate for each value was then doubled toestimate the 95 percent confidence interval. The same procedure was used to estimate the relative errors for
product-formation factors (B). The corresponding estimates for the Tier 2a method were derived for the Tier 2b
estimates, using the estimates of gas usage employed in development of the emission factors (see Section 6.2.2
Tier 2).
Tier 1 emission factors will have an uncertainty range that is skewed towards values close to zero extending up
to 200 percent (95 percent confidence interval for semiconductor and TFT-FPD manufacture). Uncertainty
estimates for PV manufacturing are not available.

6.3.2

Activity data uncertainties

Gas consumption constitutes the unit of activity to estimate emissions during semiconductor, TFT-FPD and PV
manufacture for the Tier 2a and 2b methods. Gas consumption can be either measured or estimated from data on
gas purchases, and requires knowledge of h, the unused gas returned to gas suppliers in the shipping containers.
The uncertainties (95 percent confidence interval) in gas consumption and h, whether measured or estimatedusing expert judgment are shown in Table 6.10, Relative Errors (95 percent confidence interval) for Activity
Data for Tier 2a and 2b Methods for Semiconductor and TFT-FPD Manufacture.
For Tier 1 method, the unit of activity is substrate consumption. Uncertainties in the Tier 1 activity data are
attributed principally to missing data entries in the WFW and FPD databases. An estimate of the reliability of
entries derived from the WFW in Table 6.7 is ± 10 percent (95 percent confidence interval), which reflects errors
due to missing and incorrect entries in the database. The 95 percent confidence interval in capacity utilisation
over the 1991-2000 period is ± 12 percentage points (i.e., from 70 percent utilisation to 94 percent utilisation).
The corresponding entries for TFT-FPD and PV manufacture are assumed to be similar to those forsemiconductor manufacturing.

6.26

2006 IPCC Guidelines for National Greenhouse Gas Inventories

90
NA
NA

NA

NA

NA

BCF4

BC2F6

BC3F8

30
200
NA
80
NA
NA

10

NA

NA

NA

NA

NA

CVD 1-Ui

Etch BCF4

Etch BC2F6CVD BCF4

CVD BC2F6CVD BC3F8

NA

NA

NA

NA

300

NA

100

NA

NA

300

100

CHF3

NA

NA

NA

NA

200

NA

700

NA

NA

200

400

CH2F2

NA

NA

60

NA

NA

0.4

NA

NA

NA

60

20

C3F8

NA

NA

NA

NA

NA

NA

300

NA

NA

NA

300

SF6

NA

NA

NA

200

200

NA

300

NA

200

200

300

2006 IPCC Guidelines for National Greenhouse Gas Inventories

NA
NA
80

†
†

NA

NA

60

200

200

40

NA

40
†

30

NA
†

40
†

200

NA

200

NA

80

100

40

†

C4F8O

†

80

C5F8

Greenhouse Gases
without TAR GWP
C4F6Values that exceed 100% imply a distribution that is skewed towards values close to zero extending up to the value given.

NA

NA

200

NA

NA

70

300

NA

NA

200

70

NF3

Estimate relies on an analogy to c-C4F8 as the data for C5F8 were insufficient to estimate a confidence interval.

NA

NA

200

NA

NA

400

NA

NA

NA

200

400

NF3
Remote

†

NA

NA

60

200

200

30

200

NA

200

100

80

c-C4F8*Notes: NA denotes not applicable based on currently available information

100

60

Etch 1-Ui

Tier 2b

30

C2F6

15

CF4

1-Ui

Tier 2aProcess Gas (i)Greenhouse Gases with TAR GWP

NA

NA

200

NA

NA

NA

NA

NA

NA

200

NA

F2

NA

NA

200

NA

NA

NA

NA

NA

NA

200

NA

COF2

Non-GHGs
Producing FC
By-products

TABLE 6.9
TIER 2 DEFAULT ESTIMATES OF RELATIVE ERRORS (%) FOR EMISSION FACTOR FOR FC EMISSIONS FROM SEMICONDUCTOR MANUFACTURING,
95 PERCENT CONFIDENCE INTERVALS*

6.27

Chapter 6: Electronics Industry Emissions

NA
NA
NA

NA

NA

NA

BCF4

BCHF3

BC2F6

NA
NA
NA
NA
NA
NA
NA

NA

NA

NA

NA

NA

NA

NA

CVD 1-Ui

Etch BCF4

Etch BCHF3

Etch BC2F6CVD BCF4

CVD BC2F6CVD BC3F8

NA

NA

NA

40

NA

30

NA

8

40

NA

30

8

CHF3

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

CH2F2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C3F8

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Notes: NA denotes not applicable based on currently available information

100

50

Etch 1-Ui

Tier 2b

NA

C2F6

50

CF4

1-Ui

Tier 2aProcess Gas (i)

NA

NA

NA

NA

20

40

NA

5

NA

20

40

5

c-C4F8

NA

NA

NA

NA

NA

NA

70

NA

NA

NA

NA

70

NF3
RemoteGreenhouse Gases with TAR GWP

NA

NA

NA

NA

NA

NA

20

60

NA

NA

NA

20

NF3

NA

NA

NA

NA

NA

NA

6

NA

NA

NA

NA

20

SF6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F6

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C5F8

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

C4F8O

Greenhouse Gases
without TAR GWP

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

F2

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

NA

COF2

Non-GHGs
Producing FC
By-products

TABLE 6.10
TIER 2 DEFAULT ESTIMATES OF RELATIVE ERRORS (%) FOR EMISSION FACTOR FOR FC EMISSIONS FROM LCD MANUFACTURING,
95 PERCENT CONFIDENCE INTERVALS

Volume 3: Industrial Processes and Product Use

6.28

Chapter 6: Electronics Industry Emissions

6.4

QUALITY ASSURANCE/QUALITY CONTROL(QA/QC), REPORTING AND
DOCUMENTATION

6.4.1

Quality Assurance/Quality Control (QA/QC)

It is good practice to conduct quality control checks as outlined in Volume 1, Chapter 6, and an expert review ofthe emissions estimates. Additional quality control checks as outlined in Volume 1 and quality assurance
procedures may also be applicable, particularly if higher tier methods are used to determine emissions from thissource category. Inventory compilers are encouraged to use higher tier QA/QC for key categories as identified inVolume 1, Chapter 4.
Additional general guidance for higher tier QA/QC procedures is also included in Volume 1, Chapter 6. Due tothe highly competitive nature of the semiconductor industry, provisions for handling confidential businessinformation should be incorporated into the verification process. Methods used should be documented, and a
periodic audit of the measurement and calculation of data should be considered. A QA audit of the processes andprocedures should also be considered.

6.4.2

Reporting and Documentation

Care should be taken not to include emissions of HFCs used as ODS substitutes with those used insemiconductor manufacturing. It is good practice to document and archive all information required to produce
the national emissions inventory estimates as outlined in Volume 1, Section 6.11. It is not practical to include all
documentation in the national inventory report. However, the inventory should include summaries of methods
used and references to source data such that the reported emissions estimates are transparent and steps in theircalculation may be retraced.
Explicit reporting on emissions in this industry would improve the transparency and comparability of emissions.
As a number of FCs gases are emitted by this industry, reporting by individual gas species rather than bychemical type would also improve the transparency and usefulness of this data. Efforts to increase transparency
should take into account the protection of confidential business information related to specific gas use. Countrylevel aggregation of gas-specific emissions data should protect this information in countries with three or moremanufacturers. Table 6.11, Information Necessary for Full Transparency of Estimates of Emissions from
Semiconductor Manufacturing, shows the supporting information necessary for full transparency in reported
emissions estimates.
Good practice for Tier 3 is to document the development of company-specific emission factors, and to explain
the deviation from the generic default values. Given confidentiality concerns, inventory compilers may wish toaggregate this information across manufacturers. In cases where manufacturers in a country have reported
different emission or conversion factors for a given FC and process or process type, inventory compilers may
provide the range of factors reported and used.

2006 IPCC Guidelines for National Greenhouse Gas Inventories

6.29

Volume 3: Industrial Processes and Product Use

TABLE 6.11
INFORMATION NECESSARY FOR FULL TRANSPARENCY OF ESTIMATES OF EMISSIONS FROMELECTRONICS MANUFACTURING

Data

Tier 1

Tier 2aTier 2b

Tier 3Emissions of each FC (rather than aggregated for all FCs)

X

X

X

Sales/purchases of each FC

X
X

X

X

X

2

Total surface area of electronics substrate processed (e.g., m silicon,
m2 glass)

X

Capacity utilisation for semiconductor, TFT-FPD and PV
manufacturing

X

Fraction of PV manufacturing capacity that uses FC gases

X

Mass of each FC used in each process or process type
Fraction of each FC used in processes with emission control
technologies

X

Use rate for each FC for each process or process type (This andfollowing information is necessary only if default value is not used)

X

Fraction of each FC transformed into CF4 for each process or process
type

X

Fraction of gas remaining in shipping container

X

Fraction of each FC destroyed by emission control technology

X

Fraction of CF4 by-product destroyed by emission control technology

X

6.30

2006 IPCC Guidelines for National Greenhouse Gas Inventories

Chapter 6: Electronics Industry Emissions

References
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Processes for Cystalline Silicon Solar Cells: Sustainability for Mass Production”, presented at the 19th
European Photovoltaic Solar Energy Conference, Paris, 2004.
Alsema, E. A., Bauman, A. E., Hill, R. and Patterson, M. H. (1997) “Health, Safety and Environmental Issues inThin Film Manufacturing”, 14th European PV Solar Energy Conference, Barcelona, Spain. 1997.
Burton, C. S. (2004a). “Uses and Air Emissions of Liquid PFC Heat Transfer Fluids from the Electronics Sector:
Initial Findings”, report prepared for U. S. EPA’s Climate Change Division, October 2004.
Burton, C. S. (2004b). “PFC Uses, Emissions, and Trends in FPD Manufacture: An Update”, draft report
prepared for U. S. EPA’s Climate Change Division, June 2004.
Burton, C. S. (2006). “Sources and Methods Used to Develop PFC Emission Factors from the Electronics
Sector”, report prepared for U. S. EPA’s Climate Change Division, February 2006.
Cowles, D. (1999) “Oxide Etch Tool Emissions Comparison for C5F8 and C4F8 Process Recipes”, presented at
A Partnership for PFC Emissions Reductions, SEMICON Southwest 99, Austin, TX. October 1999.
Fthenakis, V. (2005) Personal communication to S. Bartos on 5 February 2005 of data tables quantifying
historical and current CF4 and C2F6 usage in PV manufacture for U. S. and Europe.
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monitoring FC emissions from European PV industry. Feb. 6, 2006.
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T1-13:2004, September 2004.
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IPCC/OECD/IEA/IGES, Hayama, Japan.
ITRS(2004),“International
Technology
http://public.itrs.net/report.htm

Roadmapfor

Semiconductors”

availableatKim, D-H., (2006) 9 January 2006 Personal communication to Hideki Nishida identifying the historical average(50:50) proportion of SF6 usage for etching and CVD chamber-cleaning in Japanese, Korean and Taiwan
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Silicate Glass Etching and Edge Isolation for Crystalline Silicon Solar Cells”, Presented at the 20th
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Association (SIA), San Jose, California, USA, February 2000
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Since 1994, January 2004 Edition.
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Since 1994, October 2004 Edition.
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