TECHNICAL SUPPORT DOCUMENT (UPDATED) 

FOR PROCESS EMISSIONS FROM ELECTRONICS 

MANUFACTURE (e.g., SEMICONDUCTORS, LIQUID 

CRYSTAL DISPLAYS, PHOTOVOLTAICS, AND 

MICRO-ELECTRO-MECHANICAL SYSTEMS): 

 PROPOSED RULE FOR MANDATORY REPORTING 

OF GREENHOUSE GASES 

 Office of Air and Radiation 

U.S. Environmental Protection Agency 

MARCH 22, 2010
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 1

TABLE OF CONTENTS 

1 SOURCE DESCRIPTION 3

1.1 TOTAL U.S. EMISSIONS 4

1.2 EMISSIONS TO BE REPORTED 4

2 OPTIONS AND SELECTION FOR REPORTING THRESHOLD 5

2.1 OPTIONS CONSIDERED FOR REPORTING THRESHOLDS 5

2.2 EMISSIONS-BASED THRESHOLD CALCULATIONS 6

2.3 REPORTER THRESHOLD APPLICABILITY DETERMINATIONS 6

3 OPTIONS FOR MONITORING METHODS 8

3.1 OPTIONS FOR ESTIMATING EMISSIONS FROM ETCHING AND CLEANING 8

3.1.1 IPCC TIER 1 APPROACH 8

3.1.2 IPCC TIER 2A APPROACH 9

3.1.3 IPCC TIER 2B APPROACH 9

3.1.4 MODIFIED IPCC TIER 2B APPROACH 10

3.1.5 THE REFINED METHOD 10

3.1.6 IPCC TIER 3 APPROACH 11

3.1.7 HYBRID APPROACH A 11

3.1.8 HYBRID APPROACH B 11

3.1.9 CONTINUOUS EMISSIONS MONITORING SYSTEMS (CEMS) 11

3.2 OPTIONS FOR ESTIMATING FACILITY GAS CONSUMPTION 11

3.2.1 IPCC DEFAULT HEEL FACTOR 12

3.2.2 GAS-AND FACILITY-SPECIFIC HEEL FACTORS 12

3.3 OPTION FOR APPORTIONING GAS CONSUMPTION 13

3.3.1 ENGINEERING MODEL BASED 13

3.4 OPTIONS FOR ESTIMATING NITROUS OXIDE (N2O) EMISSIONS 13

3.5 OPTIONS FOR ESTIMATING HEAT TRANSFER FLUIDS (HTFS) EMISSIONS 14

3.5.1 IPCC TIER 1 APPROACH 14

3.5.2 IPCC TIER 2 APPROACH 14

3.6 OPTIONS FOR REPORTING CONTROLLED EMISSIONS FROM ABATEMENT SYSTEMS 15

3.6.1 PROPER INSTALLATION, OPERATION, AND MAINTENANCE 15

3.6.2 MONITORING OF A SYSTEM’S UPTIME 15

3.6.3 EPA DEFAULT DRE VALUE 16

3.6.4 PROPER MEASUREMENT OF ABATEMENT SYSTEM DRE 17

4 PROCEDURES FOR ESTIMATING MISSING DATA 18

5 QA/QC REQUIREMENTS 18

6 REPORTING AND RECORD KEEPING PROCEDURES 18
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 2

7 REFERENCES 21

APPENDIX A – DEFAULT EMISSION FACTORS FOR THRESHOLD APPLICABILITY 

DETERMINATION AND IPCC TIER 2B EMISSION FACTORS FOR LCD MANUFACTURING AND 

PV MANUFACTURING 23

APPENDIX B – SUPPORTING ANALYSIS FOR THE USE OF REFINED PROCESS CATEGORIES 

FOR ESTIMATING EMISSIONS FROM SEMICONDUCTOR MANUFACTURING 25

B.1 ANALYSIS APPROACH 25

B.2 SOURCES OF INFORMATION 25

B.3 METHOD FOR ESTIMATING UNCERTAINTY 28

B.4 RESULTS 28

APPENDIX C- EPA PUBLISHED EMISSIONS FACTOR RANGES FOR THE REFINED METHOD 30

TABLE OF TABLES 

TABLE 1. SELECTED FLUORINATED GREENHOUSE GASES USED BY THE ELECTRONICS INDUSTRY .......... 3

TABLE 2. EMISSIONS-BASED THRESHOLD FOR ELECTRONICS MANUFACTURE............................................... 5

TABLE 3. RULE APPLICABILITY UNDER THE PROPOSED EMISSIONS-BASED THRESHOLDS.......................... 6

TABLE 4. ILLUSTRATIVE CALCULATION FOR NF3 EXAMPLE AT ONE FACILITY.............................................. 13

TABLE 5. DATA SET TO DEVELOP EPA DEFAULT DRE VALUE.............................................................................. 16

TABLE 6. SUMMARY STATISTICS AND DEFAULT DRE (LOWER ONE-SIDED TOLERANCE INTERVAL)....... 17
Subpart I (Electronics Manufacture) TSD 

March 2010 3

1 Source Description 

The electronics industry uses multiple long-lived fluorinated greenhouse gases (fluorinated GHGs), as well as nitrous oxide 

(N2O) during manufacturing of electronic devices, including, but not limited to, semiconductors, liquid crystal displays 

(LCDs), micro-electro-mechanical systems (MEMS), and photovoltaic cells (PV).1 Fluorinated GHGs are used for plasma 

etching of silicon materials, cleaning deposition tool chambers, and wafer cleaning. N2O is also used in depositing certain 

films and other manufacturing processes. Besides dielectric film etching and chamber cleaning, much smaller quantities of 

fluorinated GHGs are used to etch polysilicon films and refractory metal films like tungsten. Additionally, some 

electronics manufacturing may employ fluorinated GHGs liquids as heat transfer fluids (HTFs). The most common 

fluorinated GHGs in use are trifluoromethane (HFC-23 or CHF3), perfluoromethane (CF4), perfluoroethane (C2F6), nitrogen 

trifluoride (NF3), and sulfur hexafluoride (SF6), although other compounds such as perfluoropropane (C3F8) and 

perfluorocyclobutane (c-C4F8) are also used (EPA, 2008a). Table 1 presents examples of fluorinated GHGs known to be 

used during manufacture of different types of electronics. 

Table 1. Selected Fluorinated Greenhouse Gases Used by the Electronics Industry 

Product Type Fluorinated GHGs Used During Manufacture 

Semiconductor CF4, C2F6, C3F8, c-C4F8, c-C4F8O, C4F6, C5F8, CHF3, CH2F2, 

NF3, SF6, and HTFs.a

MEMSb CF4, c-C4F8, and SF6

LCD CF4, CHF3, c-C4F8, NF3, and SF6

PV CF4, C2F6, CHF3, C3F8, NF3, SF6 a For commonly used heat transfer fluids please refer to the U.S. EPA report entitled “Uses and Emissions of Liquid PFC Heat Transfer Fluids” 

available at: http://www.epa.gov/semiconductor-pfc/documents/pfc_heat_tranfer_fluid_emission.pdf. b IPCC guidelines do not specify the F-GHGs used by the MEMS industry. Literature reviews revealed that among others, CF4, SF6, and the Bosch 

process (e.g., Bosch process consists of alternating steps of SF6 and C4F8) are used to manufacture MEMS. 

Source: IPCC, 2006; Lyshevshi, S., 2001; Gaitan, M. & Takacs, M., 2008. 

• The etching process uses plasma-generated fluorine atoms, which chemically react with exposed dielectric film, to 

selectively remove the desired portions of the film. The material removed, as well as undissociated fluorinated 

gases flow into waste streams and, unless emission abatement systems are employed, into the atmosphere. 

• Deposition is a fundamental step in the fabrication of a variety of electronic devices. During deposition, layers of 

dielectric, barrier, or electrically conductive films are deposited or grown on a wafer or other substrate. Chemical 

vapor deposition (CVD) enables the deposition of dielectric or metal films. During the CVD process, gases that 

contain atoms of the material to be deposited react on the wafer surface to form a thin film of solid material. Films 

deposited by CVD may be silicon oxide, single-layer crystal epitaxial silicon, amorphous silicon, silicon nitride, 

dielectric anti-reflective coatings, low-k dielectric, aluminum, titanium, titanium nitride, polysilicon, tungsten, 

refractory metals or silicides. N2O may be the oxidizer of choice during deposition of silicon oxide films. 

• Chambers used for depositing dielectric films are cleaned periodically using fluorinated and other gases, such as 

N2O. During the cleaning cycle the gas is converted to fluorine atoms in plasma, which etches away residual 

material from chamber walls, electrodes, and chamber hardware. Undissociated fluorinated gases and other 

products pass from the chamber to waste streams and, unless abatement systems are employed, into the 

atmosphere. 

• During wafer processing, any residual photoresist material can be removed through an ashing process, which 

consists of placing partially processed wafers in an oxygen plasma to which CF4 may be added. The edges of 

wafers (the bevel) may also require cleaning to remove yield-reducing residual material. Bevel cleaning may also 

use a plasma process with fluorinated GHG chemistry. In both of these wafer cleaning processes, unused 

fluorinated GHGs are emitted unless abated. 

 

1 The electronics industry as presented here does not include facilities that manufacture light emitting diodes (LEDs) or disk readers. 

EPA understands that facilities that manufacture LEDs and disk readers use fluorinated GHGs in similar manufacturing processes as 

semiconductors. EPA is seeking more information on these source categories and if their emissions meet or exceed the threshold, EPA 

intends to include them as part of the electronics source category in a final rule. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 4

• In addition to emissions of unreacted gases, some fluorinated GHGs can also be transformed in the plasma 

processes into different fluorinated GHGs which are then exhausted, unless abated, into the atmosphere. For 

example, when C2F6 is used in cleaning or etching, CF4 is generated and emitted as a process by-product. 

• Additionally, fluorinated GHG liquids are used as heat transfer fluids (HTFs) at several semiconductor facilities to 

cool process equipment, control temperature during device testing, and solder semiconductor devices to circuit 

boards, and their high vapor pressures can lead to evaporative losses during use (EPA, 2008b; IPCC, 2006). Other 

electronics manufacturing facilities may also employ HTFs for similar uses. 

1.1 Total U.S. Emissions 

Emissions of fluorinated GHGs from 216 electronics facilities were estimated to be 6.1 Tg CO2 Eq in 2006. Below is a 

breakdown of emissions by electronics product type. 

• Semiconductor: Emissions of fluorinated GHGs, including emissions from the use of HTFs, from 175 facilities 

were estimated to be 5.9 Tg CO2 Eq. in 2006 (Burton, C.S., & Beizaie, R., 2001; ITRS, 2008; SEMI, 2008; VLSI 

Research, Inc., 2008).2 Of the total semiconductor emissions 5.4 Tg CO2 Eq. are from etching/chamber cleaning 

at full-scale facilities and 0.5 Tg CO2 Eq. are from HTF usage from all facilities.3 Only etching/cleaning 

emissions from full-scale facilities are accounted for in the U.S. Inventory of GHG Emissions and Sinks (EPA, 

2008a). Partners of the PFC Reduction/Climate Partnership for Semiconductors comprise approximately 80% of 

U.S. semiconductor production capacity. These Partners have committed to reduce their emissions (exclusive of 

HTF emissions) to 10% below their 1995 levels by 2010, and their emissions have been on a general decline 

toward attainment of this goal since 1999. 

• MEMS: Emissions of fluorinated GHGs from 12 facilities were estimated to be 0.1 Tg CO2 Eq. in 2006 (SEMI, 

2008.4 

• LCD: Emissions of fluorinated GHGs from 9 facilities were estimated to be 0.02 Tg CO2 Eq. in 2006 

(DisplaySearch, 2007).5

• PV: Emissions of fluorinated GHGs from 20 PV facilities were estimated to be 0.07 Tg CO2 Eq. in 2006 (Burton, 

2006; Roedern, B.V. & Ullal, H.S., 2008; Earth Policy Institute, 2007).6

1.2 Emissions to be Reported 

On-site combustion emissions from electronics manufacturing facilities are not addressed within this document; see the 

background Technical Support Document for Stationary Combustion (EPA-HQ-OAR-2008-0508-046). EPA is requiring 

the electronics industry report direct emissions from the following processes and activities: 

• Fluorinated GHGs from plasma etching. 

• Fluorinated GHGs from chamber cleaning. 

• Fluorinated GHGs from wafer cleaning. 

• N2O from chemical vapor deposition or other manufacturing processes. 

 

2 Total semiconductor facilities include both full-scale, pilot, and R&D facilities. 

3 All full scale facilities are assumed to have the same utilization. 

4 The estimated total number of MEMS facilities in the U.S. is an underestimate. The estimate was based on the World Fab Watch 

database, which provides an incomplete listing of total U.S. MEMS facilities (SEMI, 2007). 

5 Estimated total LCD facilities include LCOS, a-Si TFT-LCDs, OLEDs (assuming active matrix), HTPS, TFT, Single Crystal AMLCD, 

LTPS facilities. Where, TFT = Thin Film Transistor; LCOS = Liquid Crystal on Silicon; a-Si = amorphous silicon; OLED = Organic

Light Emitting Diode; HTPS = High Temperature Polysilicon; and AMLCD = Active Matrix Liquid Crystal Display. 

6 Estimated total PV facilities includes only silicon based PV facilities (both crystalline and amorphous silicon based PV facilities are 

included). 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 5

• Fluorinated GHGs from use of HTFs. 

2 Options for and Selection of Reporting Threshold 

2.1 Options Considered for Reporting Thresholds 

EPA evaluated a range of emissions threshold options for electronics manufacturing facilities. This range included 

emissions thresholds of 1,000, 10,000, 25,000, and 100,000 metric tons CO2e per year for each type of electronics device 

manufacturing facility. Table 2 shows these emissions-based threshold options and the number of electronics 

manufacturing facilities that would be captured by the respective emissions thresholds. The EPA selected 25,000 metric 

tons CO2e per year threshold covers 44 percent of facilities and 94 percent of national emissions, thereby maximizing 

emissions reporting while excluding small facilities that do not contribute significantly to the overall GHG emissions. 

Table 2. Emissions-Based Threshold for Electronics Manufacture (1,000, 10,000, 25,000 and 100,000 Mt CO2e) 

Emissions Covered Facilities Covered 

Emission Threshold 

Level metric tons 

CO2e/yr 

Total 

National 

Emissions 

(MtCO2e) 

Total National 

Facilities 

Metric tons 

CO2e/yr Percent Facilities Percent 

1,000 5,984,463 216 5,962,091 99.6% 165 76% 

10,000 5,984,463 216 5,813,200 97% 114 53% 

25,000 5,984,463 216 5,622,570 94% 94 44% 

100,000 5,984,463 216 4,737,622 79% 55 26% 

Table 3 shows the estimated emissions and number of electronics facilities that would report for each source; 

semiconductors, MEMS, LCD, and PV, under the proposed 25,000 metric tons CO2e emissions-based threshold. The 

proposed emissions-based threshold is estimated to include approximately 50 percent of semiconductor facilities and 

approximately 17 percent and 5 percent of the facilities manufacturing MEMS and PV, respectively. At the same time, the 

threshold is expected to cover 96 percent of fluorinated GHG emissions from semiconductor facilities, 66 percent of 

fluorinated GHG emissions from facilities manufacturing MEMS, and 47 percent of fluorinated GHG emissions from 

facilities manufacturing PV. 

Based on the presented analysis, facilities that manufacture LCDs are not expected to meet the 25,000 Mt CO2e threshold; 

however, the information available and used in the analysis at this time is limited and incomplete. Facilities that 

manufacture LCDs are nonetheless covered by the rule because they use similar fluorinated GHG and N2O manufacturing 

processes as semiconductor manufacturing, and because emissions are expected to increase due to high growth in the LCD 

manufacture sector. 
Subpart I (Electronics Manufacture) TSD 

March 2010 6

Table 3. Rule Applicability under the Proposed Emissions-Based Thresholds 

Emissions Covered Facilities Covered 

Emissions 

Source Threshold 

Total National 

Facilities 

Total Emissions 

of Source (metric 

tons CO2e) 

metric tons 

CO2e/yr Percent Facilities Percent 

Semiconductors 

25,000 Mt 

CO2 Eq. 175 5,741,676 5,492,066 96% 91 52% 

MEMS 

25,000 Mt 

CO2 Eq. 12 146,115 96,164 66% 2 17% 

LCD 

25,000 Mt 

CO2 Eq. 9 23,632 0 0% 0 0% 

PV 

25,000 Mt 

CO2 Eq. 20 73,039 34,340 47% 1 5% 

2.2 Emissions-Based Threshold Calculations 

Emissions based threshold estimations for each sector were derived in the following ways: 

• Semiconductors emissions based threshold estimations were derived using outputs from the EPA PFC Emissions 

Vintaging Model (PEVM), as well as EPA PFC Reduction/Climate Partnership for Semiconductors partner and 

non-partner shares of U.S. emissions. Additionally, the semiconductor emissions threshold estimations 

determined accounted for heat transfer fluid emissions by assuming that these emissions were equivalent to 11% 

of total clean and etch emissions at a facility. 

• MEMS emissions based threshold estimations were derived using an emission factor estimated by EPA. EPA 

estimated an emission factor because no IPCC Tier 1 default emission factor exists. Assuming that MEMS are 

manufactured using the Bosch etching process, the utilization of SF6 in the production of MEMS was assumed to 

be the same as the utilization of SF6 in the etching of semiconductors due to the similarity between both the 

manufacturing processes.7 However, because SF6 is used in only about 20% of semiconductor processes, the 

majority of which are etching processes, and it is assumed in this analysis that SF6 is used in all MEMS processes, 

the 2006 IPCC Tier 1 SF6 semiconductor emission factor (per area of substrate) was multiplied by five to estimate 

the MEMS emission factor per area of substrate. Additionally, the MEMS emission factor was scaled up by an 

additional factor 1.2 to account for increased growth in the MEMS sector. 

• LCD emissions based threshold estimations were derived using 2006 IPCC Tier 1 emission factors. 

• PV emissions based threshold estimations were derived using 2006 IPCC Tier 1 emission factors. 

Emissions reductions from the use of abatement systems were not accounted for in the any of the threshold analyses. 

2.3 Reporter Threshold Applicability Determinations 

Presented below are the methods reporters would be required to use to determine whether their electronics manufacturing 

facility(ies) meets or exceeds the proposed threshold of 25,000 metric tons CO2e.8 

• Semiconductor and LCD: To determine whether a semiconductor or LCD facility meets the threshold, the facility 

would use the IPCC Tier 1 approach and IPCC Tier 1 emission factors. To account for heat transfer fluid use at 

 

7 Although the Bosch etching process uses both SF6 and C4F8, C4F8 was not included because it has a high utilization rate (i.e., a high 

fraction of C4F8 is dissociated during the etching or cleaning process). 

8 Note that manufacturing capacity in Equations 1-3 means the facility’s full planned design capacity. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 7

semiconductor facilities, a facility would add an additional 10% of their clean and etch emissions to their total 

facility emissions.9 

• MEMS: To determine whether MEMS facility meets the threshold, the facility would use the IPCC Tier 1 

approach and the EPA estimated emission factor for MEMS. 

• PV: To determine whether a PV facility meets the threshold, the facility multiply annual fluorinated GHG 

purchases or consumption by the gas-appropriate 100-year GWPs (as defined in Table A-1 to subpart A of part 

98). This method for PV facilities is proposed because it is expected to provide a more representative estimate of 

emissions than the IPCC Tier 1 approach and emission factors. IPCC Tier 1 factors for PV are highly uncertain 

because they were developed based on analogy to the IPCC Tier 1 factors for LCD due to limited PV data 

availability. 

Calculations to determine applicability are presented below. Note, that the equations below are to be used only for 

determining whether an electronics manufacturing facility falls above or below the threshold of 25,000 metric tons 

CO2e. 

• Facilities that manufacture semiconductors: 

ET 1.1* S *EFi* 0.001

i

= ∑ (Eq. 1) 

Where: 

ET = Total annual process emissions (metric tons). 

1.1 = Factor accounting for heat transfer fluid emissions, estimated as 10% of total clean and 

etch emissions at a facility. 

S = 100% of manufacturing capacity of a facility (m2

). 

EFi = Emission factor for input gas i (see Appendix A). 

0.001 = Conversion factor from kg to metric tons. 

 

• Facilities that manufacture LCDs: 

ET S *EFi* 0.000001

i

= ∑ (Eq. 2) 

Where: 

ET = Total annual process emissions (metric tons). 

S = 100% of manufacturing capacity of a facility (m2). 

EFi = Emission factor for input gas i (see Appendix A). 

0.000001 = Conversion factor from g to metric tons. 

• Facilities that manufacture MEMS: 

ET S *EFi* 0.001

i

= ∑ (Eq. 3) 

 

9 For simplicity semiconductor facilities would estimate HTF emissions as 10% of total clean and etch emissions, as 

opposed to 11% which was used in our threshold analyses as presented above. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 8

Where: 

ET = Total annual process emissions for (metric tons). 

S = 100% of manufacturing capacity of a facility (m2

). 

EFi = Emission factor for input gas i (see Appendix A). 

0.001 = Conversion factor from kg to metric tons. 

• Facilities that manufacture PVs: 

ET i*

i

*0.001

i

= ∑ C GWP (Eq. 4) 

Where: 

ET = Total annual process emissions (metric tons). 

Ci = Annual fluorinated GHG (gas i) purchases or consumption (kg). 

GWPi = Gas-appropriate GWP (see Table A-1 to subpart A, Global Warming 

 Potentials) 

0.001 = Conversion factor from kg to metric tons. 

None of the methods that EPA is proposing account for controlled emissions by abatement systems. EPA is not permitting 

accounting for emissions reductions from abatement systems because while electronics manufacturers may employ 

emissions abatement systems (e.g., thermal oxidizers) to lower their emissions and use the manufacturer published 

destruction or removal efficiency (DRE) for the system, abatement systems may fail to achieve their rated DREs for two 

reasons. First, the equipment may not be properly operated and maintained. Second, the DRE itself may have been 

incorrectly measured due to a failure to account for the effects of dilution (e.g., CF4 can be off by as much as a factor of 20 

to 50 and C2F6 can be off by a factor of up to 10 because of failure to properly account for dilution [Burton, 2007].) In 

either event, the actual emissions from facilities employing abatement systems may exceed estimates based on the rated 

DREs of the systems and may therefore exceed the MtCO2e threshold without the knowledge of the facility operators. 

Hence, accounting for reductions in emissions from the use of abatement systems when determining if a facility exceeds the 

proposed 25,000 metric ton CO2e threshold limit is not permitted because the DRE used in such a calculation can not be 

verified. 

3 Options for Monitoring Methods 

EPA evaluated a range of options for estimating process emissions from semiconductor facilities and other electronics 

manufacturing facilities (MEMS, LCD, and PV facilities). Each one of these options is briefly described below. 

3.1 Options for Estimating Emissions from Etching and Cleaning 

To estimate and report fluorinated GHGs from etching and cleaning, EPA evaluated the 2006 IPCC Tier 1, Tier 2a, Tier 2b, 

and Tier 3 methods, as well as hybrids and refinements of and modifications to those methods.10 Lastly, EPA evaluated the 

use of continuous monitoring emissions systems (CEMS). 

3.1.1 IPCC Tier 1 Approach 

In the Tier 1 approach, the surface area of substrate (e.g., silicon, LCD or PV-cell) produced during manufacture is 

multiplied by a default gas-specific emission factor. The advantages of the Tier 1 approach lie in its simplicity. However, 

this method does not account for the differences among process types (i.e., etching versus cleaning), individual processes, 

 

10 It is important to note that the IPCC methods were developed to estimate national averages of emissions for specific sources (e.g. 

national emissions from semiconductor manufacturing) and not for facility specific emissions. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 9

or tools, leading to uncertainties in the default emission factors of up to 200% at the 95% confidence interval (IPCC, 

2006).11 Moreover, facilities routinely monitor gas consumption in the ordinary course of business, making it technically 

feasible to employ a method with the complexity of at least the 2006 IPCC Tier 2a approach without additional data 

collection efforts. 

3.1.2 IPCC Tier 2a Approach 

In the Tier 2a approach, chemical-specific gas consumption is multiplied by default factors for utilization, by-product 

formation, and destruction. The Tier 2a approach is relatively simple, given that gas consumption data is collected in the 

ordinary course of business. However, due to variation in gas utilization between etching and cleaning processes, the 

emissions estimated using the Tier 2a approach have greater uncertainty than emissions estimated using the Tier 2b 

approach. 

3.1.3 IPCC Tier 2b Approach 

In the Tier 2b approach, chemical-specific gas consumption by process type (etch or chamber clean) is multiplied by default 

factors for utilization, by-product formation, and destruction. This approach requires facilities to determine gas 

consumption by process type (etch and clean). Equation 5 below is used to estimate fluorinated GHG emissions for process 

type (j) for gas (i), and Equation 6 below is used to estimate byproduct gas (p) that results from gas (i) utilization during 

process type (j).12

Eij = Cij*(1− Uij) *(1− aij*dij)*0.001 (Eq. 5)

Where: 

Eij = Annual emissions of input gas (i) from process type (j) (metric tons). 

Cij = Amount of input gas (i) consumed in process type (j) (kg). 

Uij = Process utilization for input gas (i) during process type (j). 

aij = Fraction of input gas (i) used in process type (j) with abatement systems. 

dij = Fraction of input gas (i) destroyed in abatement systems connected to process type (j). 

0.001 = Conversion factor from kg to metric tons. 

BEij = Bkij*Cij*(1− aij* dkj) *0.001 (Eq. 6) 

Where: 

BEkij = Annual emissions of by-product (k) formed from input gas (i) during process type (j) (metric 

tons). 

Bkij = Amount of gas (k) created as a by-product per kg of input gas (i) consumed in process type (j) 

(kg). 

Cij = Amount of input gas (i) consumed in process type (j) (kg). 

aij = Fraction of input gas (i) used in process type (j) with abatement systems. 

dkj = Fraction of by-product gas (k) destroyed in abatement systems connected to process type (j). 

0.001 = Conversion factor from kg to metric tons. 

Although the uncertainty relative to Tier 2a is reduced, the Tier 2b approach does not account for variation among 

individual processes or tools and, therefore, the estimated emissions will have greater uncertainty compared to Tier 3 

emissions estimates. 

 

11 This uncertainty refers only to semiconductors and LCDs. Tier 1 emission factor uncertainty for PV were not estimated in the IPCC 

Guidelines (IPCC, 2006). Additionally emissions from MEMS are not addressed in the 2006 IPCC Guidelines.

12 Note the 2006 IPCC Guidance for National Greenhouse Gas Inventories equations for estimating emissions and by-product emissions 

in the electronics industry (Equations 6.7 through 6.11) include a term for the heel of gas cylinders/containers. However, the heel term 

has been excluded in Equations 5 and 6 because it is already accounted for when overall gas consumption is estimated (shown in 

Equations 7 and 8). 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 10

3.1.4 Modified IPCC Tier 2b Approach 

The Modified IPCC Tier 2b approach is based on the 2006 IPCC Tier 2b method (as described above). However, the 

Modified approach takes into account gas- and facility- specific heel factors, as opposed to utilizing a default value for heel

factor as done in the IPCC Tier 2b method. Emissions estimations using the Modified IPCC Tier 2b approach are assumed 

to be less uncertain than estimations determined using the 2006 IPCC Tier 2b method. This is because when using a default 

heel factor, gas consumption is likely to be less representative of actual gas consumption, and hence emissions, in 

comparison to using gas- and facility- specific heel factors. 

3.1.5 The Refined Method 

The Refined Method expands on the two process types (etch and clean) of the IPCC Tier 2b method by requiring that 

emissions be estimated from etch, chamber clean and wafer clean process types based on a specific set of refined process 

categories.13 For the Refined Method, gas consumption apportioned by process category is multiplied by emission factors 

for utilization and by-product formation, using Equations 5 and 6, respectively.14 

While process categories can be defined in many ways, the EPA Refined Method utilizes nine refined process categories 

which include four categories for wafer patterning (etching), three categories for chamber cleaning, and two categories for 

wafer cleaning. The etching categories include oxide etch, nitride etch, silicon etch, and metal etch; the chamber cleaning 

categories include in situ plasma cleaning, remote plasma cleaning, and in situ thermal cleaning; and the wafer cleaning 

categories include bevel cleaning and ashing. 

EPA considered additional potential refined categories for patterning/etching and chamber cleaning to replace or 

complement the process categories defined above. For patterning/etching, in addition to the four thin-film based categories 

proposed in the rule, are contact etch, self-alignment contact etch, gate etch, deep trench etch, isolation trench etch, through 

silicon vias and regular vias. Each of these represents a specific feature achieved through etching (instead of subcategories 

based on the type of thin film etched). For chamber clean, alternative categories may distinguish between the types of films 

being removed from the chamber during cleaning. These might include distinguishing between chambers coated with 

tungsten and silicon-based films, or distinguishing between thin-film deposition equipment manufacturers. 

There are no published emission factors for the refined process categories as defined in the Refined Method, therefore to 

obtain emission factors (i.e. utilization and by-product formation rates) for each process category, EPA evaluated two 

options. This first option being that EPA would collect data from industry, evaluate it, and then create emission factors 

through an averaging scheme, either simple or weighted depending on information received. These emission factors would 

then be published in the rule for use. The second option EPA evaluated was for facilities to develop emission factors 

themselves, or acquire factors from process equipment suppliers. The first option described is further discussed in 

Appendix C. 

Results from an uncertainty analysis performed by EPA indicate that an emissions estimation method that uses refined 

process categories, such as the Refined Method, is approximately twice as certain as the 2006 IPCC Tier 2b approach. The 

Tier 2b total fluorinated GHG emissions estimate uncertainty is approximately ±39%.15 For a typical large semiconductor 

fab with emissions of approximately 113,000 MtCO2e, this relative uncertainty equates to an absolute uncertainty of 

±44,000 MtCO2e.16 The Refined Method total fluorinated GHG emissions estimate uncertainty is approximately ±24%.15 

For a typical large semiconductor fab with emissions of approximately 113,000 MtCO2e, this relative uncertainty equates to 

an absolute uncertainty of ±27,000 MtCO2e.16 (For more details on the uncertainty analysis see Appendix B). 

 

13 EPA is only proposing the Refined Method for semiconductor facilities, as semiconductor manufacturing is understood to be more

variable and complex than other electronics manufacturing. The goal in establishing the process categories is to account for variability in 

emission factors across processes, while limiting the total number of process categories for which gas usage must be tracked. 

14 When using Equations 5 and 6 for the Refined Method “j” indexes process categories as opposed to process types. 

15 This is at a 95% confidence interval and assuming a log normal distribution. 

16 The emissions for a typical large fab, 113,000 MtCO2e, were first introduced in Subpart I TSD for the initial proposed rule (January, 

2009) 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 11

3.1.6 IPCC Tier 3 Approach 

The Tier 3 approach uses the same equations as the IPCC Tier 2b and Refined Method approaches (Eqs. 5 and 6)17, but 

requires company-specific data on (1) gas consumption, (2) gas utilization, (3) by-product formation, and (4) DREs for all 

processes at the facility, rather than applying default values. The use of the Tier 3 method is estimated to result in the least 

uncertain estimates amongst the methods presented by IPCC (IPCC 2006). Information on gas consumption by individual 

processes is sometimes gathered in the ordinary course of business. Gas utilization and by-product formation factors may 

be available from tool manufacturers or can be experimentally measured on-site at the facility (International Sematech, 

2006). To obtain accurate estimates of these parameters, the guidance prepared by International SEMATECH Technology 

Transfer ( #06124825A-ENG) should be followed when conducting gas utilization and by-product formation measurements 

(December 2006). 

3.1.7 Hybrid Approach A 

Hybrid Approach A was evaluated as part of the initial proposal and requires large semiconductor facilities (as defined in 

the initial proposal as semiconductor facilities with production capacities of greater than 10,500 m2 silicon) to estimate their 

etching and cleaning emissions using an approach based on the IPCC Tier 3 method; all other facilities (including relatively 

smaller semiconductor manufacturing and other electronics manufacturing facilities) would be required to use the IPCC 

Tier 2b method. 

3.1.8 Hybrid Approach B 

Hybrid Approach B requires Tier 3 reporting for all semiconductor facilities, but only for the top three gases emitted at each 

facility. For all other gases, the Tier 2b approach is required. Hybrid Approach B was also evaluated as part of the initial 

proposal. The top three gases emitted, based on data in the Inventory of U.S. GHG Emissions and Sinks, are C2F6, CF4, and 

SF6 (EPA, 2008a). These top three gases accounted for approximately 80% of total fluorinated GHG emissions from 

semiconductor manufacturing during etching and chamber cleaning in 2006. 

3.1.9 Continuous Emissions Monitoring Systems (CEMS) 

CEMS requires facilities to install and operate CEMS to measure process emissions. A typical electronics manufacturing 

facility may have many individual process tools that influence emissions. Process tool exhaust is managed within the 

facility using stainless steel plumbing and ductwork. Due to the complexity of the manufacturing layout, CEMS would 

either need to be attached to every tool or to a final exhaust point (e.g., scrubber stacks). One possible option is to use 

Fourier Transform Infrared Spectrometers (FTIRs) in scrubber stacks to measure facility emissions. FTIR spectroscopy is 

presently used to conduct short-term fluorinated GHG emission measurements on single tools. 

3.2 Options for Estimating Facility Gas Consumption 

Several of the estimation methods described above require gas consumption to be used to estimate emissions. Equations 7 

and 8 below are used to estimate gas consumption for any input gas i used at an electronics manufacturing facility. 

Ci = (IBi – IEi + Ai – Di) * 0.001 (Eq. 7) 

Where: 

Ci = Annual consumption of input gas i (metric tons/year). 

IBi = Inventory of input gas i stored in cylinders or other containers at the beginning of the year, including 

heels (kg). 

IEi = Inventory of input gas i stored in cylinders or other containers at the end of the year, including heels in 

cylinders or other container returned to the electronics manufacturing facility (kg). 

 

17 When using Equations 5 and 6 for the IPCC Tier 3 approach “j” indexes individual processes as opposed to process types. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 12

Ai = Acquisitions of gas i during the year through purchases or other transactions, including heels in 

cylinders or other containers returned to the electronics manufacturing facility (kg). 

Di = Disbursements under exceptional circumstances of gas i through sales or other transactions during the 

year, including heels in cylinders or other containers returned by the electronics manufacturing facility 

to the chemical supplier, calculated using Equation 8 (kg). 

0.001 = Conversion factor from kg to metric tons. 

 Di = hi * Ni* Fi + Xi (Eq. 9) 

Where: 

Di = Disbursements of gas i through sales or other transactions during the year, including heels in cylinders 

or other containers returned by the electronics manufacturing facility to the gas distributor (kg). 

hi = Facility-wide gas-specific heel factor for input gas i (%). 

Ni = Number of cylinders or other containers returned to the gas distributor containing the standard heel of 

gas i. 

Fi = Full capacity of cylinders or other containers containing gas i (kg). 

Xi = Disbursements under exceptional circumstances of gas i through sales or other transactions during the 

year. These include returns of containers whose contents have been weighed due to an exceptional 

circumstance (kg). 

For the heel factor18 (hi) used in Equation 8, EPA evaluated two options including the IPCC default heel factor and gas-and 

facility-specific heel factors. Both of these options are described below. 

3.2.1 IPCC Default Heel Factor 

The IPCC default value for the fraction of gas remaining in the shipping container (i.e. the “heel”) is 10% (IPCC, 2006). 

This value is intended to be applicable to all gas containers, regardless of the gas type or container size or shape. However,

heels may vary among gases and container sizes and shapes. Therefore, the use of the IPCC default heel factor may result 

in misestimating gas consumption and emissions. 

3.2.2 Gas-and Facility-Specific Heel Factors 

Gas-and facility-specific heel factors are based on the residual weight or pressure of the gas container, or trigger point for 

change out, that a facility uses to change out that container for each container type for each gas used. By using these trigger 

points, along with the initial mass of the container, gas- and facility-specific heel factors can be calculated.19 

To account for exceptional circumstances20 when gas containers are not changed precisely when they reach the targeted 

trigger points, EPA evaluated the option of requiring reporters to weigh or determine the pressure of the gas container as 

opposed to using the facility-wide gas-specific heel factor as part of determining the net amount of gas used at a facility. 

The use of a gas-and facility-specific heel factor is expected to produce more accurate estimates of gas consumption in 

comparison to the use of the IPCC default value of 10%. This is because the amount of gas that remains in a gas container 

after it is discharged or off-loaded is not the same for every gas and container type, and the default value does not account 

for exceptional circumstances. Therefore applying a broad default value to every gas container will lead to estimations that 

may not be representative of actual facility gas consumption, and hence facility emissions.

 

18 Heel is defined as the amount of gas that remains in a gas cylinder or container after it is discharged or off-loaded. 

19 The initial mass of a container may be determined through gas supplier documents; however the reporter remains responsible for the 

accuracy of these records. 

20 EPA is proposing an exceptional circumstance be defined as one in which a cylinder/container is changed at a residual mass or 

pressure that differs by more than 20 percent from the “trigger point for change out.” 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 13

3.3 Option for Apportioning Gas Consumption 

3.3.1 Engineering Model Based 

When estimating emissions using methods such as the Modified IPCC Tier 2b or the Refined Method, and a fluorinated 

GHG is used in more than one process type or category (e.g., C2F6 used for both etch and clean processes), facility-wide gas 

consumption must be apportioned to the appropriate process types or categories. The product of that apportioned gas usage 

and the corresponding emission factor will equate to a facility’s uncontrolled emissions for a specific process type or 

category. These emissions can be summed over all process types and categories at a facility to determine total facility-wide 

uncontrolled emissions. 

3.3.1.1 Wafer Pass 

Wafer pass can be used to develop facility-specific engineering models to apportion gas consumption by process type or 

category. Wafer passes is a count of the number of times a silicon wafer is processed in a specific process category. The 

total number of wafer passes over a reporting period is the number of wafer passes per tool times the number of operational 

process tools during the reporting period. 

An illustrative case for a semiconductor facility that can be considered where wafer passes are the quantifiable indicator of 

gas usage activity used, in a facility-specific engineering model, is a facility that uses NF3 for chamber cleaning with 

remote plasma systems and for etching polysilicon and oxide films. With knowledge of the NF3-specfic heel and the 

number of NF3 containers used, the facility knows the amount of NF3 consumed. To estimate emissions the facility must 

now apportion NF3 usage between the chamber cleaning, polysilicon etching, and oxide etching processes. To do this it 

might use the total number of wafer passes through each and every NF3-cleaning system together with the time and nominal

(not measured actual) gas flow rate for each and every NF3-cleaning system and the corresponding figures for polysilicon 

etch processes and oxide etch processes to arrive at the proportion of NF3 used for cleaning chambers and etching 

polysilicon and oxide films. (For the example presented in Table 4 the annual nominal gas usage is 56,009 kg of NF3). 

Once developed, these apportioning factors could be used to estimate NF3 gas usage for the cleaning and etching process 

categories proposed in our method. This example is illustrated further below in Table 4. 

Table 4. Illustrative Calculation For NF3 Example at One Facility 

Gas Type – Annual Usage, 

kg. 

Process Category Apportioning Factor Process category gas usage, 

kg. 

RPS Chamber 

Cleaning 

82% 46,202 

Polysilicon Etch 17% 9,561 

NF3 – 56,286 kg 

Oxide Etch 1% 523 

Annual gas usage presented is the modeled usage not the nominal usage 

While the manufacturing process for other electronics manufacturers are less complex as compared to semiconductor 

manufacturing as most gases are used for a single process type, facilities that manufacture LCDs, MEMS and PV may also 

use engineering models based on quantifiable indicators of manufacturing activity for apportioning gas consumption by 

process type. 

3.4 Options for Estimating Nitrous Oxide (N2O) Emissions 

EPA evaluated two methods to estimate emissions of N2O during CVD or other N2O-using manufacturing processes, such 

as chamber cleaning, both of which would utilize Equation 9. The first option is the use of two facility-specific N2O 

utilization factors for each CVD and other N2O-using manufacturing processes. These factors would be developed by 

directly measuring N2O utilization at a facility in accordance with International SEMATECH Manufacturing Initiative’s 

Guideline for Environmental Characterization of Semiconductor Process Equipment #06124825A-ENG, December 2006 

(2006 ISMI Guidelines). 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 14

E(N2O) N , * (1 UN , ) * (1 a N , * d N , )*0.001 2 2 2 2 O j O j O j O j

j

= ∑ C − − (Eq.9) 

Where: 

E(N2O) = Annual emissions of N2O (metric tons). 

CN2O,j = Amount of N2O consumed for N2O using process j and apportioned to N2O processes (kg). 

UN2O,j = Process utilization for N2O for N2O using process j. 

a N2O,j = Fraction of N2O used in N2O using process j with abatement systems. 

dN2O,j = Fraction of N2O for N2O using process j destroyed by abatement devices connected process j. 

0.001 = Conversion factor for kg to metric tons. 

Alternatively, default N2O utilization factors for CVD and other N2O-using manufacturing processes would be applied in 

Equation 9. The default N2O utilization factor for CVD used would be in the proposed range of 0% to 40%. EPA 

determined the upper bound of this range through information collected in an industry survey presented in a comment 

received in response to the initial rule proposal. This industry survey concluded that on average the utilization of N2O for 

all processes at a fab is ~40%. In the industry survey, the measured utilization factors were largely from newer 300 mm 

manufacturing equipment. EPA did not consider the 40% as representative because N2O utilization of older manufacturing 

equipment, such as 150 mm and 250 mm tools is not fully represented. In addition, the information provided did not fully 

identify the specific processes from which the average N2O utilization factor was calculated. EPA understands that the 

majority of N2O is used in CVD processes; therefore 40% was considered the upper bound of the range for the CVD default 

N2O utilization factor. To be conservative and to avoid the potential for underestimation of emissions the lower bound of 

~0% was considered. 

For other manufacturing processes, such as chamber cleaning, the default N2O utilization factor applied would be 0%, 

which is equivalent to assuming that all N2O used in manufacturing processes, other than CVD, is emitted. EPA took this 

approach because of a lack of information about N2O utilization for other N2O-using process. 

3.5 Options for Estimating Heat Transfer Fluids (HTFs) Emissions 

3.5.1 IPCC Tier 1 Approach 

The Tier 1 approach for HTF emissions is based on the utilization capacity of a semiconductor facility multiplied by a 

default emission factor. Although, the Tier 1 approach has the advantages of simplicity, it relies on a default emissions 

factor to estimate HTF emissions and has relatively high uncertainty compared to the Tier 2 approach (IPCC, 2006). 

3.5.2 IPCC Tier 2 Approach 

The IPCC Tier 2 approach, which is a mass-balance approach, uses company-specific data and accounts for differences 

among electronics manufacturing facilities’ HTFs (which vary in their global warming potentials), leak rates, and service 

practices, and has an uncertainty on the order of ±20% at the 95% confidence interval (IPCC, 2006). Equation 10 below 

shows the company-specific mass-balance equation for estimating HTF emissions. Facilities are required to provide the 

total nameplate capacity (HTF charge) of equipment that contains fluorinated heat transfer fluids “newly installed” during 

the reporting period. 

 001 *( ) *0. i io it it it it Dit EH = density I + P − N + R − I − (Eq. 10)

Where: 

EHi = Emissions of fluorinated GHG heat transfer fluid i, (metric tons/year). 

Density = Density of fluorinated heat transfer fluid i (kg/l). 

Iio = Inventory of fluorinated heat transfer fluid i (kg) (in containers, not equipment) at the beginning of 

the reporting year (l). The inventory at the beginning of the reporting year must be the same as the 

inventory at the end of the previous reporting year. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 15

Pit = Acquisitions of fluorinated heat transfer fluid i (kg) during the current reporting year (l). Includes 

amounts purchased from chemical suppliers, amounts purchased from equipment suppliers with or 

inside of equipment, and amounts returned to the facility after off-site recycling. 

Nit = Total nameplate capacity (full and proper charge) of equipment that uses fluorinated heat transfer 

fluid i and that is newly installed during the reporting year (kg). 

Rit = Total nameplate capacity (full and proper charge) of equipment that uses fluorinated heat transfer 

fluid i and that is removed from service during the current reporting year (kg). 

Iit = Inventory of fluorinated heat transfer fluid i (kg)(in containers, not equipment) at the end of current 

reporting year (l). 

Dit = Disbursements of fluorinated heat transfer fluid i (kg) during the current reporting year (l). Includes 

amounts returned to chemical suppliers, sold with or inside of equipment, and sent off site for 

verifiable recycling or destruction. Disbursements should include only amounts that are properly 

stored and transported so as to prevent emissions in transit. 

0.001 = Conversion factor from kg to metric tons. 

3.6 Options for Reporting Controlled Emissions from Abatement Systems 

While the 2006 IPCC Guidelines offer gas-specific default DREs, these values were optimized for specific processes and 

tools, and are not expected to be representative for all tools and gas flow rates. The IPCC default DRE values are also not 

applicable to abatement systems which can not abate CF4 at DREs greater than 85%. (IPCC, 2006). Because of the 

aforementioned reasons, and to ensure the accuracy of controlled emissions estimations, EPA evaluated the following two 

options for the reporting of controlled emissions: the use of an EPA developed DRE default value and the direct, proper 

measurement of DRE values using EPA’s Protocol for Measuring Destruction or Removal Efficiency of Fluorinated 

Greenhouse Gas Abatement Equipment in Electronics Manufacturing (EPA 430-R-10-003) (EPA DRE Protocol) (EPA, 

2010). As part of both of these options, EPA evaluated requiring certification of proper installation, maintenance, and 

operation of abatement systems, as well as monitoring the uptime of abatement systems. 

3.6.1 Proper Installation, Operation, and Maintenance 

There are many abatement system manufacturers, all of whom manufacture many models of systems that are marketed as 

F-GHG-destruction capable (Beu, L. 2005). While some of these systems may be capable of destroying some fluorinated 

GHGs, they may not be effective in abating CF4 (Beu, L., 2005), which in some processes can constitute 10% – 20% (by 

volume) of fluorinated GHG exhaust composition (EPA, 2008d). This variability may be partially attributable to 

installation as well as operating and maintenance practices (Beu, L. 2005), although variations in how destruction is 

measured may also contribute to this variability (Beu, L., 2005). Additionally it is well known across the industry that 

abatement system performance varies greatly depending on a variety of abatement device and process parameters such as 

temperature, flow and exhaust composition (Beu, L., 2005, EPA 2008c, 2008d)). 

Therefore, ensuring that abatement systems are properly installed, operated, and maintained according to manufacturers’ 

specifications is important to reduce the likelihood of inaccurate estimations of DREs. It should be noted that this is also in 

line with 2006 IPCC applicability requirements for reporting controlled emissions due to abatement system use. 

(IPCC,2006) 

3.6.2 Monitoring Abatement System Uptime 

Applying a DRE value that is not discounted for the time an abatement system at a facility is not properly operated, 

installed and maintained but the associated tool(s) are still operational, would result in an underestimation of total facility

emissions. The total time during the reporting period when the abatement system for which controlled emissions will be 

reported was properly installed, operated, and maintained is referred to as uptime. Time during which a system is in bypass mode, undergoing maintenance, or not operating with O2-flow (in the case of a CF4 combustion system) is not 

included in uptime. An exception to this is time during which exhaust flows are passed through a redundant abatement 

system that is in the same abatement system class (discussed below) as the primary abatement system. Such time may be 

included in the uptime of the primary system. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 16

Uptime is calculated as the sum of time during the reporting period that an abatement system is in a standby, productive, 

and engineering state as described in SEMI Standard E10-0304, Specification for Definition and Measurement of 

Equipment Reliability, Availability, and Maintainability (SEMI 2004). Abatement system uptime is expressed as the sum 

of an abatement system’s operational productive, standby, and engineering times divided by the total operations time of its 

associated manufacturing tool. To accurately reflect total facility emissions, abatement system uptime should be applied to 

discount the DRE values used to report controlled emissions. For example, if the uptime for a device is 98% over the 

reporting period, then the measured (or class average of measured DREs when a system has not yet been measured) is 

multiplied by 0.98. 

3.6.3 EPA Default DRE Value 

As discussed previously, the 2006 IPCC gas-specific default DRE value were optimized for specific processes and tools. 

However DREs are expected to vary across abatement systems and gas flow rates. For this reason, EPA estimates that the 

use of the IPCC default DRE value will result in controlled emissions estimates that are not representative of actual facility 

operations. Manufacturer supplied DREs may also result in emissions estimates that are not representative of actual facility 

operations because the DRE itself may have been incorrectly measured due to a failure to account for the effects of dilution 

(e.g., CF4 can be off by as much as a factor of 20 to 50 and C2F6 can be off by a factor of up to 10 [Burton, 2007].) This 

understanding is supported by industry assessments as presented in Beu, 2005. Therefore, EPA developed a default DRE to 

be used to report controlled emissions provided that the abatement system for which the default value is representing is 

properly installed, operated and maintained and specifically designed for fluorinated GHG and N2O abatement. 

EPA developed this default value using data from the EPA DRE measurement program, in which measurements have been 

made at 3 separate facilities.21 All of the data collected through the measurement program properly took into account the 

effects of dilution. Using the DRE data set from these measurement studies, the following data selection criteria were 

applied to determine values to include in the development of the default DRE. 

• Data must be from abatement devices that were properly installed, operated, and maintained, as well as 

designed to abate fluorinated GHGs and N2O. 22 This is consistent with the requirements EPA is proposing for 

all abatement systems for which emissions are reported. In cases where this criterion was not met, the DRE values 

measured were often indistinguishable from zero. 

• Data must be in the form of a discrete value. Under the EPA DRE measurement program, some DRE 

measurements taken exceeded 99%. In these instance the measured data was expressed as a non-discrete value, 

(i.e. ≥ 99% (e.g. for CHF3, NF3, SF6)), which could not be applied to a method to determine a default DRE value. 

After evaluating the data based on these criteria, a set with a population of 11 measured DREs was used to develop the EPA 

default DRE value. These 11 DREs in the set were for CF4, and were measured on two thermal abatement systems each 

attached to two etch tools, which, in turn, had four chambers. This data set, which can be referenced in Table 5 contains 

results from two measurement conditions: (a) DRE measurement when the process tool plasma is off, when just CF4 and 

diluent gas from each chamber enters the abatement system, and (b) measurement of DRE during wafer processing, when 

CF4 together with other waste effluents leave the tool during actual wafer processing enters the abatement system. 

Measured DREs are shown for each etch tool. These are regarded as independent measurements of the DRE for abating 

CF4 for each abatement system. 

Table 5. Data set to develop EPA default DRE value. 

Experiment ID Comment about experiment Measured CF4 DRE Source of dataa

FK15 #1 No plasma 87.5 Table IV 

FK15 #2 No plasma 63.1 Table IV 

FK15 #3 No plasma 79.4 Table IV 

 

21 For more information about the three studies, please see the following reports: Developing a Reliable Fluorinated Greenhouse Gas (FGHG) Destruction or Removal Efficiency (DRE) Measurement Method for Electronics Manufacturing: A Cooperative Evaluation with

IBM (EPA 430-R-10-004); Developing a Reliable Fluorinated Greenhouse Gas (F-GHG) Destruction or Removal Efficiency (DRE) 

Measurement Method for Electronics Manufacturing: A Cooperative Evaluation with NEC Electronics, Inc. (EPA 430-R-10-005); and 

Developing a Reliable Fluorinated Greenhouse Gas (F-GHG) Destruction or Removal Efficiency (DRE) Measurement Method for

Electronics Manufacturing: A Cooperative Evaluation with Qimonda (EPA 430-R-08-017).

22 While the EPA DRE measurement program only looked at abatement systems performance for fluorinated GHGs, it was assumed, for 

this use, that abatement systems that were designed to treat fluorinated GHGs were also designed to treat N2O. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 17

FK15 #4 No plasma 77.4 Table IV 

FE05#1 No plasma 84.5 Table IV 

FE05#2 No plasma 82.2 Table IV 

FE05#3 No plasma 91.7 Table IV 

FE05#4 No plasma 96.0 Table IV 

Additional data from wafer tests, all chambers 

FK15 Trench etch, #1 & #3 only 83 Table VIII 

FK15 Via etch, #1 & #3 only 85 Table VIII 

FE05 FE etch #3 & #4 only 90 Table IX 

a Source: EPA, 2009. 

The summary statistics of the data set in Table 5 is presented in Table 6. Also presented in Table 6 is the default DRE 

determined under the assumption that the measured DREs are distributed normally, and under the condition that 95% of the 

population will be above the value of 59% (i.e. the lower one-sided tolerance interval). For simplicity the value was 

rounded to one significant figure, equating to a default DRE of 60%. 

Table 6. Summary Statistics and Default DRE (Lower One-Sided Tolerance Interval) 

Mean of Measured Values Stdev of Measured Values Lower One-Sided 

Tolerance Interval 

No Plasma Measured DRE 82.73 10.054 - 

All Measured DRE 83.62 8.70 59 

3.6.4 Proper Measurement of Abatement System DRE 

For purposes of this rule, proper measurement of DRE values are those measured in accordance EPA’s DRE Protocol. The 

EPA DRE Protocol provides a practical and reliable method for measuring DREs of POU abatement devices while also 

providing flexibility to users. In addition, the use of the EPA DRE Protocol will ensure EPA that reporters will properly 

account for dilution when determining DREs. (Please refer to the EPA DRE Protocol for a more detailed discussion on the 

justification for the development and application of the Protocol). 

A representative random sampling approach can be used to reduce burden associated with directly and properly measuring 

DREs of each abatement system at a facility. Therefore, EPA evaluated the use of a random sampling abatement system 

testing program (RSASTP) that would span all classes of abatement systems for which controlled emissions are reported. 

(For these purposes class refers to a group of abatement systems with the same specific manufacturer model number(s) used 

for either abating N2O, and CF4 direct and by-product formation, for abating other fluorinated GHGs , and any other 

abatement systems for which the reporting entity wishes to report controlled emissions 23.) 

EPA qualitatively evaluated a range of options, from 10% to 100%, for what would constitute an appropriate annual 

representative sample of abatement systems to be tested in a reporting year. EPA selected 20% as it would balance the 

annual measurement burden for reporters and anticipated reliable maintenance periods and useful lifetimes of abatement 

systems. The RSASTP, with the selected 20%, is described below. 

An annual representative sample would consist of three or 20% of installed abatement devices, whichever is greater, for 

each model type each year. In the case that 20% of total abatement systems at a facility does not equal a whole number, the 

number of devices to be tested should be rounded up.24 Each reporting period the DRE for a different three or 20% set of 

devices would be measured. For systems for which a DRE has not been measured in a reporting period, a simple average 

of the measured DREs for systems of that specific class of abatement system is used. If redundant abatement systems are 

tested during periods of maintenance or repair, then the most recently measured or class average DRE for that system may 

be used. 

 

23 CF4 is a very stable chemical and especially difficult to effectively abate. It may be used as an input gas and generated as a byproduct 

of other fluorinated GHG process reactions. 

24 For example, 16 abatement devices, 20% of which equals 3.2; therefore, four abatement devices would be measured each year, which 

exceeds three. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 18

Using the RSASTP, as outlined in the paragraph above, would ensure the eventual measurement of each device but over the 

course of several years. The importance of measuring the DRE for each abatement device lies in the fact that the robustness 

of installed abatement systems varies by gas and operating principle. Therefore, while some abatement devices may 

receive regular maintenance and perform optimally, others may, because of the specific nature of the exhaust they treat, not 

be functioning properly. 

4 Procedures for Estimating Missing Data 

Gas consumption data and indicators of activity are expected to be collected as part of business as usual operations, 

therefore EPA did not evaluate any options for estimating these values. When estimating HTF emissions, the use of the 

mass-balance approach requires correct records for all inputs. Therefore facilities that use HTFs and have missing data for 

one or more of the inputs for the mass-balance equation (see Eq. 10), can estimate HTF emissions using the arithmetic 

average of the emission rates for the year immediately preceding the period of missing data and the months immediately 

following the period of missing data. Alternatively, missing information may be estimated from the heat transfer fluid 

supplier’s records. 

5 QA/QC Requirements 

QA/QC methods for reporting F-GHG and N2O emissions include: 

• Following the 2006 ISMI Guidelines for QA/QC procedures when estimating gas process utilization and byproduct gas formation, as well as facility-specific N2O utilization rates. 

• Following the QA/QC procedures in the EPA DRE Protocol when estimating abatement device DRE. 

• Tracking gas consumption as BAU to a high-degree of precision , and ensuring the gas inventory at the beginning 

of a reporting year is the same as the gas inventory at the end of the previous reporting year. 

QA/QC methods for reporting emissions from HTFs use and annual gas consumption for each F-GHG and N2O used 

include: 

• Reviewing inputs to the gas consumption equation and HTF mass balance equation (Eqs. 7 and 10), to ensure 

inputs and outputs to the facility’s system are all accounted for in all appropriate sections. 

• Ensuring no negative inputs are entered in the gas consumption equation and HTF mass balance equation (Eqs. 7 

and 10) and negative emissions are not calculated. 

• Ensuring that the beginning of year inventory matches end of year inventory from previous year. 

General QA/QC methods include: 

• Ensuring all instruments used to determine the concentration of fluorinated GHG and N2O in process streams shall 

be calibrated just prior to measurement through analysis of certified standards with known concentrations of the 

same chemicals in the same ranges as the process samples. 

• Ensuring all flowmeters, weigh scales, pressure gauges, and thermometers used to measure quantities that are used 

to meet requirements of subpart I have an accuracy and precision of one percent of full scale or better. 

6 Reporting and Record Keeping Procedures 

The following supplemental data would be useful for confirming emissions calculations and/or calculating emission factors 

that could be compared across facilities for quality control purposes: 

• Report: 

o Annual emissions of each GHG and N2O emitted from each individual process, process category, or 

process type and from all HTF use. 

o Emissions estimation method used (i.e. Refined Method, Tier 2b, or Tier 3). 

o Production in terms of substrate surface area (e.g., silicon, PV-cell, LCD). 

o Emission factors used (i.e. specific or default factors) for gas utilization and by-product 

formation, and their sources by gas. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 19

o Descriptions of individual processes or process categories used to estimate emissions where the nine 

refined process categories for semiconductor facilities, as defined by EPA, are not used. 

o The apportioning factors for each process category (i.e., fractions of each gas fed into each individual 

process or process category used to calculate fluorinated GHG and N2O emissions) and a description of 

the engineering model used for apportioning gas usage. 

o For each fluorinated GHG and N2O, annual mass of gas consumed during the reporting year as calculated 

using both of the following two ways: 

 Calculate facility annual gas consumption using the engineering model by summing the gas 

consumed at a facility over all relevant processes and process categories. Calculate annual gas 

consumed during the reporting year for each process or process category using apportioning 

factors, purchase records and facility-wide gas-specific heel-factors.25

 Calculate facility annual gas consumption by summing the nominal gas usages used to develop 

apportioning factors for each process category over all relevant processes and/or process 

categories.26 

o Fraction of gas fed into each process type that is fed into tools with abatement systems. 

o Description of all abatement devices through which fluorinated GHGs or N2O flow at the 

facility, including the number of devices of each manufacturer, model numbers, manufacturers 

guaranteed DRE, and record of DRE measurements over its in-use life (if any). 

o For all abatement devices for which the reporter is reporting controlled emissions, the following: 

 Certification that the abatement device is installed, operated, and maintained according to 

manufacturers’ specifications. 

 The uptime and the calculations to determine uptime for that reporting period. 

 The default DRE value or properly measured destruction or removal efficiencies for each 

abatement system used in that reporting year to reflect controlled emissions. 

 Certification that the abatement system for which controlled emissions are being reported, using 

the default DRE value, are specifically designed for fluorinated GHG and N2O abatement. 

 Where properly measured DREs or class averages of DREs are used, the following: 

• A description of the class including the abatement system manufacturer and model 

number, and the fluorinated GHG and N2O in the process effluent stream; 

• The total number of systems in that class for the reporting year. 

• The total number of systems for which DRE was measured in that class for the 

reporting year. 

• A description of the calculation used to determine the class average, including all inputs 

of the calculation. 

• A description of method of randomly selecting class members for testing. 

o Inputs used in the mass-balance equation for HTFs. 

o Example calculations for fluorinated GHG, N2O, and HTF emissions. 

• Keep records of: 

o Data and copies of calculations used to estimate emissions. 

o Documentation for the values used for fluorinated GHG and N2O utilization and by-product 

formation rates. Where facility-specific, recipe-specific gas utilization and by-product formation 

rates are used, the following records: 

 Documentation that these were measured using the 2006 ISMI Guidelines. 

 Documentation that the measurements made are representative of fluorinated GHG and 

N2O emitting processes at the facility. 

 The date and results of the initial and any subsequent tests to determine process tool gas 

utilization and by-product formation rates. 

o For each abatement device through which fluorinated GHGs or N2O flows at the facility, for 

which the reporter is reporting controlled emissions, the following: 

 

25 This estimate of gas consumption, calculated using purchase records and facility wide gas-specific heel factors, will be used by a 

facility to estimate and report emissions (in Eqs. 5 and 6). See Table 4. 

26 This estimate of gas consumption, calculated using nominal gas usages, will be used as a QA/QC check. It is not to be used by a 

facility to estimate and report emissions. See in Section 3.3.1.1. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 20

 Documentation to certify that the abatement device is installed, maintained, and 

operated according to manufacturers’ specifications. 

 The uptime and the calculations to show how uptime was used to discount DREs. 

 Calibration and maintenance records for the abatement system. 

 Documentation from the abatement system supplier describing the equipment’s 

designed purpose and emission control capabilities where the default DRE is used. 

o Where properly measured destruction or removal efficiency is used to report controlled 

emissions, dated certification by the technician who made the measurement that the destruction 

or removal efficiency was calculated according to methods in the EPA’s DRE Protocol, and 

documentation of the results of any initial and subsequent tests, and final reports as specified in 

the EPA DRE Protocol. 

o Purchase records for gas purchased. 

o Invoices for gas purchases and sales. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 21

7 References 

Beu, L. (2005). “Reduction of Perfluorocarbon (PFC) Emissions: 2005 State-of-the-Technology Report”, TT#0510469AENG, International SEMATECH Manufacturing Initiative (ISMI), December 2005. Available at: 

http://www.epa.gov/highgwp/semiconductor-pfc/documents/final_tt_report.pdf. 

Burton, C.S., & Beizaie, R. (2001). EPA’s PFC Emissions Model (PEVM) v. 2.14: Description and Documentation. 

Prepared for Office of Global Programs, U. S. Environmental Protection Agency, Washington, DC. 20001 November 2001. 

Available at: http://www.epa.gov/highgwp/semiconductor-pfc/documents/pevm_draft.pdf. 

Burton (2006). PV Emissions during Photovoltaic (PV) Cell Fabrication: A Scoping Report. Available in EPA docket 

EPA-HQ-OAR-2009-0927. 

Burton (2007). Assessing the need for FC abatement standards, Solid State Technology, January 2007. Available at: 

http://www.electroiq.com/index/display/semiconductors-article-display/281422/articles/solid-state-technology/volume50/issue-1/departments/industry-forum/assessing-the-need-for-fc-abatement-standards.html. 

DisplaySearch (2007). Flat Panel Fabs on a Disk. Q2 2007 Edition. Available for purchase at: 

http://www.displaysearch.com/cps/rde/xchg/displaysearch/hs.xsl/index.asp. 

Earth Policy Institute (2007). Solar Cell Production Jumps 50 Percent in 2007. Author: Jonathan G. Dorn. Available at: 

http://www.earth-policy.org/index.php?/indicators/C47/. 

EPA (2008a) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007. U.S. Environmental Protection Agency, 

Washington, DC. 

EPA (2008b). Uses and Emissions of Liquid PFC Heat Transfer Fluids from the Electronics Sector. Office of Air and 

Radiation Office of Atmospheric Programs, Climate Change Division, U.S. Environmental Protection Agency, 

Washington, DC. Available at: http://www.epa.gov/semiconductor-pfc/documents/pfc_heat_tranfer_fluid_emission.pdf. 

EPA (2008c). Developing a Reliable Fluorinated Greenhouse Gas (F-GHG) Destruction or Removal Efficiency (DRE) 

Measurement Method for Electronics Manufacturing: A Cooperative Evaluation with NEC Electronics, Inc. (EPA 430-R10-005). Office of Air and Radiation Office of Atmospheric Programs, Climate Change Division, U.S. Environmental 

Protection Agency, Washington, DC. Available at: http://www.epa.gov/highgwp/semiconductorpfc/documents/nec_report.pdf.

27 

EPA (2008d). Developing a Reliable Fluorinated Greenhouse Gas (F-GHG) Destruction or Removal Efficiency (DRE) 

Measurement Method for Electronics Manufacturing: A Cooperative Evaluation with Qimonda (EPA 430-R-08-017). 

Office of Air and Radiation Office of Atmospheric Programs, Climate Change Division, U.S. Environmental Protection 

Agency, Washington, DC. Available at: http://www.epa.gov/highgwp/semiconductorpfc/documents/qimonda_report.pdf.27

EPA (2009). Developing a Reliable Fluorinated Greenhouse Gas (F-GHG) Destruction or Removal Efficiency (DRE) 

Measurement Method for Electronics Manufacturing: A Cooperative Evaluation with IBM (EPA 430-R-10-004), Office of 

Air and Radiation Office of Atmospheric Programs, Climate Change Division, U.S. Environmental Protection Agency, 

Washington, DC. Available at: http://www.epa.gov/highgwp/semiconductor-pfc/documents/ibm_report.pdf. 

 

27 The NEC and Qinonda studies were conceived and conducted over the course of 2006 through 2007, and are referenced as such in the 

Electronics Manufacture preamble. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 22

EPA (2010). Protocol for Measuring Destruction or Removal Efficiency (DRE) of Fluorinated Greenhouse Gas Abatement 

Equipment in Electronics Manufacturing (EPA 430-R-10-003), Office of Air and Radiation Office of Atmospheric 

Programs, Climate Change Division, U.S. Environmental Protection Agency, Washington, DC. Available in EPA docket 

EPA-HQ-OAR-2009-0927. 

Gaitan, M. & Takacs, M. (2008). The state of standards. Solid State Technology, February 2008. Available at: 

http://www.electroiq.com/index/display/semiconductors-article-display/319143/articles/solid-state-technology/volume51/issue-2/departments/mems/the-state-of-standards.html. 

International Sematech (2006). Guideline for Characterization of Semiconductor Process Equipment. International 

Sematech, Technology Transfer # 06124825A-ENG, December 22, 2006. Available in EPA docket EPA-HQ-OAR-2009-

0927. 

International Sematech (2004). Specification for Definition and Measurement of Equipment Reliability, Availability, and 

Maintainability. SEMI Standard E10-0304, March, 2004. Available for purchase at: http://www.semi.org/en/index.htm. 

Contact the EPA Docket Center for more information. 

IPCC (2006) 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The National Greenhouse Gas Inventories 

Programme, The Intergovernmental Panel on Climate Change, H.S. Eggleston, L. Buendia, K. Miwa, T Ngara, and K. 

Tanabe (eds.). Hayama, Kanagawa, Japan. Available at: http://www.ipccnggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_6_Ch6_Electronics_Industry.pdf. 

ITRS (2008) International Technology Roadmap for Semiconductors: 2007 Update. January 2008. This and earlier 

editions and updates are available at <http://public.itrs.net.> Information about the number of interconnect layers for years 

1990 – 2010 is contained in Burton and Beizaie, 2001. PEVM is updated using new editions and updates of the ITRS, 

which are published annually. 

Lee et al. (2007). Evaluation Method on Destruction and Removal Efficiency of Perfluorocompounds from Semiconductor 

and Display Manufacture. Bull. Korean Chem. Soc. 28 (8), 1383-1388 (2007). Available at: 

http://newjournal.kcsnet.or.kr/main/j_search/j_download.htm?code=B070824. 

Li et al., (2001). Improved Technique for Evaluating Point-of-use Abatement Systems. Semiconductor Fabtech, 14th 

Edition, June 2001. Available at: http://www.fabtech.org/. 

Lyshevshi, S. (2001). MEMS and NEMS System, Devices, and Structures, CRC Press. Available for purchase at: 

http://www.crcpress.com/ecommerce_product/product_detail.jsf?catno=1262&isbn=0000000000000. 

Roedern, B.V. & Ullal, H.S. (2008). Critical issues for commercialization of thin-film PV technologies. Solid State 

Technology, February 2008. Available at: http://www.electroiq.com/index/display/semiconductors-articledisplay/319149/articles/solid-state-technology/volume-51/issue-2/features/thin-film-technology/critical-issues-forcommercialization-of-thin-film-pv-technologies.html. 

Semiconductor Equipment and Materials Industry (SEMI) (2008). World Fab Watch, January 2007 Edition. Available for 

purchase at: http://www.semi.org/en/index.htm. 

VLSI Research, Inc. (2008). Document 327028, V6.12.1—Worldwide Silicon Demand by Wafer Size, by Linewidth and 

by Device Type. January 2007. Available for purchase at: http://www.vlsiresearch.com. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 23

Appendix A – Default Emission Factors for Threshold Applicability Determination and IPCC 

Tier 2b Emission Factors for LCD Manufacturing and PV Manufacturing 

Table A-1. Default Emission Factors for Threshold Applicability Determination 

Emission Factors EFi

Product Type CF4 C2F6 CHF3 C3F8 NF3 SF6

Semiconductors (kg/m2

Si) 0.90 1.00 0.04 0.05 0.04 0.20 

LCD 

(g/m2 LCD) 0.50 NA NA NA 0.90 4.00 

MEMS 

(kg/m2 Si) NA NA NA NA NA 1.02 

Notes: NA denotes not applicable based on currently available information. 

Source: IPCC, 2006 
Subpart I (Elec

March 22, 2010 

Table A-2. IPCC Tier 2b Emission Factors for LCD Manufacturing and PV Manufacturing 

Greenhouse Gases with TAR GWP Green

withou

Process Gas CF4 C2F6 CHF3 CH2F2 C3F8 c-C4F8

NF3

Remote NF3 SF6 C4F6 

Etch 1-Ui 0.6 NA 0.2 NA NA 0.1 NA NA 0.3 NA CVD 1-Ui NA NA NA NA NA NA 0.03 0.3 0.9 NA Etch BCF4 NA NA 0.07 NA NA 0.009 NA NA NA NA Etch BCHF3 NA NA NA NA NA 0.02 NA NA NA NA Etch BC2F6 NA NA 0.05 NA NA NA NA NA NA NA CVD BCF4 NA NA NA NA NA NA NA NA NA NA CVD BC2F6 NA NA NA NA NA NA NA NA NA NA 

LCD 

MANUFACTURING 

CVD BC3F8 NA NA NA NA NA NA NA NA NA NA Etch 1-Ui 0.7 0.4 0.4 NA NA 0.2 NA NA 0.4 NA CVD 1-Ui NA 0.6 NA NA 0.1 0.1 NA 0.3 0.4 NA Etch BCF4 NA 0.2 NA NA NA 0.1 NA NA NA NA Etch BC2F6 NA NA NA NA NA 0.1 NA NA NA NA CVD BCF4 NA 0.2 NA NA 0.2 0.1 NA NA NA NA CVD BC2F6 NA NA NA NA NA NA NA NA NA NA 

PV 

MANUFACTURING 

CVD BC3F8 NA NA NA NA NA NA NA NA NA NA 

Notes: NA denotes not applicable based on currently available information ‡ The default emission factors for F2 and COF2 may be applied to cleaning low-k CVD reactors with ClF3. * Estimate includes multi-gas etch processes † Estimate reflects presence of low-k, carbide and multi-gas etch processes that may contain a C-containing FC additive 

Notes: NA denotes not applicable based on currently available information. Source: IPCC, 2006 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 25

Appendix B – Supporting Analysis for the Use of Refined Process Categories for Estimating 

Emissions from Semiconductor Manufacturing 

To evaluate the method for estimating emissions based on a refined set of process categories, an uncertainty analysis was 

performed comparing the uncertainty of emissions estimates using both the 2006 IPCC Tier 2b utilization factors and 

utilization factors for a set of refined process categories. It should be noted that 13 process categories were used in this 

analysis, as opposed to the 9 categories proposed in the regulation for the Refined Method. The variation increase in the 

number of categories is due to the etching/patterning categories that are representative of a specific feature achieved 

through etching in the uncertainty analysis (instead of subcategories based on the type of thin film etched in the proposed 

categories). The results of this analysis, while not exactly representative of the categories proposed for the Refined 

Method, are still applicable in justifying the conclusion that the use of process categories which are more refined than those 

of the Tier 2b approach will result in less uncertain emissions estimates. 

It is understood, as discussed above, that the 2006 IPCC Tier 1 and Tier 2a approaches result in the most uncertain 

estimates because the variations in gas usage per process category (clean and etch, or further refined categories) are not 

accounted for. In addition, the use of the 2006 IPCC Tier 3 method results in the least uncertain estimates (IPCC, 2006). 

Because both the 2006 IPCC Tier 2b approach and a refined process category method distinguish between gas usages for 

process categories, but do not require recipe-specific measurement, it is assumed the uncertainty associated with estimates 

for the 2006 IPCC Tier 2b and refined process categories are between 2006 IPCC Tier 2a and Tier 3. Therefore the 

selection of the methods to compare in this uncertainty analysis was aimed to confirm there is a sufficient decrease in 

uncertainty in emissions estimates when using a refined process category method as opposed to the 2006 IPCC Tier 2b 

method, such that any additional burden associated with a refined process category method is justifiable. 

B.1 Analysis Approach 

In comparing the uncertainties for the 2006 IPCC Tier 2b approach and a refined process category method for 

semiconductor facilities, only uncertainties in emissions factors across sets of factors were considered. It was assumed that 

uncertainties in usages are the same for each method which is consistent with the proposed rule. A Monte Carlo simulation 

analysis was preformed, applying the @Risk software, generating 10,000 simulated output values. Distributions were 

applied around the input variables that avoid distortions that result when normal distribution is assumed and uncertainties in 

emission factors are large. 

B.2 Sources of Information 

2006 IPCC Tier 2b emission factors, one minus utilization factors and by-product formation factors, were taken from the 

2006 IPCC Guidelines, Table 6.3. Emission factors for a refined process category method were developed for thirteen 

process categories. Data from a database containing industry confidential business information were averaged to create 

emission factors for the thirteen process categories. 28 

Relative errors for the 2006 IPCC Tier 2b emission factors were taken from the 2006 IPCC Guidelines, Table 6.9. Relative 

errors for a refined process category method were developed based on number of values per process category and the 

variation among the values per process category. Tables B-1 through B-3 show the relative errors for the utilization factors 

and by-product formation rates by process category. 

 

28 This database contains information collected through the U.S. Environmental Protection Agency’s PFC Emissions Reduction/Climate 

Partnership for the Semiconductor Industry. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 26

Table B-1. Relative Errors for Utilization Factors for a Refined Process Category Method 

 Chamber Cleaning Patterning Wafer Cleaning 

 

In situ 

plasma 

In situ 

thermal Remote Contact SAC Gate 

Deep 

trench Isolation 

Regular 

Via TSV 

Metal 

etch 

Bevel 

Cleaning Ashing 

CF4 46% NA NA 104% NA 61% NA NA 109% NA 43% NA 61% 

C2F6 8% NA NA 30% NA NA NA NA 68% NA 35% NA NA 

CHF3 NA NA NA 16% NA 51% NA NA 46% NA 47% NA NA 

C3F8 8% NA 2% NA NA NA NA NA NA NA NA NA NA 

C4F8 NA NA NA 20% 6% NA NA NA 10% NA NA NA NA 

SF6 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C4F6 NA NA NA NA NA NA NA 14% 29% NA 14% NA NA 

CH2F2 NA NA NA 2% NA NA NA 26% NA NA 26% NA NA 

NF3 9% NA 5% NA NA 35% NA NA NA NA NA NA NA 

Table B-2. Relative Errors for CF4 By-Product Formation Rates for a Refined Process Category Method 

 Chamber Cleaning Patterning Wafer Cleaning 

 

In situ 

plasma 

In situ 

thermal Remote Contact SAC Gate 

Deep 

trench Isolation 

Regular 

Via TSV 

Metal 

etch 

Bevel 

Cleaning Ashing 

CF4 

C2F6 14% NA NA NA NA NA NA NA 6% NA 83% NA NA 

CHF3 NA NA NA 34% NA NA NA NA NA NA NA NA NA 

C3F8 23% NA NA NA NA NA NA NA NA NA NA NA NA 

C4F8 NA NA NA 77% 78% NA NA NA NA NA NA NA NA 

SF6 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C4F6 NA NA NA 71% NA NA NA NA 61% NA 102% NA NA 

CH2F2 NA NA NA NA NA NA NA NA NA NA NA NA NA 

NF3 45% NA 156% NA NA NA NA NA NA NA NA NA NA 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 27

Table B-3. Relative Errors for C2F6 By-Product Formation Rates for a Refined Process Category Method 

 Chamber Cleaning Patterning Wafer Cleaning 

 

In situ 

plasma 

In situ 

thermal Remote Contact SAC Gate 

Deep 

trench Isolation 

Regular 

Via TSV 

Metal 

etch 

Bevel 

Cleaning Ashing 

CF4 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C2F6 

CHF3 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C3F8 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C4F8 NA NA NA 52% 67% NA NA NA 70% NA NA NA NA 

SF6 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C4F6 NA NA NA 50% NA NA NA NA 63% NA 94% NA NA 

CH2F2 NA NA NA NA NA NA NA NA NA NA NA NA NA 

NF3 NA NA NA NA NA NA NA NA NA NA NA NA NA 

Gas usage distribution was based on data from one of the partner companies of EPA’s PFC Reduction/Climate Partnership 

for Semiconductors. Data from the Partnership audit was used, specifically the 2006 and 2007 gas-specific submissions for 

a large emitting partner. Based on expert judgment, gas-specific gas consumption was split into refined process categoryspecific shares that could then be recombined into simpler chamber cleaning-etch categories for the 2006 IPCC Tier 2b 

analysis. The gas usage distributions are shown in Tables B-4 and B-5. 

Table B-4. Gas Usage Distribution Used for Analysis for a Refined Process Category Method 

 Chamber Cleaning Patterning Wafer Cleaning 

 

In situ 

plasma 

In situ 

thermal Remote Contact SAC Gate 

Deep 

trench Isolation 

Regular 

Via TSV 

Metal 

etch 

Bevel 

Cleaning Ashing 

CF4 NA NA NA 1% NA NA NA 1.45% 1.45% NA NA NA 0.10% 

C2F6 NA NA NA NA 2% NA NA NA 5% 5% NA NA NA 

CHF3 NA NA NA 0.1% NA NA NA 0.1% 0.2% NA 0.5% NA NA 

C3F8 NA NA NA NA NA NA NA NA NA NA NA NA NA 

C4F8 NA NA NA 1% 1% NA NA NA 3% NA NA NA NA 

SF6 NA NA NA NA NA 6% NA NA NA NA NA NA NA 

C4F6 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 

NF3 NA NA 70% NA NA 2% NA NA NA NA NA NA NA 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 28

Table B-5. Gas Usage Distribution used for Tier 2b Analysis 

C2F6 Etch 12% 

CF4 Etch 4% 

CHF3 Etch 0.9% 

SF6 Etch 6% 

NF3 Etch 2% 

C4F8 Etch 5% 

NF3 Remote Clean 70% 

B.3 Method for Estimating Uncertainty 

A Monte Carlo simulation was conducted using @Risk, generating 10,000 simulated output variables based on input 

parameters (e.g., relative errors and distributions around emission factors). The analysis conducted used three different 

distributions: Normal with truncation, which was unavoidable with a normal distribution to avoid estimating negative 

emissions during the simulation. Assuming lognormal and Gamma distributions avoided having to truncate the distribution 

during the simulations. For the both the lognormal and Gamma distributions, location and shape parameters were 

calculated using the mean and standard deviations based on data in the 2006 IPCC tables for Tier 2b and Tables B-1 

through B-3 for a refined process category method. In this way an internally consistent set of parameters were used. 

In developing the emission factors for a refined process category method, there were cases where there was only a single 

entry for developing an emission factor. Regarding these factors, two runs were conducted. For one run, we assumed zero 

percent relative error around these factors and for the other run we assumed 10% relative error per the ISMI Guidelines. 

The difference in results between these two runs based on these different assumptions was inconsequential. 

B.4 Results 

The results of our analysis are summarized in Tables B-6 and B-7. Uncertainty estimates are based on a 95% confidence 

interval.

Table B-6. Tier 2b Uncertainty Analysis Results 

 Mean 

Standard 

Deviation 

Relative 

Error 

Estimated 0.595 

Simulated (Normal) 0.764 0.162 21% 

Simulated (LogNormal) 0.592 0.229 39% 

Simulated (Gamma) 0.594 0.228 38% 

Table B-7. Uncertainty Analysis Results for a Refined Process Category Method 

 Mean 

Standard 

Deviation 

Relative 

Error 

Estimated 0.662 

Simulated (Normal) 0.765 0.117 15% 

Simulated (LogNormal) 0.662 0.160 24% 

Simulated (Gamma) 0.661 0.162 25% 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 29

Key points of the results are as follows: 

• When using a normal distribution, the utilization and by-product formation factors were truncated in order to avoid 

negative emission estimates. This truncation had distorting effects: simulated means were increased artificially. This 

distorting effect was no longer an issue when lognormal and Gamma distributions were applied. 

• The 2006 IPCC Tier 2b approach and a refined process category method give roughly the same mean, which is 

expected because factors were drawn from the database used to develop 2006 IPCC emission factors. 

• The uncertainty results indicate that a refined process category method is about twice as certain as the 2006 IPCC Tier 

2b approach. 

• The most sensitive determinant of uncertainty is the emission factor for RPS because its usage exceeds all others by 

large margin (and its GWP is of comparable magnitude to other gases). 

• The distributions show some right-handed skewness, which is expected when using lognormal and Gamma 

distributions. For emission factors that are large in value, lognormal and gamma give about the same results since 

asymptotically these two distributions are identical. 
Subpart I (Electronics Manufacture) TSD 

March 22, 2010 30

Appendix C- EPA Published Emissions Factor Ranges for the Refined Method 

In developing the emission factors for the nine refined process categories, as defined as part of the Refined Method, EPA’s 

intent is to reduce the uncertainties relative to the Tier 2b factors in Chapter 6 of the 2006 Guidelines. 29

 To accomplish 

this, in part, EPA intends to develop emission factors for 150 mm, 200 mm and 300 mm wafer processing technologies to 

the extent feasible, as opposed to one set that would apply to all wafer technologies, as is the case for the 2006 IPCC Tier 

2b emission factors. 

EPA requested that semiconductor device manufacturers and equipment manufacturers voluntarily provide information to 

develop emission factors for the refined emitting process categories for the three wafer technologies. This information is 

currently being provided to EPA via SEMI. Figure C-1 shows the emission factor collection form that SEMI provides, 

when completed, to EPA. 

EPA is proposing a range of values for each default emission factor because the Agency has not yet received sufficient data 

to select a specific value within each range. In developing the ranges EPA considered, in addition to the information 

provided by SEMI, the emission factors and associated relative errors (95 % confidence interval) provided in Tables 6.3 

and 6.9 from Chapter 6 of the 2006 IPCC Guidelines. Noting that the standard deviations provided in the 2006 IPCC 

Guidelines equate to ranges in some cases that are physically unrealistic (viz., emission factors below zero or above one) 

and there were gaps in the limited data from SEMI, it was not feasible for EPA to simply apply this information to develop 

emission factor ranges across all gases and all refined process categories. In those instances where information provided 

via SEMI at the time of EPA’s proposal was not available for a specific category (e.g., metal etch for each wafer 

technology), EPA’s emission factor ranges rely only on information from the IPCC tables. In those instances where there 

was information available from SEMI, EPA used both the SEMI-provided and IPCC information. Tables C-1 through C-3 

present the proposed ranges in emission factors for each wafer technology and refined emission process category. EPA 

used “NA” in instances where currently available information (i.e., either data received from SEMI or our current 

understanding of specific processes) did not exist to support a range. If information is received to support a value, EPA 

intends to include an emission factor in a final rule. 

Using additional information (i.e. information provided via SEMI, in comments to the proposed rule, during development 

of the 2006 IPCC emission factors (which do not carry confidential restriction), and any other relevant information), EPA 

intends to develop default emission factors for utilization and by-product formation rates for each wafer technology (i.e. 

150 mm, 200 mm, and 300) to the extent feasible for each refined process category. EPA intends to use a method of 

aggregation similar to the 2006 IPCC factor development methodology. 

If additional data are received in a timely fashion, EPA may develop draft emission factors prior to issuance of the final rule

and will determine an appropriate way to promptly and clearly inform the regulated community. EPA welcome comments 

on such draft emission factors, recognizing that depending on when the emission factors are made available, such 

comments could be submitted after the close of the formal comment period. EPA will make every effort to consider such 

comments, including late comments, to the extent practicable in the development of the final rule.

 

29 Uncertainties associated with the Tier 2b method are associated with aggregating, for each gas, all usage into just two process 

categories—etching films and chamber cleaning—and all wafer technologies—150 mm, 200mm and 300 mm wafer sizes—into one, and 

giving equal weights to all process recipes. EPA’s refined category approach seeks, as much as is practical, to keep these separate, which 

reflects actual device manufacturing practices. 
Subpar

March 22, 2010 

Figure C-1. Data form submitted by semiconductor device manufacturers and equipment manufacturer

Information for Developing EPA’s Refined F-GHG Emission Process Categories and Corresponding Emissio

(one form per process of record)

Source/Contact (TBR)1 (For SEMI use, information redacted) Date of measurement Location of study (TBR) (For SEMI use, information redacted)Emission process category and subcategory (s) of process category2 

Emission Process Category Subcategory of Process Category Alternative P

Equipment (Manufacturer name/model number) (TBR)3

Letter denotes each reporting entity. 

(Information redacted, it is sought to facilitate sufficient consideration of equipment manufacturer equipment usage in device manufacture.)

Patterning/etching subcategories (Check preference and explain each). Specify both film type and etched feature regardless of preference. 

Film Etch Feature Etch

Explanation: Specify/describe film type: Specify/describe etched feature: 

Substrate size (Si wafer) Measurement method/protocol4 (Either ISMI Guidelines or equivalent alternative measurement protocol with brief explanation reg

equivalent to ISMI Guidelines.)

Achieved ISMI Fluorine target mass balance >90%? Check answer.5

YES NO (Explain) 

Corresponding Emission Factors for Emission Process Categories 

Process Gases (i) CF4 C2F6 C3F8 c-C4F8 CHF3 SF6 NF3 C4F6 C5F8 C4F8O Measured emissions: 1-Ui6 Standard deviation: 
Subpar

March 22, 2010 

Meas. CF4 byproduct, Bip7 CF4 B standard deviation: Meas. C2F6 byproduct, Bip7 C2F6 B standard deviation: Meas. C3F8 byproduct, Bip7 C3F8 B standard deviation: Unit of measurement (mass): No. of wafers in study (number of wafers measured) Comments 

Information for developing average emission factors 

Estimate of U. S. share of selected process usage category, % (Check answer) 

10% 20% 30% 40% 50% 60% 70% 80

Notes: 

1. TBR denotes To Be Redacted by SEMI. 2. Distinguish between four emission process categories: 1. Chamber Cleaning; 2. Wafer Cleaning; 3. Patterning/etching; and 4. Dep

Cleaning category distinguish between the subcategories remote plasma cleaning and in situ cleaning. Within Wafer Cleaning catego

subcategories ashing and bevel cleaning. Within Deposition category (N2O only) distinguish between the subcategories thermal and P

Patterning/etching categories under consideration: Film Etch and Feature Etch. The process subcategories under the Film Etch alter

and metal. The process subcategories under the Feature Etch alternative are: Contact, SAC, Gate, Capacitor, Deep Trench, Isolation T

silicon via and Metal etch. Select one subcategory from each of the Film Etch and Feature Etch categories and enter onto Data Form in 

Subcategory spaces. Distinguishing between Film Etch and Feature Etch on the Data Form is not necessary. 

3. SEMI will assign a separate letter for each entity that provides emission factor data. 

4. Provide a brief explanation that supports using an alternative to ISMI Guidelines for characterizing process emissions. 5. Provide a brief explanation that supports the reliability of the reported emission factors despite not achieving the F mass balance targe6. Ui denotes gas utilization, i.e., fraction of gas destroyed or transformed during the process step. Many etch recipes use multiple F-GHG

those gases and the measured utilization of each. In this instance also note the convention adopted for reporting the by-product formati

below. 

7. Bi denotes fraction of gas i transformed into other F-GHGs such as CF4 formed from C2F6 or CHF3, C2F6 and C3F8 formed from other 

such as CF4 is formed in recipes containing multiple F-GHGs (e.g., CHF3, c-C4F8 and C4F6) Bi, by convention, is the ratio of measured 

largest quantity of F-GHG comprising the recipe. 
Subpart I (Elec

March 22, 2010 

Table C-1. Default Emission Factor Ranges for Refined Process Categories for Semiconductor Manufacturing for 150 

Refined Process Gas i 

Process 

Category CF4 C2F6 CHF3 CH2F2 C3F8 c-C4F8 NF3 SF6 C4F

PATTERNING/ETCHING Oxide etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.05-0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.02-0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.02-0 BC3F8 NA NA NA NA NA NA NA NA NA Nitride etch  1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.05-0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.02-0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.02-0 BC3F8 NA NA NA NA NA NA NA NA NA Silicon etch  1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.05-0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.02-0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.02-0 BC3F8 NA NA NA NA NA NA NA NA NA Metal etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.05-0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.02-0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.02-0 BC3F8 NA NA NA NA NA NA NA NA NA 
Subpart I (Elec

March 22, 2010 

CHAMBER CLEANING In situ plasma cleaning  1-Ui 0.8-0.95 0.4-0.8 NA NA 0.2-0.6 0.05-0.3 0.05-0.3 NA NA  BCF4 NA 0.05-0.2 NA NA 0.05-0.2 0.05-0.2 0.05-0.2 NA NA  BC2F6 NA NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA NA Remote plasma cleaning  1-Ui NA NA NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA NA In situ thermal cleaning  1-Ui NA NA NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA NA WAFER CLEANING Bevel cleaning 1-Ui NA NA NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA NA Ashing  1-Ui NA NA NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA NA 

Notes: NA denotes not applicable based on currently available information. 
Subpart I (Elec

March 22, 2010 

Table C-2. Default Emission Factor Ranges for Refined Process Categories for Semiconductor Manufacturing for 200 

Refined Process Gas i 

Process 

Category CF4 C2F6 CHF3 CH2F2 C3F8 c-C4F8 NF3 SF6 C

PATTERNING/ETCHING Oxide etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.0 BC3F8 NA NA NA NA NA NA NA NA NNitride etch  1-Ui 0.2-0.8 0.2-0.7 0.1-0.7 0.02-0.3 NA 0.05-0.3 0.1-0.4 0.1-0.4 0.0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.02-0.3 NA NA 0.0 BC2F6 NA NA NA NA NA 0.005-0.3 NA NA 0.0 BC3F8 NA NA NA NA NA NA NA NA NSilicon etch  1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.0 BC3F8 NA NA NA NA NA NA NA NA NMetal etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0.0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0.0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0.0 BC3F8 NA NA NA NA NA NA NA NA N
Subpart I (Elec

March 22, 2010 

CHAMBER CLEANING In situ plasma cleaning  1-Ui 0.8-0.95 0.4-0.8 NA NA 0.2-0.6 005-0.3 0.05-0.2 NA N BCF4 NA 0.05-0.2 NA NA 0.05-0.2 0.05-0.2 0.05-0.1 NA N BC2F6 NA NA NA NA NA NA NA NA N BC3F8 NA NA NA NA NA NA NA NA NRemote plasma cleaning  1-Ui

NA 

NA NA NA NA NA 0.005-0.03 NA N

 BCF4 NA NA NA NA NA NA 0.0001-0.2 NA N BC2F6 NA NA NA NA NA NA NA NA N BC3F8 NA NA NA NA NA NA NA NA NIn situ thermal cleaning  1-Ui NA NA NA NA NA NA NA NA N BCF4 NA NA NA NA NA NA NA NA N BC2F6 NA NA NA NA NA NA NA NA N BC3F8 NA NA NA NA NA NA NA NA NWAFER CLEANING Bevel cleaning 1-Ui NA NA NA NA NA NA NA NA N BCF4 NA NA NA NA NA NA NA NA N BC2F6 NA NA NA NA NA NA NA NA N BC3F8 NA NA NA NA NA NA NA NA NAshing  1-Ui NA NA NA NA NA NA NA NA N BCF4 NA NA NA NA NA NA NA NA N BC2F6 NA NA NA NA NA NA NA NA N BC3F8 NA NA NA NA NA NA NA NA N

Notes: NA denotes not applicable based on currently available information. 
Subpart I (Elec

March 22, 2010 

Table C-3. Default Emission Factor Ranges for Refined Process Categories for Semiconductor Manufacturing for 300 

Refined Process Gas i 

Process 

Category CF4 C2F6 CHF3 CH2F2 C3F8 c-C4F8 NF3 SF6 

PATTERNING/ETCHING Oxide etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.4 0.1-0.8 NA 0.05-0.3 0.1-0.4 0.1-0.4 0 BCF4 NA 0.05-0.5 0.005-0.03 0.001-0.01 NA 0.005-0.1 NA NA 0 BC2F6 NA NA NA NA NA 0.005-0.1 NA NA 0 BC3F8 NA NA NA NA NA NA NA NA Nitride etch  1-Ui 0.2-0.8 0.2-0.7 0.2-0.4 0.1-0.8 NA 0.08-0.3 0.1-0.4 0.1-0.4 0 BCF4 NA 0.05-0.5 0.003-0.1 0.01-0.1 NA 0.02-0.3 NA NA 0 BC2F6 NA NA NA NA NA 0.02-0.3 NA NA 0 BC3F8 NA NA NA NA NA NA NA NA Silicon etch  1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0 BC3F8 NA NA NA NA NA NA NA NA Metal etch 1-Ui 0.2-0.8 0.2-0.7 0.2-0.7 0.02-0.3 NA 0.1-0.3 0.1-0.4 0.1-0.4 0 BCF4 NA 0.05-0.5 0.01-0.8 0.05-0.1 NA 0.01-0.3 NA NA 0 BC2F6 NA NA NA NA NA 0.01-0.3 NA NA 0 BC3F8 NA NA NA NA NA NA NA NA 
Subpart I (Elec

March 22, 2010 

CHAMBER CLEANING In situ plasma cleaning  1-Ui NA NA NA NA NA NA 0.1-0.4 NA  BCF4 NA NA NA NA NA NA 0.001-0.6 NA  BC2F6 NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA Remote plasma cleaning  1-Ui NA NA NA NA NA NA 0.002-0.03 NA  BCF4 NA NA NA NA NA NA 0.001-0.05 NA  BC2F6 NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA In situ thermal cleaning  1-Ui NA NA NA NA NA NA 0.1-0.4 NA  BCF4 NA NA NA NA NA NA 0.005-.05 NA  BC2F6 NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA WAFER CLEANING Bevel cleaning 1-Ui 0.3-0.8 NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA Ashing  1-Ui 0.3-0.8 NA NA NA NA NA NA NA  BCF4 NA NA NA NA NA NA NA NA  BC2F6 NA NA NA NA NA NA NA NA  BC3F8 NA NA NA NA NA NA NA NA 

Notes: NA denotes not applicable based on currently available information.