### MEMORANDUM

TO: Docket EPA

- HQ

- OAR

- 2011

- 0028

FROM: Alexis McKittrick, EPA/Climate Change

DATE: August 1 6, 2013

SUBJECT: Final Technical Documentation

- Revision of Default Utilization Rates and By

- Product Formation Rates; Revision of Default Destruction and Removal Efficiencies for Semiconductor Facilities under Subpart I; and Revision of

Maximum Field Detection Limits for the Stack Test Method

This memo documents the upda tes to the analyses that EPA performed for the proposed amendments to subpart I published on October 16, 2012 (77 FR 63538). EPA updated these analyses to account for additional data and comments that EPA received in response to the proposed amendments.

S ection 1 of this memo documents the updated analysis of the revised etch emission factors, originally documented in “Technical Support for Modifications to the Fluorinated Greenhouse Gas Emission Estimation Method Option for Semiconductor Facilities under Subpart I” (docket item EPA

- HQ

- OAR

- 2011

- 0028

- 0083).

Section 2 of this memo documents the updated analysis of the revised default factors for abatement system destruction or removal efficiency, originally documented in “Technical Support for Accounting for Destruction or Removal Efficiency for Electronics Manufacturing Facilities under Subpart I” (docket item EPA

- HQ

- OAR

- 2011

- 0028

- 0082).

Section 3 of this memo documents the updated analysis of the maximum allowed field detection limits (FDLS) used in the stac k test method, originally documented in “Technical Support for the Stack Testing Option for Estimating Fluorinated Greenhouse F

- GHG Emissions from Electronics Manufacturing Facilities under Subpart I” (docket item EPA

- HQ

- OAR

- 2011

- 0028

- 0085).

1.0 REVISION OF DE FAULT UTILIZATION RA TES AND BY

- PRODUCT

FORMATION RATES FOR SEMICONDUCTOR FACILI TIES UNDER

SUBPART I

1.1 Introduction
On October 16, 2012, The U.S. Environmental Protection Agency (EPA) proposed amendments to the calculation and monitoring methodologies for Sub part I, Electronics Manufacturing, of the Greenhouse Gas Reporting Rule (see 77 FR 63538). As part of that action, EPA proposed revisions to the default plasma etch and chamber cleaning gas utilization rates and by

- product formation rates for semiconductor manufacturing facilities. Please refer to the memorandum entitled “Technical Support for Modification to the Fluorinated Greenhouse Gas

### 2 Emissions Method Option for Semiconductor Facilities under Subpart I, August 2012,” (Docket

ID EPA

- HQ

- OAR

- 2011

- 0028

- 008 3) for details regarding the development of revised factors.

In response to the proposed rulemaking, the Semiconductor Industry Association (SIA) submitted additional utilization and by

- product formation rate data from semiconductor manufacturing facilitie s. This part briefly describes the additional data submitted by SIA and the incorporation of those data into the calculation of the revised utilization and by

- production formation rates for the final rulemaking. This part also summarizes the results of the revised utilization and by

- production formation rate calculations using the new data and presents noted differences between EPA calculated factors and those calculated by SIA. This part is organized

as follows:

1.2 Description of Newly Submitted Data

1.3 Incorporation of New Data into Emission Factor Calculations

1.4 Summary of Revised Default Utilization and By

- product Formation Rates

1.2 Description of Newly Submitted Data
As part of their public comment submission (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0095), SIA provided EPA with 168 additional gas utilization and by

- product formation rate data sets for 200 millimeter (mm) and 300 mm plasma etch equipment. SIA noted in their comment submission that the data were provided by semiconductor process equipment supplie rs and device manufacturers. SIA provided the data in PDF and Microsoft Excel format. SIA’s comment letter and the associated attachments can be found in the subpart I rulemaking docket,

Docket ID: EPA

- HQ

- OAR

- 2011

- 0028.

On May 8, 2013, EPA conducted a meet ing with SIA where EPA asked clarifying questions regarding possible typographical errors in the data submitted by SIA. SIA acknowledged the errors and submitted a corrected version of the data in question, but did not include any new data or information. The corrections are located in the document entitled “EPA/SIA Meeting

– May 8, 2013,” Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0101.

For semiconductor manufacturing using 200 mm wafers, the data provided by SIA included one gas utilization rate for which no data w ere previously available (C 5 

### F 8 

### ) and revised the utilization rates of four fluorinated greenhouse gases (F

- GHGs). For semiconductor manufacturing using 300 mm wafers, the new data included two new gas utilization rates for

C 3 

### F 8 

### and CH 3 

### F, and additional utilization rates for nine F

- GHGs. The new data also provided 75 revised by

- product formation rates, including three new by

- products not previously identified (C 5 

### F 8 

### , CH 3 

### F, and CH 2 

### F 2 

### ).

1.3 Incorporation of New Data into Emission Factor Calculations
Upon receipt of the additional data from SIA, EPA combined the new utilization and by

product formation rates with the existing data set used to develop revised emission factors at proposal. We then reorganized all of the available emission factors for analysis. This reorganization consisted of separating the database into two separate worksheets, one for default utilization rates and the other for by

- product formation rates. The by

- product formation rate

### 3 worksheet was further modified such that each row represented a single by

- product emission factor for each input gas. We reorganized the data sets in such fashion as to calculate revised factors using Microsoft Excel Pivot Tables.

EPA used the emission factor calculation methodology outlined in the proposed rule to

eva luate the new and revised emission factors. Specifically, EPA: 1) Used a simple arithmetic averaging method to develop default utilization and by

- product emission factors by gas for the etch process type; and 2) Used the “all inputs gas” convention for as signing by

- product formation rates (emission factors) for etch gases. This convention assigns by

- product emission to input F

- GHGs used in a process by dividing the measured mass emitted of a specific by

- product by the total mass of all input F

- GHGs for tha t process and assigning this by

- product factor to each input F

- GHG used in that process. These methods were described in detail at proposal in the memorandum entitled “Technical Support for Modification to the Fluorinated Greenhouse Gas Emissions Method Op tion for Semiconductor Facilities under Subpart I, August 2012,” (Docket ID EPA

- HQ

- OAR

- 2011

- 0028

- 0083). Based on their public comment submission (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0095), SIA used the same approach described here, and

in the aforementioned me morandum, to calculate the revised default utilization and by

production formation rates presented in Tables I.1, I.2, and I.3 of their public comments, and in their subsequent corrections to those tables (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0101)

submitted to EPA following the May 8, 2013 meeting between EPA and SIA.

EPA also calculated revised Tier 2a emission factors for semiconductor manufacturing facilities for use with the stack testing alternative using the additional data submitted by SIA. Per

SIA’s rec ommendation on page 18 of their public comments, EPA calculated revised Tier 2a factors for semiconductors using a consumption weighted average where gas usage data were available, and an arithmetic (i.e., sample weighted) average where gas usage data were not
available. To perform these calculations, EPA used the gas consumption weighting factors from
the Microsoft Excel Workbook entitled “Tier_2a_NF3_and_C2F6_Emission_Factor_ Calculations.xls” (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0090). The weighting factors presented in the workbook were originally obtained from the document entitled “Report to EPA on Etch Factor Proposal for Fab GHG Emissions Reporting” (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0074). To address SIA’s suggestion that EPA rework the NF 3 

### emission facto rs to incorporate weighting for the remote clean process sub

- type, EPA revised the Tier 2a factors for semiconductors to include a separate NF 3 

### remote clean factor. For consistency with previous rulemakings, EPA selected the same default emission factor fo r NF 3 

### remote clean as described in

the November 2010 TSD (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0195)

.

1.4 Summary of Revised Default Utilization and By

- production Formation Rates
Tables 1.1 through 1.8 summarize the new and revised default utilization and by

- produ ct formation rates that are included in the final subpart I rule amendments.

Table 1

- 1. Revised Default Emission Factors (1

- U ij 

### ) for Gas Utilization Rate (U ij 

### ) for Semiconductor Manufacturing for 150 mm and 200 mm Wafer Sizes for the Plasma Etching/Wafer Cleaning Process Type

Input Gas Proposal Presented by SIA Revised Final

No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij )

C 2 F 6 40 0.76 43 0.72 43 0.72

### 4 Input Gas Proposal Presented by SIA Revised Final

No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij )

C 2 HF 5 31 0.064 31 0.064 31 0.064

C 4 F 6 14 0.17 14 0.17 14 0.17

C 4 F 8 44 0.14 53 0.14 53 0.14

C 5 F 8 0 NA 1 0.072 1 0.072

CF 4 126 0.81 134 0.81 134 0.81

CH 2 F 2 43 0.13 44 0.13 44 0.13

CH 3 F 1 0.66 3 0.70 3 0.70

CHF 3 131 0.50 136 0.51 136 0.51

NF 3 22 0.20 23 0.19 23 0.19

SF 6 129 0.55 132 0.55 132 0.55



### Table 1

- 2. Revised Default Emission Factors (1

- U ij 

### ) for Gas Utilization Rate (U ij 

### ) and for Semiconductor Manufacturing for 300 mm and 450 mm Wafer Sizes for the Plasma Etching/Wafer Cleaning Process Type

Input Gas Proposal Presented by SIA Revised Final

No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij ) No. Of Data Sets (1

- U ij )

C 2 F 6 2 0.80 1 0.81 2 0.80

C 4 F 6 37 0.18 46 0.15 45 0.15

C 4 F 8 77 0.17 90 0.19 90 0.18

C 5 F 8 12 0.13 16 0.10 16 0.10

CF 4 78 0.63 101 0.65 104 0.65

CH 2 F 2 39 0.15 56 0.20 57 0.21

CH 3 F 0 NA 13 0.33 13 0.33

CHF 3 66 0.39 90 0.43 91 0.42

NF 3 52 0.17 66 0.16 66 0.15

SF 6 37 0.23 46 0.32 46 0.32

C 3 F 8 0 NA 4 0.30 4 0.30

Bold values indicate a difference between the SIA presented value and the final EPA value.



### Some differences in Table 1

- 2 are noted between the values presented by SIA and the final values determined by EPA for C 2 

### F 6 

### , C 4 

### F 6 

### , C 4 

### F 8 

### , CF 4 

### , CH 2 

### F 2 

### , and CHF 3



### . EPA was able to identify the source of all the differences except for one, as explained in the following paragraphs.

In Table I.2 on page 8 of SIA’s public comment submission (Docket ID: EPA

- HQ

- OAR

2011

- 0028

- 0095), SIA indicates that only one data set was available in 2011 for C 2 

### F 6 

### for 300mm, and lists an emission factor of 0.811 kg per kg. However, in the October 16, 2012 proposal (77 FR 63538), EPA proposed a default emission factor for C 2 

### F 6 

### of 0.80 kg per kg based on two data sets (0.779 kg per kg and 0.811 kg per kg), which were included in the document “Draft Emission Factors for Refined Semiconductor Manufacturing Process Categories,” (Docke t ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0073). The latter document was referenced by the May 13, 2010 Federal Register notice, “Mandatory Reporting of Greenhouse Gases: Notice of Data Availability; Default Emission Factors for Semiconductor Manufacturing Refined

Proces s Categories” (75 FR 26904). Additionally, these two data sets were used to develop the

default emission factor for C 2 

### F6 

### for 300 mm in Table I

- 4 to subpart I in the final rule promulgated on December 1, 2010 (75 FR 74774). In the final rule, the EPA is usi ng the two data sets instead of the single data set cited by SIA.

### 5 SIA indicated in Table I.2 of their public comment submission that 46 data sets are now

available for C 4 

### F6 

### for 300 mm fabs. EPA believes that SIA may be counting an emission factor

for C 4 

### F6 

### of “N/A,” which was provided by SIA in the document “International SEMATECH Manufacturing Initiative Environmental Safety and Health Technology Center Etch Process Equipment Emissions Characterization Data,” (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0071).

EPA did not include this “N/A” emission factor in the final count of data sets presented in Table

1

- 2 above.

The difference in the final emission factor for C 4 

### F 8 

### shown in Table 1

- 2 above as calculated by SIA and EPA appears to be due to a transcription error of t he factor 0.0581 kg per kg. In “Attachment A” to SIA’s public comment submission, the last 13 emission factors were offset one column to the left. EPA believes SIA may have included the line item for this factor in their count of data sets, but did not inc lude the actual value in their calculation of the average for

C 4 

### F 8 

### . Similarly, for CF 4 

### , EPA believes SIA included the three values that were offset (0.0891, 0.85, 0.7304 kg per kg) in their final calculation of the average, but not in their final count of

data sets.

The difference in the data set count and emission factor for CH 2 

### F 2 

### shown in Table 1

- 2

above appears to originate from an inadvertent omission of one emission factor data set by SIA. In Table I.2 on page 8 of SIA’s public comment submission, SIA indicated that for the total number of data sets available at proposal, 38 data sets were available for CH 2 

### F 2 

### , and calculated an emission factor of 0.144961 kg per kg. Based on the data available to EPA, 39 data sets were available at proposal for a calcul ated emission factor of 0.147397 kg per kg. EPA is able to reproduce the count and emission factor calculated by SIA by excluding the wafer clean factor of 0.24 kg per kg provided on page 16 of 29 of the document “Draft Emission Factors for Refined

Semicon ductor Manufacturing Process Categories,” (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0073). Because EPA is able to reproduce SIA’s count and average emission factor by omitting this value, we believe SIA may have inadvertently omitted the value from their emission f actor
calculations for CH 2 

### F 2



### .

The difference in the data set count and emission factor for CHF 3 

### shown in Table 1

- 2

above also appears to originate from an inadvertent omission of one emission factor data set by SIA. In Table I.2 on page 8 of SIA’s public comment submission, SIA indicates that for the total number of data sets available at proposal, 65 data sets were available for CHF 3 

### , and calculated an emission factor of 0.386291 kg per kg. Based on the data available to EPA, 66 data sets were

available a t proposal for a calculated emission factor of 0.387029 kg per kg. EPA is able to reproduce the count and emission factor calculated by SIA by excluding the emission factor for an oxide film type and via feature type of 0.435 kg per kg provided on page 6 o f 15 of “International SEMATECH Manufacturing Initiative Environmental Safety and Health Technology Center Etch Process Equipment Emissions Characterization Data,” (Docket ID:

EPA

- HQ

- OAR

- 2011

- 0028

- 0071). Because EPA is able to reproduce SIA’s count and ave rage emission factor by omitting this value, we believe SIA may have inadvertently omitted the value

from their emission factor calculations.

EPA was unable to determine the origin of the discrepancy between SIA’s calculated

emission factor for NF 3 

### and EPA ’s calculated factor shown in Table 1

- 2 above. We note that in Table I.2 on page 8 of SIA’s public comment submission, SIA indicate d , at proposal, a c ount of

### 6 52 data sets for NF 3 

### and a calculated emission factor of 0.171608 kg per kg. Based on the data

ava ilable to EPA, we confirmed that at proposal, a total of 52 data sets were available, all of which originated from the document “International SEMATECH Manufacturing Initiative Environmental Safety and Health Technology Center Etch Process Equipment Emissi ons Characterization Data,” (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0071). However, using the same 52 data sets used to calculate the proposed emission factor, EPA calculated an emission factor of 0.16766 kg per kg, which agrees with the previous emission factor calculation. The difference between the previously calculated value and the SIA value from the data at proposal is 0.003948 kg per kg. Though the source of this discrepancy is unclear , we believe that this

difference was carried forward and led to SIA cal culating a value of 0.15503 (rounded to 0.16) and EPA a value 0.15048 (rounded to 0.15) for the emission factor for NF 3



### . Because EPA was able to confirm the previous calculation of the proposed emission factor, we are using the results of our current analy sis in the final rule.

Table 1

- 3. Revised Default Emission Factors for By

- Product For mation Rates (B ijk 

### ) for Semiconductor Manufacturing for 150 mm and 200 mm Wafer Sizes for the Etching/Wafer Cleaning Process Type

Input Gas By

- Product Proposal Presented by SIA Revised Final

No. Of Data Sets (B ijk ) No. Of Data Sets (B ijk ) No. Of Data Sets (B ijk )

C 2 F 6 CF 4 36 0.10 39 0.10 39 0.10

CHF 3 0 NA 3 0.047 3 0.047

C 2 HF 5 C 2 F 6 31 0.024 31 0.024 31 0.024

CF 4 31 0.077 31 0.077 31 0.077

C 4 F 6 C 2 F 6 12 0.11 12 0.11 12 0.11

CF 4 12 0.13 12 0.13 12 0.13

CHF 3 1 0.066 1 0.066 1 0.066

C 4 F 8 C 2 F 6 38 0.037 44 0.037 44 0.037

CF 4 41 0.12 47 0.11 47 0.11

CHF 3 0 NA 5 0.040 5 0.040

C 5 F 8 0 NA 2 0.0086 2 0.0086

C 5 F 8 C 2 F 6 0 NA 1 0.014 1 0.014

CHF 3 0 NA 1 0.0039 1 0.0039

CF 4 C 2 F 6 96 0.048 102 0.046 102 0.046

CHF 3 60 0.11 63 0.10 63 0.10

C 5 F 8 0 NA 1 0.0012 1 0.0012

CH 2 F 2 C 2 F 6 34 0.025 35 0.025 35 0.025

CF 4 40 0.081 41 0.079 41 0.079

CHF 3 1 0.066 2 0.049 2 0.049

CH 3 F C 2 F 6 0 NA 2 0.0034 2 0.0034

CHF 3 C 2 F 6 65 0.031 70 0.030 70 0.030

CF 4 72 0.085 72 0.085 72 0.085

C 5 F 8 0 NA 1 0.0012 1 0.0012

NF 3 C 2 F 6 0 NA 1 0.025 1 0.025

CF 4 1 0.0040 1 0.0040 1 0.0040

SF 6 C 2 F 6 1 0.17 2 0.11 2 0.11

CF 4 2 0.15 3 0.13 3 0.13

CHF 3 0 NA 1 0.0012 1 0.0012

### 7 Table 1

- 4. Revised Default Emission Factors for By

- Product For mation Rates (B ijk 

### ) for Semiconductor Manufacturing for 300 mm and 450 mm Wafer Sizes for the Etching/Wafer Cleaning Process Type

Input

Gas By

Product Proposal Presented by SIA Revised Final

No. Of Data

Sets (B ijk ) No. Of Data

Sets (B ijk ) No. Of Data

Sets (B ijk )

C 2 F 6 CF 4 1 0.21 0 NA 1 0.21

C 4 F 6 C 2 F 6 22 0.090 27 0.074 27 0.074

CF 4 33 0.066 37 0.059 37 0.059

CHF 3 30 0.022 34 0.019 34 0.019

CH 2 F 2 0 NA 4 0.000030 4 0.000030

C 4 F 8 C 2 F 6 50 0.030 57 0.031 57 0.031

C 4 F 6 2 0.018 2 0.018 2 0.018

CF 4 71 0.046 80 0.045 80 0.045

CHF 3 65 0.028 73 0.027 73 0.027

CH 2 F 2 0 NA 4 0.0015 4 0.0015

C 5 F 8 C 2 F 6 9 0.083 9 0.083 9 0.083

CF 4 12 0.15 16 0.11 16 0.11

CHF 3 8 0.010 12 0.0069 12 0.0069

C 3 F 8 0 NA 4 0.00012 4 0.00012

CF 4 C 2 F 6 60 0.092 75 0.079 75 0.079

C 4 F 8 3 0.00063 3 0.00063 3 0.00063

CHF 3 40 0.011 41 0.011 41 0.011

CH 3 F 0 NA 1 0.0080 1 0.0080

CH 2 F 2 C 2 F 6 15 0.068 22 0.052 22 0.052

CF 4 27 0.059 34 0.049 34 0.049

CHF 3 27 0.052 34 0.050 34 0.050

CH 3 F 0 NA 1 0.0080 1 0.0080

CH 3 F C 2 F 6 0 NA 4 0.00087 4 0.00087

CF 4 0 NA 5 0.045 5 0.045

CHF 3 0 NA 5 0.0057 5 0.0057

CH 2 F 2 0 NA 4 0.0023 4 0.0023

CHF 3 C 2 F 6 47 0.078 64 0.064 64 0.064

C 4 F 6 1 0.00010 1 0.00010 1 0.00010

C 4 F 8 2 0.00080 2 0.00080 2 0.00080

CF 4 48 0.10 54 0.10 54 0.10

CH 3 F 0 NA 1 0.0080 1 0.0080

CH 2 F 2 0 NA 3 0.0036 3 0.0036

NF 3 C 2 F 6 11 0.057 14 0.045 14 0.045

CF 4 31 0.052 36 0.046 36 0.046

CHF 3 9 0.035 13 0.025 13 0.025

CH 3 F 0 NA 1 0.0080 1 0.0080

CH 2 F 2 0 NA 4 0.00086 4 0.00086

SF 6 C 2 F 6 8 0.067 13 0.044 13 0.044

CF 4 15 0.045 19 0.040 19 0.040

CHF 3 0 NA 5 0.0037 5 0.0037

CH 2 F 2 0 NA 2 0.000029 2 0.000029

C 3 F 8 C 2 F 6 0 NA 4 0.18 4 0.18

CF 4 0 NA 4 0.21 4 0.21

CHF 3 0 NA 4 0.012 4 0.012

CH 3 F 0 NA 3 0.00073 3 0.00073

### 8 Table 1

- 5. Revised Tier 2a Default Emission Factors (1

- U ij 

### ) for Gas Utilization Rate (U ij 

### ) for Semiconductor Manufacturing for 150 mm and 200 mm Wafer Sizes

Input Gas Proposed Tier 2a

Emission Factor Final Tier 2a Emission

Factor Calculation Note

C 2 F 6 0.71 0.56 Consumption weighted

C 2 HF 5 0.064 0.064 Arithmetic average

– Emission factor data available for etch only

C 4 F 6 0.17 0.17 Arithmetic average

– Emission factor data available for etch only

C 4 F 8 0.14 0.13 Consumption weighted

C 5 F 8 NA 0.072 Arithmetic average

– Emission factor data available for etch only

CF 4 0.81 0.85 Consumption weighted

CH 2 F 2 0.13 0.13 Arithmetic average

– Emission factor data available for etch only

CH 3 F 0.66 0.70 Arithmetic average

– Emission factor data available for etch only

CHF 3 0.50 0.51 Arithmetic average

– Emission factor data available for etch only

NF 3 0.19 0.16 Consumption weighted

– outliers removed [A]

NF 3 Remote Clean [ B ] 0.018 [ C ]

SF 6 0.55 0.55 Arithmetic average

– Emission factor data available for etch only

C 3 F 8 0.40 0.40 Arithmetic average

– Emission factor data available for in

- situ plasma cleaning only

C 4 F 8 O 0.14 0.14 Arithmetic average

– Emission factor data available for in

- situ pla sma cleaning only
[A]

– Three NF 3 emission factor values under remote plasma cleaning were identified as outlier values. These outlier values were identified i n “Tier_2a_NF3_and_C2F6_Emission_Factor_Calculations.xls” (Docket ID: EPA

- HQ

- OAR

- 2011

- 0028

- 0090). [B]

– An Tier 2a NF 3 remote clea n factor was not included in the October 16, 2012 proposed amendments (see 77 FR 63538)

. [ C ]

– The remote clean beta distribution emission factor (CVD Remote) was not developed using a simple averaging method. Please ref er to the analysis in the November

2 010 TSD (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0195) of the NF 3 Remote Clean emission factor, which states that emission factor values with utilization efficiencies between 81 percent and 89 percent were removed after a statistical analysis was performed on the data. A mean value of 0.018 was chosen by EPA after removing the

outliers for remote plasma chamber cleaning with NF 3 for both 200 and 300 mm wafer processing systems by fitting the data to a beta distribution.

### 9 Table 1

- 6. Revised Tier 2a Default Emission Factors (1

- U ij 

### ) for Gas Utilization Rate (U ij 

### ) for Semiconductor Manufacturing for 300 mm and 450 mm Wafer Sizes

Input Gas Proposed Tier 2a

Emission Factor Final Tier 2a Emission

Factor Calculation Note

C 2 F 6 0.80 0.80 Arithmetic average

– Emission factor data available for etch only

C 4 F 6 0.18 0.15 Arithmetic average

– Emission factor data available for etch only

C 4 F 8 0.17 0.18 Arithmetic average

– Emission factor data available for etch only

C 5 F 8 0.13 0.10 Arithmetic average

– Emission factor data available for etch only

CF 4 0.63 0.65 Arithmetic average

– Emission factor data available for etch only

CH 2 F 2 0.15 0.21 Arithmetic average

– Emission factor data available for etch only

CH 3 F NA 0.33 Arithmetic average

– Emission factor data available for etch only

CHF 3 0.39 0.42 Arithmetic average

– Emission factor data available for etch only

NF 3 0.17 0.20 Consumption weighted

NF 3 Remote Clean [ A ] 0.018 [ B ]

SF 6 0.23 0.32 Consumption weighted

C 3 F 8 0.063 0.20 Arithmetic average

– Consumption data available for etch only [ C ]

[A]

– A Tier 2a NF 3 remote clean factor was not included in the October 16, 2012 proposed amendments (see 77 FR 63538)

. [ B ]

– The remote clean beta distribution emission factor (CVD Remote) was not developed using a simple averaging method. Please refer to the analysis in the November

2010 TSD (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0195) of the NF 3 Remote Clean emission factor, which states that emission factor values with utilization efficiencies between 81 percent and 89 percent were removed after a statistical analysis was performed on the data. A mean value of 0.018 was chosen by EPA a fter removing the outliers for RPS chamber cleaning with NF 3 for both 200 and 300 mm wafer processing systems by fitting the data to a beta distribution. [ C ]

– Emission factor data available for both etch and remote plasma cleaning, however, consumption data are only available for etc h.

### 10 Table 1

- 7. Revised Tier 2a By

- product For mation Rates (B ijk 

### ) for Semiconductor Manufacturing f or 150 mm and 200 mm Wafer Sizes

Input Gas By

- Product Proposed Tier 2a

Emission Factor Final Tier 2a

Emission Factor Calculation Note

C 2 F 6 CF 4 0.13 0.19 Consumption weighted

CHF 3 NA 0.047 Arithmetic average

– Emission factor available for etch only

C 2 HF 5 C 2 F 6 0.024 0.024 Arithmetic average

– Emission factor available for etch only

CF 4 0.077 0.077 Arithmetic average

– Emission factor available for etch only

C 4 F 6 C 2 F 6 0.11 0.11 Arithmetic average

– Emission factor available for etch only

CF 4 0.13 0.13 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.066 Arithmetic average

– Emission factor available for etch only

C 4 F 8 C 2 F 6 0.037 0.037 Arithmetic average

– Emission factor available for etch only

C 5 F 8 NA 0.0086 Arithmetic average

– Emission factor available for etch only

CF 4 0.12 0.11 Consumption weighted

CHF 3 NA 0.040 Arithmetic average

– Emission factor available for etch only

C 5 F 8 C 2 F 6 NA 0.014 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.0039 Arithmetic average

– Emission factor available for etch only

CF 4 C 2 F 6 0.048 0.046 Arithmetic average

– Emission factor available for etch only

C 5 F 8 NA 0.0012 Arithmetic average

– Emission factor available for etch only

CHF 3 0.11 0.10 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 C 2 F 6 0.025 0.025 Arithmetic average

– Emission factor available for etch only

CF 4 0.081 0.079 Arithmetic average

– Emission factor available for etch only

CHF 3 0.066 0.049 Arithmetic average

– Emission factor available for etch only

CH 3 F C 2 F 6 NA 0.0034 Arithmetic average

– Emission factor available for etch only

CHF 3 C 2 F 6 0.031 0.030 Arithmetic average

– Emission factor available for etch only

C 5 F 8 NA 0.0012 Arithmetic average

– Emission factor available for etch only

CF 4 0.085 0.085 Arithmetic average

– Emission factor available for etch only

NF 3 C 2 F 6 NA 0.025 Arithmetic average

– Emission factor available for etch only

CF 4 0.021 0.045 Consumption weighted

NF 3 Remote Clean CF 4 [A] 0.015 [B]

SF 6 C 2 F 6 0.17 0.11 Arithmetic average

– Emission factor available for etch only

CF 4 0.15 0.13 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.0012 Arithmetic average

– Emission factor available for etch only

C 3 F 8 CF 4 0.20 0.20 Arithmetic average

– Emission factor available for in

- situ plasma cleaning only

C 4 F 8 O C 2 F 6 0.045 0.045 Arithmetic average

– Consumption data unavailable for C 4 F 8 O

CF 4 0.13 0.13 Arithmetic average

– Consumption data unavailable for C 4 F 8 O
[A]

– A Tier 2a NF 3 remote clean factor was not included in the October 16, 2012 proposed amendments (see 77 FR 63538)

. [ B ]

– The remote clean beta distribution emission factor (CVD Remote) was not developed using a simple averaging method. Please ref er to the analysis in the November

2010 TSD (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0195) of the NF 3 Remote Clean emission factor, which states that emission factor values with utilization efficiencies between 81 percent and 89 percent were removed after a statistical anal ysis was performed on the data. A mean value of 0.018 was chosen by EPA after removing the

outliers for remote plasma chamber cleaning with NF 3 for both 200 and 300 mm wafer processing systems by fitting the data to a beta distribution.

### 11 Table 1

- 8. Revised Tier 2a By

- product For mation Rates (B ijk 

### ) for Semiconductor Manufacturing for 300 mm and 450 mm Wafer Sizes

Input Gas By

- Product Proposed Tier 2a Emission Factor Final Tier 2a Emission Factor Calculation Note

C 2 F 6 CF 4 0.21 0.21 Arithmetic average

– Emission factor available for etch only

C 4 F 6 C 2 F 6 0.090 0.074 Arithmetic average

– Emission factor available for etch only

CF 4 0.066 0.059 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 NA 0.000030 Arithmetic average

– Emission factor available for etch only

CHF 3 0.022 0.019 Arithmetic average

– Emission factor available for etch only

C 4 F 8 C 2 F 6 0.030 0.031 Arithmetic average

– Emission factor available for etch only

C 4 F 6 0.018 0.018 Arithmetic average

– Emission factor available for etch only

CF 4 0.046 0.045 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 NA 0.0015 Arithmetic average

– Emission factor available for etch only

CHF 3 0.028 0.027 Arithmetic average

– Emission factor available for etch only

C 5 F 8 C 2 F 6 0.083 0.083 Arithmetic average

– Emission factor available for etch only

C 3 F 8 NA 0.00012 Arithmetic average

– Emission factor available for etch only

CF 4 0.013 0.11 Arithmetic average

– Emission factor available for etch only

CHF 3 0.010 0.0069 Arithmetic average

– Emission factor available for etch only

CF 4 C 2 F 6 0.092 0.079 Arithmetic average

– Emission factor available for etch only

C 4 F 8 0.00063 0.00063 Arithmetic average

– Emission factor available for etch only

CH 3 F NA 0.0080 Arithmetic average

– Emission factor available for etch only

CHF 3 0.011 0.011 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 C 2 F 6 0.068 0.052 Arithmetic average

– Emission factor available for etch only

CF 4 0.059 0.049 Arithmetic average

– Emission factor available for etch only

CH 3 F NA 0.0080 Arithmetic average

– Emission factor available for etch only

CHF 3 0.052 0.050 Arithmetic average

– Emission factor available for etch only

CH 3 F C 2 F 6 NA 0.00087 Arithmetic average

– Emission factor available for etch only

CF 4 NA 0.045 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 NA 0.0023 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.0057 Arithmetic average

– Emission factor available for etch only

CHF 3 C 2 F 6 0.078 0.064 Arithmetic average

– Emission factor available for etch only

C 4 F 6 0.00010 0.00010 Arithmetic average

– Emission factor available for etch only

C 4 F 8 0.00080 0.00080 Arithmetic average

– Emission factor available for etch only

CF 4 0.10 0.10 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 NA 0.0036 Arithmetic average

– Emission factor available for etch only

CH 3 F NA 0.0080 Arithmetic average

– Emission factor available for etch only

NF 3 C 2 F 6 0.057 0.045 Arithmetic average

– Emission factor available for etch only

CF 4 0.062 0.040 Consumption weighted

CH 2 F 2 NA 0.00086 Arithmetic average

– Emission factor available for etch only

CH 3 F NA 0.0080 Arithmetic average

– Emission factor available for etch only

CHF 3 0.035 0.025 Arithmetic average

– Emission factor available for etch only

NF 3 Remote Clean CF 4 [A] 0.075 [B]

SF 6 C 2 F 6 0.067 0.044 Arithmetic average

– Emission factor available for etch only

CF 4 0.062 0.040 Arithmetic average

– Emission factor available for etch only

CH 2 F 2 NA 0.000029 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.0037 Arithmetic average

– Emission factor available for etch only

C 3 F 8 C 2 F 6 NA 0.18 Arithmetic average

– Emission factor available for etch only

### 12 Input Gas By

- Product Proposed Tier 2a Emission Factor Final Tier 2a Emission Factor Calculation Note

CF 4 NA 0.21 Arithmetic average

– Emission factor available for etch only

CH 3 F NA 0.00073 Arithmetic average

– Emission factor available for etch only

CHF 3 NA 0.012 Arithmetic average

– Emission factor available for etch only
[A]

- A Tier 2a NF 3 remote clean factor was not included in the October 16, 2012 proposed amendments (see 77 FR 63538)

. [ B ]

– The remote clean beta distribution emission factor (CVD Remote) was not developed usin g a simple averaging method. Please refer to the analysis in the November

2010 TSD (Docket ID: EPA

- HQ

- OAR

- 2009

- 0927

- 0195) of the NF 3 Remote Clean emission factor, which states that emission factor values with utilization efficiencies between 81 percent an d 89 percent were removed after a statistical analysis was performed on the data. A mean value of 0.018 was chosen by EPA aft er removing the

outliers for remote plasma chamber cleaning chamber cleaning with NF 3 for both 200 and 300 mm wafer processing syst ems by fitting the data to a beta distribution.

### 13 2.0 DERIVATION OF DEFAUL T DRES USING VARIANC E COMPONENTS

METHOD

2.1 Introduction
This part provides technical support for the changes to the derived default destruction and removal efficiencies (DREs) for point

- of

- us e (POU) abatement systems under subpart I, Electronics Manufacturing, of the Greenhouse Gas Reporting Program (GHGRP). Specifically, this part provides EPA’s methodology for derivation of default DREs, which is based on a statistical method suggested by th e Semiconductor Industry Association (SIA) in Attachment C of their comments to the proposed amendments to Subpart I (Docket Id. No. EPA

- HQ

- OAR

2011

- 0028

- 0095), and using the data available for the final rule amendments.

In their comments on the proposed amendments published on October 16, 2012 (77 FR 63538), SIA indicated that it performed a Components of Variance Analysis, using a random effects model, to generate variance components to estimate how much of the overall variability is

associated with the differences among fabs (σ 2 

### Fabs) versus the differences among the devices in a fab (σ 2 

### Devices). (See docket item EPA

- HQ

- OAR

- 2011

- 0028

- 0095, attachment C, for the SIA’s explanation of their methodology.) The SIA argued that this method was more appropriate

f

or developing a default DRE value for all the devices in a fab and would result in higher default DRE values that the method used by EPA to develop the proposed values.

EPA has reproduced this analysis using the full DRE dataset that is based on the data

u sed in the development of the final 2010 subpart I rule, the proposed amendments, and additional data provided during the public comment period for the proposed amendments. The EPA’s rationale for selecting the SIA’s method over the EPA method used for the proposed amendments is included in the preamble to the final rule amendments.

2.2 Overview for Estimation of Variance Components
Analysis of Variance (ANOVA) is a statistical analysis that can be used to test the hypothesis that the means among two or more gr oups are equal. In an ANOVA, the variation in the measurements is segregated into components that correspond to different sources of variation (i.e., the variation in the average DRE across fabs ( σ 2 

### Fabs ) versus the variation in DRE across individual devices in a fab (σ 2 

### Devices). Individual fabs that provide DRE test data will have averages that are affected by both sources of variability. The mathematical model that describes the relationship between the response and treatment for the one

- way ANOVA is given by:

Y

ij 

### = μ + τ i 

### + ε ij



### where Y ij 

### represents the j

- th observation ( j = 1, 2, ... n i 

### ) on the i

- th treatment ( i = 1, 2, ..., k levels). The parameter μ represents the overall average DRE in the data for a gas, τ i 

### represents
the i

- th treatment effect (e.g., the differences between fabs) and ε ij 

### represents the random error present in the j

- th observation on the i

- th treatment (the differences between the p erformance of device j from the average in its fab). For the DRE data, this may be conceptually written as:

DRE Fab I, Device J 

### = DRE 0 

### + ΔDRE Fab I 

### + ΔDRE Fab I, Device J

### 14 where DRE 0 

### is equivalent to μ , ΔDRE Fab I 

### is τ i 

### , and ΔDRE Fab I, Device J 

### is ε ij.



### Because the sampling of the DRE population is based on a random selection of fabs from the larger population, the model used is a random effects model, with errors ε ij 

### assumed to be normally and independently distributed, with mean zero and variance σ

ε 2 

### , a nd treatments τ i 

### normally and independently distributed with mean zero and variance στ2. A random effects model is used because we do not know whether a particular fab or device is above or below the average for fabs or for devices within the fab.

The ra ndom effects model is acceptable for the purpose of identifying the sources of variance in a sample and making inferences regarding the size (magnitude) of each source of variance, which are estimated as the variance components σ

ε 2 

### and σ

τ 2 

### . These variance components are used to derive the default DREs for each gas (see Section 2. 3 of this document).

2.3 Methodology

EPA performed the ANOVA on the available DRE dataset using data and information from the following:

**•** Technical Support Document for Process Emission s from Electronics Manufacture (e.g., Micro

- electro

- mechanical systems, liquid crystal displays, photovoltaics, and semiconductors): Proposed Rule for Mandatory Reporting of Greenhouse Gases, Revised

– November 2010 , docket item EPA

- HQ

- OAR

2009

- 0927

- 0195.

**•** Technical Support for Accounting for Destruction or Removal Efficiency for Electronics Manufacturing Facilities under Subpart I, docket item EPA

- HQ

- OAR

2011

- 0028

- 0082.

**•** Data submitted by SIA during the public comment period and available in docket

item EPA

- HQ

- OAR

- 2011

- 0028

- 0095, attachment B.

EPA followed a basic methodology to complete the ANOVA that was referenced by the

commenters and is outlined in the NIST/SEMATECH e

- Handbook of Statistical Methods. 1



### An alternative method to fit random

- effects models is Maximum Likelihood Estimation (MLE). Unlike LSE, MLE requires no minimal distributional assumptions, and therefore can be used with data that are not normally distributed. MLE is a standard approach to parameter estimation and inference in statistics and econometrics. The principle of maximum likelihood estimation states that the desired probability distribution is the one that makes the available data Standard ANOVA uses a least

- squares estimation (LSE ) approach, which hinges on the assumption that the analyzed variable is normally distributed. However, for the available DRE data, observations are typically restricted in the interval between 0 and 100 and clustered towards the top end of the distributio n.

1 http://www.itl.nist.gov/div898/handbook/ (accessed May 18, 2013.)

### 15 “most likely” to be observed. 2



### EPA first performed an ANOVA on an individual

- gas basi s and calculated restricted maximum likelihood estimates of the variance components for all gases using Stata software. The variance components for the DRE data are defined as σ

τ 2 

### = **σ** 2 

### (Fabs) and σ

ε 2 

### = **σ** 2 

### (Devices). The variance components from this model ar e provided in Table 2

- 1 of this document and are used to calculate default DREs for each gas (see Section 2. 3 of this document). The MLE estimation method is known to be biased when the true population mean is unknown (e.g., for small sample sizes, the sample average is less likely to be a good predictor of the population mean). Therefore, a variant of MLE, the restricted maximum likelihood (REML) me thod, is used. REML is typically used for fitting mixed models that have

both fixed

- effect and random

- effect portions. In contrast to the MLE method, the REML methodology produces less biased results.

In the proposed amendments, EPA grouped together the non

- CF 4 

### carbon

- based etch gases

to set a group

- average default of 98 perce nt. In their comments on the proposed rule, SIA recommended that EPA continue to group the non

- CF 4 

### carbon

- based etch gases, and provided an analysis that augmented the random effects model to calculate the variance components for the combined gases, includ ing a variance component for differences among the individual gases. This analysis assumed that the different carbon

- based etch gases have the same DRE

distributions.

To determine a group

- average for the non

- CF 4 

### carbon

- based etch gases, EPA has

calculated variance components using a joint model where the gas is treated as a fixed effect and

the fab and individual device error are treated as random effects. Fixed effects are variables that do not change and are not based on a random sample. This model is more appropriate for estimating the variance components of the combined carbon

- based gases because, in contrast to the SIA approach, as it does not treat the gas as a random effect of the sampling. The use of a joint model also avoids the limitations of the individual

- gas approach that arise when only small sample sizes are available. Because MLE estimates are calculated as the best fit to the observed data, when fewer observations are available, there is a greater risk that the estimates will be further from the actual population parameters. Because the sample sizes of several carbon

- based etch gases are quite small (less than 10 observations), the estimated variance components from the joint model may have better statistical po wer than those calculated using the individual gas

method.

For the same reasons, EPA also used the REML methodology discussed above to develop variance estimates in the joint model. In small samples, REML produces variance component

estimates that are les s biased because it takes into consideration the degrees of freedom from the fixed effects. The variance components for the combined carbon

- based etch gases are provided

in Table 2

- 2 of this document. These variance components are used to calculate a group

- average default DRE as discussed in Section 2. 3 of this document.

2 For details on MLE estimation, see Myung, IJ. 2002. Tutorial on maximum likelihood estimation. Journal of Mathematical Psychology

47 (2003), pp. 90

– 100. Available at: http://people.physics.anu.edu.au/~tas110/Teaching/Lectures/L3/Material/Myung03.pdf (accessed June 13, 2013).

### 16 2.4 Derivation o f Default D RE s The variance components derived in Section 2. 2 are used in the derivation of the default DREs based on the method suggested by SIA, which uses the variance compon ents to adjust the standard deviation of the fab average. In particular, if a fab is picked at random, and it contains N devices abating a particular gas, its average DRE would be expected to vary from the overall average for the gas by an amount governed by the standard deviation for fab averages: σ = sqrt ( **σ** 2 

### (Fabs) + **σ** 2 

### (Devices)/N). Therefore, the lowest average DRE for a fab is estimated using the

formula:

Default DRE = DRE 0 

### - 2 x sqrt [ **σ** 2 

### (Fabs) + **σ** 2 

### (Devices) / N ] (Equation 1)

where the mean DRE 0 

### is the overall average DRE in the data for the gas, the variance
components σ 2 

### (Fabs) and σ 2 

### (Devices) are defined above, and N is based on the smallest number of abatement devices that one is expected to find in a fab. The values of N are based on the

res ults of an SIA survey of its members and are as follows:

Etch CF 4 

### : N = 20

NF 3 

### : N = 15

SF 6 

### : N = 10

Other Carbon

- based Gases: N = 5

NF 3 

### Chamber Cleaning: N = 20

Although SIA did not include singleton data points (i.e., data points from fabs in which

on ly one DRE measurement is available) in calculating the fab average DRE for each gas, EPA has included the singleton data points in both the analysis of the variance components and in the calculation of the default DREs for consistency in the treatment of the available data from each fab. The calculation of the default DRE relies on the average of individual observations. Therefore, the singleton observations are not more likely to be outliers and would not affect the overall mean differently than a fab wit h more than one data point for a particular gas.

In Table 2

- 1, the default DRE is assigned for each gas on an individual

- gas basis. This approach would allow for facilities to take advantage of the higher DREs for individual gases but may be more burdensom e to reporters accounting for many of these gases in their abatement

related calculations . EPA estimated variance components ( **σ** (Fabs) and **σ** (Devices)) for the

individual

- gas approach, as described in Section 2. 2, and developed the default DREs for each

gas using Equation 1.

Table 2

- 1. Etch and Clean DRE, Analysis of Variance, Restricted Maximum Likelihood (Individual Gas Basis)

Input

Gas DRE Average DRE

Count Fabs **σ** (Fabs) **σ** Devices) N Default

DRE SIA value

included in

comments

C 2 

### F 6 

### 98.8 5 3 1.849 0.497 5 95.1 2 97

C 4 

### F 6 

### 98.6 9 2 2.57E

- 09 2.541 5 96. 28 96

C 4 

### F 8 

### 98.5 24 2 0.748 1.687 5 96. 37 97

C 5 

### F 8 

### 96.6 1 1 0.000 0.000 5 96. 59 97

CF 4 

### 83.6 66 7 4.79E

- 05 18.309 20 75. 37 75

### 17 Input

Gas DRE Average DRE

Count Fabs **σ** (Fabs) **σ** Devices) N Default

DRE SIA value

included in

comments

CH 2 

### F 2 

### 98.7 30 2 0.623 1.590 5 96.8 5 97

CH 3 

### F 99.2 4 3 7.83E

- 11 0.927 5 98.4 1 98

CHF 3 

### 99.1 43 4 0.691 1.140 5 97. 38 98

NF 3 

### (etch) 98.5 31 3 3.27E

- 07 4.205 15 96.3 4 96

NF 3 

### (clean) 93.3 110 6 1.829 9.377 20 87. 76 88

SF 6 

### 98.7 2 0 6 0.659 1.010 10 97.2 2 98



### For the combined non

- CF 4 

### carbon

- based etch gases, the default DRE is calculated similarly, with the exception that DRE 0 

### (from Equation 1) is the modeled DRE Fixed Effect estimate for each gas. The DRE Fixed Effect estimate is derived from the REML methodology

and is calculated in Stata. This estimate is used in lieu of the raw DRE ave rage for each gas because the raw averages for each gas include variations between fabs, and are therefore less precise. For example, even if a high raw average is observed for an individual gas, this may be caused by the fact that a disproportionate amoun t of the observations are coming from a fab which has "above average" DRE.

EPA calculated the variance components ( **σ** (Fabs) and **σ** (Devices)) for the non

- CF 4 

### carbon

- based etch gases using Stata. The results are shown in Table 2

- 2 below. The variance components only describe the variability between fabs and between devices (a ny difference between gases is already accounted for by the gas effect, which is assumed to be fixed), thus, these values do not change for each gas. The defa ult DRE may be averaged over all the gases to produce a group

- average DRE of 96.7 1 percent for the non

- CF 4 

### carbon

- based etch gases.

Table 2

- 2. Etch DRE for non

- CF 4 

### carbon

- based F

- GHG, Joint Model, Restricted Maximum Likelihood

Input

Gas DRE

Fixed

Effec t DRE

Count Fabs **σ** (Fabs) **σ** (Devices) N Default

DRE Group

Average

DRE SIA

group

average

value

C 2 

### F 6 

### 98.6 116 5 0.631 1.523 5 96. 76

96.71 97 C 4 

### F 6 

### 98.6 116 5 0.631 1.523 5 96.7 4

C 4 

### F 8 

### 98.7 116 5 0.631 1.523 5 96.8 0

C 5 

### F 8 

### 96.8 116 5 0.631 1.523 5 94.97

CH 2 

### F 2 

### 98.9 116 5 0.631 1.523 5 97.0 0

CH 3 

### F 99.2 116 5 0.631 1.523 5 97.3 3

CHF 3 

### 99.2 116 5 0.631 1.523 5 97. 35



### In this final rule, EPA is adopting the single default DRE for all of the non

- CF 4 

### carbon

based F

- GHG shown in Table 2

- 2. This approach should reduce burden on reporters with abatement systems while still reflecting the high DRE values expected for these gases.

Therefore , the final table of default DRE values will be those listed below in Table 2

- 3.

### 18 Table 2

- 3 . Final default DRE values using a single combined

DRE for non

- CF 4 

### car bon

- based F

- GHG s

Process Type Input Gas Default DRE

Plasma Etch and Wafer

Clean CF 4 

### 75

C 2 

### F 6



### 97 C 4 

### F 6 

### C 4 

### F 8 

### C 5 

### F 8 

### CH 2 

### F 2 

### CH 3 

### F

CHF 3 

### All other carbon

- based F

- GHG 60

NF 3 

### 96

SF 6 

### 9 7

Chamber Clean NF 3 

### 8 8

All other chamber clean F

- GHG 60

N 2 

### O Using Processes CVD and all other N 2 

### O

- using processes 60



### 3.0 REVISION OF MAXIMUM FIELD DETECTION LIMI TS FOR THE STACK

TEST METHOD

3.1 Introduction
This part provides technical support for the changes to the proposed maximum field detection limits (FDLs) under subpart I, Electronics Manufacturing, of the Greenhou se Gas Reporting Program . Specifically, this part provides EPA’s methodology for developing revised

maximum FDLS , base d on comments on the proposed a mendments to Subpart I and using the

data available.

The FDL is the lowest concentration at which an F

- GHG can be detected during a specific field measurement. The maximum allowed FDL is the concentration at which an F

- GHG

s hould be detectable when the method is conducted properly and the analytical instruments are used correctly and of reasonable quality. Maximum FDLs are specified to ensure that the field

measurements of F

- GHG emissions are of adequate accuracy and precisio n , and that the fraction of total emissions that are below the FDL (and which have to be assumed to be one

- half the FDL) is minimized. EPA Method 320 is greatly enhanced by the specification of maximum

FDLs because the FDLs achieved by a method and analytical instruments can have a significant impact on the quality of the measurements. M aximum FDLs are necessary because if the FDL

for a F

- GHG is too high

, measurements may miss a relatively large fraction of the fab’s

emission s of that F

- GHG that may occur at concentrations that are lower than what is detectable by the instrumentation. This results in the uncertainty of the emission estimate s being correspondingly h igh.

Commenters on the proposed amendments (7 7 FR 63538 ) indicated that the maximum

FDL values in Table I

- 10 of the proposed amendments to subpart I have been achieved in very limited circumstances with specifically enhanced FTIR measurement systems. The commenters

### 19 noted that stack testing at three f abs was completed in support of the proposed testing alternative and the emissions reports from these tests revealed that the proposed maximum FDLs were not always met. The commenters recommend ed that the maximum FDLs b e increased by a factor of

five to av oid limiting the number of available testing contractors with enhanced measurement equipment and to avoid rendering test results invalid if the FDLs exceeded the maximum

allowed FDLs.

In light of these comments, EPA further examined the FDLs that have been achieved at three semiconductor facilities (see test reports for Intel, IBM, and Texas Instruments available in

docket EPA

- HQ

- OAR

- 2011

- 0028) and correspondingly analyzed potential changes to the

maximum FDLs for subpart I

.

3.2 Review of Proposed Maximum FDL s EPA acknowledges the industry commenters’ assertion that two of the three facilities that

submitted information on FDLs used enhanced FTIR technology during stack testing and that not all stack testing contractors have the capability to perform these enhan ced FTIR measurements.
The EPA re

- analyzed the available information for the three semiconductor facilities to assess the FDL levels that were achievable by the facilit y using other accurate and well

- maintained , but not enhanced, FTIR,. The FTIR equipment used by these three facilities is anticipated to be representative of what would be used by the field of reporters and represent accurate and well

maintained equipment in the industry

.
EPA first examined the FDLs achieved for each analy te based on data from the stack test reports for the three semiconductor facilities. Using these data, EPA considered the standard deviation between the FDLs achieved at each facility, as well as the percent differences between the two facilities using the enhanced FTIR method (Facilities A and B in Table 3

- 1) and the third facility, which used standard FTIR procedures (Facility C in Table 3

- 1).

Table 3

- 1

. Differences Between Facility Field Detection Limits

Analyte FDLs Achieved by Facility (ppbv) Facility

A and B Average

FDL (ppbv) Average

FDL of

All

Facilities

(ppbv) St. Dev

of All

Facilities

(ppbv) Percent

Difference c (Facility A

and B) Percent

D ifference d
(Facility A and B Average & Facility C FDL ) Facility

A a Facility

B a Facility

C b

CF 4 n/a 0.889 3 0.9 1.9 237%

C 2 F 6 2 0.962 15.8 1.5 6.3 8.3

- 52% 967%

C 3 F 8 1.5 1.5 1.5

C 4 F 6 2.6 4.7 2.6 3.65 81%

C 5 F 8 0.8 0.8 0.8

cC 4 F 8 0.8 1.249 7.2 1.0 3.1 3.6 56% 603%

CH 2 F 2 3.5 29 3.5 16.25 729%

CH 3 F 34.7 34.7

CHF 3 n/a 1.06 12.2 1.1 6.6 1051%

NF 3 3 0.886 5.5 1.9 3.1 2.3

- 70% 183%

SF 6 0.1 0.802 1.7 0.5 0.9 0.8 702% 277%

a Facilities A and B used enhanced FTIR measurement techniques.

### 20 b Facility C used standard FTIR measurement techniques.

c This is determined by the equation: [(Facility B FDL)

– (Facility A FDL)/(Facility A FDL)*100%

d This is determined by the equation: [(Facility C FDL)

- (Facility A and B average FDL)]/(Facility A and B average FDL)*100%



### Based on this analysis, EPA concl uded that although there were some differences between the FDLs achieved by the two facilities using enhanced FTIR (Facilities A and B), there were generally significant differences between the FDLs achieved for specific F

- GHGs by the facilities using enha nced FTIR equipment ( Facilities A and B ) and the facility using standard

FTIR equipment (Facility C). As such, EPA determined that the proposed maximum FDLs could be too low to be achieved by facilities not using enhanced FTIR equipment

.
In the proposed r ule, the GWP of the corresponding gases was used to determine the overall effect on emissions (in CO 2 e) of different maximum FDLs. To determine the maximum

FDL s for the final rule, EPA also considered how the maximum FDLs in the October 16, 2012 proposed r ule and the FDLs achieved by Facility C translated into corresponding F

- GHG emissions (in CO 2 e). To determine these emissions, the EPA used the known molecular weights for each gas, an assumed fab

- wide gas stack flow rate, and simple unit conversions.

Tabl e 3

- 2 presents the original analysis of how the proposed maximum FDLs translate into corresponding F

- GHG emissions at the proposed maximum FDLs at an example facility.

Table 3

- 3 presents EPA’s analysis of how the FDLs achieved by Facility C translate into corresponding F

- GHG emissions.

Table 3

- 2

. Emissions at Pr oposed Maximum Field Detection Limits

Analyte Proposed

Maximum

FDL a (pp b v) M olecular

W eight (g/mole) Assumed

Fab

- Wide

Flow rate

(scfm) Emission rate ( mt/yr ) GWP Emission

rate ( mtCO2e/yr )

CF 4 5 88 150,000 0.04 1 6

, 500 266

C 2 F 6 5 138 150,000 0.06 4 9

, 200 590

C 4 F 8 5 200 150,000 0.09 3 8

, 700 808

CH 2 F 2 1 0 52 150,000 0.0 48 675 33

CHF 3 5 70 150,000 0.03 3 11

, 700 380

NF 3 5 71 150,000 0.03 3 17

, 200 567

SF 6 1 146 150,000 0.01 4 23

, 900 324

Total 2,968

a From 77 FR 63538 ( October 16, 2012 )

.



### Table 3

- 3

. Facility C Emissions at Achiev ed Field Detection Limits

Analyte Measured FDL (pp b v) M olecular

W eight (g/mole) Assumed

Fab

- Wide

Flow rate

(scfm) Emission

rate ( mt/yr ) GWP Emission

rate ( mtCO2e/yr )

CF 4 3 88 150

, 000 0. 02 5 6

, 500 159

C 2 F 6 15.8 138 150

, 000 0. 2 0 9

, 200 1

, 86 3

C 4 F 8 7.2 200 150

, 000 0.13 8

, 700 1

, 163

### 21 Analyte Measured FDL (pp b v) M olecular

W eight (g/mole) Assumed

Fab

- Wide

Flow rate

(scfm) Emission

rate ( mt/yr ) GWP Emission

rate ( mtCO2e/yr )

CH 2 F 2 29 52 150

, 000 0.14 675 9 5

CHF 3 12.2 70 150

, 000 0. 0 79 11

, 700 92 8

NF 3 5.5 71 150

, 000 0.0 36 17

, 200 62 4

SF 6 1.7 146 150

, 000 0. 023 23

, 900 55 1

Total 5
, 38 3



### It should be noted that the maximum FDLs included in the proposed rule were based primarily on the technical achievability of those detection levels. To determine maximum FDLs for the final rule that are achievable by facilities using standard FTIR techniq ues, EPA determined at what level the maximum FDLs would be achievable by Facility C. EPA examined maximum FDLs based on raising the proposed FDLs by three, four, and five times (shown in

Table 3

- 4). Based on this review, EPA determined that Facility C cou ld achieve maximum FDLs based on four times the proposed FDLs.

Table 3

- 4

. Comparison of Facility C A chieved FDLs with Proposed Values

Analyte Facility C

Ach i e ved FDLs Proposed FDL s Proposed FDLs x 3 Proposed FDLs x 4 Proposed

FDLs x 5

CF 4 3 5 15 20 2 5

C 2 F 6 15.8 5 15 20 2 5

C 3 F 8 Not Measured 5 15 20 2 5

C 4 F 8 7.2 5 15 20 2 5

CH 2 F 2 29 10 30 40 50

CHF 3 12.2 5 15 20 2 5

NF 3 5.5 5 15 20 2 5

SF 6 1.7 1 3 4 5

C 4 F 6 4.7 5 15 20 2 5

C 5 F 8 Not Measured 5 15 20 2 5



### EPA determined that it was not necessary to increase the maximum allowed FDLs by a

facto r of five to establish levels that could be achieved by testing companies using EPA Method

320 . T he analysis of data and information provided to EPA on this topic demonstrate s that an increase by a factor of four results in achievable maximum FDL values. The se final FDLs (shown in Table 3

- 5) achieve the necessary balance between achievable FDLs and minimum uncertainty in the emission measurements derived from stack testing. All of the final maximum

FDLs are higher than the FDLs achieved at the three facilities during their stack testing and are expected to be achievable by sources using the stack test method

.

### 22 Table 3

- 5

. Final Maximum Field Detection Limits (Table I

- 10 in Subpart I)

A nalyte CF 4 C 2 F 6 C 3 F 8 C 4 F 6 C 5 F 8 c

- C 4 F 8 CH 2 F 2 CH 3 F CHF 3 NF 3 SF 6 Other F ully

F luorinated

GHGs Other

F luorinated

GHGs

Max imum FDLs (ppbv) 20 20 20 20 20 20 40 40 20 20 4 20 40