Outstanding Questions / Topics from SIA / EPA Discussions as of April 24, 2012
Response as of April 26 , 2012 The following represents the list of questions / topics EPA believes still need to be resolved as part of our discussions and workplan with SIA leading to a rule proposal revising subpart I. We ask that SIA review this document and add any additional ques tions / topics SIA believes are still unresolved. The goal of this document is to cover all outstanding questions / topics by Monday, April 30 th

. Outstanding questions for SIA from 4/19 call:
Apportioning model verification :

1. Please provide a suggested definition of "representative of normal operation".
Industry response in progress.
DRE summary paper :

1. Please provide an outline / bullet points that describe what content from the ISMI guidelines SIA is proposing to include in s ubpart I with regard to measurement of site

specific DRE values. Please also provide the purpose / use of each guideline method in the context of subpart I.
Responded to in prior submittal “Questions for 4

- 19

- 12...”

2. Can SIA provide, for the chamber clean NF3 DRE tests, which abatement system tests operated outside of the manufacturer's recommendations and which ones did not? Please also provide information on what caused the unit to operate outside of allowed parameters (i.e. high flow) for the cases wher e manufacturer's recommendations were
not observed

. Responded to in prior submittal “Questions for 4

- 19

- 12...”
Outstanding question for SIA from 4/23 call:

1. N2O default emission factor

– EPA has noted the average N2O emission factor from data submitted by SIA is above 1, which suggests N2O is being generated as a byproduct. Would SIA prefer to use one default EF for all N2O emissions, which would theoretically be above 1, or use two default EFs

– one for input N2O and one for byproduct N2O? The industry pref ers one default factor. If the latter, can SIA elaborate on which semiconductor processes are expected to generate N2O as a byproduct? The industry is uncertain whether or not emission factor values above 1.0 are due to measurement errors or N2O byproduct formation ; however, we are unaware of semiconductor manufacturing processes that generate N2O as a byproduct.

In our March 7, 2012 response to EPA’s Stack Question 1, we indicated that the measured stack N2O EF for the f abs were univers ally anomalous, that N2O Limits of Detection are relatively high because the FTIR’s used for stack testing have largely b een tuned to optimize for F

- GHG , and because the ambient conc entration of N2O is high. Consequently we recommended the use of a default EF for N2O.Based upon the data that we have, the cause for the large range in N2O EF is not

clear. Ana lysis of multiple years of one semiconduct or company ’ s (C ompany A) N2O stack measurement data shows an anomalous high emission factor in 2005. This high emission factor is believed to be due to incorrectly recorded N2O usage data (2005 usage is 3

- 4X lower than usage in 2004 and 2006). If calculated N2O EF for 200 6

-

2011 are averaged, the Intel EF=1.2. A second semiconductor company B tested for N2O in accordance with Method 320 and submitted data showing Fab 1
EF= 0.34 in March and EF=0.66 in August. Company B ’ s Fab 1 average EF=0.5. The av erage of Company A ’ s and B ’ s EF=1.02.

Because it is not clear that the large N2O EF are due to byproducts, and also because there doesn’t seem to be any data supporting a technical appr oach for assigni ng a distinct EF for feed N2O vs

. byproduct N2O, we recommend a single factor.

Based on fact that the a verage EF for Company A and B is 1.02 and because there is doubt that N2O is generated as a byproduct, we would propose : a) A ssume a default EF=1.0 ; b) If industry develops additional data to support an alternative N2O emission factor, it will be introduced before the end of the comment period or as part of an emission factor update report.

Summary of other outstanding topic s & curre nt status/task :

1. DRE

a. Infrequently used gas threshold / clause

– EPA to send feedback to SIA for
review

b. Revisit clean NF3 default DRE

– SIA to send revised data; EPA to review

c. Process to validate an alternative DRE measurement method

– EPA to send draft to SIA for feedback

d. Recordkeeping, requirements suggestions on page 1 of DRE summary response

– EPA to provide response to SIA ’s feedback

2. Stack method

– Process to validate an alternative stack testing method

– SIA to provide comments on EPA draft text

3. Etch / Default EFs method

– no outstanding issues