Questions for SIA Response from April 19, 2012 SIA/ EPA Call With April 25, 2012 SIA Response

The following are questions raised during the SIA/E PA conference call on 4/19/12. They cover questions on SIA feedback / responses related to ap portioning model verification and the DRE

summary paper.

Apportioning model verification:

1. Please provide a suggested definition of "repres entative of normal operation". Response in progress.

DRE summary paper:

• Please provide an outline / bullet points that des cribe what content from the ISMI guidelines SIA is proposing to include in subpart I with regard to measurement of sitespecific DRE values. Please also provide the purpo se / use of each guideline method in the context of subpart I. SIA is requesting that EPA allow for use of the 200 9 ISMI guideline or most recent

version 1 for process emissions and abatement DRE characteri zation in place of the 2006 ISMI guideline currently specified in 98.7 (n) (1) . The 98.7 references are detailed on pages 74816 and 74817 of the December 1, 2010 Feder al Register. This will apply to the current references for Subpart I. References s hould also be added to 98.7(n)(1) for 98.94(f)(4)(i); 98.94(g)(3); 98.97(d)(4), and 98.98 to incorporate the Appendix B; Section

B.1.5 “POU Abatement Device Dilution Factor Determi nation” procedure into the DRE testing and certification requirements.

In order to incorporate the 2009 ISMI guideline and the complete mixing demonstration protocol into 98.7(m)(3),the “Protocol for Measurin g the Destruction or Removal Efficiency (DRE) of Fluorinated Gas Abatement Equip ment in Electronics Manufacturing Version 1”, two subsections need to be added. 1. 98.7(m)(3)(i) should indicate that the 2009 ISMI guideline referenced in 98.96(n)(1) can be used in place of the 2006 guideline where th e 2006 guideline is referenced in the “Protocol for Measuring the Destruction or Remo val Efficiency (DRE) of Fluorinated Gas Abatement Equipment in Electronics Manufacturing Version 1. 2. 98.7(m)(3)(ii) should state the EPA reference me thod 7E should be used to demonstrate that the gases are well mixed in the du ct downstream of the POU device at the sampling point. The specific languag e that SIA recommend be

referenced is “ 

### Measure at three points on a line passing through t he centroidal area. Space the three points at 16.7, 50.0, and 83.3 perc ent of the measurement line. Sample for a minimum of twice the system response t ime (see Section 8.2.6) at each traverse point. Calculate the individual point and mean F-GHG concentrations. If the

1 Over time, the industry has revised the ISMI guide line to incorporate improved analytical methods. S IA requests

that EPA allow use of the most recent version of th e ISMI guideline.

### concentration at each traverse point differs from t he mean concentration for all traverse points by no more than: (a) ± 10.0 percent of the mean concentration; or (b) ± 0.5 ppm (whichever is less restrictive) the gas s tream is considered unstratified and you may collect samples from a single point that mo st closely matches the mean.” This is the language that SIA proposed in the 4/18/ 202 comments to EPA’s DRE summary document.

Incorporating these references into 98.7 will enabl e companies to use the most recent ISMI guideline and incorporate the revised Dilution Factor Determination methodology and QA/QC requirements in both the abatement and em issions factor testing protocols.

SIA wants to incorporate the 2009 ISMI guidelines u pdates to section 6 and Appendices A and B into the emissions factor and DRE testing p rotocols for Subpart I.

A. The 98.7 references to the 2009 ISMI guideline w ould include the following important updates from the 2006 guideline: 1. Appendix B, Section B.1.5 “POU Abatement Device Dilution Factor Determination” which is not in the 2006 ISMI guidel ine and which enables dilution determination using FTIR. This is the critical addi tion in the 2009 ISMI Guideline

for Environmental Characterization of Semiconductor Process Equipment –

Revision 2. 2. Updates to Chapter 6 which clarifies and updates the “Test for Air Emissions” procedures. The updates do not materially change th e testing protocols and approach for emissions factor and abatement systems testing, but reflect new knowledge learned from applying the protocol from 2 006 to 2008. 3. Updates to Appendix A, specifically A.1 Mass Spe ctrometry Protocol and A.2: Fourier Transform Infrared (FTIR) Spectroscopy Prot ocol, which clarifies and updates the instructions for the analytical and sam pling processes. The updates do not materially change the testing protocols and approach for emissions factor and abatement systems testing, but reflect new know ledge learned from applying the guideline from 2006 to 2008.

B. Inclusion of the EPA reference method 7E: This reference provides the transverse sampling method to validate that the concentration measurement is being taken in a completed mix zone of the ductwork downstream of th e POU abatement device. This is the addition requested by EPA in their 4/12/2012 comments to the DRE proposal.

The other option to include this would be for ISMI to update Appendix B, Section B.1.5,

“POU Abatement Device Dilution Factor Determination ”, Section titled "Using a Gas at

POU Abatement Device Outlet" Item 5 of the Guidelin e for Environmental Characterization of Semiconductor Process Equipment – Revision 2 to specifically reference the transverse sampling method detailed i n EPA reference method 7E and providing the text that SIA provided in the respons e to the EPA 4/12/2012 comments tothe DRE proposal. EPA could then reference the thi rd revision in 98.7, simplifying the reference and clarifying the requirements.

• Can SIA provide, for the chamber clean NF3 DRE tes ts, which abatement system tests operated outside of the manufacturer's recommendati ons 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 where man ufacturer's recommendations were

not observed.

There were three chamber clean abatement units whic h tested with DREs lower than the manufacturer’s specifications for the abatement of NF3. Two of the units abated in-situ plasma chamber clean processes and one unit abated a remote plasma clean chamber. Two of the units, Tool #1 and Tool #2 had low DREs due to high output flows, outside the range of the manufacturer’s specifications. The flows were adjusted to both units and a retest of Tool #1 validated that reducing the out put flow improved the DRE above the expected DRE for the unit.

On Tool #3 adjustments were made to the combustion blower to increase the flow of air and DRE improved to within 10% of the expected DRE, but was still slightly below the expected DRE. Because of this low DRE, further work was done on this unit in March of 2012. The combustion liner was replaced, adjustment s were made to the pump purge flow to slightly reduce flows in the individual cha mber lines, and combustion gas flow was further adjusted to improve the residual oxygen . This unit has been retested and preliminary indications are that the unit is perfor ming above the expected DRE. Per the results of this work, the maintenance procedures ha ve been modified to include flow

checks of the Volume In and Volume Out.

TOOL# Test Date Total Vol in SLPM Total

Vol out SLPM Dilution

Factor DRE

NF3 Process

Type Comments Expected
DRE

1 Sept 27

2012 142.171 1226.663 8.628 35.832 In-situ Plasma 70%

1 Sept 28

2012 136.17 1031.208 7.573 82.019 In-situ Plasma Retest 70%

2 July 27

2012 124.944 1300.149 10.406 50.51 In-situ Plasma 70%

3 May 12

2012 188.1 628.2 3.34 49.55 Remote Plasma 70%

3 Sept 7 2012 174.718 721.771 4.131 63.355 Remote Plasma Retest 70%

Removing a total of four tests for the three device s that had low DREs, the statistical analysis yields the results shown in Revised Table B-1 (next page). The average DRE for NF3 in chamber cleaning (the last line of the table ) is raised by 3.5 percentage points from 88.7% to 92.2%. There is no change in the data for etch processes and the etch DRE results are therefore unchanged.The substantial issue is the large effect that EPA’ s discounting of the average has on the default DRE value to be used in reporting. EPA’s m ethod is to discount the DRE 2 standard deviations below the mean, which would result in a value of 75% for NF3 in chamber cleaning using the revised data. At this low level , 43 of the 45 MfrZ devices tested actually outperform the 75% average. In a fab using 60 MfrZ devices to abate NF3 in chamber cleaning (the smallest number of devices reported b y SIA members), the odds of the actual average DRE being as low as 75% are vanishingly sma ll (less than 1 in 1 million). Even if the fab uses some non-MfrZ devices, it is still hig hly unlikely that the actual average DRE would be as low as 75%, as long as the performance of the non-MfrZ equipment is reasonably similar to the MfrZ equipment.

We discussed two other approaches for calculating a discounted default DRE on the April 19th call. One approach applied a log transform to the DRE data before discounting 2 standard deviations below the mean. With the chang e to remove the four low DRE test results, the remaining data now pass the tests for skewness and kurtosis, and there is no need to consider this approach.

A second approach discounts 2 standard errors (of t he mean) below the mean value, without transforming the data, which results in pla cing confidence limits on the mean. We believe there is considerable merit in this approac h, because it is the mean DRE for a fab that influences emissions and placing confidence li mits on the mean would be the usual statistical approach for controlling the risk of un derstating or overstating the mean value. As the table shows, when applied to the revised data t his approach yields 90% as the discounted value that would be used in reporting. This is still a conservative estimate.

Two-thirds of the MfrZ devices that have been teste d outperform the 90% value and onethird perform below the 90% value. This approach i ntroduces a substantial, but reasonable, degree of conservatism to the default DRE.

Considering a fab that uses 60 MfrZ devices to abat e NF3 in chamber cleaning, if the default DRE is set at 90%, then we can be 97.5% con fident that the actual average DRE is

at least 90%. If some non-MfrZ devices were used i n the fab, the confidence level could vary depending on the number of such devices and th eir performance in comparison to MfrZ devices. But, there is a margin of safety in this approach to help it meet a 95% confidence level, even if the presence of non-MfrZ devices proves to have an adverse effect on DRE. Whenever MfrZ equipment is the large major ity of devices in a fab, the actual average DRE and the statistical confidence level wi ll largely be determined by the MfrZ

devices.**Revised Table B-1. Summary of Average DREs in Abat ement Testing** **Original Dataset (Feb 29, 2012)** **Dataset Revised to Remove 4 NF3 Tests in Chamber Cleaning** **Process Gas N** **(Tests) Average DRE (%)** **(± standard error) EPA** **Proposed Defaults** 1/**N (Tests)** **Average DRE (%) (± standard error)** **Discounted 2 Std Devs** **Below the Mean** **Discounted 2 Std Errors** **Below the Mean** **Plasma Etch**Etch (CF4)CF42354.5 ± 7.560%Not changed by revision to database.Etch (Other Gases)NF31499.27± 0.1398%SF6499.14 ± 0.3198%C2F6199.060%C2F8, C5F8, CH3F060%C4F6599.06 ± 0.2898%C4F81498.85 ± 0.1898%CHF31999.18 ± 0.3698%CH2F21698.94 ± 0.1998%All Etch (Excluding CF4) NF3/Other 73 99.07± 0.13**Chamber Cleaning**In-situ PlasmaNF32288.7 ± 3.72093.2±1.8Remote PlasmaNF32688.4 ± 2.62491.0±1.9Thermal CleanNF3198.9198.9**All Chamber Cleaning NF3** **49 88.7 ± 2.1** **60% 45** **92.2 ± 1.3 75%** **90%**1/Discounted 2 standard deviations below the mean (assuming normal distribution for DRE values)SIA v. EPA, (D.C. Cir. No. 1024) Privileged and Con fidential, For Settlement Purposes Only - Do Not Ci te or Quote

At this point, SIA is not in a position to provide additional data on abatement system DREs. As SIA has noted in earlier submittals, we are work ing to collect additional DRE testing data for several process gas/combinations from several a bated fabs. The plan is to include test data from multiple abatement device manufacturers w here available.

SIA requests that EPA specifically make a request i n the preamble to the reproposed rule

for the submittal of additional DRE data and statis tical analysis during the comment period to support the creation of more representative defa ult DREs for additional process/gas combinations. This will give SIA and ISMI sufficie nt time to collect additional testing data and perform the statistical analysis necessary to j ustify the use of more representative industry wide default DREs.

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