Technical Support for 

Accounting for Destruction or 

Removal Efficiency for 

Electronics Manufacturing 

Facilities under Subpart I

Office of Air and Radiation, U.S. Environmental Protection Agency

August 2012
August 2012 Subpart I DRE Technical Support 

Page 2 of 14

1. Introduction

This document provides technical support for the proposed changes to the provisions to account for 

controlled emissions associated with point-of-use (POU) abatement systems under subpart I, Electronics 

Manufacturing, of the Greenhouse Gas Reporting Program (GHGRP). Specifically, the Environmental 

Protection Agency (the EPA) is proposing the following changes to subpart I: 

1) revising the default destruction or removal efficiency (DRE) value for semiconductor 

manufacturing facilities to establish new default DREs grouped by gases and process types (etch 

and chamber cleaning); 

2) providing facilities multiple options to directly measure abatement system DREs;

3) revising the provisions that specify the number of abatement systems that must be tested, and 

the required frequency of abatement system testing to determine fab-specific DRE values (i.e., 

the random sampling abatement system testing program, or the RSASTP); and 

4) expanding the provisions for ensuring proper abatement systems installation, operation, and 

maintenance to include an on-site a maintenance plan for abatement systems.

This document was developed using information from two sources. The first is the Technical Support 

Document for Process Emissions 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 (hereafter, the November 2010 TSD), available in docket 

EPA-HQ-OAR-2009-0927. The second is non-confidential materials submitted to the EPA by the 

Semiconductor Industry Association (SIA). These materials are listed at the end of this document.

2. Revised Default DRE Values

The December 2010 subpart I rule provided all electronics manufacturing facilities the option to use a 

default DRE value (60 percent) so long as abatement systems for which the default DRE was being 

applied were designed to abate fluorinated greenhouse gases (F-GHGs) and/or nitrous oxide (N2O) and 

the systems were properly installed, operated, and maintained (see Section 4). The default DRE of 60 

percent was developed using data from the EPA DRE measurement studies done through the EPA PFC 

Reduction/Climate Partnership for the Semiconductor Industry. The data set from these studies was 

limited and relatively small in comparison to the DRE data set SIA submitted to the EPA after subpart I 

was finalized (see November 2010 TSD and SIA, 2012a for the data sets). The SIA data set represents the 

most comprehensive DRE database the EPA has seen to date. The DREs provided by SIA were based on 

measurements made by two semiconductor device manufacturers. The DRE measurements for the most 

part (126 tests) were done in 2011 by one company according to Method 1 of the EPA Protocol for 

Measuring Destruction or Removal Efficiency (DRE) of Fluorinated Greenhouse Gas Abatement 

Equipment in Electronics Manufacturing (hereafter the EPA DRE Protocol, available in docket EPA-HQOAR-2009-0927). A small portion of the DRE data (19 tests) submitted by SIA represents tests done over 

the time period 2003 to 2011, using a method comparable to Method 2 in the EPA DRE Protocol. SIA 

analyzed its DRE data to determine if there were differences in DREs due to the measurement method 

used. Based on this analysis the SIA concluded that “at most, any test method difference would appear 

to be very small.” (SIA, 2012a)
August 2012 Subpart I DRE Technical Support 

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Using the SIA DRE dataset and available EPA DRE data, the EPA is proposing to revise the subpart I 

default DRE for semiconductor manufacturing processes. The revision would provide multiple default 

DREs grouped by gas and process type as opposed to one default factor for all gases and process types.

1

The EPA is proposing this change for several reasons. First, the EPA now has access to a larger DRE 

database that covers more gas and process combinations. Second, some gases are more difficult to 

abate than others due to differences in the strength of chemical bonds, which can now be reflected in 

the default DREs due to the broader DRE database. For example CF4 is known to be harder to abate in 

combustion systems (the most commonly used abatement systems per SIA, 2012a) than other F-GHGs, 

which will typically result in a lower DRE for CF4 (Beu, 2005). Finally, abatement system DREs are 

dependent on inlet and outlet system flows and it is known that process flow rates are higher for 

chamber clean processes than etch processes (larger precursor flows and dilution factors), which—for a 

given type of abatement system—will typically result in lower DREs for chamber cleaning than for etch.

2

To assess how to establish new default DREs for semiconductor manufacturers the EPA analyzed the 

DRE data and supporting information submitted by SIA and data from the November 2010 TSD. 

Etch Process Type Default DREs

Table 1 presents a summary and analysis of the available etch DRE data SIA submitted to the EPA and

DRE data available through the EPA DRE measurement studies (SIA, 2012a and November 2010 TSD). 

The EPA analyzed the etch DRE data by looking at the mean and the standard deviations of the data by 

gas. To analyze potential default DREs the EPA evaluated the value of arithmetic mean minus two 

standard deviations of the population. This conservative method was employed to account for the 

limited representativeness of the SIA DRE dataset: while the number of data points is relatively large, 

the data comes almost exclusively from one abatement system manufacturer (i.e. approximately 97

percent of the systems tested were manufactured by one abatement system supplier). Based on SIA 

abatement systems inventory information, the EPA estimated that over 70 percent of systems installed 

in the US are manufactured by that one supplier. Five other suppliers are also in the market in the US; 

about three percent of the field DRE performance data are for systems from some combination of these 

five manufacturers (SIA, 2012a). DRE performance can vary depending on the specific design of each 

manufacturer, which is often proprietary. Consequently, a conservative approach was used to estimate 

the DRE.

 

1

The EPA does not have information to support a revised default DRE(s) for electronics manufacturers outside of 

semiconductor manufacturing; however, the EPA is specifically seeking comment in this proposal on additional information that 

may be available to revise default DREs. Any new data provided would be analyzed in a similar manner to the data analysis 

provided in this memo.

2

See SIA, 2012c and SIA, 2012d.
August 2012 Subpart I DRE Technical Support 

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Table 1. Summary and Analysis of All Available Etch DRE Measurement Data (SIA, 2012a and 2012e 

and November 2010 TSD)

Gas Mean 

(Percent)

Standard Deviation 

(Percent)

Number of Data 

Points Available

Mean Less Two 

Standard Deviations 

(Percent)

Etch

CF4 63.93 32.19 34 -0.45

C2F6 99.00 NA 1 99.00

C4F6 99.06 0.28 5 98.50

C4F8 98.85 0.66 14 97.53

NF3 99.27 0.47 14 98.32

SF6 99.14 0.53 4 98.08

CH2F2 98.94 0.73 16 97.49

CHF3 99.18 1.54 19 96.09

NA: Standard deviation could not be calculated because only one data point was available.

Due to the similarities of the calculated etch DREs (as seen in Table 1) for many gases used in etch 

processes3, the EPA is proposing to group C4F6, CHF3, C4F8, NF3, SF6, and CH2F2 used in etching into one 

DRE category and assign one average DRE of 98 percent. A DRE of 98 percent was selected as it was the 

approximate average of all of the aforementioned gas DREs.

The available DRE measurements for CF4 emissions from etch processes varied across a wide range of 

values as indicated by the large standard deviation for the total available CF4 etch DRE data set seen in 

Table 1. This variability was due to underperforming abatement systems resulting from operating 

outside manufacturers’ specifications. Following the same guidelines used to establish the initial 

subpart I DRE (see November 2010 TSD), the EPA is proposing to remove some of the available data 

from the CF4 etch data set because the data represent the DREs of systems that were not properly 

installed, operated, and/or maintained.4Based on an EPA request, SIA identified the CF4 measured DREs 

that were associated with systems that were not properly operated. Approximately half of the available 

CF4 measured DREs were removed from the dataset based on SIA input (SIA, 2012f). This resulted in 15 

of the 34 CF4 etch DRE measurements summarized in Table 1 being removed from the dataset that could 

be used to develop a default DRE. Given that such a high percentage of data were collected under 

operating conditions that do not meet the requirements in the current subpart I (i.e., systems that were 

not abating CF4 as expected because of improper operation and maintenance), the EPA has concerns 

about the reliability of the entire data set. Therefore, the EPA is proposing to maintain the current DRE 

of 60 percent for CF4 for the etch process type. 

 

3

Etch DREs would apply to the combined wafer clean/etch process type. Please refer to Technical Support for Modifications to 

the Fluorinated Greenhouse Gas Emission Estimation Method Option for Semiconductor Facilities under Subpart I for a 

discussions on the combining of these process types.

4

Subpart I contains requirements for proper installation, operation, and maintenance of abatement systems, so the default 

DREs needs to also represent DREs of properly installed, operated, and maintained systems.
August 2012 Subpart I DRE Technical Support 

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Little (i.e., one data point) or no DRE data were available for four gases emitted from etch processes, 

C2F6, CH3F, C3F8 and C5F8. Therefore, the EPA is proposing to assign default DREs for these gases used in 

the etch process type on the following basis:

 C2F6: one DRE measurement of 99.0 percent is available for this F-GHG; however, in the absence 

of additional DRE measurements, the EPA is proposing to assign a default DRE of 60 percent to 

C2F6, the same DRE for CF4, because C2F6, like CF4, is also known to be difficult to abate. Both are 

highly fluorinated with no C-H bonds or C=C double bonds (Tsang et. al., 1998), making these 

compounds relatively harder to abate than most other F-GHGs.

 CH3F, C3F8, and C5F8: no DRE data are available for these F-GHGs, so the EPA is proposing to 

maintain the previous subpart I DRE value of 60 percent.

Chamber Clean Process Type Default DREs

As can be seen by the large standard deviations in Table 2, a wide range of NF3 DREs for chamber clean 

were measured due to underperforming abatement systems that were not properly installed, operated, 

and/or maintained (SIA, 2012e).

5

The EPA analyzed the chamber clean DRE data to determine a default 

DRE using the mean DRE less two standard deviations for the same reasons as stated above for the etch 

default DREs. 

Table 2. Summary and Analysis of All Available NF3 Chamber Clean DRE Measurement Data (SIA, 

2012a)

Gas

(Cleaning Sub-type)

Mean 

(Percent)

Standard Deviation 

(Percent)

Number of Data 

Points Available

Mean Less Two 

Standard 

Deviations 

(Percent)

Chamber Clean

NF3 (All sub-types 

combined)

88.72 14.61 49 62.22

NF3 (In-Situ Plasma) 88.67 16.71 22 61.04

NF3 (In-Situ

Thermal) 98.90 NA 1 NA

NF3 (Remote 

Plasma)

88.37 13.08 26 62.22

 NA: Only one data point available, standard deviation could not be calculated. 

As was done for CF4 etch DREs, the EPA requested that SIA identify the NF3 chamber clean DREs that 

were associated with abatement systems that were not properly installed, operated, and/or maintained. 

Removing the four DRE data points that represented underperforming systems (as detailed in SIA, 

2012e) resulted in the DRE values shown in Table 3 below.

 

5

Subpart I contains requirements for proper installation, operation, and maintenance of abatement systems, so the default 

DREs should represent DREs of properly installed, operated, and maintained systems.
August 2012 Subpart I DRE Technical Support 

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Table 3. Analysis of Revised NF3 Chamber Clean DRE Dataset (SIA, 2012a and SIA, 2012e)

Gas

(Cleaning Sub-type)

Mean 

(Percent)

Standard Deviation 

(Percent)

Mean Less Two 

Standard 

Deviations 

(Percent)

NF3 (All sub-types 

combined) 92.18 8.63 74.93

NF3 (In-Situ Plasma) 93.23 7.94 77.35

NF3 (In-Situ 

Thermal) 98.90 NA NA

NF3 (Remote 

Plasma) 91.03 9.27 72.48

 NA: Only one data point available, standard deviation could not be calculated.

In reviewing the results displayed in Table 3, the EPA decided to propose a default DRE for NF3 of 75 

percent for the entire chamber clean process type, and to not propose specific default DREs for process 

sub-types. This was done for simplicity and because of the close proximity of the DREs for in-situ plasma 

and remote plasma clean, which are the most commonly used chamber clean processes in the industry. 

For all other gases used in chamber clean, the EPA is proposing to maintain the previous subpart I 

default DRE of 60 percent because no other data are available to support proposing revised DREs.

N2O Default DRE

Because no data are available to support establishing a default DRE for N2O used in chemical vapor 

deposition or other processes, the EPA is proposing to maintain the previous subpart I default DRE of 60 

percent for N2O emissions.

If additional DRE data are submitted to the EPA in response to this proposal, they will be evaluated in a 

similar manner to the DRE analyses above.

Revised Default DRE Summary

A summary of the proposed, expanded semiconductor manufacturing default DREs is provided in Table 

4.

Table 4. Proposed DRE Default Values for Semiconductor Manufacturing Facilities 

Process Type/Gas Proposed Default 

DREs

Etch

CF4, C2F6, C3F8, C5F8, CH3F (and all other F-GHGs not listed in the subsequent 

row)

60%

CHF3, CH2F2, C4F8, NF3, SF6, C4F6 98 %

Chamber Clean

NF3 75 %

All other gases 60 %

N2O

CVD and all other N2O-using processes 60 %
August 2012 Subpart I DRE Technical Support 

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The EPA is proposing that the revised default DRE values only apply to semiconductor manufacturing 

facilities because the EPA did not receive any additional data for other electronics manufacturing 

facilities to support a change. For the use of abatement systems at other electronics manufacturing 

facilities, the EPA is proposing to maintain the previous subpart I default DRE of 60 percent.

3. Measurement of Fab-Specific DREs 

As an alternative to using default DREs, the December 2010 subpart I provides all electronics 

manufacturing facilities the option to measure and develop fab-specific DREs to use in place of the 

default DREs. The EPA is proposing to amend the provisions for measuring DRE to be more flexible and 

to require less frequent abatement system testing. 

3.1. Methods for Measuring Fab-Specific DREs

The November 2010 TSD and the EPA DRE Protocol contain detailed discussions on the justification for 

the required adherence to the EPA DRE Protocol for proper measurement of fab-specific DREs. 

However, based on new information that SIA submitted to the EPA on an alternate method for 

measuring total volume flow (TVF) of an abatement system, the EPA is proposing to amend the 

provisions for measuring fab-specific DREs for all facilities covered under subpart I.

6

The EPA is 

proposing to allow facilities to use a method for determining TVF of gas through the abatement system 

that is an alternative to the method outlined in the EPA DRE Protocol which suggests the use of

quadrupole mass spectroscopy (QMS). The proposed alternative method would consist of injecting a 

non-native polar tracer gas into the abatement system outlet stream and measuring the downstream 

tracer gas concentration using Fourier transform infrared (FTIR) spectroscopy to determine TVF. This 

proposed alternative, which is a lower cost option than using a QMS-based method (ISMI, 2010), was 

tested by SIA on three abatement systems at one semiconductor manufacturing facility. The results of 

the tests comparing the use of the FTIR-based and QMS-based methods are presented in the 

International SEMATECH Manufacturing Initiative (ISMI) Technology Transfer #10095115A-ENG 

Comparison of Fourier Transform Infrared (FTIR) and Quadrupole Mass Spectroscopy (QMS) Methods for 

Determining POU Abatement System Effluent Flow. The EPA reviewed the method comparison and 

concluded that the results of these tests adequately showed that using the suggested alternative FTIR 

method was suitable for determining dilution across an abatement system, provided that the injected 

tracer gas is well-mixed at the abatement system exit stream sampling location (ISMI, 2010), or that the 

sampling procedure accounts for any stratification (lack of mixing). Therefore the EPA is proposing to 

include this alternate FTIR method as an option in Appendix A to subpart I, with an additional procedure 

to ensure that the sampling location and procedures account for the fact that the tracer gas may not be 

well mixed.

As discussed above, ensuring adequate mixing is essential to provide accurate results, but can 

sometimes be difficult to achieve due to the short duct lengths commonly found downstream of 

abatement systems. Ideally, sampling would be done well downstream of the abatement system to 

ensure complete mixing.

 

6

Total volume flow is a parameter used to calculate the dilution across an abatement system. Taking into account dilution is 

critical to properly measuring abatement system DREs. Failure to account for the effects of dilution may lead to DREs for CF4

that can be off by as much as a factor of 20 to 50 and DREs for C2F6that can be off by a factor of up to 10 (Burton, 2007).
August 2012 Subpart I DRE Technical Support 

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To demonstrate complete mixing in the abatement system exhaust stream, or to account for any 

stratification in the exhaust if it is present, the EPA is proposing that facilities using the alternative

method to determine dilution should use an adaptation of section 8.1.2 of EPA Method 7E, 

Determination of Nitrogen Oxides Emissions From Stationary Sources (Instrumental Analyzer 

Procedure), in 40 CFR part 60, Appendix A-4.

7

This adaptation, which is also included in the proposed 

Appendix A to subpart I, includes the following requirements: 

 The concentration of the tracer would be measured at three traverse points at 16.7, 50.0, and 

83.3 percent of the diameter of the duct. 

 If the tracer gas concentration at each traverse point differs from the mean concentration for all 

three traverse points by no more than ±5.0 percent of the mean concentration, the gas stream 

would be considered un-stratified and the facility would be allowed to collect samples of the 

tracer gas from a single point that most closely matches the mean.

 If the 5.0 percent criterion were not met, but the concentration of the tracer gas at each 

traverse point differed from the mean concentration for all traverse points by no more than 

±10.0 percent of the mean, a facility would be able to take samples from two points and use the 

average of the two measurements. The sampling could be performed at any two of the three 

points spaced at 16.7, 50.0, or 83.3 percent of the line. 

 If the concentration at each traverse point differed from the mean concentration for all traverse 

points by more than ±10.0 percent of the mean but less than ±20.0 percent, the facility would 

take samples of the tracer gas from three points at 16.7, 50.0, and 83.3 percent of the 

measurement line and use the average of the three measurements. 

 If the gas stream were found to be stratified because the ±20.0 percent criterion for a threepoint test were not met, the facility would be required to locate and sample the tracer gas from 

traverse points in accordance with Sections 11.2 and 11.3 of EPA Method 1 in Appendix A-1 to 

Part 60. The tracer gas concentration used for measuring flow would be determined from the 

average of the concentrations measured at each of the traverse points.

This method has not been used in practice at an electronics manufacturing facility, but it is expected to 

be sufficient for demonstrating complete mixing and ensuring that a concentration value used in 

calculations is representative of a well-mixed stream. This is because the method outlined above is 

based on the EPA’s Method 7E, which has been used in practice in other applications. Also the method

includes thresholds for differences in measured concentrations and contingencies for when a threshold 

cannot be met. This structure helps ensure that the effluent stream concentration used is representative 

of a well-mixed stream at a sampling location.

In addition, the EPA is also proposing to allow facilities to request approval to use an alternative 

sampling and analysis method that is not included in subpart I to measure abatement system DRE. The 

EPA is proposing that alternative test methods would have to be validated according to EPA Method 301 

(Field Validation of Pollutant Measurement Methods From Various Waste Media).8 Under this proposal, 

 

7

This method is based on suggestions from SIA regarding the use of the alternate methods for measuring site-specific DREs. See 

SIA, 2012g. 

8Method 301 can be access at: http://www.epa.gov/ttn/emc/methods/method301.html
August 2012 Subpart I DRE Technical Support 

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prior to using an alternate test method, the facility would be required to submit the method along with 

a proposed test plan to the EPA for review and receive approval from the EPA. This process would 

ensure that any method outside of those specified in subpart I are viable and appropriate. Once the EPA 

approves an alternate method, the method could be used by other fabs that meet the same conditions 

under which the alternative method was approved. The EPA would specify those conditions in the 

approval of the alternative method. The regulatory language that addresses this option is included in the 

body of the text, not in the proposed Appendix A to subpart I.

Regardless of the method used to determine dilution (either using krypton and a QMS as specified in the 

EPA DRE Protocol, a polar species and a FTIR (as proposed in Appendix A of subpart I), or an alternative

method approved by the EPA), facilities would still be required to meet the EPA DRE Protocol 

performance benchmark, which is that the relative error of the true fraction emitted must be less than 

or equal to five percent, and to follow all other aspects of the EPA DRE Protocol with one exception. 

That exception is that facilities may use the FTIR and QMS Protocols specified in the proposed Appendix 

A of subpart I in lieu of the 2006 ISMI Guideline for Environmental Characterization of Semiconductor 

Process Equipment FTIR and QMS Protocol as required in the EPA DRE Protocol. The FTIR and QMS 

protocols contained in the proposed Appendix A to subpart I are modeled after the FTIR and QMS 

Protocols in Appendix A of the 2009 ISMI Guideline for Environmental Characterization of Semiconductor 

Process Equipment and reflect advancements in experience in using FTIR/QMS in the industry. Although

ISMI-SEMATECH is a common source of best practices for the semiconductor manufacturing industry, 

the EPA does not have any information on whether, and in what way, the modifications to the FTIR and 

QMS protocols in Appendix A of the 2009 ISMI Guideline would impact DRE measurements, compared 

to the 2006 ISMI Guideline. Therefore, the EPA is specifically seeking comment on the appropriateness 

of using the 2009 ISMI Guideline as the basis for the proposed Appendix A to subpart I. 

3.2. Abatement System Sampling Protocol

The EPA is proposing to modify the random sampling abatement system testing program (RSASTP) in 40 

CFR 98.94(f)(4)(ii) to make the required testing frequency less burdensome for facilities that elect to 

measure fab-specific DREs. Table 5 below summarizes the elements of the RSASTP as finalized in the 

December 2010 version of subpart I, the proposed changes to the RSASTP, and the technical justification 

for the modifications.

Table 5. Summary of Proposed Revisions to the RSASTP

December 2010 Provisions Proposed Revised Provisions Justification for 

Modification/Addition

Required Testing Frequency

 Each year, test three

systems or 20% of 

installed abatement 

systems for each class.

 Do not repeat 

measurements for 

systems measured in the 

previous year.

 For each process type/sub-type

and gas combination, test 10% of 

systems in each fab annually for 

two years (20% total) or 20% in 

the first year to set a baseline 

average DRE for that process 

type/sub-type and gas 

combination.

The EPA is proposing to modify the 

RSASTP because:

 The previous definition of “class”

combined with the permutations 

of process and abatement type 

resulted in testing requirements 

representing an average of 45

percent of the total number of 
August 2012 Subpart I DRE Technical Support 

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 If a DRE was measured for 

a particular system during 

the previous 2 years, the 

facility must use the most 

recently measured DRE.

 If the DRE was not 

measured for a particular 

system during the 

previous 2 years, use the 

simple average of the 

measured DREs for that 

class.

 Use default DREs until DREs have 

been measured for 20% of 

systems. 

 For every 3-year period after, test 

15% of the systems in the fab for 

each process type/sub-type and 

gas combination. A fab can choose 

to test 15% in the first year of a 3 

year period but must test at least 

5 percent of the systems each year 

until 15 percent are tested. 

 The fab-specific DRE would be 

calculated as the average of the 

first 2 years (or first year if 20% 

are tested) and thereafter as the 

average of the most recent t 30% 

tested.

abatement systems in a fab, which 

is higher than the 20 percent 

required to be tested by the 

RSASTP. (SIA, 2012a)

 The proposed changes would

reduce testing burden by requiring 

fewer tests compared to current 

subpart I, yet provide sufficient 

information to ensure that the 

DRE values used represent current 

system performance as abatement 

systems age (see DRE versus 

abatement system age 

information in SIA, 2012a).

Definition of Class

Class means a category of 

abatement systems grouped 

by manufacturer model 

number(s) and by the gas 

that the system abates, 

including N2O and CF4 direct 

emissions and by-product 

formation, and all other FGHG direct emissions and byproduct formation. Classes 

may also include any other 

abatement systems for which 

the reporting facility wishes 

to report controlled 

emissions, provided that

class is identified.

Delete the definition of “class.” 

Require that DREs be determined for 

abatement systems based on the 

gas(es) that the systems abate and 

the process type connected to the 

systems, including etch/wafer clean, 

chamber clean, and all N2O using 

processes. 

The EPA is proposing to delete the 

definition of class because:

 Testing by gas and process 

type/sub-type combination would

simplify apportionment and 

uptime calculations, and 

recordkeeping, and hence reduce 

burden.

 Abatement system categories 

based on gas and process type 

combinations would be consistent 

with calculation methods for 

subpart I default emission factor 

based methods.

 Broader categories of abatement 

systems would reduce the number 

of systems that need to be tested.

Accounting for Under-Performing Abatement Systems in Calculating Emissions or Average DRE

Not specifically addressed.

(If a facility uses the default 

DRE of 60%, the facility must 

certify that the system is 

installed, operated, and 

maintained according to the 

manufacturer’s 

specifications.

If a facility measures the DRE 

of a system, they must use 

 If proper maintenance and 

operation procedures are 

followed, and the measured DRE 

of an abatement system is below 

the manufacturer-claimed DRE, 

the data from the low DRE test 

would be included in calculating 

the fab-specific average DRE for 

that gas and process combination. 

 If proper maintenance and 

operation procedures are not 

These provisions would be added as 

part of requirements for DRE 

measurement because they would:

 Ensure that the DREs used in 

calculations reflect actual 

performance.

 Ensures measured values are used 

by not allowing a reporter to select 

the higher of the default or the 

measured DRE.
August 2012 Subpart I DRE Technical Support 

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that measurement in 

calculating emissions.)

followed, then the appropriate 

operational change or system 

maintenance (per the 

manufacturer instructions or the 

fab maintenance plan) would need 

to be implemented, and a retest 

would be required that year to 

replace the measured value. 

Alternatively, the fab could use 

the measured value in the DRE 

determination and then include 

the same system in next year’s 

abatement system testing in 

addition to the testing of randomly 

selected systems.

Testing of Systems That May Be Disruptive to Production

Not addressed.

(No provisions to allow 

deferring testing of 

abatement systems if the 

testing would be disruptive 

to production.)

Where testing of systems randomly 

selected for testing would be 

disruptive to production, such 

systems could be (a) replaced by 

another randomly selected system 

for testing, and (b) returned to the 

sampling pool for subsequent testing. 

If testing of a system is deferred, that 

system could be chosen for testing in 

one of the next two sampling years. 

The EPA is proposing that a system 

cannot be returned to the pool in 

more than three consecutive 

selections.

This provision would be added to

address situations where testing of a 

specific abatement system would

disrupt manufacturing productivity.

IF deferred, a system could be 

specifically selected for testing so that 

production and testing could be 

coordinated to avoid disrupting 

production.

4. Ensuring Proper Abatement System Installation, Operation, and Maintenance

As discussed in Section 3.6.1 (Proper Installation, Operation, and Maintenance) of the November 2010 

TSD, proper installation, operation, and maintenance of the abatement systems in accordance with 

manufacturer specifications is essential to ensuring that abatement systems are performing as 

expected. This concept is supported by the circumstances described in Section 2 of this document for 

CF4 and NF3, in which some DREs were lower than expected as a result of system operational and/or 

maintenance issues. The wide range of measured values for CF4 used in etching and NF3 used in 

chamber cleaning from the complete available DRE dataset, which includes data that was removed in 

the Section 2 analysis, can be seen in Figure 1 below (where ‘IS’ denotes the In-Situ chamber cleaning 

technology and ‘RPS’ the Remote Plasma System, a.k.a. the remote cleaning process). The broad ranges 

were not typical of the DRE data provided by SIA, but were not wholly unexpected due to issues the EPA 

has seen with CF4 DREs during measurement studies (see EPA 2008a and 2008b) and because of the 

known high flow rates of NF3 used during remote chamber clean processes (SIA, 2012c and SIA, 2012e).
August 2012 Subpart I DRE Technical Support 

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Figure 1. Range in Measured DREs for CF4 Etch and NF3 Chamber Clean (SIA, 2012a)

SIA suggests the variation in flows through the abatement system that was outside of manufacturer 

specifications were the primary reason for the observed variation in NF3 DREs for chamber clean 

processes (SIA, 2012a and SIA, 2012b). Low CF4 DREs resulted from operating and maintaining the 

abatement systems outside the manufacturer specifications; for example, system inlet/outlet volumetric 

flows were at higher levels than recommended by the manufacturer (SIA, 2012b).9 More specifically, for 

the low CF4 DREs associated with etch processes, it was found that operators were not complying with 

the manufacturers’ recommended set points for flow rate and/or pressure for fuel, oxygen, and air that 

should have been verified during abatement installation, and that ongoing maintenance to ensure that 

the systems performed as expected was not being performed. For systems that were operating as 

expected during testing for CF4, it was determined that the flow, fuel, and oxygen settings were properly 

set and the flow out of the abatement system was within the recommended manufacturer range (SIA, 

2012b).

Abatement system manufacturers provide general guidance on operation and maintenance of their 

products. However, lessons learned from the EPA DRE measurement studies and from SIA’s experiences 

highlight the need to expand the subpart I provisions to require facilities to take more specific actions to 

ensure abatement systems are properly operated and maintained over time. Therefore, the EPA is 

proposing to add a requirement for facilities to develop, follow, and keep on-site a maintenance plan for 

abatement systems. The EPA is proposing to require that the plan must include a defined preventive 

maintenance process and checklist (built on the manufacturer’s recommended maintenance program) 

and a corrective action process to follow whenever an abatement system fails to operate properly.

 

9

High inlet flows can be caused by incorrectly setting the abatement system vacuum pump purge flows, while a high V(out) can 

result from several high inlet flows or from high fuel and/or combustion air flows to the combustion burner.
August 2012 Subpart I DRE Technical Support 

Page 13 of 14

5. References 

Beu, L. (2005). Reduction of Perfluorocarbon (PFC) Emissions: 2005 State-of-the-Technology Report, 

TT#0510469A-ENG, International SEMATECH Manufacturing Initiative (ISMI), December 2005. Available 

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

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

Available at: http://www.electroiq.com/index/display/semiconductors-articledisplay/281422/articles/solid-state-technology/volume-50/issue-1/departments/industryforum/assessing-the-need-for-fc-abatement-standards.html.

EPA (2008a). 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). 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/nec_report.pdf. 

EPA (2008b). 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/semiconductor-pfc/documents/qimonda_report.pdf.

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. 

ISMI (2010). Comparison of Fourier Transform Infrared (FTIR) and Quadrupole Mass Spectroscopy (QMS) 

Methods for Determining POU Abatement System Effluent Flow. International SEMATECH Manufacturing 

Initiative (ISMI) Technology Transfer #10095115A-ENG. October 30, 2010. Available at: 

http://ismi.sematech.org/docubase/document/5115aeng.pdf

SIA (2012a). SIA Briefing Paper on Abatement Issues: Destruction Removal Efficiency (DRE), January 10, 

2012. Available in EPA docket EPA-HQ-OAR-2011-0028.

SIA (2012b). Questions Generated from SIA/EPA Conference Calls and Outstanding Questions from Work 

Plan Appendices 120329 SIA EPA Outstanding Questions, March 29, 2012. Available in EPA docket EPAHQ-OAR-2011-0028.

SIA (2012c). CVD Abatement units with flow data. March 6, 2012. Available in EPA docket EPA-HQ-OAR2011-0028.

SIA (2012d). Etch DRE testing with flow data. March 6, 2012. Available in EPA docket EPA-HQ-OAR2011-0028.

SIA (2012e). Questions for SIA Response from April 19, 2012 SIA/EPA Call With April 25, 2012 SIA 

Response. April 25, 2012. Available in EPA docket EPA-HQ-OAR-2011-0028.
August 2012 Subpart I DRE Technical Support 

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SIA (2012f). Outstanding Questions / Topics from SIA / EPA Discussions as of April 26, 2012. May 9, 2012.

Available in EPA docket EPA-HQ-OAR-2011-0028.

SIA (2012g). Proposal to Incorporate ISMI 2009 Guideline References in Subpart I. May 17, 2012. 

Available in EPA docket EPA-HQ-OAR-2011-0028.

Tsang et al. ( 1998) Tsang, W., Burgess Jr., D. R., and Babushok, V. (1998) “On the Incinerability of Highly 

Fluorinated Organic Compounds,” Combustion Science and Technology, 139:1, 385-402.