Version 1 

Protocol for Measuring Destruction or Removal Efficiency (DRE) of 

Fluorinated Greenhouse Gas Abatement Equipment in Electronics 

Manufacturing 

March 2010 

Office of Air and Radiation 

Office of Atmospheric Programs, Climate Change Division 

EPA 430-R-10-003 
Table of Contents

List of Tables................................................................................................................................. 3 

List of Figures................................................................................................................................ 3 

PREFACE...................................................................................................................................... 4 

1. INTRODUCTION.................................................................................................................... 5 

1.1 Protocol Purpose ........................................................................................................... 6 

1.2 Protocol Objectives....................................................................................................... 7 

1.3 Protocol Scope ............................................................................................................... 7 

1.4 Development of the Protocol........................................................................................ 8 

1.5 Expected Results........................................................................................................... 8 

2. MEASUREMENT PLAN, PREPARATION, METHODOLOGY, AND DATA 

ANALYSIS .................................................................................................................................... 8 

2.1 Prepare Measurement Plan ......................................................................................... 8 

2.1.1 Description of Experimental System................................................................... 9 

2.1.2 Sampling Configuration....................................................................................... 9 

2.1.3 Required Resources.............................................................................................. 9 

2.1.4 Measurement Schedule....................................................................................... 10 

2.1.5 Safety.................................................................................................................... 10 

2.1.6 Quality Assurance/Quality Control................................................................... 11 

2.2 Measurement Methodology........................................................................................ 11 

2.2.1 Method 1—Dilution Adjusted Concentration Measurement ......................... 12 

2.2.2 Method 2—Total Volume Measurement.......................................................... 12 

2.2.3 Equipment Needed.............................................................................................. 13 

2.2.4 FTIR and QMS Protocols .................................................................................. 14 

2.2.5 Calibration Curves.............................................................................................. 14 

2.2.6 Flow and Dilution Measurements...................................................................... 16 

2.2.7 F-GHG Measurements....................................................................................... 17 

2.3 Data Treatment and Analysis.................................................................................... 18 

2.3.1 Abatement System Dilution ............................................................................... 19 

2.3.1.1 Total Volume Flow........................................................................................... 19 

2.3.1.2 Dilution Factor ................................................................................................. 21 

2.3.2 Abatement System DRE Estimate and Relative Errors.................................. 22 

2.3.2.1 Method 1—Dilution Adjusted Concentration Measurements..................... 22 

2.3.2.1.1 Concentration Measurements......................................................................... 22 

2.3.2.1.2 DRE................................................................................................................... 23 

2.3.2.2 Method 2—Total Volume Measurements...................................................... 24 

2.3.2.2.1 Total Volume Measurements.......................................................................... 24 

2.3.2.2.2 DRE................................................................................................................... 24 

3. BENCHMARK RELATIVE ERROR ................................................................................. 25 

3.1 Method 1—Dilution Adjusted Concentration Measurements................................ 25 

3.2 Method 2—Total Volume Measurements................................................................. 25 

4. DOCUMENTATION AND REPORTING.......................................................................... 26 

5. REFERENCES....................................................................................................................... 28 

2
Appendix A – History of and Revisions to the Protocol.......................................................... 30 

Appendix B – Sample Calculation............................................................................................. 32 

List of Tables 

Table 1. Measurement Study Equipment Needs.......................................................................... 14 

Table 2. Acceptable Gases for Monitoring Total Abatement System Flows .............................. 17 

Table 3. Minimum detection levels (CMDL) and threshold F-GHG concentrations (C*) for 

measuring relative error of total fraction emitted when sample C < C* ....................................... 18 

List of Figures 

Figure 1. Sampling Schematic for Single and Multiple Chamber Inlet Flow(s) ........................ 10 

Figure 2. Sample Calibration Curve ............................................................................................ 16 

3
PREFACE 

The U. S. Environmental Protection Agency (EPA) initiated preparation of this Protocol as part 

of its commitment to assist the PFC Emissions Reduction/Climate Partnership for the 

Semiconductor Industry (the Partnership) to achieve its voluntary fluorinated greenhouse gas (FGHG) emission reduction and reporting goals. F-GHGs include the most powerful and often 

persistent greenhouse gases such as perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), sulfur 

hexafluoride (SF6), and nitrogen trifluoride (NF3). The Partnership’s reduction goal is to 

decrease F-GHG emissions to 10 percent below the 1995 base-year amounts by 2010. Several FGHG-reducing options are available, with reduction-efficiencies ranging from 10 to 99 percent 

or higher. Practical reduction strategies comprise modifying manufacturing processes—

optimizing processes and switching to alternative gases with lower emissions potential—as well 

as installing point-of-use (POU) F-GHG abatement systems. Detailed methods for measuring FGHG emissions from manufacturing processes were standardized in 1999 and are documented 

and continually updated in the industry’s International Semiconductor Manufacturing Initiative 

(ISMI) Guidelines. Standard methods for measuring and documenting the destruction or removal 

efficiencies (DREs) from POU abatement systems have lagged those for measuring process 

emissions. One objective of this document (the Protocol) is to align measurement of emissions 

from manufacturing processes with those from abatement systems. 

The Protocol builds on three DRE measurement studies of POU F-GHG thermal abatement 

systems conducted onsite at three U. S. semiconductor manufacturing facilities, each a member 

of the Partnership. Air Products performed and documented the measurements under subcontract 

to ICF International, who was contracted by EPA to support development of the Protocol. In 

total, four abatement systems were tested and all were connected to plasma-enhanced chemical 

vapor deposition (PECVD) or etch process equipment. During the studies, DRE measurements 

were made with the plasma on (during wafer processing) and with the plasma off. A key feature 

of these measurement studies was development and testing of a reliable method for measuring 

the dilution of F-GHGs during abatement. 

This is the third version of the Protocol. It reflects two rounds of external reviews, one each for 

the first and second version. The first version, prepared after measurements were made at two 

facilities, was circulated to Semiconductor Industry Association (SIA), Japan Electronics and 

Information Technology Industries Association (JEITA), and Taiwan’s Industrial Technology 

Research Institute (ITRI) as well as to abatement manufacturers and industry consultants 

experienced in measuring the DRE of F-GHG abatement systems. The comments and responses 

to those comments were documented and discussed with reviewers. This discussion led to the 

third and latest onsite measurement study, as well as to a second version of the Protocol. The 

second version of the Protocol was again circulated to a subset of the reviewers to the first 

version. The comments and responses to those comments were also documented and discussed 

with reviewers. 

A consistent theme that emerged from EPA’s testing and all the reviews of the Protocol is the 

diversity of manufacturing practices and conditions across the electronics manufacturing sector. 

Therefore experienced and resourceful metrologists are central to successful DRE measurements. 

This Protocol is aimed for use by experienced metrologists—experienced not only in the use of 

4
advanced analytical measurement systems such as FTIR and QMS, but also in performing in-fab 

measurements of F-GHG emissions. Moreover, the Protocol does not constitute a recipe—a 

single approach for all circumstances—for making DRE in-fab measurements. Instead, properly 

construed, the Protocol permits flexibility in measurement practice provided the measurements 

achieve the performance standard that is integral to this Protocol 

1. INTRODUCTION 

Members of the U.S. Environmental Protection Agency’s PFC Emissions Reduction/Climate 

Partnership for the Semiconductor Industry (the Partnership) operate under a voluntary 

agreement to reduce perfluorocompound (PFC, henceforth called fluorinated greenhouse gas, FGHG) emissions to 10 percent below the 1995 base-year amounts by 2010. A variety of practical 

F-GHG-reducing options—with reduction-efficiencies that range from 10 to >99 percent—are 

available. These options include process optimization techniques, switching to alternative gases 

with lower emissions potentials, and point-of-use (POU) F-GHG abatement. While there are 

industry-standard guidelines that set forth methods for measuring and documenting process 

emissions (ISMI, 2006), that is not so for measuring the destruction-removal efficiencies (DRE) 

of POU F-GHG abatement systems, although published reports of DRE measurement studies are 

available (Beu et al., 1994; Li et al., 2001, 2002 and 2004; Lee et al., 2007). 

The U.S. Environmental Protection Agency (EPA) initiated preparation of this document (the 

Protocol) as part of its commitment to assist the Partnership in achieving the F-GHG emission 

reduction and reporting goals. The development of this Protocol builds on three DRE 

measurement studies of POU F-GHG abatement systems conducted onsite at three U.S. 

semiconductor fabrication facilities (fabrication facilities are henceforth called fabs). (EPA 

2008a, 2008b, and 2009) 

5
1.1 Protocol Purpose 

The purpose of the Protocol is to provide a practical and reliable method for measuring DREs of 

POU abatement systems of F-GHG gases used during the manufacture of electronics products, 

specifically semiconductor systems, micro-electro-mechanical systems (MEMS), thin film 

transistor (TFT) arrays and amorphous silicon (a-Si) and tandem amorphous silicon/

nanocrystaline silicon (a-Si/nc-Si) thin-film photovoltaic (PV) panels.1 

The Protocol sets forth two specific methods for measuring abatement system inlet and outlet 

flows, and hence DREs, for single or multi-chamber process tools. These methods address 

measuring the mass or volume flows of F-GHGs entering and leaving the abatement system. 

Both methods account for the dilution that occurs in thermal abatement systems.2 

The first and simplest, Method 1 - Dilution Adjusted Concentration Measurement, involves 

measuring DRE when the process tool is off. This approach will produce reliable results when FGHG byproducts are not formed, for example, during chamber cleaning with CF4, SF6 or with 

NF3 when carbon films are not present. A variation of Method 1 may be used that imitate 

byproducts formation. This involves taking appropriate steps to add proper amounts of byproduct 

F-GHG to the influent abatement-system flow of unutilized F-GHG(s). 

The second method, Method 2 – Total Volume Flow Measurement, is the preferred method for 

measuring DRE when byproducts are formed. Method 2 measures abatement-system DRE under 

actual process conditions. One of two approaches may be used when applying Method 2, 

dependent upon if measurements are being taken sequentially or simultaneously. 

Method 2, requires introducing a chemically stable material – a tracer or spiking agent that 

neither affects the performance of nor is affected by the abatement system—into the process 

line(s). Using this method will provide a reliable estimate of the effective dilution associated 

with in-fab thermal POU abatement systems3

 and, in turn, the DREs. This chemical-spiking 

approach is a special application of ASTM E 2029 – 99 (Re-approved 2004), which provides a 

method for measuring volumetric or mass flow rate of a gas in a duct, pipe, etc. using a tracer 

dilution technique (ASTM, 2004). ASTM E 2029-99, like this Protocol, addresses irregular and 

non-uniform flow conditions where conventional pitot tube or thermal anemometer velocity 

measurements are difficult or inappropriate due to the absence of a suitable run of duct/pipe 

upstream and downstream of the measurement location. 

Establishing DREs based on this Protocol will (a) assure reliable comparisons of vendors’ 

abatement systems; (b) assure third-parties of the reliability of reported emissions; (c) improve 

understanding of appropriate and necessary system maintenance; and (d) serve as a starting point 

 

1

 The electronics manufacturing sector includes, but is not limited to those industry sub-sectors that are listed. This 

Protocol is applicable to all electronics sectors; but it was developed based on work at a semiconductor 

manufacturing facilities. However EPA sees no limitation on why the Protocol may not be applied when measuring 

DREs at other electronics manufacturing facilities. 2

 Testing for the development of the Protocol focused on POU thermal abatement systems because dilution is 

greatest. It is expected the Kr tracer method is suited to POU plasma systems. However, EPA was not aware of 

fully operational plasma abatement systems in production fabs at the time of the Protocol’s publication. 3

 See footnote 2. 

6
for emerging carbon trading opportunities (i.e., measuring baseline and actual emission 

reductions).4

1.2 Protocol Objectives 

The objectives of the Protocol are to specify: 

 

• a method for measuring and reporting F-GHG-specific DREs of installed, in-fab 

abatement systems that are operating during normal production processing; 

• a method for measuring and reporting F-GHG-specific DREs of abatement systems that 

are offered to manufacturers of electronic products that use F-GHGs during product 

manufacturing; and 

• guidance to fab Environmental Safety &Health staff and to providers of POU abatementtesting services on best-practice procedures for measuring, documenting and reporting of 

in-fab determinations of F-GHG abatement system DREs. 

1.3 Protocol Scope 

The Protocol is applicable to measuring and reporting DREs of installed POU systems whose 

input flows may contain CF4, CHF3, CH2F2, C2F6, C3F6, C3F8, C4F6, c-C4F8, C4F8O, C5F8, NF3

and SF6. These high-GWP gases may be used directly in fab processes and, in some 

circumstances, may be formed during those processes. 

The Protocol is intended to complement the guidance prepared by International SEMATECH 

Technology Transfer # 06124825A-ENG (December 2006); this Protocol adopts in its entirety 

Appendix A of SEMATECH TT # 06124825A-ENG (December 2006), which explains best 

known methods for measuring, among other things, F-GHG emissions. The principal difference 

between the 2006 updated SEMATECH guidance and this Protocol is the emphasis given here to 

POU abatement system DRE measurement and to measuring dilution across the abatement 

system. 

The Protocol institutes two practices to establish the veracity of reported results. The first is 

adoption of a benchmark metric together with a performance standard for that metric. The 

benchmark metric is the relative error, which is a precision metric, in the reported true fraction 

emitted of which the DRE is its complement. The performance standard the relative error must 

meet is ±5 percent relative error.5,6

 The second practice is the requirement for metrologist 

 

4

 The Executive Board of the Clean Development Mechanism has final authority for approving methods for 

measuring emissions of greenhouse gases, for purposes of establishing a CDM project. However, CDM does not 

have authority in the United States.. 

5

 The fraction emitted is chosen as the performance metric rather than the DRE because the relative error of the 

measured DRE is a function of the true fraction emitted. As the true fraction emitted approaches one (DRE 

approaching zero), the relative error becomes very large even when the relative error in the true fraction is 

acceptably small. Similarly, when the true fraction approaches zero (DRE approaches one), the relative error in DRE 

can become small even when the relative error in the true fraction emitted is large. When the post-abatement 

concentration approaches or falls below minimum detection an alternative calculation is provided (vide infra). 6

 Experience demonstrates that ±5 percent or better is readily achievable in a fab environment. In three separate 

studies (EPA 2008a, 2008b, and 2009), the estimated relative error for the true fraction emitted for four POU 

7
certification, certifying that the methods set forth in the Protocol were followed, including that 

the conditions under which the measurements were made (with the plasma off or actual process 

conditions). 

EPA wishes to strike an appropriate balance between assuring reliable results and flexibility. In 

the remainder of the Protocol, where EPA anticipates the need for flexibility it has provided 

examples to demonstrate the nature and extent of the permitted flexibility. EPA will consider 

updating the Protocol given the availability of and access to additional testing experiences and 

well-documented results. 

1.4 Development of the Protocol 

The Protocol has gone through five stages of development: conceptualization, onsite tests, initial 

drafting, and two informal peer review processes. During the informal peer review processes 

EPA received comments from both national and international parties, including semiconductor 

manufacturers, equipment manufacturers, gas suppliers and analytic service providers. Appendix 

A discusses some of these comments, as well if and how the Protocol was revised to reflect 

them. 

1.5 Expected Results 

This Protocol results in an estimate for the DRE of F-GHG abatement systems, where the 

relative error of true fraction emitted estimate (the benchmark metric), measured under in-fab 

production processing circumstances and typical (in-fab, as-installed) POU system operating 

circumstances, is less than ±5 percent (the performance standard). The value of relative error of 

the true fraction emitted is determined by the methods outlined in the remainder of this Protocol. 

2. MEASUREMENT PLAN, PREPARATION, METHODOLOGY, AND DATA 

ANALYSIS 

2.1 Prepare Measurement Plan 

A measurement plan serves two main purposes. First, it provides background on the tools, 

processes, and abatement systems to be tested; and second, it facilitates coordination between 

facility personnel and testing service providers. An understanding of the tools, processes, and 

abatement systems provides testing service providers with background on the experimental 

system in preparation for the study. Coordination with facility personnel reduces the likelihood 

of encountering unexpected problems of measurement execution during the study. Testing 

service providers should prepare a measurement plan and submit it to facility personnel at least 

two weeks prior to the measurement study. At a minimum, the measurement plan should contain 

detailed descriptions of the experimental system, the sampling configuration, required/expected 

 systems attached to either etch or CVD process tools was below ±3 percent. Adoption of ±5 percent as a 

performance standard assures the accuracy of the measured true fraction emitted will be ±5 percent or better, under 

the reasonable assumptions that the accuracy of calibration gases and mass flow controllers are each ±3 percent or 

better. 

8
resources/support from the fab, a measurement schedule, address safety and a quality 

control/quality assurance plan (QA/QC) as described in the following sections. In preparing the 

plan, attention to Appendix A of the 2006 ISMI Guidelines is essential to assuring best in-fab 

FTIR and QMS measurement practice is achieved. 

2.1.1 Description of Experimental System 

An understanding of the tools, processes, and abatement systems to be tested prepares the testing 

service provider for the onsite measurement study. For example, the experimental system setup 

informs the study’s sampling configuration, whereas the expected dilution, flows, and DRE 

inform the type of analytical tools for data treatment needed for the study. To ensure that testing 

service providers are adequately prepared for conducting onsite measurements, information on 

the following aspects of the experimental system should be included in the measurement plan: 

• Description of the process tool and abatement system; 

• Configuration of the process tool and abatement system; 

• Presence of vacuum pump purges and additional purges; 

• Process operating conditions; 

• Measurement conditions (i.e., plasma off or actual process conditions); 

• Gases/flow rates (when measuring with the plasma off) and/or process recipe (when 

measuring during actual conditions); 

• Number of process chambers served by abatement system; 

• Nominal abatement system reactor temperature; 

• Nominal abatement system exhaust flows; 

• Nominal process exhaust flows; 

• Nominal dilution factor (Note: Nominal dilution factor is defined as the ratio of the 

nominal abatement system exhaust flow to the nominal process exhaust flow); and 

• Nominal DRE(s) for F-GHG(s) being tested. 

2.1.2 Sampling Configuration 

An example schematic of the sampling configuration, which illustrates the configuration of the 

process tool and abatement system, should be developed by testing service providers prior to 

onsite measurements. In the schematic the planned/proposed sampling and measurement layout 

in relation to the process tool and abatement systems, the process tool and abatement system 

effluent sampling locations, and the type of sampling port (e.g., tie-in type) should be clearly 

labeled (see Figure 1). 

2.1.3 Required Resources 

One of the primary purposes of the measurement plan is to facilitate coordination between the 

testing service providers and the facility personnel. The plan should include a sufficiently 

detailed description of all resources needed from the facility including sampling ports and 

fittings, gas supplies, electrical outlets, and assistance of facility personnel including roles, 

responsibility, and an anticipated schedule. Advance preparation by facility personnel is essential 

for maximizing the utility of testing service providers’ time at the facility. 

9
Figure 1. Sampling Schematic for Single and Multiple Chamber Inlet Flow(s) Source: EPA, 2009. 

Note: Metrologists need to be mindful of recirculation issues when returning the sampled gas flows 

to exhaust lines. 

2.1.4 Measurement Schedule 

In order to minimize any interference with facility production, a measurement schedule should 

be agreed upon prior to conducting the onsite study. The measurement schedule should clearly 

indicate the sampling start and end times. Additionally, the tool operator should approve and be 

familiar with the measurement plan and experimental system including the process 

tools/chambers and abatement systems, the process conditions during sampling (i.e., plasma off 

versus actual process conditions), and the gas flow rates/process recipe to be supplied to the tool. 

2.1.5 Safety 

Safety of the measurement study participants is of highest priority. Prior to conducting any work 

onsite, testing service providers will be instructed by appropriate fab personnel about all 

pertinent safety requirements and practices. For example, appropriate personal protective 

equipment (PPE) should be worn while conducting measurements in a fabrication environment 

(e.g., head protection, hearing protection, eye protection, and foot protection). Additionally, 

testing service providers are responsible for acquainting themselves with the hazards that exist in 

the IC fabrication environment (e.g., hazardous gases, chemical spills, and heavy objects) and 

taking all steps to avoid adverse impacts. Special consideration should be given to the benefits 

and risks of mixing pyrophoric/flammable and oxidizing gases. Most abatement systems are 

10
designed to prevent such mixing prior to combustion and measurement methodologies that defeat 

manfuacturers’ design goal should be thoroughly considered. 

2.1.6 Quality Assurance/Quality Control 

In preparation for the measurement study, testing service providers should gather information on 

the experimental system and its expected characteristics, such as expected reactor temperature, 

exhaust flows, etc (see Section 2.1.1). This information serves as a check to ensure the 

experimental system is functioning as expected. Testing service providers should also be aware 

of any leaks or instrument malfunctioning that could nullify results of the study. 

2.2 Measurement Methodology 

This Protocol describes two methodologies for obtaining DRE measurements: Method 1 

(Dilution Adjusted Concentration Measurement), which is performed with the plasma off, and 

Method 2 (Total Volume Measurement), which measures emissions during actual production 

processing conditions. Two approaches may be followed when using Method 2 to measure the 

DRE: Sequential Single-Chamber Process Inlet Abatement System Flow Sampling (SSPISF) or 

Multi-Chamber Process Inlet Abatement System Flow Sampling (MPISF). Proper application of 

these methods (or approaches) will ensure that the DRE measured has a relative error below ±5 

percent. The relative error of the estimated true fraction emitted provides one benchmark for 

assessing the quality of the sampling methodology, and is the metric used in this Protocol to 

determine the acceptability of the DRE measurement methodology. If the relative error of the 

true fraction emitted is less than ±5 percent at one standard deviation the methodology used is in 

accordance with the best practices defined in this Protocol via Methods 1 and 2. 

Whether Method 1 or Method 2 (SSPISF or MPISF) is most applicable depends on several 

considerations, including the experimental system to be tested, measurement study objectives, 

and safety (cf., Sec. 2.1.5). All named methods and approaches require similar sampling and 

analytical methodologies, which are described in detail in this section of the Protocol. Where the 

methods and approaches differ is Method 1 requires sampling when the process tool is off while 

Method 2 (SSPISF or MPISF) requires sampling under normal process conditions. The 

differences in sampling conditions lead to differences in data analysis and DRE calculations for 

Methods 1 and 2. Using alternate methodologies to the ones described here is acceptable, as 

long as the relative error in the true fraction emitted measurement is less than ±5 percent. If an 

alternate methodology is used, the burden falls on the testing service provider to demonstrate that 

the relative error requirement (±5 percent) is met, to provide detailed descriptions of the 

methodology used, and to provide the appropriate supporting data analysis. 

In instances when concentrations exiting the abatement system are below FTIR detection limits a 

modification of the performance metric is required. Because the concentrations exiting the 

abatement system cannot be measured in these instances, a predefined F-GHG concentration is 

used (which exceeds the lower limit of FTIR detection) to demonstrate proper measurement. To 

calculate the performance metric, the relative error of that concentration is used, with the result 

compared to the performance standard of ±5 percent. 

11
Methodologies and approaches described in this Protocol make extensive use of Fourier 

Transform Infrared (FTIR) Spectroscopy and Quadrupole Mass Spectrometry (QMS) techniques. 

Testing service providers are directed to the guidance prepared by International SEMATECH 

Technology Transfer #0612485A-ENG for detailed descriptions for best practice FTIR and QMS 

Protocols (December, 2006).7

2.2.1 Method 1—Dilution Adjusted Concentration Measurement 

In Method 1, the process tool plasma (RF) is off while data are collected, so DRE measurement 

is made with the F-GHG and diluent gases entering the abatement system. An advantage of 

Method 1 lies in controlling the flow rates of the F-GHGs measured, resulting in steady-state 

conditions, which make the subsequent data analysis and DRE calculations simpler than dealing 

with non-steady state flows. However, when the process tool is off, by-product gas DRE's will 

not be measured, requiring modification of the process tool setup to imitate by-product gas 

flows. Method 2 overcomes this difficulty and is, therefore, preferred. 

When using Method 1, F-GHG flows entering the abatement system should be 120 percent of the 

F-GHG flows entering the abatement system during normal production processing to ensure the 

abatement tool is being tested under conditions that may occur during processing. For example, 

if the process flow for an F-GHG, f, is x sccms during production processing (which corresponds 

to y g/sec) and the corresponding default utilization is Uf, then the flow entering the abatement 

system during testing should be 1.2 * y * (1-Uf) g/sec of gas f. In a circumstance when 

byproducts are formed, the sum of the imitated emissions of the F-GHG and byproduct gas(es) 

should equal 120 percent of the value obtained using the appropriate IPCC 2006 default emission 

factors (Volume 3, Table 6.3). 

2.2.2 Method 2—Total Volume Measurement 

Method 2 involves collecting data during actual process conditions. Method 2 requires no 

modifications to the process tool for either process or byproduct gas DRE measurements. 

However, collecting data during actual process conditions may not result in steady-state 

conditions, making the data analysis and DRE calculations more involved than Method 1 (see 

section 2.3 for detailed discussion of data analysis). Sampling to measure total F-GHG volume 

flow leaving the process tool and the abatement system may be accomplished through two 

approaches, which are applicable to process tools with single or multiple process chambers 

(reference Fig. 1). 

One approach consists of sequentially measuring the F-GHG volume flow entering the 

abatement system from each chamber while also measuring the corresponding F-GHG volume 

flow leaving the abatement system. This sampling approach is called the Sequential SingleChamber Process Inlet Abatement System Flow (SSPISF) method. The second sampling 

approach consists of simultaneously measuring the volume flow from all operating chambers that 

 

7

 See Appendix A – Technical Protocols of Air Emissions Characterization of SEMATECH Technology Transfer 

#0612485A-ENG (December 2006). This Appendix augments EPA Test Method 320, Measurement of Vapor Phase 

Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy, as 

it might apply to measuring F-GHG emissions in waste streams produced during electronic device manufacture 

12
is entering the abatement system while also measuring the corresponding F-GHG volume flow 

exiting the abatement system. This second sampling approach is called the Multi-chamber 

Process Inlet Abatement System Flow (MPISF) method. Both approaches employ sampling 

during actual process conditions. The SSPISF method uses a slip-stream of the effluent from a 

single process chamber as its sample and the MPISF method uses multiple slip-streams of the 

effluent (one for each operating chamber with each representing the appropriate proportion of the 

total process flow from all operating chambers) that are then mixed to account for actual process 

conditions. Sampling to measure the total F-GHG volume flow entering the abatement system 

may be accomplished using the MPISF method provided appropriate safety precautions are taken 

when mixing the flows of combustible gases. 

2.2.3 Equipment Needed 

Two FTIRs are optimal for measuring F-GHG concentrations in the effluent streams.8

 One FTIR 

is used to sample from the process effluent and another to sample from the abatement system 

effluent. Additionally, a QMS, inert gas supply, and mass flow controller (MFC) are needed to 

measure the dilution that occurs through the abatement system. When measuring DREs in 

systems that do not abate CF4 and/or SF6, it is possible to measure dilution using an FTIR instead 

of a QMS/MFC/inert gas supply system. When a tracer other than a noble gas is used, such as 

CF4 or SF6, the metrologist should provide documentation demonstrating that less than 5 percent 

of the tracer gas is destroyed. For purposes of testing using such tracers, the tracer gas is treated 

as undestroyed. Two examples of an acceptable demonstration are: (1) the manufacturer of the 

POU abatement system provides results, based on the methods of this Protocol, that the DRE of 

the chemical tracer is <5 percent under the operating conditions being tested at the fab using the 

QMS and the noble gas tracer methodology or (2) in-fab tests showing <5 percent destruction of 

the chemical tracer on a POU abatement system (based on the QMS and noble gas tracer 

methodology of this Protocol for one abatement system in the fab) may be used on abatement 

system in the facility of the same make and model installed and operated in the same manner as 

the abatement system tested. 

Metal bellows sampling pumps should be installed after each FTIR and/or QMS to collect 

effluent samples. Installing adjustable flow rate valves to control the sample flow rates and 

capacitance manometers to monitor the sample line pressure are recommended. A sample filter 

should be used in the abatement system sampling line to prevent particulate emissions from the 

abatement system from damaging the FTIR or QMS. Lastly, when sampling using the MPISF 

method, mass flow controllers (MFCs) are needed—one for each operating chamber during 

sampling—to create a representatively proportional slip stream composition of the total flow. 

Table 1 provides a summary of the equipment required and Figure 1 shows a sample schematic 

of the experimental setup. 

 

8

 One FTIR can be used, but it would be necessary to alternate abatement system inlet and outlet measurements. 

Steady-state behavior would have to be verified by sampling for a sufficiently long period of time. It must be shown 

that sufficient precision can be achieved with just one FTIR system. Using one FTIR will require knowing with 

confidence what the abatement system loading is. If sufficient inlet data is acquired to accomplish this, and then the 

FTIR is switched to the outlet of the abatement system and the same process is run on the tool then the Protocol will 

work just as well as using two FTIRs. The emission factors for a particular process run on the same chamber are 

usually reproducible. Sufficient data can be collected to achieve the desired precision. 

13
Table 1. Measurement Study Equipment Needsa

Equipment Type Quantity Required 

FTIR 

QMS 

Inert gas supply/mass flow controller (MFC) 

Metal bellows sampling pumps 

Adjustable flow rate valves 

Capacitance manometers 

Sample filter 

1-2b

0-1 

0-1 

2-3 

2-3 

2-3 

1-2 

MFC for exhaust streams No. of chambers tested 

. a Not exhaustive 

 b When using 1 FTIR, it must have variable path length 

2.2.4 FTIR and QMS Protocols 

FTIR measurements should be taken following the best practice guidelines specified in the 

guidance prepared by International SEMATECH Technology Transfer #0612485A-ENG 

(December, 2006).9 The FTIR should be operated at a resolution of 0.5 cm-1 or 1.0 cm-1, 

provided that calibrations match resolution used during sampling. The sampling frequency for 

the FTIR should be less than 3 seconds.10 The FTIR absorbance range should be between 0.1 and 

1.0; however, lower and higher absorbencies may be used provided sample data are bracketed by 

calibration data. Alternate short- and long-path gas cells should be used, to ensure that the 

measured absorbance for process effluent concentrations and abatement system effluent 

concentrations falls within the range 0.1 to 1. 

QMS measurements should be taken following the best practice guidelines specified in the 

guidance prepared by International SEMATECH Technology Transfer #0612485A-ENG 

(December, 2006).11 To account for fluctuations/drift in QMS sensitivity, the ion signals should 

be normalized to the signal obtained for the nitrogen fragment N+, which is formed during 

ionization of N2. 

2.2.5 Calibration Curves 

 

9

 See Appendix A.2 – Fourier Transform Infrared (FTIR) Spectroscopy Protocol of SEMATECH Technology 

Transfer #0612485A-ENG (December 2006). 

10 In the tests EPA performed, 4 FTIR scans were co-added for one data point, which takes 2.2 secs at 0.5 cm-1

resolution and provides adequate temporal resolution to follow time-varying process emissions. Thus, each data 

point requires 2.2 sec, so 40 data points requires approximately 1.5 minutes. 

11 See Appendix A.1 – Mass Spectrometry Protocol of SEMATECH Technology Transfer #0612485A-ENG 

(December 2006). 

14
The Protocol permits either onsite or offsite calibration for FTIR measurements of F-GHGs, with 

both governed by the guidance provided in Appendix A.2 of SEMATECH Technology Transfer 

(December 2006). In either circumstance, the range in absorbance for the calibration curves 

should bracket the corresponding absorbance range for the onsite measured concentrations, with 

a preferable range for the absorbance between 0.1 and 1. In situations where the onsite measured 

absorbance lies outside the 0.1 to 1 range, either (a) a calibration must be available at the high or 

low absorbance, (b) an alternative absorption band should be used that lies, for that specific 

molecule, within the 0.1 – 1 absorbance, or (c) an alternate FTIR gas cell should be used.12

Further, while the measured absorbance of large molecules, like the F-GHGs of concern here, is 

not expected to be sensitive to reasonable differences in resolution (say, 0.5 vs. 1 

cm

-1), this concern is mitigated by requiring the use of the same resolution for calibration 

sampling. 

For onsite calibration, the metrologist must report/show the calibration graphs and report the 

corresponding calibration and measurement conditions for all F-GHGs measured. The 

measurement conditions to report are gas temperature and pressure, as well as the FTIR 

resolution used during sampling and calibration. When reported DREs employ offsite 

calibration, the metrologist must report/show calibration graphs as well as the conditions 

(temperature, pressure and resolution) used for calibration and during onsite sampling. If 

calibration and onsite temperatures, pressures or both differ then corrections must be made to 

account for the change in gas number density. These corrections are often standard features of 

modern FTIR software packages. The calibration curves for both onsite and offsite testing should 

be generated using at least three calibration points such that expected measured absorbance range 

is covered. Quality of calibration may be judged by proximity of R2

 to 1.00. For non-linear 

calibration curve, it’s important that highest observed concentration is within not outside the 

range of concentrations used to define the calibration curve. 

Prior to conducting measurements of the process and abatement system effluents, onsite QMS 

calibration should be completed for all compounds to be measured. The calibration curves 

should be generated using at least 1 zero and 5 non-zero data points. The recommended ion 

intensity range for the QMS should be within one decade. Calibration plots with the signal 

intensity versus compound concentration data points and the line of best fit should be included in 

the measurement report. Additionally, the slope, the relative error of the slope (one standard 

deviation), the y-intercept, and the correlation coefficient (i.e., R2

) of the correlation line should 

be presented and each parameter clearly labeled (see Figure 2 as an example). 

To ensure that the ±5 percent benchmark relative error is achieved, all calibration curves should 

meet the following criteria: 

• Slope must have an error below ±5 percent; and 

• Correlation coefficient must exceed 0.98 

 

12 Some FTIR quantitative analysis software packages (e.g. AutoQuant Pro used by Midac Corporation) has the 

ability to shift to different absorbance peaks over several orders of magnitude depending on the concentration of the 

material being measured. In this case, multiple gas cells may not be required. However, that shifting to another peak 

may risk influence of interferent that also absorbs at that same wave number. Using multi-path cells is best practice 

for this FTIR application. 

15
 

Figure 2. Sample Calibration Curve The R2

 and relative error of the slope for both calibration 

curves shown are >±99 percent and <±1 percent, respectively. Source: EPA, 2008a and 2008b. 

2.2.6 Flow and Dilution Measurements 

Determining dilution across the abatement system is a two step process. The first step is 

determining the total volume flow of the process effluent, and the second step is determining the 

total volume flow of the abatement system effluent. The total volume flow of the process effluent 

can be estimated by flowing known quantities (flows) of F-GHG through the tool with the RF 

turned off, while a FTIR system measures the F-GHG concentration of the process effluent. The 

total volume flow of the abatement system effluent can be estimated by supplying known 

quantities of inert gas into the process stream effluent, while a QMS system measures the inert 

gas concentration in the abatement system effluent. Controlled volume flows of inert gas can be 

supplied to the process effluent using a mass flow controller (MFC). When measuring DREs in 

systems that do not abate CF4 and/or SF6 it is possible to measure total abatement system flow 

using an FTIR instead of a QMS. In such systems CF4 or SF6 can be used in place of an inert gas 

since their DREs are zero percent. Table 2 provides a list of acceptable gases for measuring total 

abatement system flows, along with their use conditions. 

16
Table 2. Acceptable Gases for Monitoring Total Abatement System Flows 

Tracer Gas Analytical Equipment Limitations 

Kr QMS None 

Xe QMS May be used in some etch 

processes recipes. 

Ar QMS Must subtract out air 

concentration background; 

cannot use if Argon is used 

as a process gas. 

CF4 FTIR DRE must be zero 

SF6 FTIR DRE must be zero 

To ensure that the ±5 percent relative error is met, the following conditions should be met: 

• Accuracy of calibration gases in the concentration of the inert gas supplied to the 

process effluent stream should be ±3 percent or less. 

• 3-5 different flow rates should be supplied to the process tool and/or abatement 

system, and at least 40 distinct measurements made for estimating the average 

concentration at each flow rate. 

• Appropriately sized MFC such that accuracy of lowest flow is ±3 percent or better 

2.2.7 F-GHG Measurements 

The Protocol suggests that using two FTIRs is optimal.13 One FTIR is used to measure F-GHG 

concentration in the process effluent and another to measure F-GHG concentration in the 

abatement system effluent. The concentration of F-GHGs in both effluent streams should be 

recorded, as well as the gases/flow rates and/or process recipes that are fed into the process tool. 

Absorption bands should be chosen to minimize the influence of interfering substances and to 

hold absorbance within the range 0.1 to 1. 

To ensure that the ±5 percent relative error is achieved, the following conditions should be met: 

• Method 1: For each process gas tested, 3-5 different flow rates should be supplied to 

the process tool, and at least 40 process tools and abatement system effluent 

concentration measurements averaged for each flow rate. 

• Method 2 (SSPISF and MPSIF): For each process gas tested, 3-5 data points should 

be collected for total volume in and total volume out of the abatement system and at 

least 40 process tools and abatement system effluent concentration measurements 

averaged for each flow rate.

When the concentration exiting the abatement system approaches or falls below the minimum 

detectable level the metrologist can demonstrate proper measurement practice by introducing 

into the sampling stream a flow of that gas such that its concentration entering the abatement is 

low but exceeds the minimum detection level. This concentration is denoted as C*

. To 

 

13 See footnote 8. 

17
demonstrate proper measurement of C*

, the relative error of the C*measurement is used in place 

of Co (the exit concentration) to calculate the performance metric. The precision of C*

 is 

estimated with data from the FTIR used to measure the F-GHG exiting the abatement system. 

Table 3 sets forth C*

, in units of ppm-m, for the gases governed by this Protocol. Table 3 

identifies the minimum detection (concentration) levels for the gases of interest at standard 

temperature and pressure (STP), defined as a signal to noise of 3 for a HgCdTe liquid nitrogen 

cooled detection, 0.5 cm-1 resolution. A single value for C* was chosen for simplicity. It is 

evident from comparison of the second and third column that, for the selected C*

, the signal to 

noise ratio (S/N) will be much greater than 3 so the precision should be high. Further, for the 

typical long-path used in such tests, the C*

 concentration being sampled should correspond to 

DREs in the range 95-99%. 

Table 3. Minimum detection levels (CMDL) and threshold F-GHG concentrations (C*) for measuring 

relative error of total fraction emitted when sample C < C*, ppm-m 

F-GHG Typical CMDL, ppm-m C*, ppm-m Primary absorbtion 

band, cm-1 

CF4 0.12 10 1280

CHF3 0.40 10 1150

C2F6 0.21 10 1250

C3F8 0.2 10 1150

c-C4F8 0.7 10 965

NF3 1.1 10 910

SF6 0.1 10 943

Note: CMDL values based on calibration data using path lengths between 10 cm and 5 m, 

resolution of 0.5 cm-1, gases at STP, HgCdTe liquid cooled detector and a S/N of 3 10-3

absorbance units. 

Of the several ways for preparing a sample stream with concentration C*, two that are acceptable 

are described here. The first is to ask the process tool operator to provide a sufficiently low flow 

of gas such that after dilution by the pump purge, C* is achieved at the sampling point ahead of 

the abatement system. For example, if the target concentration, C*

, is 2 ppm and the pump purge 

is 50 lpm (determined previously), then 50 ppm is achieved with a process flow of C of 0.1 

sccm. For process tools with MFCs that cannot deliver sufficiently low flows, the sampled slip 

stream can be diluted with nitrogen using either a separate MFC or needle valve. The actual 

concentration sampled may be within ±20 percent of C*

, i.e., ±0.4 ppm in the example (vide 

supra). 

A second approach for preparing C*

 is for the metrologist to have available a gas cylinder with 

the appropriate concentration to introduce ahead of the abatement system, which, accounting for 

the pump purge flow, will produce C* ±20 percent of the value taken from Table 3. The first 

approach may be preferable because it doesn’t require the availability of additional gas cylinders 

of the appropriate concentrations.

2.3 Data Treatment and Analysis 

18
The procedures for treating flow and concentration measurements as well as calculating total 

flows, dilution factor and DRE of the abatement system are described in this section. Also 

described are the methods for consistently estimating the precision associated with measuring 

gas concentrations, flows, dilution factors and DREs. The data treatment and analysis 

component consists of two sections. The first section addresses data used to calculate bestestimate values for flows and the abatement system dilution factor as well as their standard 

deviations. The second section addresses the data used to calculate best-estimate of the 

abatement system DRE and associated relative errors, using either Method 1 or Method 2. In the 

following sections absolute error is referred to as σ and relative error is referred to asε , and all 

relative and absolute errors are presented at 1 standard deviation. 

When an alternative methodology, such as the Physical Flow Measurement method, to the two 

described in this Protocol is used to estimate DRE, the data treatment and analysis procedure 

described below may not be applicable. In such cases, the testing service provider should 

determine and use the appropriate procedures to calculate both the DRE and its corresponding 

error. 

2.3.1 Abatement System Dilution 

2.3.1.1 Total Volume Flow 

Total volume flow (TVF) is the total volume of gas that flows across a process tool or abatement 

system, and is generally measured in standard liters per minute (slm). For both Methods 1 and 2, 

measurements of TVF entering and exiting the abatement system are needed. TVF or F is 

calculated using Equation 1: 

6 10 − × =

ef

f

C

S

F (1) 

where, 

F = total volume flow based on a single concentration data point [slm] 

f S = spike gas flow into the process tool/abatement system [slm] 

Cef = measured concentration of standard gas in the process tool/abatement system effluent 

[ppmv] 

To ensure that the error of TVF is low enough to meet the relative error requirement of ±5 

percent, TVF measurements should be collected during at least three different standard gas flow 

rates. During each gas flow rate, at least 40 concentration measurements (FTIR or QMS scans) 

should be collected at the effluent side of the process tool/abatement system. For example, when 

measuring the TVF exiting the process tool, a process gas such as C2F6 should be fed into the 

process tool at multiple flow rates (e.g., 0.2, 0.6, and 1.0 slm), and during each flow rate, a 

minimum of 40 concentration data points of the process effluent should be collected using a 

FTIR. Similarly, when measuring the TVF exiting the abatement system, an inert gas such as Kr 

should be spiked into the abatement system at multiple flow rates (e.g., 0.010, 0.030, and 0.050 

19
slm), and during each flow rate a minimum of 60 concentration data points of the inert gas in the 

abatement effluent should be measured using a QMS. 

The measurements above will result in at least 120 TVF data points, which will need to be 

averaged appropriately. A simple average, denoted as F determines the average TVF and 

corresponding standard deviation during each flow rate applied, denoted by subscript m (see 

Equation 2 and Equation 3). 

F m =

1

n Fi

n ∑ (2) 

where, 

F m = simple average of TVF [slm] for the mth flow 

n = number of concentration measurements taken while at a constant standard gas flow (e.g., 40 

concentration data points collected during a 0.2 slm standard gas flow rate) 

mF σ = ∑( − ) n

i FF m

n 1

1 2

 (3) 

The TVF simple average ( F m ) only applies to values that are collected during the same standard 

gas flow rate. Therefore, if three different standard gas flow rates are collected, three different 

simple averages must be derived. 

When combining the multiple TVF simple average ( F m ) values for each flow rate into a single 

average TVF, a variance weighted average must be applied (denoted as Fˆ ). The equations for 

determining the variance weighted average and its corresponding standard deviation, are shown 

in Equations 4 and 5. 

ˆ

F

g

 = 

2

1

2

1

1

m

m

M

m

F

M

F

F

σ

σ

∑

∑

 (4) 

where, 

ˆ

F

g = variance weighted average TVF [slm] for flow standard gas, g 

M = number of flow rates used per standard gas, g 

= Fgσ ˆ

2

1

1

2

11 −

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

× ∑

M

F m

n σ

 (5) 

20
where, 

n = number of concentration measurements 

The variance weighted TVF average ( Fˆ ) can only be calculated using average TVF values ( F ) 

obtained using the same standard gas. For example, if two different standard gases are used, 

then a variance weighted average is calculated for each standard gas. 

Equation 5 assumes that the number of concentration measurements during each flow rate is 

constant (i.e., is the same for each simple average). If varies for each simple average, then 

Equation 5 must be altered to account for variations in n. Alternatively, when varies, the 

lowest can be used in Equation 5 to generate a conservative estimate of the standard deviation 

(i.e., the standard deviation will err on the larger side). 

n n

n

n

In the case when multiple standard gases (e.g., Kr and Xe for abatement system or C2F6 and CF4

for process tool) are used to calculate TVF, then the variance weighted average ( ˆ

F

g ) for each 

gas, g, can be combined to determine a TVF best estimate (denoted as F ) and its corresponding 

error as shown below (see Equations 6 and 7). 

∑

∑

= G

F

G

F

g

g

g

F

F

1

2

ˆ

1

2

ˆ

1

ˆ

σ

σ

 (6) 

where, 

F = Best estimate for TVF [slm] 

G = number of standard gases used to determine TVF 

2

1

1

2

ˆ

1

−

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

= ∑

G

F

F

g

σ

σ (7) 

 

The absolute errors or standard deviations obtained from equations 3, 5 and 7 measure the 

precision of each standard gas flow for each gas, for all flows for each gas, and for all gases, 

respectively, when more than one gas is used (e.g., if Xe and Kr were both used). The overall 

accuracy is determined by the accuracy of the calibration, calibration standard gas 

concentrations, and mass flow controller. In order to obtain a DRE relative error of less than ±5 

percent, the concentration standard gas should have a relative error of less than 3 percent of the 

designated concentration, and the accuracy of the MFC should be less than 3 percent for the 

lowest flow rate used during the measurements. 

2.3.1.2 Dilution Factor 

21
The dilution factor describes the total volumetric dilution that occurs across an abatement 

system. The dilution factor is determined by calculating the best estimate for TVF into ( F in ) 

and out of the abatement system ( Fout ). (See Section 2.3.1 for determining the best estimate for 

TVF). The TVF exiting the abatement system divided by the TVF entering the abatement 

system defines the dilution factor as shown in Equation 8. The standard deviation or precision of 

the dilution factor is determined by the standard deviation of each TVF measurement, and is 

estimated using error propagation techniques (See Equation 9). 

DF

in

out

F

F = (8)

where, 

DF = Best estimate for dilution factor [dimensionless] 

Fout = Best estimate for TVF exiting abatement system [slm]

F in = Best estimate for TVF entering the abatement system [slm] 

ε DF)(

2 2

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+ ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

=

in

F

out

F

FF

out in

σσ

 (9)

where, 

ε DF = The relative error of DF (the standard deviation divided by the mean value) 

Fout

σ = The standard deviation of Fout [slm] (see Equation 7)

Fin

σ = The standard deviation of F in [slm] (see Equation 7)

2.3.2 Abatement System DRE Estimate and Relative Errors 

The formulas for calculating DRE depend on the method used. For Method 1, the ratio of the 

measured effluent concentration to measured influent concentration is multiplied by the 

measured dilution factor (i.e., dilution adjusted concentration fraction, which equals the mass- or 

volume-emitted fraction). For Method 2, the ratio of effluent to influent gas volumes is used (i.e., 

volume fraction); the affect of dilution is accounted for when calculating total flows. For either 

method it can be shown that, for the formulas given below, the calculated DRE is a bestestimate, i.e., statistically unbiased. The subscripts 1 and 2 differentiate formulas for Method 1 

and 2, respectively. 

2.3.2.1 Method 1—Dilution Adjusted Concentration Measurements 

2.3.2.1.1 Concentration Measurements 

22
During Method 1, the concentration of process gas entering and exiting the abatement system is 

monitored, while the process tool is off, and while a known flow rate of process gas is fed into 

the abatement system. For each flow rate, the concentration of process gas in the abatement 

influent and effluent is in steady state. For each process gas at least three different process gas 

flow rates should be used to collect a minimum of 60 concentration data points per flow rate, to 

ensure relative error is achieved. As described in section 2.2, an FTIR should be used to monitor 

concentration of process gases, and the FTIRs absorbance signal should be converted to a 

concentration using a calibration curve. The relative error of each concentration data points 

measured by the FTIR is equal to relative error of the calibration curve slope.14 Using the 

concentration data points, the variance weighted average and corresponding error for 

concentration can be estimated using a procedure analogous to that shown for total volume flow 

(see Section 2.3.1.1; Equations 1 to 5). The variance weighted average is considered the best 

estimate for F-GHG concentration entering and exiting the abatement system. 

2.3.2.1.2 DRE 

DRE1

( ) percent

C

DFC

in

out 1 ×100 ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ × −= (10)

where, 

DRE1 = Best estimate for Destruction and Removal Efficiency [percent] 

Cout = Best estimate for concentration of F-GHG exiting the abatement system [ppm] 

Cin = Best estimate for concentration of F-GHG entering the abatement system [ppm] 

( DF)

DF

DRE

C

C

λ

λ

ε

−

=

1

)( 1

2 2

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+ ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

DF

DF

C

C

σ

λ

σ λ (11)

where, 

in

out

C

C

C λ =

)(λC ε

2 2

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+ ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ =

in

C

out

C

C C

out in

σ σ

σ λ c = The standard deviation of λc 

DF

σ = The standard deviation of DF 

 

14 The relative error of the calibration curve slope should not exceed ±5 percent (at one standard deviation) to ensure 

the Protocol benchmark error of ±5 percent is obtained. 

23
o Cout

σ = The standard deviation of ut C [ppm]

Cin

σ = The standard deviation of Cin [ppm] 

2.3.2.2 Method 2—Total Volume Measurements 

ady 

tal 

ess, the best estimate and error of the total 

olume measurement is equal to the simple average and its standard deviation, which are 

tions 2 and 3 in Section 2.3.1.1. 

2.3.2.2.2 DRE 

2.3.2.2.1 Total Volume Measurements 

When measuring the DRE using Method 2, the concentration of the gas in the abatement influent 

and effluent is monitored while the process tool is on, and cannot be assumed to be at ste

state. Therefore, the total volume of process gas entering and exiting the abatement system must 

be estimated by integrating the FTIR signal over time (The absorbance signal should be 

converted to concentration using the calibration curve, prior to integration). When multiple to

volume measurements are collected for a single proc

v

analogous to Equa

percent

V

V DRE 2 =

⎝ in ⎠

re, 

out 1 ×100 ⎟

⎟

⎞

⎜

⎜

⎛ − (12) 

whe

V out = Best estimate for total volume of F-GHG exiting the abatement system [sl] 

V in = Best estimate for total volume of F-GHG entering the abatement system [sl]. 

Vi = , ,

1 1

( )

N N

i ij j i ij j

j j

Vi t FC t F C t = =

∫ = Δ= Δ ∑ ∑ (13) 

where i denotes either the outlet or inlet F-GHG gas, F denotes the corresponding inlet or outlet 

ow, 

T

0

j Δt denotes the integration interval, is the concentration of F-GHG either entering or Ci j , fl

exiting the abatement system and the sum is taken over the period, T, of production processing. 

( ) V

V DRE

λ

σ

ε ( 2

λ

− = 1 )

 (14)

where, 

out

V

in

V

V

λ =

( ) λV ε

2 2

V V out in

V V out in

= + ⎜ ⎟⎜ ⎟

⎝ ⎠⎝ ⎠

⎛ ⎞⎛ ⎞ σ σ

V out

σ = The standard deviation V out [slm]

24
V in

σ = The standard deviation of V in [slm]. 

It can be shown that λV ε , the relative error in the true fraction of emitted F-GHG estimated using 

Method 2 is, to a very good approximation, governed by relative error in the effluent process and 

abatement system flows, or the relative error in the dilution factor. This simplification occ

because, in calculating the volume flow, integrating the measured concentrations over the perio

of production processing averages out the uncertainties in FTIR measured concentrations 

compared to the 15

urs 

d 

 corresponding measured flow rates. The relative error for Method 2 may be 

stimated, to a very good approximation, as the relative error in the dilution factor, which is 

an 

e

given by Eq. 9.

3. BENCHMARK RELATIVE ERROR 

For Protocol to be considered valid, the relative error for true fraction emitted must be less th

±5 percent. Presented below are the formulas for estimating relative error (i.e., ε ( ) TFE ) of

true fraction emitted for both Method 1 (Equation 14) and Method 2 (Equation 15). All the 

parameters used to estimate the relative error of true fraction emitted have been defined in 

section 2.3, and therefore, are not redefined here. These formulas may not be applicable when

alternative methodologies to those

 the 

 presented in this Protocol are used, and in such cases, testing 

rvice providers should determine and use the appropriate formulas to calculate the relative 

3.1 Method 1—Dilution Adjusted Concentration Measurements 

se

error of the true fraction emitted. 

ε TFE1 )( =

2 2

⎟

⎟

⎠ ⎜⎝

⎞ ⎜⎛

+ ⎟

⎟

⎞

⎜

⎜

⎛ C DF

σ σ λ (15) 

3.2 Method 2—Total Volume Measurements 

λC ⎠⎝ DF

≤ 5percent

2 2

⎟

⎟ ⎜

⎜ + ⎟⎟ ⎜

⎜ V V

V V

out in )( = ≤ 5perc TFE2 ε

⎠

⎞

⎝

⎛

⎠

⎞

⎝

⎛

out in

σ σ

 (16) 

 those instances where the concentrations exiting the abatement system, Cout in the equations is 

placed with C*, so λc is calculated using C*. 

 

ent

which may be estimated using Eq. 9. 

In

re

15 This can be shown using the expression for )(λV ε given in Eq. 14 and noting that relative errors, 2

VO ε and 2VI ε , 

are each the sums in quadrature of the relative errors of the outlet/inlet flows and outlet/inlet concentrations, 

respectively. Using the method of simulation to estimate the relative error in the outlet or inlet concentrations, it 

becomes evident that the relative error in measured outlet or inlet concentration is more than an order of magnitude 

less than the relative error in the corresponding measured abatement system outlet or inlet flows. The reduced 

relative error in the integrated concentration profile occurs because in the course of integrating over the measured 

FTIR concentration profile the error in each FTIR measurement is reduced through averaging. 

25
4. DOCUMENTATION AND REPORTING 

Proper documentation and reporting ensures transparency of the DRE measurement process

allowing users of DREs and third-parties to review and understand the measurements collec

as well as the data treatment and analysis conducted. Therefore, it is important that test

, 

ted 

ing 

ervice providers adequately document their analyses, and present the results in a clear and 

he Protocol also requires certification by the testing provider. The final report should contain 

s

concise report. A suggested structure for the report is presented in the text box below. 

T

the following language together with the appropriate signature. 

The tester/metrologist principally responsible for the measurements and content presented in this

report and obtained during the period ____ to _____ at (name of facility) hereby certifies th

methods and calculations set forth in the Protocol were followed and that material departures o

deviations therefrom, if any, are fully documented in this report dated, ___________. The 

tester/metrologist also certifies that th

at the 

r 

e calculations and benchmark relative error presented in 

this report properly and accurately reflect the actual measurements made at the facility during the 

ation. 

Date ____________________ 

test period noted in this certific

Signed __________________ 

26
27

Final Report Structure 

I. Introduction 

a. General information about testing 

II. Experimental Setup 

a. Actual sampling/testing configuration 

b. Description of how measurements are taken (reference to Protocol 

encouraged) 

c. Sampling Configuration 

III. Data Analysis 

a. Documentation 

i. Formulas Used 

ii. Figures showing calibration curves for each F-GHG and tracer 

gas (the regression equation should be displayed for each. 

calibration curve along with relative error of the slope and yintercept). 

iii. Figures showing the FTIR spectra at the abatement inlet and 

outlet, which each F-GHG peak clearly labeled. 

iv. Figures showing the temporal concentration profiles of the 

abatement inlet and outlet concentration for each F-GHG and 

tracer gas. 

v. Tables showing the means and standard deviations of the FGHG and tracer gas inlet and outlet concentrations and/or 

volumes (see Section 2.3 for description of the means and 

standard deviations appropriate for each quantity). 

vi. Tables showing the mean and standard deviation of the dilution 

factor and DRE for each F-GHG. 

b. Comparison of estimated DRE error with the 5 percent benchmark 

relative error. 

IV. Discussion 

V. Metrologist certification that reported results conform to Protocol. 

Appendix A: Measurement Plan 
5. REFERENCES 

40 CFR 60. 1998. Appendix A, Method 2, as amended. U.S. Environmental Protection Agency, Method 2 - 

Determination of Stack Gas Velocity and Volumetric Flow Rate. U.S. Code of Federal Regulations. 

40 CFR 52. 1998. Appendix E, Performance Specifications and Specification Test Procedures for Monitoring 

Systems for Effluent Stream Gas Volumetric Flowrate. U.S. Code of Federal Regulations. 

ASTM. (2004) Standard Test Method for Volumetric and Mass Flow Rate Measurement in a Duct Using 

Tracer Gas Dilution. Designation E 2029 – 99 (Reapproved 2004). 

Beu. Laurie S. International Sematech Manufacturing Initiative (ISMI 2005). Reduction of 

Perfluorocompound (PFCF-GHG) Emissions: 2005 State-of-the-Technology Report. International Sematech 

Document ID 05104693A-ENG, December 1, 2005. 

Beu, L. et al.(1994)., Results of Delatech Controlled Decomposition/Oxidation (CDO) Unit Testing for 

Perfluorocompound (PFC) Emission Abatement Applications, SEMATECH Technology Transfer 

#94092543A, October 1994. 

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. 

http://www.epa.gov/semiconductor-pfc/documents/qimonda_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. 

http://www.epa.gov/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. http://www.epa.gov/semiconductorpfc/documents/ibm_report.pdf 

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

International Sematech, Technology Transfer # 06124825A-ENG, December 22, 2006. Note that this is an 

update to previous guideline, TT from International Sematech # 01104197A-XFR, December 2001. 

IPCC Guidelines for National Greenhouse Gas Inventories. 2006. Volume 3 Industrial Processes 

and Product Use. Chapter 6, Electronics Industry Emissions. 

Laush, Curtis, Mike Sherer and Walter Worth. International Sematech Manufacturing Initiative (ISMI 2006). 

Guideline for Environmental Characterization of Semiconductor Process Equipment. International Sematech 

Document ID 06124825A-ENG, December 20, 2006. 

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

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

28
Li et al., (2001). Improved Technique for Evaluating Point-of-use Abatement Systems. Semiconductor 

Fabtech, 14th Edition, June 2001. 

Li et al., (2002). FTIR spectrometers measure scrubber abatement Efficiencies. Solid-State Technology, July 

2002. 

Li et al.,(2004). Default values appear to be overestimating F-GHG emissions from fabs. Solid-State 

Technology, Sep. 2004. 

Stuart L. Meyers (1974). Data Analysis for Scientists and Engineers. John Wiley & Sons, Inc., New York 

1974. Page 146-147. 

29
Appendix A – History of and Revisions to the Protocol 

The Protocol has gone through five stages of development: conceptualization, onsite tests, initial 

drafting, and two informal peer review processes. During the informal peer review processes 

EPA received comments from both national and international parties, including semiconductor 

manufacturers, equipment manufacturers, gas suppliers and analytic service providers. EPA 

addressed these comments directly with reviewers in verbal and written form. 

Modifications were made to the Protocol to address this feedback. In addition to specific 

technical issues that reviewers raised, an overarching concern emerged that the Protocol provide 

as much flexibility as possible without compromising the integrity of the Protocol’s 

measurement process. Calls for flexibility stemmed from the diversity of fab environments, as 

well as from the diversity of established measurement practices and technologies. International 

reviewers were unanimous in seeking acceptable alternatives to QMS systems (used for 

measuring abatement system dilution via the gas tracer method of chemical spiking) for onsite 

testing, although central to the method favorably evaluated by Lee et al. (Lee, 2007) is the use of 

a magnetic type precision gas mass spectrometer rather than a quadrupole mass spectrometer 

(QMS). To provide for more flexibility and to address the technical issues that reviewers raised, 

EPA considered and made substantive changes to the Protocol: 

• Removal of suggested temperature limitations at which a POU system would not abate 

CF4 or SF6 in reference to instances where CF4 or SF6 may be used as tracers gases to 

measure flow across the abatement system 

• Allowance of off-site Fourier Transform Infrared (FTIR) Spectrometer calibration 

• Consideration of alternative DRE measurement methods. The alternative methods 

considered were: 

o The Multi-chamber Process Inlet Flow Sampling (MPIFS) Method 

o The Physical Flow Measurement Method16

o The Abatement system De-tuning Method17

o The Post-abatement Flow Tracer Method 

Of these listed methods, the Protocol expands Method 2 to include the MPIFS method. The 

MPIFS method was tested in December 2008. The results using the MPIFS method agreed with 

results obtained using the Sequential Single-Chamber Process Inlet Flow Sampling (SSPIFS).18. 

The Physical Flow Measurement Study, because it is already an EPA method, is allowable under 

 

16 Physical Flow Measurement Methods are allowable per the Protocol to measure the Total Volume Flow in order 

to determine DRE. Acceptable flow measurement methods would be those that have pre-determined specified 

measurement standards in place, such as EPA Appendix A Method 2 and EPA Appendix E. However, these 

methods are not preferred because often they require laminar flow regimes, where that is often not the case in in-fab 

testing. When using a physical method for measuring gas flow rate, the performance benchmark metric and standard 

given in Section 3 applies. 

17 The Abatement system De-tuning Method involves either turning off the methane or oxygen flow to the burner of 

the abatement system, lowering the temperature of the abatement system, or a combination of the two. The Protocol 

does not permit this method because to do so would defeat the purpose of the abatement system and intentionally 

release F-GHG emissions to the atmosphere during testing. 

18 EPA cautions, however, that the MPIFS method holds potential safety risks when mixing pyrophoric/flammable 

and oxidizing gases. 

30
31

 

this Protocol; and the Abatement system De-Tuning Method in not permitted under this Protocol. 

The Post-abatement Flow Tracer Method, while theoretically attractive, has not been compared 

to the pre-abatement tracer method used in the Protocol and is therefore not permitted under this 

Protocol.19 

19 While the Post-abatement Flow Tracer Method is not permitted in the Protocol, EPA is interested in learning 

more, through in-fab testing, about the validity of this method. 
Appendix B – Sample Calculation 

Step 1 Determine the Mean Total Flow 

Data Calculations: Data Treatment 

n = 60 

Measured effluent flows Variance weighted mean of efflu

Kr 

Flow 

(slm) 

Avg Kr 

Conc 

(ppm) 

Avg Effluent 

Flow, F 

(slm) 

Standard deviation in 

measured effluent 

flow,σ

(slm) 

Variance in 

measured effluent 

flow, σ2 

(slm2) 1/σ2 F/σ

0.01 14.1 709.2 80 6400 0.0001563 0.1100.02 25.5 784.3 52 2704 0.0003698 0.2900.03 38.8 773.2 34 1156 0.0008651 0.6680.04 52.2 766.3 28 784 0.0012755 0.9770.05 65.8 759.9 28 784 0.0012755 0.969

Sum of F/σ2 = 3.01Sum of 1/σ2 = 0.0039

Mean total flow = 

(Sum of 1/σ2)-1/2 = 15Sqrt (1/n) = 0.129

σ of effluent flow 

95% C I Upper bound of mean flow = Lower bound of mean flow = 

Relative error, % = 0

Step 2 Determine the Dilution Factor 

Data Calculations: Dilution Factor 

TF 

(slm) 

σTF

(slm) 

σTF/TF (σTF/TF)2 Units 

Out 765 2 0.0026144 0.0000068 NA In 15.5 0.1 0.0064516 0.0000416 NA 

DF = 49.35483871 dimensionlessSum of (σTF/TF)2 = 0.0000485 dimensionlessRelative Error = 0.7% dimensionless
Step 3 For Method 1: Determine the Relative Error of the TFE 

*The TFE error must meet the +/- 5% performance standard 

Data Calculations: λ, DRE, and True Fraction Emitted 

Value σ σ/Best Estimate (σ/Best Estimate)2 U

CO 200 2 0.0100000 0.0001 CI 12,134 195 0.0160705 0.000258262 DF 49.4 2 0.0405229 0.001642103 

λC = 0.0167450 dimensσλ = 0.0001033 dimensλ * DF = 0.8264455 dimens1 - (λ * DF) = 0.1735545 dimensSum of (σCO/CO)2 and (σCI/CI)2 = 0.0003583 dimensσλ/λC = 0.0061710 dimens

(σλ/λC)2 = 0.0000381 dimens

Sum of (σλ/λC)2 and (σDF/DF)2 = 0.0016802 dimens

Relative Error λ = 1.9% dimensDRE, % = 19% dimensRelative Error DRE = 20% dimens

Relative Error of TFE = 4% dimens
Step 3 For Method 2: Determine the Relative Error of the TFE 

*The TFE error must meet the +/- 5% performance standard 

Data Calculations: λ, DRE, and True Fraction Emitted 

Best Est. 

V 

(slm) 

σV

(slm) 

σV/V (σV/V)2 

Out 0.425 0.005 0.0110448 0.00012198847956824 In 0.443 0.006 0.0127318 0.0001620981711280 

λV = 0.958843303 dimeσλ = 0.016194732 dime

1 - λV = 0.041156697 dime

Sum of (σV/V)2 = 0.0002841 dime

Relative Error λ = 1.7% dime

DRE, % = 4% dimeRelative Error DRE = 2% dimeRelative Error TFE = 2% dime