Guideline for Environmental Characterization of Semiconductor 

Process Equipment – Revision 2 

International SEMATECH Manufacturing Initiative 

Technology Transfer #06124825B-ENG 
© 2009 International SEMATECH Manufacturing Initiative, Inc. 

Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and 

ISMI are servicemarks of SEMATECH, Inc. SEMATECH and the SEMATECH logo are registered servicemarks 

of SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners. 
Guideline for Environmental Characterization of Semiconductor 

Process Equipment – Revision 2 

Technology Transfer #06124825B-ENG 

International SEMATECH Manufacturing Initiative 

December 9, 2009 

Abstract: This revised document from the ESHT001 project provides a guideline for suppliers of 

semiconductor process equipment and point-of-use (POU) abatement devices for environmental 

characterization of their equipment. The characterization consists of quantifying air emissions, 

liquid effluents, and solid waste. The guideline includes a data collection template for presenting 

and summarizing the test data as well as recommended protocols for air emissions testing. The 

document is revised versions of SEMATECH Technology Transfer #01104197A-XFR and 

#06124825A-ENG. For this edition of the guideline, the testing protocols for process emissions 

and POU abatement devices were updated to provide additional information for characterizing 

these emissions. Included with this document is the Excel data collection template. 

Keywords: Design of Experiments, Emissions Control, Environmental Characterization, Flow Rates, Fourier 

Transform Infrared Spectroscopy, Point of Use Abatement, Procedures, Quadrupole Mass 

Spectroscopy 

Authors: Bryan Benaway and Steven Hall (URS), Curtis Laush (IMACC), Robert Ridgeway (Air Products 

and Chemicals), Mike Sherer (Sherer Consulting Services, Inc.), and Steve Trammell (ISMI) 

Approvals: Steve Trammell, Author 

Ron Remke, Project Manager 

Joe Draina, Director 

Laurie Modrey, Technology Transfer Team Leader 

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ISMI Technology Transfer #06124825B-ENG 

Table of Contents 

1 EXECUTIVE SUMMARY .....................................................................................................1

1.1 Guideline Objective ........................................................................................................1 

1.2 Background .....................................................................................................................1 

2 EMISSIONS DATA EXPECTATIONS...................................................................................1

2.1 Chemical/Water Mass Balance .......................................................................................2 

2.2 Air Emission Measurements ...........................................................................................3 

2.3 Liquid Effluent Measurements........................................................................................3 

2.4 Solid Waste Measurements.............................................................................................3 

3 SELECTION OF THIRD PARTY FOR EMISSIONS MEASUREMENTS ..........................3

4 TARGET GASEOUS EMISSIONS ........................................................................................4

5 EMISSIONS CHARACTERIZATION...................................................................................6

6 TEST FOR AIR EMISSIONS .................................................................................................7

6.1 Process Recipe ................................................................................................................7 

6.2 Pump Purge Estimation...................................................................................................7 

6.3 Calibration Curves ..........................................................................................................7 

6.4 Emission Values..............................................................................................................8 

6.5 Volume Closure ..............................................................................................................9 

6.6 Chemical Utilization Efficiency....................................................................................10 

6.7 Process Tools Using Open/Covered Tanks/Baths ........................................................10 

6.8 Spray Processes.............................................................................................................11 

6.9 POU Abatement Device DRE Testing..........................................................................11 

7 TEST FOR LIQUID EFFLUENTS.......................................................................................11

7.1 Block Diagram Showing Connections to Tool .............................................................12 

7.2 Chemical/Water Inputs and Effluents ...........................................................................12 

8 SOLID WASTE GENERATED DURING WAFER PROCESSING ....................................13

9 EMISSIONS ASSOCIATED WITH PREVENTIVE MAINTENANCE (PM)....................13

10 DATA COLLECTION TEMPLATE......................................................................................13

Worksheet #1 – General Information ....................................................................................14 

Worksheet #2 – Template for Reporting Process Air Emissions ..........................................16 

Worksheet #3 – Template for Reporting Liquid Effluents....................................................20 

Worksheet #4 – Template for Reporting Solid Waste...........................................................22 

Worksheet #5 – Template for Reporting Preventive Maintenance (PM) Emissions ............23 

Worksheet #6 – Template for Data Summary.........................................................................1 

APPENDIX A – TECHNICAL PROTOCOLS FOR AIR EMISSIONS 

CHARACTERIZATION .........................................................................................................2

A.1 Mass Spectrometry Protocol ...........................................................................................2 

A.1.1 Introduction.........................................................................................................2 

A.1.2 Sampling Conditions...........................................................................................5 

A.1.3 Operating Procedures........................................................................................11 

A.1.4 Calculations.......................................................................................................11 
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Technology Transfer #06124825B-ENG ISMI 

A.2 Fourier Transform Infrared (FTIR) Spectroscopy Protocol..........................................13 

A.2.1 Introduction.......................................................................................................13 

A.2.2 Method Development........................................................................................13 

A.2.3 Laboratory Studies ............................................................................................14 

A.2.4 Field Studies......................................................................................................15 

A.2.5 Method Application ..........................................................................................18 

A.2.6 Description of Extractive FTIR Spectrometry ..................................................18 

A.2.7 Mathematical Description of Beer’s Law .........................................................22 

A.2.8 Mathematical Description of a Least Squares Analysis....................................23 

A.2.9 References.........................................................................................................26 

A.2.10 Definitions of Symbols and Terms ...................................................................26 

A.3 Modifications to QMS/FTIR Protocols to Quantify Corrosive Air Emissions.............28 

A.4 Fluorine Chemiluminescence (FC) Protocol: Standard Quantitative Analytical 

Method for Measuring Gaseous Molecular Fluorine....................................................29 

A.4.1 Theory and Practice of Chemiluminescence.....................................................30 

A.4.2 General Design and Use....................................................................................30 

A.4.3 Sequence of Operation and Monitoring Procedures .........................................31 

A.4.4 Sampling and Maintenance Considerations......................................................32 

A.4.5 Examples of Field Data and Analysis ...............................................................33 

APPENDIX B – PROTOCOL FOR CHARACTERIZATION OF POINT-OF-USE 

ABATEMENT DEVICES .....................................................................................................35

B.1 Point-of-Use (POU) Abatement Protocol .....................................................................35 

B.1.1 Representative Sampling...................................................................................35 

B.1.2 Acid Gas Analyses ............................................................................................36 

B.1.3 Sequentially Varied Effluent Streams...............................................................36 

B.1.4 Solid Particulates Clogging...............................................................................36 

B.1.5 POU Abatement Device Dilution Factor Determination ..................................37 

APPENDIX C – STANDARD METHODS FOR LIQUID AND SOLID WASTE 

SAMPLING AND ANALYSIS .............................................................................................39
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List of Figures 

Figure 1 Sample Calibration Curve ..........................................................................................7 

Figure 2 FTIR CLS Calibration Curve and Fitting Errors........................................................8 

Figure 3 Example of Process Emission Plots ...........................................................................9 

Figure 4 Connection Hookup Diagram...................................................................................12 

Figure A-1 Process Tool Exhaust Sampling System.....................................................................5 

Figure A-2 Mass Spectrum for Sulfur Hexafluoride (SF6)...........................................................6 

Figure A-3 Mass Spectrum for Nitrogen Trifluoride (NF3)..........................................................7 

Figure A-4 Mass Spectrum for Trifluoromethane (CHF3)............................................................7 

Figure A-5 Mass Spectrum for Carbon Tetrafluoride (CF4) .........................................................8 

Figure A-6 Mass Spectrum for Hexafluoroethane (C2F6).............................................................8 

Figure A-7 Mass Spectrum for Octafluoropropane (C3F8) ...........................................................9 

Figure A-8 Fully Integrated FC System Housed in a Small Container (11”  10”  5”, 

5 lbs.)........................................................................................................................31 

Figure A-9 FC System Monoblock.............................................................................................31 

Figure A-10 Example of a) Exhaust Emissions from a CVD Chamber Clean Process 

Chamber Clean Compounds and Byproducts and b) F2 Byproduct.........................34 

Figure B-1 Sampling Setup to Minimize Particle Clogging.......................................................35 

List of Tables 

Table 1 Required Tool Emissions Information .......................................................................2 

Table 2 Target Compounds Guideline (Some of Possible Species) ........................................5 

Table A-1 Monitored Fragment Ions...........................................................................................6 
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Technology Transfer #06124825B-ENG ISMI 

Acknowledgments 

ISMI wishes to thank the authors of the original document: Dr. Jerry Meyer of Intel, Dr. Peter 

Maroulis of Air Products & Chemicals, Inc. and Dr. David Green of NIST and the authors of the 

first revision Mr. Mike Sherer, P.E. of Sherer Consulting Services, Inc., Dr. Curtis Laush of 

URS, and Dr. Walter Worth, ISMI. Special thanks to Mr. Mike Sherer, P.E. of Sherer Consulting 

Services, Inc., Dr. Curtis Laush of IMACC, Mr. Steven Hall of URS, Mr. Bryan Benaway of 

URS and Dr. Robert Ridgeway of Air Products & Chemicals, Inc. for their technical input for 

this second revision of the document. 
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ISMI Technology Transfer #06124825B-ENG 

1 EXECUTIVE SUMMARY 

1.1 Guideline Objective 

The semiconductor industry has a responsibility to its employees and the community to minimize 

the environmental impact of its manufacturing processes and operations. To fulfill this 

responsibility, environmental performance goals have been set for its processes and operations. It 

is essential that equipment suppliers help the semiconductor industry achieve these goals. 

Equipment includes process tools, peripheral equipment, and point-of-use (POU) abatement 

devices. Consequently, equipment suppliers are expected to design their equipment to minimize 

the consumption of chemicals, production of waste emissions, and usage of utilities such as 

energy and water. 

This document provides guidance to device manufacturers and equipment suppliers on how to 

characterize the environmental performance of their tools and processes. The characterization 

must include the quantification of material inputs, air emissions, liquid effluents, and solid waste 

generated by the process equipment (tool), peripheral equipment and point-of-use (POU) 

abatement device. These characterizations must be based on actual measurement data during idle 

and process operations. Results must be presented in a final report that includes measurements 

on the baseline process recipe during wafer processing, tool idling, and preventive maintenance 

activities. The guideline includes an Excel-based template for data collection consisting of six 

worksheets, not all of which may be required for every tool or device. Also provided are 

protocols for the analytical methods recommended for collecting the data, which include 

quadrupole mass spectrometry (QMS), Fourier transform infrared (FTIR) spectroscopy, and 

fluorine gas analysis based on chemiluminescence. These measurements will be customized to 

the specific process and the semiconductor manufacturer will use the data provided by the 

equipment suppliers for several purposes, such as selecting equipment, securing site 

environmental permits, planning for exhausts and drains, handling solid waste, specifying 

abatement equipment, and facilitating equipment. 

1.2 Background 

Since this guideline was first published in 2001 and revised in 2006, additional testing 

information has become available and more regulations have been promulgated, prompting the 

need to revise this document. These are addressed in this 2009 revision. The 2009 guideline 

includes process peripheral equipment (e.g., chillers, etc.), additional chemicals and byproducts, 

revised QMS and FTIR methodologies, and additional POU abatement device testing 

information. 

2 EMISSIONS DATA EXPECTATIONS 

Table 1 is a partial list of generic tools, indicating the types of emissions information required for 

each tool type. In general, if the tool has any air emissions, liquid effluents, or solid wastes, they 

should all be characterized. 

Similarly, POU abatement devices and process peripheral equipment may generate air emissions, 

liquid effluents, and solid wastes that should be reported. In addition, destruction and removal 

efficiency (DRE) should be measured for POU abatement devices. The DRE values reported for 

POU abatement devices must be measured over a range of conditions that are representative of 

the tool’s process or processes. These conditions must be clearly documented. 
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Table 1 Required Tool Emissions Information 

Tool Type Air Testing 

Liquid Effluent 

Testing 

Solid Waste 

Testing 

Parts Clean/PMs/

Wipedowns 

Diffusion Furnaces X X 

Wet Hoods X X X X 

Tracks X X X 

CVD X X 

Dry Etch X X 

Implanters X X X 

CMP X X X X 

Plating X X X X 

Metrology X 

PVD X X 

The detailed data requirements are outlined in Section 10, which includes the Excel-based 

workbook, containing the following worksheets: 

 Worksheet #1 – General Information (about the tool, peripheral equipment, and POU 

abatement device) 

 Worksheet #2 – Air Emissions

 Worksheet #3 – Liquid Effluents

 Worksheet #4 – Solid Wastes

 Worksheet #5 – Preventive Maintenance

 Worksheet #6 – Data Summary (based on the information provided in the other 

worksheets) 

The device manufacturers’ expectation is that when testing, the equipment supplier will complete 

the Data Collection Template and provide a written engineering analysis and emission 

measurement report based on the data. Note this is for both process tool and POU abatement 

device suppliers. 

For each process tool, process application, and POU abatement device that the supplier plans to 

offer for manufacturing, the following information must be provided. 

2.1 Chemical/Water Mass Balance 

It is expected that a chemical mass balance will be conducted unless specified otherwise by 

equipment purchaser. A chemical mass balance must show the composition and quantity of each 

chemical used in the supplier’s equipment and the composition and quantity discharged to each 

exhaust, separate chemical drain, and waste stream. A simple block diagram showing all the gas, 

liquid, and solid streams entering and leaving the process tool, peripheral equipment, and POU 

abatement device should be provided as part of the mass balance. 

The mass balance must 

 Be on a per wafer processed basis and mass per unit time basis (POU abatement devices 

should be reported in mass per unit time only) 
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ISMI Technology Transfer #06124825B-ENG 

 Include chemicals used for maintenance and parts cleaning 

 Be based on actual measurements 

 Achieve a 90% mass closure. An example is atomic fluorine mass closure of 90% 

from inlet(s) to outlet(s). Note that mass closure of greater than 110% needs to also be 

addressed. Another definition is mass out equals mass in within ±10%. Some exceptions 

may be noted as described in Section 6.5. 

2.2 Air Emission Measurements 

The emissions testing methods must 

 Follow an approved analytical method (i.e., FTIR, QMS, fluorine chemiluminescence, 

and/or ultraviolet [UV] spectroscopy). Accepted protocols for these methods are in 

Appendix A.1–A.4. Appendix B provides additional information for determining DREs 

for POU abatement devices. 

 Be documented in the report accompanying the Data Collection Template. 

 Include emissions resulting from peripheral equipment, maintenance and parts cleaning 

operations. 

 Include a mass or volume balance that accounts for 90% and 110% of atomic 

fluorine, atomic chlorine, atomic bromine, and other constituents (if applicable). This 

may need to include any other effluent like liquid or solid. 

2.3 Liquid Effluent Measurements 

The composition and concentrations of the constituents in the liquid phase should be determined 

using the latest version of established methods for organic and/or inorganic analytical techniques 

(i.e., “standard methods”) available at accredited, third-party laboratories. Suggested sampling 

and analytical method(s) are discussed in Appendix C. 

2.4 Solid Waste Measurements 

The composition and concentration of the constituents in the solid waste generated should be 

determined using established organic and/or inorganic analytical techniques (i.e., “standard 

methods”) available at accredited, third-party laboratories. Suggested sampling and analytical 

method(s) are discussed in Appendix C. 

3 SELECTION OF THIRD PARTY FOR EMISSIONS MEASUREMENTS 

If the supplier does not have the in-house resources for a full equipment emissions 

characterization, a consultant should be engaged to make the measurements and analyses. To 

select a competent third party, the following questions should be asked: 

 Can the third party perform a comprehensive environmental emissions analysis and 

provide a detailed emissions report for each process application you plan to offer? 

 Does the third party have the internal expertise and analytical equipment required? Do 

the standard analytical methods (e.g., this guideline, ASTM, etc.) provide analytical 

data adequate for determining mass balance closure for each constituent should be used. 
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 What is the third party’s previous experience and knowledge in conducting these types 

of characterization studies? 

 What is the third party’s semiconductor process and POU abatement device (if 

applicable) experience? 

 Is the supplier using calibration standards to quantify the results? 

 What are the technical and commercial strengths of the third party? 

 What are the weaknesses, and how will the third party compensate? 

 What engineering resources can the third party provide to help determine solutions for 

any improvements that may be identified to meet emission goals? 

 Can the third party provide POU abatement device inlet and outlet testing, if required? 

4 TARGET GASEOUS EMISSIONS 

The following list and Table 2 show a sample of emission compounds that should be quantified 

for a particular process chemical. Table 2 was designed as a guide for equipment suppliers; 

however, it may not list all the chemicals or ions that may be encountered with a specific tool 

and/or process, since many novel materials are continuously being introduced for the advanced 

technology nodes. Therefore, it is best to define the possible process emissions with the 

equipment manufacturer before testing. A block flow diagram describing inputs and outputs to 

the process equipment (including peripheral equipment), and POU abatement device (if 

applicable) can help track all substances entering and leaving the tool and abatement device. 

 The following target compounds should be quantified using calibration standards: NF3, 

C3F8, C2F6, CF4, C4F8, C4F8O, SF6, CHF3, CH2F2, CH3F, C5F8, CH3OH (methanol), 

C2H5OH (ethanol), CH3COCH3 (acetone), (CH3)2CHOH (isopropanol), NH(Si(CH3)3)2

(HMDS), C2H5OOCCC(OH)CH3 (Ethyl lactate), C4H6ON(CH3) (NMP), 

CH3COO(CH2)3CH3 (butyl acetate), CH3O(CH2)3OOCCH3 (PGMEA), C4H8SO2

(sulfolane), CH3(CO)C5H11 (2-heptanone), HF, Cl2, HCl, F2, SiF4, OF2, CO, CO2, NO, 

NO2, N2O, CH4, COF2, NH3, HBr, BR2, SO2, H2SO4, and fluorinated heat transfer 

fluids. Additional process effluents such as silane (SiH4) that may require quantification. 

 BrCl should be measured when Br- and Cl-containing compounds are part of the 

process recipe. 

 During emissions testing, a survey scan must be taken. If any unidentified intensities are 

10% of the height of the most intense peak attributed to a process gas, then the source of 

that peak needs to be identified and quantified. 

 If FTIR analysis is ineffective in determining NO or NO2 emissions, then 

chemiluminescence methods can be used to quantity the emissions. 

 If QMS analysis is ineffective in determining Cl2 emissions, then chemiluminescence or 

ultraviolet absorption spectroscopy (UVAS) can be used to quantify the emissions. A 

testing protocol should be provided for accurate measurements of Cl2, and reviewed 

before testing. 
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ISMI Technology Transfer #06124825B-ENG 

 Some particulate emissions from processes and POU abatement devices may not be 

quantified with the air emissions testing methodologies discussed here (e.g., SiO2, P2O5, 

TiO2, B2O3, WO3, NH4F, etc.). The equipment supplier should use an appropriate 

method to quantify any such emissions. 

Table 2 Target Compounds Guideline (Some of Possible Species) 

Process Chemicals Target Compounds to Quantify 

AsH3 AsH3

BCl3 Cl2, BCl3, HCl, SiCl4, CCl4, CHCl3, AlCl3

Br2 Br2, HBr, SiBr4

CF4 C2F6, CF4, CHF3, CH2F2, CH3F, HF, F2, SiF4, OF2, COF2, CO, CO2

C2F6 C2F6, CF4, CHF3, CH2F2, CH3F, HF, F2, SiF4, OF2, COF2, C2F4, CO, CO2

C3F8 C2F6, CF4, C3F8, CHF3, CH2F2, CH3F, HF, F2, SiF4, OF2, COF2, C2F4, CO, 

CO2

C4F8, C4F8O C2F6, CF4, C4F8, C4F8O, C3F8, CHF3, CH2F2, CH3F, HF, F2, SiF4, OF2, 

COF2, C2F4, CO, CO2

C5F8 C2F6, CF4, C5F8, C4F8, C4F8O, C3F8, CHF3, CH2F2, CH3F, HF, F2, SiF4, 

OF2, COF2, C2F4, CO, CO2

CHF3, CH2F2, CH3F C2F6, CF4, CHF3, CH2F2, CH3F, HF, F2, SiF4, OF2, COF2, C2F4, CO, CO2

CH3COCH3 (Acetone) CH3COCH3

CH3OH (Methanol) CH3OH 

C2H5OH (Ethanol) C2H5OH 

(CH3)2CHOH (Isopropanol) (CH3)2CHOH 

CH3O(CH2)3OOCCH3 (PGMEA) CH3O(CH2)3OOCCH3 

C2H5OOCCC(OH)CH3 (Ethyl 

lactate) 

C2H5OOCCC(OH)CH3 

CH3COO(CH2)3CH3 (Butyl acetate) CH3COO(CH2)3CH3

C4H6ON(CH3) (NMP) C4H6ON(CH3) 

C4H8SO2 (Sulfolane) C4H8SO2 

CH3(CO)C5H11 (2-Heptanone) CH3(CO)C5H11 

Cl2 Cl2, HCl, SiCl4, CCl4, CHCl3, AlCl3

HBr HBr, Br2, SiBr4

HCl Cl2, HCl, SiCl4, CCl4, CHCl3

HF HF, F2, SiF4, OF2, COF2

NF3 NF3, HF, F2, SiF4, OF2, CF4, COF2, NO, NO2, N2O 

NH3 NH3, NO, NO2, N2O 

H2SO4 H2SO4, SO2

NH[ Si(CH3)3]2 (HMDS) NH[ Si(CH3)3]2 , NH3

N2O N2O, NO, NO2

O3 O3

PH3 PH3

SiF4 HF, F2, SiF4, OF2, COF2

SiH4 SiH4

SF6 SF6, HF, F2, SiF4, OF2, COF2, SOF2, SO2F2, SO2

Si(OC2H5)4 (TEOS) Si(OC2H5)4, CH3OH, HCOOH, C2H5OH, CO, CO2
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Process Chemicals Target Compounds to Quantify 

PO(C2H5O)3 (TEPO) PO(C2H5O)3, CH3OH, HCOOH, C2H5OH, CO, CO2

B(C2H5O)3 (TEB) B(C2H5O)3, CH3OH, HCOOH, C2H5OH, CO, CO2

TiCl4 TiCl4, HCl, Cl2

WF6 WF6, HF, F2, SiF4, OF2, CF4, COF2

Fluorinated heat transfer fluids CF3–(O–CF(CF3)–CF2)n–(O–CF2)m–O–CF3, CnF2n+2, CnF2n+1(O) 

CmF2m+1, CnF2nO, (CnF2n+1)3N

5 EMISSIONS CHARACTERIZATION 

Worksheet #1 – General Information, of the Data Collection Template, describes the process 

tool, the process being run by the tool, the POU abatement device, and peripheral equipment. It 

should document the following information:

Type of tool tested 

 Name of the baseline process, name/model of the tool, description of the process 

function (e.g., “deposits 1000 Å of an oxide film”) 

 Batch or single-wafer tool, wafer throughput, wafer size 

 POU abatement device 

 Peripheral equipment that uses chemicals (lubricants, refrigerants, heat transfer fluids, 

etc.) 

The report accompanying the Data Collection Template should document the following 

information for each analytical method used and the instrumentation parameters involved: 

 The analytical methods used 

 Who performed the testing (in-house or third party ); provide a contact number for 

technical questions 

 Mass or wave number range; detection limits of the instrumentation for each of the 

analyte compounds 

 Type and model name of the instrument used 

 The sampling conditions for calibration and monitoring (source pressure, electron 

energy, sampling frequency, detection method and settings [Faraday or multiplier], etc.) 

The tool baseline recipe should be used as the basis for the tool environmental characterization. 

Emission data should be averaged over at least five wafers or five batches for batch tools. The 

average for the five wafers or batches and the standard deviation should be reported. Data should 

be collected for all activities associated with the tool: 

 During wafer processing 

 While no wafers are being processed (i.e., tool is idling or on stand-by) 

 During the dry chamber clean 

 During preventive maintenance 
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ISMI Technology Transfer #06124825B-ENG 

6 TEST FOR AIR EMISSIONS 

6.1 Process Recipe 

The equipment supplier’s baseline process recipe must include flows, times, radio frequency 

(RF) power, plasma pressure, and spin speed. All sub-steps to the process should be included. 

For example, most etching recipes consist of a stabilization, etch, and over-etch step. The process 

parameters (flows, times, etc.) listed previously should be determined for each of the steps. 

6.2 Pump Purge Estimation 

The pump purge rate on the process tool must be determined when sampling the process exhaust 

downstream of the pump. Accepted methods of determining pump purge rates can be found in 

the mass spectrometry protocol described in Appendix A.1.4. The pump purge rate can also be 

estimated using FTIR (Appendix A.2) and a process gas such as NF3. 

6.3 Calibration Curves 

For calibrations that are not multivariate (i.e., consisting of linear combinations of detector 

responses for multiple compounds over an array of x-axis components, as usually done in FTIR 

analyses), plots of signal intensity vs. analyte concentration must be provided for each of the 

compounds. The slope (with error), y intercept, and correlation coefficients must be provided 

with each plot. Figure 1 shows an example of a typical calibration curve. The error associated 

with the slope must not exceed 5%. The calibration curve should consist of at least 1 point per 

factor of 10 and no less than 5 points. 

-2000 0 2000 4000 6000 8000 10000 12000

0

1

2

3

4

5

6

7

slope = 0.00052 ± 0.00001

y-int. = 0.10 ± 0.06

R2

 = 0.9988

Intensity (a.u.)

Concentration (ppm)

Figure 1 Sample Calibration Curve 
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For the usual case of classical least squares (CLS) fitting over infrared wavelength regions when 

performing FTIR quantitative analyses, each calibration will involve the linear or quadratic 

scaling of a series of references over its optical depth range (concentration times pathlength 

product). The lower plot in Figure 2 illustrates an example of a calibration curve for carbon 

monoxide. In this case, the calibration compares the expected concentrations to CLS-computed 

concentrations when one of the references (highlighted) is chosen as the base reference for 

scaling. The upper plot shows the fit errors across the entire curve. These errors should not 

exceed 10% regardless of the base reference used. 

Figure 2 FTIR CLS Calibration Curve and Fitting Errors 

6.4 Emission Values 

If the process tool uses a plasma, then both the concentration (ppmv) vs. time plots for the no RF 

and wafer processing experiments must be included. Figure 3 illustrates how the concentration 

(ppmv) vs. time plots should be plotted. All final emission values must be expressed in g/wafer. 

The equation used to derive the g/wafer value from the raw signal intensities must be included. 

To allow a semiconductor company to relate the emission values obtained from the tool supplier 

to its particular process, a statistical design of experiments (DOE) must be conducted for 

chemical flow, RF power (if applicable), and plasma pressure (if applicable). For process tools 

that use spin coaters, spin speed should be one of the variables used in the DOE. If the DOE 

cannot be completed (i.e., insufficient resources), then the baseline recipe alone should be tested. 
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ISMI Technology Transfer #06124825B-ENG 

All baseline emission values should be the average of at least five wafers or five group of wafers 

processed (i.e., a group could be a rack of wafers or a few racks of wafers during a process run). 

The average as well as the standard deviation should be reported. The error in the average must 

not exceed 10%. If a specific compound is not detected, then the detection limit of the 

instrumentation for that compound should be given. How the detection limit was determined 

should also be clearly explained. 

15:25:00 15:30:00 15:35:00 15:40:00 15:45:00 15:50:00

0

500

1000

1500

2000

2500

Concentration (ppmv)

Time

Figure 3 Example of Process Emission Plots 

6.5 Volume Closure 

From the equivalent halide inlet and outlet amounts, a volume closure on the halogens (F, Cl, Br) 

must be calculated. The equivalent halide outlet (EHO) is calculated by Eq. [1]: 

EHO (A) = Volume emitted of compound (A)  number of halides in compound (A) Eq. [1]

Similarly the equivalent halide inlet (EHI) is calculated by Eq. [2]: 

 EHI (A) = Volume of process compound used for compound (A) (from recipe) Eq. [2]

 number of halides present in compound (A) 

The volume closure is then calculated by Eq. [3]: 

Volume closure = (total amount of EHO/total amount of EHI)  100% Eq. [3]

Note that the total amount of EHO or EHI is merely the sum of the EH for all compounds that 

are either emitted (outlet) or used (inlet) in the process. 

– Example: A process recipe of 50 sccm (0.05 slpm) of CF4 for 60 sec emits 30 scc 

(0.03 std. liters) of HF and 40 scc (0.04 std. liters) of CF4. 
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Technology Transfer #06124825B-ENG ISMI 

– Total EHI = 0.05 slpm  1 min. 4 Fluorine equivalents in CF4 = 0.20 

– Total EHO = (0.03  1 Fluorine equivalent in HF) + (0.04  4 Fluorine equivalents in 

CF4) = 0.03 + 0.16 = 0.19 

– Fluorine Volume closure = 0.19/0.20  100 = 95% 

The success criterion for volume closure is ≥90% and ≤110%. If the volume closure for volatile 

emissions is <90% or >110%, a plausible explanation and supporting data must accompany the 

report. Some possible reasons for a low volume closure are 1) solids formation, 2) unquantified 

volatile emissions, or 3) liquid emissions. For example, if the equipment supplier gets a 

60% volume closure for a specific process and believes it is due to solids formation, then the 

supplier must identify the composition of the solids. 

Volume closure for additional constituents should be provided, as applicable. 

6.6 Chemical Utilization Efficiency 

If the process tool uses plasma, the utilization efficiency (UE) for a specific process compound 

must be calculated by two methods: Method #1 and Method #2. If the process tool does not use a 

plasma source, then only Method #2 needs to be used. The calculation for both methods is as 

follows. 

 Method #1 (for process equipment that uses plasma) 

Method #1 uses the values from concentration vs. time plots (i.e., the raw 

concentrations have not been converted into grams per wafer).

Utilization Efficiency = 1 – [average concentration of process compound 

emitted1

/average concentration process compound input2]  100%. 

 Method #2 (for any process equipment) 

Utilization Efficiency = 1 – [mass of process compound emitted3/mass of process 

compound used4]  100%; where 

1 This value is the average concentration for a single wafer for the emitted process 

compound from the “wafer processing” concentration vs. time plot (Figure 3). 

2 This value is the average concentration for a single wafer for the emitted process 

compound from the “no RF experiment” concentration vs. time plot (Figure 3).

3 This value is the mass of emitted process compound for a single wafer (g/wafer), 

which is calculated by converting the average concentration to average mass flow 

rate using the average gas flow rate. 

4 This value is the mass of process compound for a single wafer (g/wafer) used as 

calculated from the process recipe. 

6.7 Process Tools Using Open/Covered Tanks/Baths 

There are additional testing concerns when characterizing the emissions of process tools that 

contain open/closed tanks/baths. The sampling point for the emissions characterizations should 

be downstream of the process tool (i.e., somewhere on the exhaust manifold of the tool). Because 

the emissions from these types of tools are continuous, testing must be completed when the 

wafer is processing and when the tool is idle. Furthermore, because data suggest that the 
11 

ISMI Technology Transfer #06124825B-ENG 

emissions from these tools depend on how many wafers are on the rack, these test must be 

conducted using full racks of wafers. The emissions should be reported in terms of g/wafer and 

mass per unit time. The emission values should be the average of at least five racks of wafers. 

The equipment supplier must also clearly indicate how many wafers are in a rack (e.g., 

25 wafers, 50 wafers, etc.). 

6.8 Spray Processes 

Spray processes are defined in this document as a process that dispenses chemical onto a wafer 

(single-wafer tool) or group of wafers (including racks of wafers). The chemical (e.g., acid 

solutions, base solutions, and organic compounds) is dispensed onto a wafer or rack of wafers 

through an applicator or is sprayed on. Air emissions can be measured in the exhaust duct from 

the spray chamber or application area. The exhaust duct may be connected to a valve that 

automatically switches the exhaust to different centralized exhaust systems, depending on what 

is being sprayed (e.g., acid solution versus ammonium hydroxide solution). Liquid drains may be 

segregated based on type of wastewater or solvent waste. Data should be determined for five 

separate runs, with a run consisting of total use of all chemicals in the process. 

6.9 POU Abatement Device DRE Testing 

DRE testing of POU abatement devices should be conducted using proper analytical techniques 

simultaneously on the inlet and the outlet locations. Testing should be conducted during all 

processes including wafer processing and dry chamber cleans. Detailed instructions for sampling 

inlet and outlet locations of POU abatement devices are in Appendix B, including dilution factor 

determination for POU abatement device. 

Any dilution effects in the POU abatement device (i.e., addition of nitrogen, air, etc. to POU 

abatement device) must be accounted for in DRE calculations. DRE calculated on a mass basis 

will remove any dilution affects. It is calculated as follows: 

 % DRE = [(mass in – mass out)/(mass in)]  100% 

DRE should not be calculated using inlet and outlet concentrations [e.g., parts per million by 

volume (ppmv)] without considering the dilution factor. DRE calculated on a concentration basis 

using dilution factor is as follows: 

 % DRE = {[inlet ppmv – (outlet ppmv  dilution factor)]/(inlet ppmv)}  100% 

where the dilution factor is the ratio of total outlet gas flow rate divided by total inlet 

gas flow rate (i.e., dilution factor = outlet gas flow rate/inlet gas flow rate with the gas 

flow rate expressed in standard liters per minute, where standard refers to 25°C and one 

atmosphere pressure). Note that POU abatement device that has more than one inlet will 

need proper calculation using multiple inlet test data. 

7 TEST FOR LIQUID EFFLUENTS 

To facilitate the understanding of the liquid inputs and outputs from the tool, POU abatement 

device, or peripheral equipment, including a block diagram in the emissions report is 

recommended. The data for all liquid effluents generated by the tool, POU abatement device or 

peripheral equipment during its operation must be entered into Worksheet #3. This includes any 
12 

Technology Transfer #06124825B-ENG ISMI 

liquid effluent resulting from any “tank pickling” operation (i.e., chemical(s) used to flush and 

condition the chemical bath before introducing the chemical used for processing).

7.1 Block Diagram Showing Connections to Tool 

The equipment supplier should provide a block diagram that clearly shows all the points of 

connection to the process tool, POU abatement device, or peripheral equipment for both input 

chemicals and output liquid chemicals and wastewater The type of drain should be labeled (i.e., 

solvent drain, acid wastewater drain, fluoride wastewater drain, etc.). Also the identity and 

concentrations of the primary constituents of the input streams and outputs streams (drains) 

should be included. 

Specific information is required for each point of connection (whether it be input chemical/water 

or output chemical/wastewater/waste). Each point of connection should be assigned a number 

and purpose. 

 Example: Connection point #1 is the input ultrapure water (UPW). Its purpose is to 

supply UPW to the process tool for wafer rinsing. 

 Example: A process tool with four connection points (three inputs [chemicals] and one 

output [drain]) is shown in Figure 4. 

Process

Tool

UPW

H2SO4

HCl

Acid Drain (100 ppm

H2SO4, 50 ppm HCl)

Input Output

Figure 4 Connection Hookup Diagram 

7.2 Chemical/Water Inputs and Effluents 

The volume associated with each connection point must be included. If the chemical/water flows 

through the equipment, then the volume should be quantified in liters per minute (lpm). For 

equipment with continuous flows, an average flow rate, a maximum flow rate, and an idle flow 

rate along with an associated time per wafer for each of the flows are required. If the 

chemical/water is used in a static bath, then the volume should be expressed in liters and the 

dump frequency specified. If chemicals are added to the bath to extend bath life, then the 

quantity and frequency of chemical addition should be specified. If the connection point is a 

drain, then the outlet flow rate of the chemicals/wastewater should be included. Finally, the 

primary constituents should be identified and quantified for each of the output connection points 

(drains). All concentrations should be the average of at least five cycles. Both the average and 

standard deviation should be included. Accredited, standard testing methods (discussed in 

Appendix C) must be used for sampling and analysis of all liquid effluents. 
13 

ISMI Technology Transfer #06124825B-ENG 

8 SOLID WASTE GENERATED DURING WAFER PROCESSING 

The equipment supplier must identify any solid waste generated during wafer processing and 

operation of the POU abatement device and peripheral equipment. The supplier must identify the 

composition and the quantity of solid waste generated in g/wafer and must enter it in 

Worksheet #4. Accredited, standard testing methods (discussed in Appendix C) must be used for 

sampling and analysis of all solid wastes. All quantities of solid waste generated should be the 

average of at least five cycles. Both the average value and standard deviation should be included. 

Consumables such as chemical mechanical planarization (CMP) pads, filter cartridges, sputtering 

targets, etc., are solid waste items that are captured in Worksheet #5 under Preventive 

Maintenance. 

9 EMISSIONS ASSOCIATED WITH PREVENTIVE MAINTENANCE (PM) 

Air emissions, liquid effluents, and solid wastes associated with preventive maintenance (PM) 

activities on the process tool, peripheral equipment, and POU abatement device are captured on 

Worksheet #5. In addition to the air, liquid, and solid emissions, the equipment supplier must 

record the use of any post-PM flushing chemical(s), all consumables, and PM-associated parts 

cleaning data on this worksheet. All the emissions generated during the PM activities must be 

added to the other tool air emissions, liquid effluents, and solid waste (Worksheets #2, #3, and 

#4) to arrive at total mass emissions per wafer, which are summarized in Worksheet #6.

10 DATA COLLECTION TEMPLATE 

The data collection template consists of an Excel-based workbook with six separate worksheets 

as follows: 

 Worksheet #1 – General Information (about the tool, peripheral equipment, and POU 

abatement device) 

 Worksheet #2 – Air Emissions

 Worksheet #3 – Liquid Effluents

 Worksheet #4 – Solid Wastes

 Worksheet #5 – Preventive Maintenance

 Worksheet #6 – Data Summary

Worksheet #6 is a compilation of the information from the other worksheets. This summary will 

help the semiconductor manufacturer review environmental emissions on a per wafer basis. If 

mass per unit time data are needed, this information can be found in other worksheets. 

The soft copy version of the spreadsheets allows the supplier to add and expand rows and 

columns, as necessary, for the full environmental characterization of a particular tool, POU 

abatement device, and peripheral equipment. 
14 

Technology Transfer #06124825B-ENG ISMI 

Worksheet #1 – General Information 

Instructions 

The template consists of the following six worksheets: 

1. Worksheet #1 asks for General Information (about your equipment) 

2. Worksheet #2 pertains to Air Emissions

3. Worksheet #3 pertains to Liquid Effluents

4. Worksheet #4 pertains to Solid Waste

5. Worksheet #5 pertains to Preventive Maintenance

6. Worksheet #6 is a Data Summary of the data provided in Worksheets #1–#5 (consult 

before you start) 

 Review all six worksheets and provide all information that applies to your specific 

equipment. 

 For the reader’s convenience, identify the equipment name and model on each worksheet. 

 Provide all data in metric units. 

 Provide explanations or any additional information in the Comments column, where 

applicable. 

 Before starting, check Worksheet #6 – Data Summary to see what data is asked for 

 Indicate how the data was obtained (in-house or by third party) and what analytical 

techniques were used in the summary report accompanying this workbook 
15 

ISMI Technology Transfer #06124825B-ENG 

Worksheet #1 – General Information

Date (form was filled out) 

Supplier Name 

Contact Name (telephone #) 

Equipment Name/Model 

Wafer Size 

Process Name 

Single Wafer (yes/no) 

Batch (yes/no) 

# of Wafers/Batch 

Design Throughput (wafers/hr) 

Chamber Clean (in situ or remote) 

Type of Film Deposited/Etched/Cleaned 

Film Thickness, Angstroms 

POU Abatement Device 

Name/Model/Technology 

Process Peripheral Equipment (List All) 

NOTE: Include environmental emissions from POU abatement device and process peripheral equipment in 

Worksheets 2 through 6. 
ISMI Technology Transfer #06124825B-ENG 

Worksheet #2 – Template for Reporting Process Air Emissions 

Equipment Name: 

Baseline Deposition or Etch Recipe Information (Repeat for Clean Recipe and Seasoning Recipe, if applicable) 

Parameters/Steps Step 1 Step 2 Step 3 

Time (sec)Pressure (Torr)RF Power (W)Flow of A (sccm) Flow of B (sccm) Flow of C (sccm) etc. [3]1.0 Processes such as PVD, CVD, etch, implant, etc.

1.1 Emissions During Wafer Processing

Input Chemical 

Volume In 

(scc/wafer) 

Mass In 

(g/wafer) Mass In (g/hr) 

ABCetc. [3]

Chemical Emitted 

Volume Out 

(scc/wafer) 

Mass Out 

(g/wafer) 

Mass Out 

(g/hr) 

Utilization[1]

(%) 

Utilization[1]

(std. dev.) 

ABCetc. [3]
ISMI Technology Transfer #06124825B-ENG 

Worksheet #2 – Template for Reporting Process Air Emissions (continued) 

1.2 Emissions During “Dry” Chamber Clean 

Input Chemical 

Volume In 

(scc/wafer) 

Mass In 

(g/wafer) 

Mass In 

(g/hr) 

ABCetc. [3]

Chemical Emitted 

Volume Out 

(scc/wafer) 

Mass Out 

(g/wafer) 

Mass Out 

(g/hr) 

Utilization[1]

(%) 

Utilization[1]

(std. dev.) 

ABCetc. [3]

1.3 Process Component Volume Closure (i.e., halides, NH3, P, etc.)

Component In 

During 

Wafer 

Processing 

(scc/wafer) 

During 

Chamber 

Clean 

(scc/wafer) 

Total 

Volume In 

(scc/wafer) 

Total Mass 

In (g/wafer) 

FClBretc. [3]

Component Out 

During 

Wafer 

Processing 

(scc/wafer) 

During 

Chamber 

Clean 

(scc/wafer) 

Total 

Volume Out 

(scc/wafer) 

Total 

Volume 

Closure[2]

(%) 

Volume 

Closure[2]

(std. dev.) 

Total Mass 

Out 

(g/wafer) 

FClBretc. [3]
ISMI Technology Transfer #06124825B-ENG 

Worksheet #2 – Template for Reporting Process Air Emissions (continued) 

1.4 Emissions During Equipment Idle (e.g., periodic chamber cleans when wafers are NOT being processed)

Input Chemical 

Mass In 

(g/hr) 

ABCetc.[3]

Chemical Emitted 

Mass Out 

(g/hr) 

Utilization[1]

(%) 

Utilization[1]

(std. dev.) 

ABCetc. [3]2.0 Emissions from Wet Stations/Benches

Tank 

Chemical 

Used Comp. (%) 

Tank 

Volume 

(liters) Temp. (oC) 

Does tank 

have a 

cover? 

(yes/no) 

% of Time 

Chemical is 

in Tank 

Typ

Agita

(e.

spa

megas

abcetc. [3]
ISMI Technology Transfer #06124825B-ENG 

Worksheet #2 – Template for Reporting Process Air Emissions (continued) 

2.1 Emissions for Tank "a" (repeat for each tank)

Chemical Emitted 

Avg. 

Emissions 

w/o Wafers 

(g/hr) 

Avg. Emissions During 

Wafer Processing (g/hr) 

Avg. 

Emissions 

per Wafer 

Processed 

(g/wafer) 

Avg. 

Process Exhaust 

Volume 

(m3/hr) [4]

Average Concentrati

Process Exhaust Du

Dispense (ppmv

ABCetc. [3]3.0 Emissions from Spray Processors

Input Chemical Comp. (%) 

Flow Rate 

(sccm) 

Duration of 

Flow (sec) Temp. (°C) 

% of Recipe 

Time 

Chemical is 

Applied 

ABCetc. [3]

Chemical Emitted 

Average 

Emissions 

for Each 

Wafer 

Processed 

(g/wafer) 

Average 

Emissions 

During 

Dispense 

(g/sec) 

Average 

Process Exhaust 

Volume 

(m3/hr) [4]

Average Concentration in 

Process Exhaust During 

Dispense (ppmv) 

ABCetc. [3]

Notes: [1] = % utilization = (mass in – mass out)/mass in  100%. 

[2] = % volume closure = volume out/volume in  100%. [3] = List all chemicals used as well as any byproducts formed. [4] = 1 cfm = 1.7 m3/hr 

Remarks: 1. List the analytical method(s) used to obtain 

2. Provide a copy of the third-party test repor3. Provide a simplified process flow diagram  streams entering and leaving the equipme
ISMI Technology Transfer #06124825B-ENG 

Worksheet #3 – Template for Reporting Liquid Effluents 

Equipment Name: 

3.0 Specific Information# of connections per equipment # of recirculation loops drain interlocks (yes/no) drain switching capability (yes/no) drain switching capability (manual/auto) 

3.1 Chemical / DI Water / Wastewater /Solvent Effluent

Input Chemical / Solvent 

/ DI Water / Purpose 

Time for 

Step (sec) 

Chemical 

Constituent 

[2] 

Concen. 

(mg/L) 

Avg. 

Flow [1] 

(lpm) 

Maximum 

Flow [1] 

(lpm) 

Idle 

Flow [1] 

(lpm) 

Volume 

(liters) 

Total 

Volume 

(ltrs/step) 

Step 1 A 

 B  C 

Step 2 A 

 B  C 

Step 3 A 

 B  C 

Effluent / Drain 

Time for 

Step (sec) 

Chemical 

Constituent

[2] [4] 

Concen. 

(mg/L) 

Avg. 

Flow [1] 

(lpm) 

Maximum 

Flow [1] 

(lpm) 

Idle 

Flow [1] 

(lpm) 

Bath 

Discharge 

Volume 

(ltrs/step) 

Bath 

Discharge 

Frequency 

(#/week) 

Step 1 A 

 B  C 

Step 2 A 

 B  C 
ISMI Technology Transfer #06124825B-ENG 

Worksheet #3 – Template for Reporting Liquid Effluents (continued) 

Effluent / Drain 

Time for 

Step (sec) 

Chemical 

Constituent

[2] [4] 

Concen. 

(mg/L) 

Avg. 

Flow [1] 

(lpm) 

Maximum 

Flow [1] 

(lpm) 

Idle 

Flow [1] 

(lpm) 

Bath 

Discharge 

Volume 

(ltrs/step) 

Bath 

Discharge 

Frequency 

(#/week) 

Step 3 A 

 B  C 

3.2 Tank Pickling Chemistry [3]

Drain 

Chemical 

Constituent

[2] 

Concen. 

(mg/L) 

Flow [1] 

(lpm) 

Total 

Volume 

(ltrs) 

Duration 

(min) 

Frequency 

(#/month) 

 A  B  C 

Note: [1] Averaged over 5–10 wafer processing cycles. 

[2] Example constituents of high interest: NH3, SO4, F, Cu, TSS, organic compounds in water. All constituents should be disclos

[3] Refers to chemical used to flush and condition the chemical bath before introducing the chemical used for processing. 

 [4] Include all materials etched or stripped. Remarks: 1. List the analytical methods used to obtain the data. 

2. Provide a copy of the third-party test report(s), where applicable. 3. Provide a simplified process flow diagram showing all the streams entering and leaving the equipment. 
22 

Technology Transfer #06124825B-ENG ISMI 

Worksheet #4 – Template for Reporting Solid Waste 

Equipment Name/Model: 

4.0 Solid Waste Produced during Wafer Processing (see 5.5 Consumables on Worksheet 5 as well)

Type of Waste 

Total Waste 

Generated 

(kg/24 hrs) 

Frequency (if 

intermittent) 

Amount 

Generated 

(g/wafer) 

Chemical 

Constituent(s)

Concentration 

(wt%) Comments 

A 

B 

C 

Remarks: 1. List the analytical methods used to obtain the data. 

2. Provide a copy of the third-party test report(s), where applicable. 

3. Provide a simplified process flow diagram showing all the streams entering and leaving the equipment. 
ISMI Technology Transfer #06124825B-ENG 

Worksheet #5 – Template for Reporting Preventive Maintenance (PM) Emissions 

Equipment Name/Model: 

5.0 General Description of procedureFrequency of procedure Time between PMs (hrs) Number of wafers between PMs Estimated length of procedure 

5.1 Air Emissions

Chemical 

Amount Used 

(g/proc.) Constituent 

Constituent 

Concen. (%) 

Mass Emitted 

(g/proc.) 

Total Mass 

(g/wafer) 

A B 

C 

5.2 Liquid Chemical/Wastewater Emissions

Chemical 

Amount Used 

(ltrs/procedure) Constituent 

Constituent 

Concentration 

(%) 

Total Mass 

(g/procedure) 

Total Mass 

(g/wafer) 

A B 

C 

5.3 Solid Waste Generated

Solid Waste 

Amount 

(g/procedure) Constituent 

Constituent 

Concentration 

(%) 

Total mass 

(g/wafer) 

A B 

C 
ISMI Technology Transfer #06124825B-ENG 

Worksheet #5 – Template for Reporting Preventive Maintenance (PM) Emissions (contin

5.4 Qualification after PM

Flushing Chemical 

Volume Used 

(g/procedure) Constituent 

Concentration 

(%) 

Air Emissions 

(g/procedure) 

Liquid Waste 

(g/procedure) 

Solid W

(g/proce

A B C 

5.5 Consumables

Frequency of Replacement 

# Wafer Passes Hours of Use Quantity 

Contaminated? 

Yes/No 

Contaminating 

Constituent(s) 

Anodes and Cathodes Targets CMP Pads Post-CMP Brushes Filters Batteries Lamps Grease Ionizer Bar Emitter Tips Contaminated Wipes Refrigerants Heat Transfer Fluids etc. 
ISMI Technology Transfer #06124825B-ENG 

Worksheet #5 – Template for Reporting Preventive Maintenance (PM) Emissions (contin

5.6 Parts Cleaning (include even if outsourcing is used)

Part Item #1 Item #2 Item #3 etc. 

After # of wafer passes After # of hours in use Cleaning method Chemical used Chemical (g/clean) Constituent Concentration (%) Air emissions (g/clean) Liquid waste (g/clean) Solid waste (g/clean) 

Remarks: 1. List the analytical methods used to obtain the data. 

2. Provide a copy of the third-party test report(s), where applicable. 3. Provide a simplified process flow diagram showing all the streams entering and leaving the equipment. 

1 

ISMI Technology Transfer #06124825B-ENG 

Worksheet #6 – Template for Data Summary 

Equipment Name/Model: 

Air Emissions [1]

Units 

Process 

Exhaust A 

Process 

Exhaust B 

Process 

Exhaust C etc. Comments 

HAPs g/wafer 

GHGs g CO2e/wafer 

VOCs g/wafer 

ODSs g/wafer 

Other g/wafer 

Liquid Effluents [1]

Units Effluent A Effluent B Effluent C etc. Comments 

Volume ltrs/wafer 

Constituent 1 mg/L 

Constituent 2 mg/L 

Constituent 3 mg/L 

etc. 

Solid Waste [1]

Units Waste A Waste B Waste C etc. Comments 

Total g/wafer 

Constituent 1 g/wafer 

Constituent 2 g/wafer 

Constituent 3 g/wafer 

etc. 

Mass Balance

Constituent 

Input to 

Equipment 

(g/wafer) 

Air Emissions 

(g/wafer) 

Liquid Waste 

(g/wafer) 

Solid Waste 

(g/wafer) 

Mass Closure 

[2] (%) Comments 

F ion 

Cl ion 

Br ion 

P ion 

S ion 

Cu ion 

NH3 [3]

etc. 

Note: [1] Includes waste generated during preventive maintenance (PM). 

[2] % mass closure = mass out / mass in  100%. 

[3] NH3 can be destroyed in process and therefore mass closure may not be 100%. 

 g CO2e = grams of carbon dioxide equivalent = g of GHG  GWP. 

HAP = hazardous air pollutant. 

VOC = volatile organic compound. 

ODS = ozone depleting substance. 

GHG = greenhouse gas 

 GWP = global warming potential 
2 

Technology Transfer #06124825B-ENG ISMI 

Appendix A – Technical Protocols for Air Emissions Characterization 

This appendix explains the best known methods for conducting air emissions studies. While 

other analytical methods can be applied to air emissions characterization, most of these 

techniques have severe limitations and more supporting data must be provided to guarantee the 

quality of the data. The three recommended techniques for conducting the air emissions studies 

are mass spectrometry (MS), Fourier transform infrared (FTIR) spectroscopy, and fluorine 

chemiluminescence. The MS protocol was written by Air Products and Chemicals Inc.; the FTIR 

protocol was written by 3M Corporation, and modified by IMACC and URS; and the fluorine 

chemiluminescence protocol was written by URS. Any alternative methodology (i.e., UV 

spectroscopic technique) must have a sample protocol associated with the methodology and be 

technically reviewed before sampling. 

A.1 Mass Spectrometry Protocol 

Mass spectrometry is a quantitative analytical method for the determination of CF4, C2F6, C3F8, 

CHF3, NF3, SF6, inert gases, etc., in process tool exhaust streams and POU abatement device 

exhaust streams. 

A.1.1 Introduction 

This procedure can be used to determine fluorinated compounds such as CF4, C2F6, C3F8, CHF3, 

NF3, and SF6 found in semiconductor processing effluent streams and to measure homonuclear 

diatomic molecules and inert gases like helium, argon and krypton (e.g., to determine the POU 

abatement device dilution factor). The fluorinated compounds are primarily found in the effluent 

of chemical vapor deposition (CVD) and plasma etch applications. The method is based on using 

primarily quadrupole mass spectroscopy (QMS). In QMS, the sample is typically ionized using 

electron impact ionization. The quadrupole mass filter separates the ions based on their mass-tocharge ratio (m/e). A secondary electron multiplier or a Faraday plate is used as a detector for 

these mass separated ions. Concentrations of the individual components in the sample are 

determined from QMS response factors, which are determined from direct calibration of the 

QMS response to the compounds listed above. 

QMS response factors are certainly obtainable for compounds outside of the above listed 

fluorinated compounds. In fact, QMS is often used as a complementary monitoring technique to 

FTIR, when detection of homonuclear diatomics or inerts like Cl2, F2, Ar, He, etc. (which FTIR 

cannot measure) is required. However, special care must be taken when sampling corrosive gas 

streams, such as exhaust streams from a process tool containing significant amounts of HF 

and/or F2. The QMS ionizer can become coated or degrade over time leading to calibration drift 

in the QMS response factors. In this case, frequent calibration runs are necessary to quantify the 

drift and to apply appropriate correction factors to the sample data. 

 Basic QMS Configuration 

The basic components of a quadrupole mass spectrometer system are an ionizer, a 

quadrupole mass filter, and a detector such as an electron multiplier. 
3 

ISMI Technology Transfer #06124825B-ENG 

 Ionizer 

Here the molecules in the sample gas are ionized. Thermionic emission from tungsten or 

thoriated iridium filaments are used to produce electrons accelerated to energies of 70 eV. 

These electrons can ionize the molecules by the following interaction: 

e

-

 + ABx  ABx

+* + 2eABx

+*

 ABx-1+ + B  ABx-2+ + 2B 

The molecule ABx is first ionized into an excited ionic state. Depending upon the structure 

of the molecule, the excited ionic state will produce different fragment ions of the type 

ABx

+

, ABx-1+, ABx-2+, etc. 

The ions produced in the ionizer are extracted using ion optics. A series of electrostatic 

lenses are used to focus the extracted ions into the entrance of the quadrupole mass filter. 

 Quadrupole Mass Filter (QMF) 

The QMF consists of four cylindrical rods to which both RF and DC voltages are applied. 

The rods opposite each other are connected together. The voltage +(U + Vcosωt) is applied 

to one set of rods, whereas the voltage -(U + Vcost) is applied to the other set of rods. The 

typical operating frequency of the RF voltage is 1.2 MHz. Under the influence of this 

quadrupolar field, the equation of motion for the ions is represented by the Mathieu 

equation: 

  d u

d qq

2

2 2 2



 + a u = 0 u  cos  Eq. [A-1] 

where 



 = 

t

2 Eq. [A-2]

and a

eU

m r u  4

2 2 

Eq. [A-3] 

where U is the DC voltage, m is mass,  is angular frequency, and r is the radius of the 

quadrupole and 

q

eV

m r u  2

2 2 

 Eq. [A-4] 

where V is the peak amplitude of the RF voltage of angular frequency . 

The solutions to the Mathieu equation fall into either stable or unstable regions, depending 

upon the mass-to-charge ratio of the ion. The ions for which the solution is stable exit the 

quadrupole, whereas all other ions have unstable trajectories and hit the rods of the 

quadrupole. By changing the amplitude of the RF field (V), different ions can be made to 

have stable trajectories. Thus by changing the RF field, the QMS can be tuned to transmit 

different masses. The resolution of the QMF is determined by the ratio U/V. For constant 

resolution, the ratio U/V is kept constant when the RF voltage is adjusted to change the 

transmitted mass. 
4 

Technology Transfer #06124825B-ENG ISMI 

 Detection System 

The ions transmitted by the QMF are detected using either a Faraday plate or an electron 

multiplier. The Faraday plate is a metal plate placed at the end of the quadrupole filter. 

A sensitive electrometer connected to this plate records the current produced when a charged 

ion hits the Faraday plate. Typically, the electrometer is sensitive enough to detect current in 

the pico ampere range. 

For currents smaller than a few pico amperes, an electron multiplier is used instead of the 

Faraday plate. In most QMS, a continuous dynode electron multiplier is used although a 

discrete dynode electron multiplier could also be used. The entrance of the electron 

multiplier is biased at about -2000 V, whereas the other end is connected to a groundreferenced amplifier. The positive ions exiting the quadrupole are accelerated towards the 

-2000 V potential on the entrance of the electron multiplier. When the ions strike the 

electron multiplier, they generate a few secondary electrons. These secondary electrons, 

under the influence of the gradient in the electron multiplier, strike a different part of the 

electron multiplier. Each electron produces a few secondary electrons. These electrons will 

cascade down the electron multiplier. This cascading effect generates about a million 

electrons for every ion that strikes the entrance of the electron multiplier. This enhanced 

signal is measured by the preamplifier. 

 QMS Resolution 

A QMS is normally operated in a unit mass resolution mode meaning masses are separated 

by one atomic mass unit. The resolution of a QMS is defined by the following equation: 

m/m = (0.126)(0.1678 - U/V)

-1 Eq. [A-5] 

For infinite resolution, U and V are given by the equations 

U (volts) = 1.212 mf2r

2

 Eq. [A-6] 

V (volts) = 7.219 mf2r

2 Eq. [A-7] 

where f is frequency. Resolution (m/m) can be empirically determined by dividing the 

center point mass by the full width at half height of the peak for each mass of interest. 

 Detection Limits 

The mass spectrometer chosen for this application should have the necessary sensitivity to 

detect the selected effluent species at a predetermined level. The typical detection limit of 

each component determined with the QMS used for this study was 1–10 ppmv. System 

detection limits can be calculated using SEMI guideline F33-0998, which describes the 

calculation of a regression-based limit of detection. Two regression-based means for 

determining a limit of detection (LOD), ordinary least squares (OLS), and weighted least 

squares (WLS) are often used. OLS analyses implicitly assume that signal variability is the 

same everywhere within the calibration window. WLS analyses allow signal variability to 

vary over the calibration window, but require an appropriate set of weights to complete the 

analysis. The LOD is calculated to obtain a 3  equivalent (in probability) upper confidence 

limit. 
5 

ISMI Technology Transfer #06124825B-ENG 

A.1.2 Sampling Conditions 

 Sampling Location 

The sample is taken downstream of the process tool and pump package (see Figure A-1). 

The exact location is determined by the specific tool and piping configuration associated 

with the process. To prevent emissions of potentially toxic process byproducts into the work 

space, the sample exhaust is vented back into the corrosive house ventilation system at a 

point downstream of the sample inlet location. 

 Sampling Conditions 

Perfluorocompound (PFC) utilization efficiencies, defined as the fraction of PFC reacted in 

the process chamber, should be determined during actual wafer processing. For etch 

applications, efficiencies should be determined while etching a wafer (product, dummy, or 

test). For chemical vapor deposition (CVD) applications, efficiencies should be determined 

during a chamber clean after deposition (efficiencies should not be determined in a clean 

chamber). All sampling is performed non-intrusively during wafer processing. Samples are 

drawn through the MS source by an external sample pump. The pressure in the exhaust is 

slightly below 1 atm. (~750 Torr). The pressure of the sample inlet is maintained at a lower 

pressure (~700–740 Torr) by throttling the sample pump. Because of the inertness of CF4, 

C2F6, C3F8, CHF3, NF3, and SF6, the sample lines do not need to be heated. 

Calibration System

Corrosive Exhaust Line

From Process 

Tool 700 Torr

Mass

Spectrometer

P

Sample

Pump

Closed Ion

Source

To Process

Exhaust

Pump Exhaust

Figure A-1 Process Tool Exhaust Sampling System 

 Mass Spectrometer Parameters

Choice of specific QMS operating conditions such as electron energy, secondary electron 

multiplier voltage, emission current, and ion focusing voltage are left to the discretion of the 

analyst provided the QMS responses to analytes are calibrated under the same conditions. 

These parameters are systems-specific and will need to be determined by the analyst. To 
6 

Technology Transfer #06124825B-ENG ISMI 

address questions in this area, analysts should consult the QMS manufacturer, the system 

manual, basic mass spectrometer textbook, and other such sources. 

 Data Acquisition Mode 

For this application, the mass spectrometer is typically operated in the selective ion 

monitoring (SIM) mode where the mass filter monitors a set of specified ions rather than the 

whole mass spectrum. The advantage of operating in SIM mode is to provide more rapid and 

sensitive analysis. The ions chosen depend on the PFC(s) used in the process and the 

byproducts being monitored. Listed in Table A-1 are the fragment ions used to determine the 

PFCs typically in CVD and etch tool exhausts. 

Table A-1 Monitored Fragment Ions 

Compound Monitored Fragment Ion m/e 

CF4 CF3

+

 69 

C2F6 C2F5

+

 119 

C3F8 C3F7

+

 169 

CHF3 CHF2

+

 51 

NF3 NF2

+

/NF3

+

 52/71 

SF6 SF5

+

 127 

To identify unknown and known components in the sample, a complete mass spectrum is 

obtained by operating the mass spectrometer in the full spectrum scan mode. Standard mass 

spectra for each of the compounds listed above are in Figure A-2 through Figure A-7. The 

spectra were obtained from the National Institute of Standards and Technology’s website. 

100

80

60

40

20

0

20 40 60 80 100 120 140

Rel. Abundance

m/z

Figure A-2 Mass Spectrum for Sulfur Hexafluoride (SF6) 
7 

ISMI Technology Transfer #06124825B-ENG 

100

80

60

40

20

0

10 20 30 40 50 60 80

Rel. Abundance

m/z

70

Figure A-3 Mass Spectrum for Nitrogen Trifluoride (NF3) 

100

80

60

40

20

0

10 20 30 40 50 60 80

Rel. Abundance

m/z

70

Figure A-4 Mass Spectrum for Trifluoromethane (CHF3) 
8 

Technology Transfer #06124825B-ENG ISMI 

100

80

60

40

20

0

20 30 45 60 75 90

Rel. Abundance

m/z

Figure A-5 Mass Spectrum for Carbon Tetrafluoride (CF4) 

100

80

60

40

20

0

0 40 80 120 160

Rel. Abundance

m/z

Figure A-6 Mass Spectrum for Hexafluoroethane (C2F6) 
9 

ISMI Technology Transfer #06124825B-ENG 

100

80

60

40

20

0

0 40 80 120 160 200

Rel. Abundance

m/z

Figure A-7 Mass Spectrum for Octafluoropropane (C3F8) 

 Flow Rates 

A sample flow rate of ~0.5–1.5 slm is drawn from the process tool exhaust stream under 

study. This typical flow rate is needed to purge the sample manifold and obtain a temporally 

representative sample of the process. The flow rate into the mass spectrometer source will be 

significantly lower and will depend on how the inlet is differentially pumped. This is usually 

accomplished using a Restrictive Flow Orifice (RFO) or a narrow diameter capillary. 

 Sample Frequency 

The required sample frequency depends on the process being monitored. The software of the 

mass spectrometer should be capable of capturing the data at the required sample frequency. 

Fast processes, such as etch processes, require rapid sampling frequencies. Typical etch 

sampling frequencies should be on the order of 0.5–1 Hz. Some CVD chamber cleaning 

processes are longer and can tolerate sampling frequencies of 0.25–0.5 Hz. 

 Dynamic Dilution Calibration Parameters 

The QMS must be calibrated for both mass location and response to analytes. A dynamic 

dilution calibration system can be used to perform both types of mass spectrometer system 

calibrations. The simplest type of dynamic calibration system includes appropriate tubing, 

fittings, and two mass flow controllers (MFC). One MFC regulates the flow rate of the 

standard component used to calibrate the system. The second MFC regulates the amount of 

diluent gas used to mix with the standard. The flow rates of the mass flow meters are 

adjusted to the appropriate settings to obtain the required concentrations of analyte for 

calibrating the QMS. These data are used to generate a calibration curve for each compound 

of interest. 
10 

Technology Transfer #06124825B-ENG ISMI 

Some Mass flow controllers (MFC) are used to accurately regulate the flow rates of the 

diluent and calibration gases. The MFC should be calibrated using the single component gas 

being used with them, which is typically nitrogen (N2) for the diluent. MFC used with 

calibration mixtures should be calibrated with the calibration mixture balance gas (typically 

N2 or He) if the analyte components are ~2% or less. They should be calibrated over their 

range of use and operated in their experimentally determined dynamic linear range. 

Bringing compressed gas standards into a fab is often impractical, whether because of space, 

safety, or other logistical concerns. Metered gas flows of target compounds into the process 

chamber, under no thermal or plasma conditions and with no wafer(s) present, must then be 

performed throughout the appropriate concentration ranges to derive calibration curves for 

the subsequent process emissions tests. This calibration method requires accurate knowledge 

or measurement of all the foreline roughing pump rates (and no process emissions from 

other tools) contributing to the sample location. 

 Mass Location Calibration 

A mixture containing 1% He, Ar, Kr, and Xe in a balance gas of nitrogen can be used to 

assure the alignment of the quadrupole mass filter. This mixture covers both low and high 

mass ranges. The mass spectrometer should be chosen so that the mass range is sufficient to 

detect the predominant peaks of the components under study. Typically 1–200 amu range is 

sufficient. 

As with the dynamic dilution calibration, inert gases or others suitable as quadrupole mass 

standards (like SF6, one with a well known fragmentation pattern over a large mass range), 

may need to be delivered by the process tool, as opposed to compressed gas standards. 

 QMS Response Calibration 

The response of the QMS to the compounds listed in Table 1 is determined by calibrating 

the system with test atmospheres containing the compounds of interest. These test 

atmospheres are created using dynamic gas phase dilution techniques as described above. 

A calibration curve should be generated for each compound of interest. 

 Calibration Frequency 

The mass spectrometer should be calibrated at the start of testing a given process. The 

calibration should be checked at the end of testing. This calibration frequency can detect 

drifts in QMS sensitivity during monitoring. It is strongly recommended that more frequent 

calibrations be performed (e.g., immediately before and after a given set of test conditions) 

when the sample stream is known to contain a significant amount of fluorinated corrosives. 

 Calibration Range 

The mass spectrometer is typically calibrated over the expected concentration range of 

analytes. A multi-level calibration is performed using a minimum of five concentrations 

including a zero. The zero point is defined as diluent containing no added analyte. Ideally 

the QMS should be calibrated over the expected concentration range of analytes in the 

process effluent. 
11 

ISMI Technology Transfer #06124825B-ENG 

A.1.3 Operating Procedures 

1. Perform a qualitative mass calibration by running a standard (or by flowing chamber gases 

under non-process conditions) containing stable components such as Ar, Kr and Xe that 

provide predominant signals at m/e values distributed throughout the mass range to be used. 

This will ensure the mass locations are properly identified and that the m/e values of the 

mass fragments are correctly identified. Adjust the quadrupole mass filter as needed to align 

with the inert gas fragments. 

2. Quantitatively calibrate the QMS for each analyte of interest. The analyte concentrations 

during calibration should include the expected concentrations in the process effluent. The 

calibration should be performed under the same operating conditions, such as inlet pressure, 

as when sampling process exhaust. One way to do this is to carefully regulate the inlet 

pressure during calibration and sampling using a flow controlling valve and monitoring the 

pressure using a capacitance manometer. If the calibration inlet pressure differs from the 

sampling inlet pressure than the relationship between inlet pressure and QMS signal 

response must be empirically determined and applied to correct for any differences between 

calibration and process emissions monitoring data. 

3. To determine the response time of the instrument to changes in a process, a process gas such 

as C2F6 should be turned on at the process tool for a fixed period of time. This should be a 

relatively short period (e.g., 20 seconds), after which the gas is shut off. The amount of time 

it takes for the QMS to respond to this process gas appearing and disappearing should be 

observed. The response should be relatively rapid with the signal increasing to a constant 

concentration within a few seconds, and decreasing to background levels also within a few 

seconds. If this is not observed, the sample flow rate through the system should be 

increased. 

4. Sample process effluent through the QMS and acquire data for the required amount of time 

to track the process. The sample frequency is set to monitor the changes in the process. 

Repeat this for at least five wafers on the same process to obtain an average and standard 

deviation of the analyte concentration. 

5. Repeat quantitative calibration at the conclusion of sampling to identify any drifts in QMS 

sensitivity. If significant drift is observed, use of an internal standard can be used to correct 

for changes in sensitivity. For semiconductor emissions monitoring nitrogen fragment (N+

) 

observed at m/e 14 works well for monitoring drift. All analyte signals can normalized to 

N+

, including those obtained during quantitative calibration. This will help to negate changes 

in sensitivity caused by reduced flow into the QMS source, which can occur quite easily 

when monitoring processes emitting particles that can clog or obscure flow through a RFO 

or thin capillary. 

A.1.4 Calculations 

 Calibration 

Plot ion intensity vs. analyte concentration for a given compound obtained when calibrating 

the analytical system. Determine the slope and intercept for each calibrated species to obtain 

response factors with which to calculate concentrations in the sample. For an acceptable 

calibration, the R2

 value of the calibration curve should be at least 0.98. 
12 

Technology Transfer #06124825B-ENG ISMI 

 Sample Analysis 

To determine the concentration of a specific component in the sample, divide the ion 

intensity of the sample response by the calibrated response factor. Repeat this for each 

component. 

 Deconvolution of Interfering Peaks

Interfering peaks must be deconvolved to obtain accurate results. As an example of this, 

C2F6 and CF4 have common fragments in their mass spectra (CF3

+

, CF2

+

, CF+, and F+). CF4

does not produce a fragment that is not observed in the mass spectra for C2F6. Thus the 

contribution of fragment ions attributable to C2F6 must be deconvoluted from the ions 

attributable to CF4 at a common mass such as m/e 69. Deconvolution can be achieved by 

using a prominent peak, such as C2F5

+ (m/e 119), which is not common to both molecules. 

Contributions to m/e 69 from C2F6 can be subtracted by using the m/e 69/ m/e 119 ion 

intensity ratio obtained when C2F6 is present alone. For example, to determine the CF4

concentration in the presence of C2F6, the following expression can be used: 

   B = 119

62

69

Total

69

CF4 FC  SSS Eq. [A-8] 

C SR    CF4 CF CF

69

4

69

4

69

 = Eq. [A-9] 

where S is QMS signal, C is concentration, R is the response factor of the QMS to CF4

determined from the calibration curve, superscripts are amu values, and B is the branching 

ratio defined by 

BC F2 6

69

119

C2F6

C2F6

S

S  Eq. [A-10] 

If other compounds are present that contribute to the signal at m/e = 69, they must also be 

included in the calculation. 

 Determining Total Process Flow (Including Pump) 

Semiconductor process pumps typically have nitrogen purges to protect the pump from 

corrosion and to prevent process effluents from accumulating. To calculate dilution of 

process emissions occurring in the pump, PFCs can be used. This is typically done by 

flowing PFCs at the process flow rate through the chamber with RF power in the chamber 

turned off. From the PFC concentration and known process flow, the dilution in the process 

exhaust and pump can be determined. The calculation below shows an example of how to 

determine pump purge dilution. Assume 50 sccm of CF4 in the process tool yielded 500 

ppmv average CF4 effluent concentration with the RF power off. 

 

    1

1

 4

6

1

CF4 L 100 min

L 10500

minL 050.0 

 



 

FlowTotal

CF L FlowTotal

 Eq. [A-11] 

Note that it is necessary to ensure RF power is off and that the compound chosen is 

thermally stable at the chamber temperature. 
13 

ISMI Technology Transfer #06124825B-ENG 

These data can be used to determine the process emission volumes and/or emission factors. 

The emission volumes are obtained by integrating the emission concentration over time with 

the total process flow. The emission factors are determined from the ratio of a volume of 

PFC added to chamber relative to the volume of PFC emitted from the chamber. For PFC 

based byproducts, such as CF4 produced during C2F6 chamber cleans, the CF4 emission 

factor would be the volume of emitted CF4 relative to the volume of C2F6 used for the 

chamber clean. Mass emission factors can also be calculated by converting volumes to mass 

using molecular weight and ideal gas law. 

A.2 Fourier Transform Infrared (FTIR) Spectroscopy Protocol 

This is a protocol for FTIR measurements of species that are not diatomic molecules and inert 

gases like argon, helium, and krypton in semiconductor process tool exhaust. 

A.2.1 Introduction 

This section provides procedural and quality assurance and quality control (QA/QC) bases for 

gaseous concentration measurements of fluorinated compounds by extractive FTIR spectrometry. 

Some of the compounds of interest are SF6, NF3, C2F6, C3F8, CF4, and CHF3. Other compounds 

can be measured using FTIR such as N2O, CH4, CO, NO, NO2, SiH4, HF and HCl. Compounds 

are to be measured in enclosed samples extracted from the effluent of semiconductor tools; the 

analytes are typically in a mixture of oxygen and nitrogen with low moisture content (less than 

0.1% by volume). Typical concentrations of the six analytes are in the 100–50,000 ppmv range. 

Because the tool effluent concentrations can change rapidly, measurements must be made at least 

twice per minute or several times per minute, if possible. This requirement places special 

emphasis on the sampling and data acquisition operations for this application.

Substantial field experience in the use of FTIR spectroscopy gained in previous SEMATECH 

studies (see Reference [1] in Appendix A.2.9) was used in the preparation of this protocol. The 

nomenclature is adopted from Reference [2]. Appendix A.2.10 lists several salient definitions. 

The intended audience is the technical community familiar with process tool operation and 

standard emission testing methodologies. However, because FTIR spectrometry is a relatively 

new emissions testing technique, it is briefly described in Appendix A.2. Additional 

mathematical details of the technique are provided in Appendices A.2.7 and A.2.8. 

A.2.2 Method Development 

The general procedure for developing and documenting an extractive, FTIR-based analysis of the 

effluent from semiconductor process tools is largely based on studies by SEMATECH and 

3M Corporation. 

Developing an FTIR method consists of two distinct phases: 1) a laboratory study phase and 

2) a field study phase. In practice, portions of these developmental phases may occur 

simultaneously, and some adjusts in the order and/or repetition of some activities may be 

necessary. 
14 

Technology Transfer #06124825B-ENG ISMI 

A.2.3 Laboratory Studies 

 Proposed Spectroscopic Conditions 

Propose a set of spectroscopic conditions under which the field studies and subsequent field 

applications are to be carried out. These include the minimum instrumental linewidth (MIL), 

spectrometer wavenumber range, sample gas temperature, sample gas pressure, absorption 

pathlength, maximum sampling system volume (including the absorption cell), minimum 

sample flow rate, and maximum allowable time between consecutive infrared analyses of 

the effluent. 

 Criteria for Reference Spectral Libraries 

On the basis of previous emissions test results and/or process knowledge, estimate the 

maximum concentrations of all of the analytes in the effluent and their minimum 

concentrations of interest (those concentrations below which the measurement of the 

compounds is of no importance to the analysis). Values between the maximum expected 

concentration and the minimum concentration of interest are referred to below as the 

“expected concentration range.” A minimum of four reference spectra must be available for 

each analyte. When the set of spectra is ordered according to absorbance, the absorbance 

levels of adjacent reference spectra should not differ by more than a factor of six. Optimally, 

reference spectra for each analyte should be available at absorbance levels that bracket the 

analyte’s expected concentration range; minimally, the spectrum whose absorbance exceeds 

each analyte’s expected maximum concentration or is within 30% of it must be available. It 

is imperative that the reference spectra be collected at or near the same temperature and 

pressure that the sample is to be analyzed under. Furthermore, the gas sample pressure and 

temperature must be continuously monitored during testing. Most modern analysis software 

packages can auto-correct for temperature and pressure differences between the sample and 

reference spectra. However, the corrections will not account for major pressure differences 

(~50%) or major temperature differences (~70oC); under vastly different temperatures or 

pressures, the absorption profiles of these compounds will be significantly different and 

quantification errors will be significant if not fit to references of similar temperature and 

pressure. 

If reference spectral libraries meeting these criteria do not exist for all the analytes and 

interferants or cannot be accurately generated from existing libraries exhibiting lower MIL 

values than those proposed for the testing, prepare the required spectra according to the 

procedures below. 

 Preparation of Reference Spectra 

When practical, reference spectra at the same absorbance level (to within 10%) of 

independently prepared samples should be recorded. The reference samples should be 

prepared from neat forms of the analyte or from gas standards of the highest quality 

commonly available from commercial sources. Either barometric or volumetric methods 

may be used to dilute the reference samples to the required concentrations, and the 

equipment used should be periodically calibrated in some independent fashion to ensure 

suitable accuracy. Dynamic and static reference sample preparation methods are acceptable, 

but dynamic preparations are more likely than static methods to give consistent results for 

reactive analytes. Any well characterized absorption pathlength may be employed in 
15 

ISMI Technology Transfer #06124825B-ENG 

recording reference spectra, but the temperature and pressure of the reference samples 

should match as closely as possible those of the proposed spectroscopic conditions. 

If an MCT or other potentially non-linear detector (i.e., a detector whose response vs. total 

infrared power is not a linear function over the range of responses employed) is used for 

recording the reference spectra, the effects of this type of response on the resulting 

concentration values should be examined and corrected for. Spectra of a calibration transfer 

standard (CTS) should also be recorded periodically with the laboratory spectrometer system 

to verify the absorption pathlength and other aspects of the system performance. All 

reference spectral data should be recorded in interferometric form and stored digitally. 

 Sampling System Preparation 

Construct a sampling system suitable for delivering the proposed sample flow rate from the 

effluent source to the infrared absorption cell. For the compounds of interest, the surfaces of 

the system exposed to the effluent stream should be limited to stainless steel and Teflon; 

because of the potential for generation of inorganic automated gases, glass surfaces within 

the sampling system and absorption cell should be Teflon-coated. Demonstrate that the 

system, when sampling from a simulated source at the estimated effluent source pressure, 

delivers a volume of sample at least four times the maximum sampling system volume in a 

time shorter than the proposed minimum time between consecutive infrared analyses. This 

may be difficult for rapidly changing processes in which case the sample retention time 

should be determined. 

 Preliminary Analytical Routines 

For the proposed absorption pathlength to be used in actual emissions testing, prepare an 

analysis method containing of all the effluent compounds at their expected maximum 

concentrations plus the field CTS compound at 20% of its full concentration. Common to 

most all FTIR software are analytical routines for calculating the six analyte concentrations 

plus the CTS compound (and their uncertainties) from a sample spectrum using a subset of 

the analyte and interferant reference spectra. 

 Documentation 

The laboratory techniques used to generate reference spectra and to convert sample spectral 

information to compound concentrations should be thoroughly documented. The required 

level of detail for the documentation is that which allows an independent analyst to 

reproduce the results from the documentation and the stored interferometric data. 

A.2.4 Field Studies 

The performance of the proposed spectroscopic system, sampling system, and analytical method 

should be rigorously examined during and after a field study. Several iterations of the analysis 

method may need to be applied depending on observed concentrations, absorbance intensities, 

and interferences. During the field study, all the sampling and analytical procedures envisioned 

for future field applications should be documented. Additional procedures not required during 

routine field applications, notably dynamic spiking studies of the analyte gases, may be 

performed during the field study. These additional procedures need to be performed only once if 

the results are acceptable and if the effluent sources in future field applications prove suitably 

similar to those chosen for the field study. If significant changes in the effluent sources in future 

applications are noted and require substantial changes to the analytical equipment and/or 
16 

Technology Transfer #06124825B-ENG ISMI 

procedures, a separate field study should be performed for the new set of effluent source 

conditions. Ideally, all data taken during the study should be carefully stored and documented, 

and all spectral information should be permanently stored in interferometric form. 

 System Installation 

The spectroscopic and sampling sub-systems should be assembled and installed according to 

the manufacturers’ recommendations. For the field study, the length of the sample lines used 

should exceed the maximum length envisioned for future field applications. The system 

should be given sufficient time to stabilize before testing begins. 

 Pre-Test Calibration 

Record a suitable background spectrum using pure nitrogen gas; alternatively, if the analytes 

of interest are in a sample matrix consistent with ambient air (e.g., from an open bath hood), 

it is beneficial to use an ambient air background to control interferences from water and 

carbon dioxide. Introduce a sample of the CTS gas directly into the absorption cell at the 

expected sample pressure and record its absorbance spectrum (the “initial field CTS 

spectrum”). Compare it to the laboratory CTS spectra to determine the effective absorption 

pathlength. If possible, record spectra of field calibration gas standards (single component 

standards of the analyte compounds) and determine their concentrations using the reference 

spectra and analytical routines developed in Appendix A.2.3; these spectra may be used 

instead of the reference spectra in actual concentration and uncertainty calculations. 

The CTS gas may be derived by flowing appropriate semiconductor tool chamber gases 

under non-process conditions (no thermal or plasma conditions and with no wafer(s) 

present) if compressed gas standards cannot be brought on-site. 

 Reactivity and Response Time Checks 

While sampling ambient air and continuously recording absorbance spectra, suddenly 

replace the ambient air flow with CTS gas introduced as close as possible to the probe tip. 

Examine the subsequent spectra to determine whether the flow rate and sample volume 

allow the system to respond quickly enough to changes in the sampled gas. Should a 

corrosive or reactive gas be of interest in the sample matrix it would be beneficial to 

determine the reactivity in a similar fashion, if practical. Examine the subsequent spectra to 

ensure that the reactivities of the analytes with the exposed surfaces of the sampling system 

do not limit the time response of the analytical system. If a pressure correction routine in not 

automated, monitor the absorption cell temperature and pressure; verify that the (absolute) 

pressure remains within 2% of the pressure specified in the proposed system conditions. 

 Analyte Spiking 

If practical, analyte spiking should be performed. While sampling actual source effluent, 

introduce a known flow rate of CTS gas into the sample stream as close as possible to the 

probe tip or between the probe and extraction line. Measure and monitor the total sample 

flow rate, and adjust the spike flow rate until it represents 10% to 20% of the total flow rate. 

After waiting until at least four absorption cell volumes have been sampled, record four 

spectra of the spiked effluent, terminate the CTS spike flow, pause until at least four cell 

volumes are sampled, and then record four (unspiked) spectra. Repeat this process until 

three spiked and three unspiked spectra have been obtained. If a pressure correction routine 

is not automated, monitor the absorption cell temperature and pressure; verify that the 
17 

ISMI Technology Transfer #06124825B-ENG 

pressure remains within 2% of the pressure specified in the proposed system conditions. 

Calculate the expected CTS compound concentrations in the spectra and compare them to 

the values observed in the spectrum. This procedure is best performed using a spectroscopic 

tracer to calculate dilution (as opposed to measured flow rates) of the injected CTS (or 

analyte) standard. The spectroscopic tracer should be a component not in the gas matrix that 

is easily detectable and maintains a linear absorbance over a large concentration range. The 

gas spike is delivered by an MFC, and the expected concentration of analyte of interest 

(AOITheoretical) is calculated as follows: 

AOITheoretical =     native

cylinder

sample

cylinder

cylinder

sample

Tracer

Tracer

Tracer

Tracer AOI 1 AOI 



 



 



 



   

 





where 

 AOITheoretical = Theoretical analyte of interest concentration (ppm); 

Tracersample = Tracer concentration (ppm) as seen by the FTIR during spiking; 

Tracercylinder = The concentration (ppm) of tracer recorded during direct injection 

of the cylinder to the FTIR cell; 

 AOIcylinder = The supplier-certified concentration (ppm) of the analyte of 

interest gas standard; and 

 AOInative = The native AOI concentration (ppm) of the effluent during stable 

conditions. 

Repeat this spiking process with all effluent compounds that are potentially reactive with 

either the sampling system components or with other effluent compounds. 

 Post-Test Calibration 

At the end of a sampling run and at the end of the field study, record the spectrum of the 

CTS gas. The resulting “final field CTS spectrum” should be compared to the initial field 

CTS spectrum to verify suitable stability of the spectroscopic system throughout the course 

of the field study. 

 Amendment of Analytical Routines

The presence of unanticipated interferant compounds and/or the observation of compounds 

at concentrations outside their expected concentration ranges may necessitate the repetition 

of portions of the Appendix A.2 procedures. Such amendments are allowable before final 

analysis of the data, but must be represented in the documentation required in next section. 

 Documentation 

The sampling and spiking techniques used to generate the field study spectra and to convert 

sample spectral information to concentrations should be thoroughly documented. The 

required level of detail for the documentation is that which allows an independent analyst to 

reproduce the results from the documentation and the stored interferometric data. 
18 

Technology Transfer #06124825B-ENG ISMI 

A.2.5 Method Application 

When the required laboratory and field studies have been completed and if the results indicate a 

suitable degree of accuracy, the methods developed may be applied to practical field 

measurement tasks. During field applications, the procedures demonstrated in the field study (see 

Appendix A.2.4) should be adhered to as closely as possible, with the following exceptions: 

1. Ideally, the sampling lines employed should be as short as practically possible and not 

longer than those used in the field study. 

2. Analyte spiking and reactivity checks are required only after the installation of or major 

repair to the sampling system or major change in sample matrix. However, it is always 

good practice to perform three spiked/unspiked samples with CTS or a surrogate analyte 

on a daily basis if time permits and gas standards are easy to obtain and get on-site. 

3. Sampling and other operational data should be recorded and documented as during the 

field study, but not all the interferometric data need be stored permanently. Store only 

the amount interferometric data to sufficiently reproduce actual test and spiking data. 

The format of this data does not necessarily need to be interferograms but could be 

absorbance spectra or single beams if desired. 

A.2.6 Description of Extractive FTIR Spectrometry 

 Molecular Rotation-Vibration Absorption and Beer’s Law 

The energy of a molecule associated with its vibrational and rotational motions is quantized 

(i.e., it may take on only particular, discrete values). The allowed values are determined by 

the molecular structure, the atomic masses, and certain other internal molecular interactions. 

A molecule can (but need not) absorb light when the energy of an incident photon closely 

matches the energy spacing between two of its allowed energy levels. For most molecular 

structures, the allowed vibrational/rotational energy level spacings correspond to the 

energies of photons in the mid-infrared range; therefore, most molecules exhibit some 

degree of absorption in that spectral range. The probability of an absorption occurring in a 

bulk sample containing a large number of similar molecules depends on several factors 

besides the incident infrared photon energy, including (but not limited to) the number of 

absorbing molecules, the total gas pressure, the gas temperature, and the distance the photon 

is allowed to travel through the sample. 

The energy of a photon is proportional to its frequency; mathematically, the energy is given 

by E = h, where h is Planck’s constant and  is the frequency of the photon;  is related to 

the speed of light c and the photon wavelength () through the relation c = . In infrared 

spectroscopy, radiation is customarily described by its wavenumber (  ), defined by the 

relation    1 / ; when  is expressed in centimeters, the units of  are cm-1. These units, 

which are proportional to the frequency and to the energy of the photon, are used almost 

exclusively in the remainder of this document. The spectral range of interest, namely the 

mid-infrared region, is usually between 400–5000 cm-1. 

FTIR spectrometers rapidly provide accurate estimates to the total energy in an infrared 

beam at hundreds to tens of thousands of particular wavenumber values across the midinfrared region. These estimates are arranged in wavenumber order to form a “single beam 

spectrum” of the infrared power versus wavenumber. In extractive spectroscopy, two such 
19 

ISMI Technology Transfer #06124825B-ENG 

spectra are used to determine molecular concentrations. The first spectrum, recorded using a 

non-absorbing gas as the sample, is called the “background” spectrum; its value at the ith

wavenumber value is referred to here as Bi. The second, or “sample,” spectrum is recorded 

under the same conditions using the sample gas of interest; its value at the ith wavenumber 

value is referred to here as Si. It is the direct availability of the quantities Bi, measured under 

the same conditions as the quantities Si, which most clearly differentiates extractive FTIR 

spectroscopy from other types described in the literature (e.g., “remote” or “open path” 

FTIR spectroscopy). 

The “transmittance” spectrum of the sample, representing the fraction of the incident 

infrared power transmitted by the sample at each wavenumber value, is calculated point-bypoint from the sample and background single-beam spectra according to 

i

i

i B

S

T  Eq. [A-12] 

The “absorbance” of the sample at each wavenumber value (Ai) is calculated according to 

the definition 

i i A T 10  log . Eq. [A-13] 

The absorbance of the sample is the quantity of greatest interest in quantitative analyses 

because it is linearly related to the gaseous concentrations of the absorbing species. The 

following equation, often referred to as Beer’s Law, relates several FTIR experimental 

parameters to the concentrations in a gaseous mixture of compounds: 

 



M

j jiji LCaA1

, Eq. [A-14] 

where: i = an index labeling the wavenumber values represented in an FTIR spectrum 

 j = an index labeling the absorbing compounds in the mixture 

 M = the number of absorbing compounds in the mixture 

 aij = the absorptivity of the jth compound at the ith wavenumber value 

 L = the absorption pathlength (length of interaction of radiation and sample) 

 Cj = the volumetric concentration of the jth compound in the mixture 

Instrumentation and techniques for determining the quantities in Eq. [A-14] are found in the 

following three sections. A modern and more complete description of the molecular physics 

related to qualitative and quantitative molecular spectroscopy is found ref. [3]. 

 Spectroscopic Instrumentation 

Modern FTIR spectrometers are available from many manufacturers and in many 

configurations. However, most spectrometers for gas phase analysis consist of the several 

standard components. Broad-band, collimated IR radiation is produced in a glowbar or other 

thermal source and directed into an interferometer. The interferometer optically processes 

the infrared beam, which consists of radiation containing all wavenumbers (wavelengths) 

across the mid-infrared region. The interferometer contains at least one moving element; this 

motion is responsible for the amplitude modulation of the infrared radiation. The modulated 

IR beam is directed through one or more enclosed sample volumes such as a series 
20 

Technology Transfer #06124825B-ENG ISMI 

combination of a multiple-pass (white) sample cell and two single-pass sample cells. After 

interacting with the sample, the infrared beam exits the sample region and illuminates a 

square-law infrared detector. 

A computer records the detector response as a function of the position of the moving 

element. The resulting plot of the detector response (total infrared power) versus position 

(more accurately, the optical retardation) is referred to as an “interferogram.” Through 

appropriate mathematical manipulations and a fast Fourier transform (FFT), the same 

computer (effectively) digitally demodulates the interferogram, and the resulting singlebeam spectrum accurately represents the power in the beam versus wavenumber. Note that, 

as is characteristic of the Fourier transform, the independent variable in the original function 

(position, in units of cm) is the inverse of the independent variable in the transformed 

function (wavenumber, in units of cm-1). Two single beam spectra (recorded with and 

without the sample present in the cell) yield the absorbance of the sample in a 

straightforward calculation. 

Many operational parameters are available for the analyst to adjust and optimize the 

spectrometer system. Discussions of most of these parameters are beyond the scope of this 

work, but are available in ref. [4] and from many other sources. Of greatest importance to 

the current application are the choices of integration time, absorption pathlength, and 

spectral resolution. 

– Integration Time 

Under optimal conditions (i.e., when “white” noise in the detector limits the system 

performance), the signal-to-noise ratio (S/N) in a single beam spectrum is proportional 

to the square root of the time spent averaging the detector signal during collection of the 

interferogram, referred to here as the “integration time.” In typical systems, the 

integration time is proportional to the number of “scans” (results of a single motion of 

the interferometer’s moving element or individual spectrum) that are co-added to form a 

complete interferogram (spectrum). The time required for a single scan depends on 

details of the detector response speed and the chosen spectral resolution (see below), but 

is typically between 0.1 and 3.0 seconds. As long as the composition of the sample gas 

changes slowly on the time scale of a single scan, the result of an integration over 

multiple scans represents a time-average (over the integration time) of the sample 

composition. Because the generation of absorbance spectra requires two single beam 

spectra, it is important that the integration time used in collecting both the background 

and sample interferograms is suitably long; in practice, the background integration is 

usually carried out over at as many scans as the subsequent sample interferograms, so 

that the noise in the background spectrum is not dominant. 

– Absorption Pathlength 

As stated in Eq. [A-14], the absorbance of a given sample is proportional to the length 

(the “absorption pathlength”) over which the infrared beam is allowed to interact with 

the sample. If all other spectral properties are held constant, including the S/N, the 

lowest concentration of a single gaseous component at which its absorbance is 

detectable in the spectral noise is inversely proportional to the absorption pathlength. 

For samples containing multiple analytes over a large range of concentrations, a single 

absorption pathlength may not allow optimal measurement of all the components. In 

typical systems, the absorption pathlength cannot be quickly and easily varied. Rather 
21 

ISMI Technology Transfer #06124825B-ENG 

than changing the pathlength of a single absorption cell, the operator can direct the 

sample stream through one of three cells while the others are purged with a nonabsorbing gas. This allows a relatively rapid adjustment of the absorption pathlength, 

limited only by the rate at which the sample and purge gases can be replaced in each 

cell. 

– Minimum Instrumental Linewidth 

For a given set of operating parameters pertaining to the interferometer and FFT, an 

FTIR spectrometer exhibits a lower limit to the full width at half-maximum (FWHM) of 

absorption features in an absorbance spectrum. This lower limit is referred to as the 

“minimum instrumental linewidth” (MIL). Significantly lowering the MIL, or 

“improving the spectral resolution” of the system, is possible only by increasing the 

physical length over which a given interferometer’s moving element is displaced during 

a single scan. For a given interferometer, there is always an upper limit to this physical 

length and therefore a lower limit to the MIL. Careful consideration must be given to 

choosing an MIL for a given application, since decreasing the MIL introduces severe 

costs in both interferometer fragility and S/N achieved per integration time. It is 

generally accepted that 0.5 cm-1 is currently the lowest practical MIL value for gas 

phase spectroscopic field applications. However, if the spectrometer hardware allows 

both a larger MIL and optimization of the effective infrared source size (usually by 

adjusting an aperture or “Jacquinot stop” located somewhere in the beam path), the 

achievable S/N per integration time can be improved significantly.

 Sampling of Effluent Gases 

The direct availability of a background spectrum Bi, measured under the same conditions as 

the sample single beam spectrum Si, is an advantage of extractive spectroscopy. However, 

this advantage comes at the sometimes considerable cost of extracting a truly representative

sample. Interactions between the components of the gas and the sampling system can change 

the composition of some samples and lead to inaccurate results. The rate and temperature at 

which gas is extracted from the effluent source, relative to the volume of sample required for 

the analysis, must also be taken into account when the concentrations of the components 

change over time. 

The gas matrix of current interest consists mainly of compounds that do not react with the 

materials used in standard gas extraction systems and are stable over normal temperature 

regimes (25–185°C). However, because of the possibility of reactions between these and 

other, unanticipated sample constituents or with condensed water vapor, both suitable 

delivery efficiency and integrity of the sampling system should be considered for each 

sample matrix. 

Standard components of a gas sampling system suitable for this application consist of a 

stainless steel sample probe, Teflon sample lines, calibration gas source, and a pump. The 

pump attaches to the outlet of the infrared absorption cell; maintains a slight negative 

pressure throughout the absorption cell, sample lines, and probe; and provides a sample gas 

flow rate of suitable for the testing (commonly 1–20 lpm). With a calibrated MFC or meter, 

the operator can introduce known rates of both nitrogen-balance calibration and “spike” 

gases into the sample stream through the calibration line, which feeds into the probe through 

a standard “tee” fitting. This allows replacement of any desired fraction of the actual sample 
22 

Technology Transfer #06124825B-ENG ISMI 

flow with known concentrations of analytes or other compounds. Procedures for calibrating 

and dynamically spiking analytes into the sample stream are discussed in Appendix A.2.4. 

 Data Acquisition and Analysis 

Equation A.14 (Beer’s Law) represents the basis for nearly all quantitative analyses of midinfrared spectra recorded with a known absorption pathlength. The literature (e.g., refs. [4], 

[5], [6]) contains substantial discussion and comparison of several types of algorithms used 

to derive estimates of multi-component gas sample concentrations from a sample spectrum 

using libraries of reference spectra. These spectral libraries are also referred to as “training 

sets.” Examples of techniques described in the literature are the “P-matrix,” “K-matrix” 

(or “classical least squares”), “principal component regression,” and “partial least squares” 

algorithms. A simplified classical least squares analysis is described in Appendix A.2.8. 

Experienced analysts can also employ visual subtraction techniques to obtain accurate 

concentration data and uncertainties. 

In most cases, the choice of an appropriate technique for determining sample concentrations 

is a matter of both trial and error and of convenience. Important features of an acceptable 

method of spectral analysis include the following: 

1. Careful preparation of multiple reference spectra for each compound of interest, and 

characterization of the extent to which the quality of the reference spectral data may 

limit the overall accuracy and uncertainty from sample spectrum analyses. 

2. Generation of both concentration data and an estimate of the associated error or 

uncertainty in the determined values for each individual spectrum analyzed. 

3. Complete documentation of the processing of the acquired field data, at the level of 

detail allowing an independent analyst to reproduce quoted concentration results and 

uncertainties from the interferometric data. 

A.2.7 Mathematical Description of Beer’s Law 

Direct calculation of the probability of absorption for a particular molecular structure is complex, 

but can be characterized for a bulk sample and radiation at a particular wavenumber ( ) by the 

absorption coefficient   , defined through the relation 

































 zd

zPd

Po

1 )(

  Eq. [A-15] 

Here, the radiation travels in the z-direction, is incident on the sample with power PO at z = 0, 

and has power P(z) as a function of location along the z axis. If the sample includes a single 

molecule with non-zero absorption coefficient   , integration of Eq. [A-15] from z = 0 to z = L

leads to the following expression for the fraction of the incident power left in the incident 

radiation after the “absorption pathlength” (L), defined as the transmittance T : 

 



L

o

e

P

zP T  















 )( Eq. [A-16] 
23 

ISMI Technology Transfer #06124825B-ENG 

If two species (1 and 2) in the sample both absorb radiation at the wavenumber (  ), with 

absorption coefficients (1 and 2), the fraction of power transmitted after distance (L), can be 

seen from Eq. [A-16] to be 

     1 2 21    

       LL L eeeT Eq. [A-17] 

This relation represents the efficacy of measuring T for a sample containing a mixture of 

compounds, since contributions to the logarithm of T from the different compounds are 

additive. 

It can be shown from first principles3,4 that the quantities j in gaseous samples are proportional 

to the average concentrations (per unit volume) of the absorbing species, labeled here by the 

index j. By defining the “absorbance” at some discrete (i th) wavenumberthrough Ai = -log10Ti, 

the following simple relation for the absorbance of a mixture of M compounds with 

concentrations Cj can be written: 

 



M

j jiji LCaA

1

 Eq. [A-18] 

Here, the absorption coefficients for the jth compound at the ith wavenumber have been replaced 

by the “absorptivity” (aij), to which it is proportional. Eq. [A-18] is often referred to as the 

“Beer-Lambert Relation,” or simply as “Beer’s Law.” It is rigorously true for gas samples only 

when all its quantities are perfectly measured at a given sample (equilibrium) pressure, and when 

the effects of spontaneous emission are small enough to be neglected. 

A useful practical strategy, and one often used in conjunction with FTIR spectrometry, is to 

determine the absorptivities (aij) for single components at a large number of wavenumber values 

under well-characterized experimental conditions. Beer’s Law can then be used to determine the 

concentrations (Cj) for a gaseous mixture from the absorption pathlength L and the mixture’s 

observed absorbance (Ai). As described in Appendix A.2.3, FTIR spectrometers rapidly estimate 

several thousand values of Ai (at various wavenumber values), providing a statistically powerful 

means for determining a large number of gaseous concentrations from a single sample spectrum. 

A.2.8 Mathematical Description of a Least Squares Analysis 

Virtually all quantitative analyses of FTIR absorption spectra are based on Beer’s Law or some 

physically reasonable adaptation of Beer’s Law indicated by the pertinent experimental 

constraints. For convenience, this equation and the definitions of its quantities are restated here: 

 



M

j jij La

1

i A C , i = 1, 2,  N Eq. [A-19] 
24 

Technology Transfer #06124825B-ENG ISMI 

where: M = the number of compounds assumed to absorb in the spectral region analyzed (with

 index j) 

N = the number of infrared frequencies used in the analysis (with index i) 

Ai = the observed sample absorbance at the ith infrared frequency 

Cj = the (unknown) volumetric concentration of the jth component of the mixture 

L = the absorption path length used in recording the sample spectrum 

aij = the absorptivity of the jth compound at the ith infrared frequency 

Once the absorbance of a sample gas (Ai) and the absorptivities are determined, many 

mathematical techniques are suitable for an inversion of Eq. [A-19]. The technique described 

here is a simple least-squares analysis using a single reference spectrum for each component in 

the mixture. 

The following approach to estimating the quantities Cj in Eq. [A-19] is similar in most respects 

to one described in Refs. [5], [6], and [7]. The following treatment follows the notation of 

Ref. [8] and rewrites Beer’s law as 

 



M

j jijii

S

i A

1

 S++ + Eq. [A-20] 

where: The measurements of the sample absorbances (Ai

S

) are made at absolute temperature

 (T), absorption path length (L) (meters), and pressure (p) (atm) 

i  = the wavenumber value of the ith absorbance point 

i  = a linear baseline error in Beer’s Law for the selected (contiguous) data + 

 points 

εi = the non-baseline error in Beer’s Law at i

Sj = a “scaling factor” for the jth compound included in the analysis 

The quantity ij in Eq. [A-20] is defined as the “reduced absorptivity” of the jth compound at the 

frequency (i). For the purposes of the present calculation, it may be estimated by 

R

ij A 

R

jjj

j

ij CpL

T

  Eq. [A-21] 

where: Aij

R

 = the absorbance of a single reference spectrum of the (pure) jth compound, 

recorded with absorption path length (Lj) (meters) at absolute temperature (Tj) and pressure 

(pj)(atm), and concentration (Cj

R

) (ppmv). 

If Eq. [A-20] is used to form least squares estimates of , , and the scaling factors (Sj), denoted 

by  ,  , and S j , then the desired least squares estimates of the concentrations (Cj) are given 

by 

S jj Lp

T C  Eq. [A-22] 
25 

ISMI Technology Transfer #06124825B-ENG 

The least squares estimates,  , and Sj can be formulated from the linear model of Eq. [A-19] 

as follows (ref. [8]): form the “design matrix” D of with M+2 columns and N rows; each the first 

M columns of D corresponds to the jth compound, and consists of the N values ij. The (M+1)th

column consists of N entries of any non-zero constant, representing the constant baseline offset 

term (), the (M+2)th column consists of the N values i. If similar vector A is defined to 

represent the values Ai, X to represent the M+2 unknown quantities {S1, S2,... SM, , }, and E to 

represent the errors (εi), the linear model in Eq. [A-22] takes the form 

  EDXA Eq. [A-23] 

In the over-determined case of interest (N  M+2), assume the errors (εi) posses a joint 

distribution with zero means, and a variance-covariance matrix of the form 































 







2

11

2

1221 1

1221 11

2

1

NN N

NN

M f

 





 Eq. [A-24] 

Assume further that Mf is known only to within a scaling factor (

2

): 

f  2NM Eq. [A-25] 

Denoting the matrix transpose with the superscript “t” and the matrix inverse with superscript 

“-1,” the least squares estimate to the desired quantity X is given simply by 

  1-t ANDDND=X 1 1-t  Eq. [A-26] 

The matrix (N-1) is the “weight matrix.” In the simplest case where all the observed quantities Ai

have equal variances 

2

, N-1 is the identity matrix I, and Mf = 2I. 

Least squares estimates of several other important quantities are available from X , including the 

errors in the components of X itself, that is, the errors in the scaling factor estimates. Calculate 

the residual vector 

 XD-AV Eq. [A-27] 

which gives the point-by-point difference between the measured Ai

S

 and its least squares estimate 

according to the linear model; from V, the parameter moment matrix (MX) can be estimated 

according to 

  1 1-t

1-t

DND VNV M 

















  MN 3 X Eq. [A-28] 

and the uncertainty i in the parameter estimate Xi is given by 

  M X ii i Eq. [A-29] 
26 

Technology Transfer #06124825B-ENG ISMI 

The least squares estimates of the concentrations and the uncertainties in these estimates are 

obtained by combining Eq. [A-22], Eq. [A-26], and Eq. [A-29] for the appropriate elements of 

the set {S1, S2,... SM, , }. 

A.2.9 References 

[1] M.D. Tucker et al., S68 Final Report: Template Methodology and Lessons Learned for 

Sampling and Analyzing Tool Effluents, SEMATECH Technology Transfer #95123039ATR, 1995. 

[2] “Protocol for the Use of Extractive Fourier Transform Infrared (FTIR) Spectrometry for 

the Analyses of Gaseous Emissions From Stationary Sources,” U.S. EPA Emission 

Measurement Center, EPA-TTN EMC-FTIR Technology. 

[3] P. Bernath, Spectra of Atoms and Molecules, Oxford Press, New York, 1995. 

[4] P. Griffiths and J. de Haseth, Fourier Transform Infrared Spectroscopy, John Wiley and 

Sons, New York, 1986. 

[5] D.M. Haaland and R.G. Easterling, “Improved Sensitivity of Infrared Spectroscopy by the 

Application of Least Squares Methods,” Appl. Spectrosc. 34(5):539–548, 1980. 

[6] D.M. Haaland and R.G. Easterling, “Application of New Least-Squares Methods for the 

Quantitative Infrared Analysis of Multicomponent Samples,” Appl. Spectrosc. 36(6):665–

673, 1982. 

[7] D.M. Haaland, R.G. Easterling, and D.A. Vopicka, “Multivariate Least-Squares Methods 

Applied to the Quantitative Spectral Analysis of Multicomponent Samples,” Appl. 

Spectrosc. 39(1):73–84, 1985. 

[8] W.C. Hamilton, Statistics in Physical Science, Ronald Press Co., New York, Chapter 4, 

1964. 

A.2.10 Definitions of Symbols and Terms 

absorbance (A) – The logarithm to the base 10 of the reciprocal of the transmittance (T). 

T

T

A - = log 1 = log10 10 



 





absorption band – A contiguous wavenumber region of a spectrum (equivalently, a contiguous 

set of absorbance spectrum data points) in which the absorbance passes through a maximum or a 

series of maxima. 

absorption pathlength – In a spectrophotometer, the distance, measured in the direction of 

propagation of the beam of radiant energy, between the surface of the specimen on which the 

radiant energy is incident and the surface of the specimen from which it is emergent. 

apodization – Modification of the instrument line shape function (ILS) by multiplying the 

interferogram by a weighing function whose magnitude varies with retardation. 

background spectrum – The single beam spectrum obtained with all system components 

without sample present. 
27 

ISMI Technology Transfer #06124825B-ENG 

baseline – Any line drawn on an absorption spectrum to establish a reference point that 

represents a function of the radiant power incident on a sample at a given wavelength. 

Beer’s law – The direct proportionality of the absorbance of a sample to the concentrations of its 

constituent compounds (see Eq. [A-14]). 

calibration transfer standard (CTS) gas – A gas standard of a compound used to achieve 

and/or demonstrate suitable quantitative agreement between sample spectra and the reference 

spectral library. 

compound – A substance possessing a distinct, unique molecular structure. 

concentration (c) – The quantity of a compound contained in a unit quantity of sample. The unit 

“ppmv” (parts-per-million volume) employed in this document is equivalent under the 

assumption of ideal gases to the same quantity expressed on a number, or molar, basis. 

double beam spectrum – A transmission or absorbance spectrum derived by dividing the 

sample single beam spectrum by the background spectrum. 

Note: The term “double-beam” is used elsewhere to denote a spectrum in which the sample and 

background interferograms are collected simultaneously along physically distinct absorption 

paths. Here, the term denotes a spectrum in which the sample and background interferograms are 

collected at different times along the same absorption path. 

fast Fourier transform (FFT) – A method of accelerating the computation of a discrete FT by 

factoring the data into sparse matrices containing mostly zeros. 

Fourier transform (FT) – The mathematical process for converting an amplitude-time spectrum 

to an amplitude-frequency spectrum, or vice versa. 

Fourier transform infrared (FTIR) spectrometer – An analytical system that employs a 

source of mid-infrared radiation, an interferometer, an enclosed sample cell of known absorption 

pathlength, an infrared detector, optical elements that transfer infrared radiation between 

components, and a computer system. The time-domain detector response (interferogram) is 

processed by a Fourier transform to yield a representation of the detector response vs. infrared 

frequency. 

Note: When FTIR spectrometers are interfaced with other instruments, a slash should be used to 

denote the interface (e.g., GC/FTIR; HPCL/FTIR, and the use of FTIR should be explicit) 

(i.e., FTIR not IR). 

frequency (v) – The number of cycles per unit time. 

infrared – The portion of the electromagnetic spectrum containing wavelengths from ~0.78–

800 μm. 

interferogram (I()) – A record of the modulated component of the interference signal 

measured as a function of retardation by the detector. 

interferometer – A device that divides a beam of radiant energy into two or more paths, 

generates an optical path difference between the beams, and recombines them to produce 

repetitive interference maxima and minima as the optical retardation is varied. 

linewidth – The full width at half maximum of an absorption band in units of wavenumbers 

(cm-1). 
28 

Technology Transfer #06124825B-ENG ISMI 

minimum instrumental linewidth (MIL) – The minimum linewidth (observed in absorbance 

spectra) exhibited by the FTIR, in wavenumbers. 

Note: The MIL of a system can be determined by observing an absorption band known (through 

higher resolution examinations) to be narrower than indicated by the system. The MIL is 

fundamentally limited by the retardation of the interferometer, but is also affected by other 

operational parameters (e.g., the choice of apodization function). 

mid-infrared – The region of the electromagnetic spectrum from ~400–5000 cm-1. 

reference spectra – Absorption spectra of gases with known chemical compositions, recorded at 

a known absorption pathlength, that are used in the quantitative analysis of gas samples. 

retardation ( – Optical path difference between two beams in an interferometer; also known 

as “optical path difference” or “optical retardation.” 

scan – Digital representation of the detector output obtained during one complete motion of the 

interferometer's moving assembly or assemblies. 

single beam spectrum – Fourier-transformed interferogram, representing the detector response 

vs. wavenumber. 

Note: The term “single-beam” is used elsewhere to denote any spectrum in which the sample and 

background interferograms are recorded on the same physical absorption path; such usage 

differentiates such spectra from those generated using interferograms recorded along two 

physically distinct absorption paths (see “double-beam spectrum” above). Here, the term applies 

(for example) to the two spectra used directly in the calculation of transmission and absorbance 

spectra of a sample. 

TR – Absolute temperature of gases used in recording reference spectra. 

TS – Absolute temperature of sample gas as sample spectra are recorded. 

transmittance (T) – The ratio of radiant power transmitted by the sample to the radiant power 

incident on the sample. Estimated in FTIR spectroscopy by forming the ratio of the single-beam 

sample and background spectra. 

wavenumber (  ) – The number of waves per unit length. 

Note: The usual unit of wavenumber is the reciprocal centimeter, cm-1. The wavenumber is the 

reciprocal of the wavelength, , when  is expressed in centimeters. 

A.3 Modifications to QMS/FTIR Protocols to Quantify Corrosive Air Emissions 

The two technical protocols specifically address the quantification of PFC emissions. Several 

issues must be addressed for these protocols to effectively quantify corrosive air emissions: 

material compatibilities and passivation of the analytical system. The four main corrosive air 

emissions of interest are HF, HCl, Cl2, and F2, but are not limited to these compounds (e.g., HBr, 

NH3, etc., may be of interest). Due to the corrosiveness and reactivity of these compounds, 

special precautions must be taken to ensure the quality of the emissions data. For material 

compatibility, all of the parts of the analytical equipment (i.e., sample lines, roughing, and turbo 

pumps, exhaust lines, etc.) must be compatible with these four gases. It is recommended that 

stainless steel and ceramic parts be used whenever possible and that Teflon and Viton parts be 

minimized. For passivation, these gases should be run through the analytical system until a stable 

signal is achieved (i.e., the system is “passivated”). This can be done by either running the 
29 

ISMI Technology Transfer #06124825B-ENG 

corrosive compounds through the system without running wafers (if the compounds are used in 

the process) or by running wafers through the system until the signals are stable (if the 

compounds are byproducts). 

Furthermore, all parts of the instrumentation in contact with these compounds should be heated 

to 

1. Drive out any water from the system 

2. Limit the reactivity of the corrosive compounds with the analytical system 

It should not be assumed that if the system is passivated with one of the compounds that it is 

passivated with the other three compounds. Passivation times can range from 15 minutes to 

2 hours depending on the condition/length of the sample lines, temperature of the sample lines, 

and nature of the compound. In general, the passivation time of the analytical system is longest 

for HF and shortest for Cl2. During emissions testing, extreme care must be taken to ensure that 

the temperature of the heated sample lines is the same during the calibration steps as it is during 

the wafer processing steps. 

In addition, the chemistry between process gases and byproducts may play a role in employing 

the proper sampling system, one that minimizes compound conversion or loss before being 

analyzed. Examples include process emissions associated with silicon-based depositions using 

silane (SiH4) or tetraethyl orthosilicate (TEOS). Significant amounts of silicon oxide particulates 

and aerosols are typically produced, which could coat the FTIR optics and/or QMS 

filaments/lenses and lead to biasing of quantitative values. Proper filtering as close to the point of 

sample extraction as possible and at temperatures above dew points becomes especially 

important. 

A.4 Fluorine Chemiluminescence (FC) Protocol: Standard Quantitative Analytical 

Method for Measuring Gaseous Molecular Fluorine 

This analytical technique and measurement procedure was developed specifically to allow 

accurate, real-time emissions monitoring of molecular fluorine (F2), a compound that cannot be 

measured by FTIR (F2 does not absorb mid-IR radiation) and is problematic for QMS (F2 is quite 

reactive and corrosive in nature, especially when combined with moisture, which leads to 

significant filament degradation and calibration drift). The FC measurement mechanism entails 

the calibrated response to light emitted from a substance that chemically interacts upon exposure 

to F2. The FC measurement system should be designed to respond to varying F2 concentrations in 

a fast (response times within seconds, or better) and sensitive (sub-ppmv detection limits) 

fashion. If a field calibration that brackets observed concentration levels is not possible because 

precisely known gas standards are not practical or obtainable, then pre- and post-field test 

calibrations under laboratory conditions are recommended. If interferants are in the sampled gas 

streams, whether they lead to false positive signals or artificially suppress/augment the calibrated 

FC signals, they must be identified and characterized. 
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A.4.1 Theory and Practice of Chemiluminescence 

Chemiluminescence is produced when a chemical reaction yields an electronically excited 

species, which emits light as it returns to its ground state. A simple type of chemiluminescent 

reaction is 

A + B → C* + D 

C* → C + h

where C* represents the excited state of a species. The instrumentation for chemiluminescence 

measurements is quite simple and may consist primarily of a reaction vessel and a 

photomultiplier tube. No wavelength separation, or modulation, device is necessary (as in FTIR) 

because the only source of radiation is the chemical reaction between the analyte and reagent. In 

most cases, the relationship between signal and concentration is linear over a concentration range 

of several orders of magnitude, thus offering a wide dynamic range. For F2 sensing, materials 

have been developed that produce a nearly instantaneous reaction (providing real-time 

response to F2) that is highly sensitive (providing F2 detection limits below 10 ppbv). The 

“substrate” materials for chemiluminescence sensors vary greatly in composition and can take 

gaseous, liquid, or solid forms. The example FC material described in this protocol is an organic 

substrate mixed as a slurry and deposited on a surface as hydrophobic paste. 

A.4.2 General Design and Use 

The FC measurement system requires a design that enables reproducible and calibrated 

measurements of very low levels of emitted radiation. System portability and a simple means to 

introduce gas streams into the chemiluminescence reaction chamber are also recommended. An 

example of a fully integrated FC system is pictured in Figure A-8. It can be operated as a 

standalone device since the detector signal (the system houses an integrated photon-counting 

module) is digitally handled by a microprocessor and interfaced to a multi-function keypad and 

LCD display. The system can also be remotely driven by laptop using Ethernet or RS232 and 

some pre-developed software applications. For instance, real-time data trending and archival are 

done through a LabView-based application, and system calibration plus curve fitting is 

automated through a C++-based utility. A relay contact has been integrated to allow the user to 

change process states based on pre-defined alarm thresholds. Additional analog data outputs are 

available as 4–20 mA or 0–10 V, as well. 

Of critical importance is that the FC system maintains the integrity of the gas matrix being 

sampled; no interactions of F2 with the system upstream of the chemiluminescence substrate 

material are acceptable. In the system described above, the actual chemiluminescence sensing 

module is a compact nickel-coated steel monoblock gas delivery system mated to the photoncounter (the integrated PMT). The 3-D drawing in Figure A-9 depicts the module’s design. The 

monoblock contains an internal Venturi pump to extract gas sample flow and a gas-substrate 

contact area near a sapphire window (behind which sits the PMT). A substrate paste has been 

deposited on a nickel-coated aluminum surface that allows a continuous and uniform interaction 

flow. The “top-hat” shaped substrate holder can be serviced, as needed, without disassembling 

any other part that makes up the system. 
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ISMI Technology Transfer #06124825B-ENG 

Note: The gas fittings and pressure transducer are 

attached and shown on the right-hand side. 

Figure A-8 Fully Integrated FC System 

Housed in a Small Container 

(11”  10”  5”, 5 lbs.) 

Figure A-9 FC System Monoblock 

A.4.3 Sequence of Operation and Monitoring Procedures 

The following sequence is recommended when monitoring sample or calibration gas streams 

with an FC system. Although these steps are specifically for the FC system described above, they 

would accurately apply to other FC methods after modifications: 

1. Attach tubing of appropriate material (PFA Teflon, stainless steel, or monel) to the gas 

fitting at the exhaust port of the FC system. The exhaust line should always be vented to 

an appropriate abatement or exhaust system to avoid any human exposure to residual 

fluorine. 

2. Attach a high pressure line from the gas fitting at the Venturi pump port on the FC 

system to a compressed dry air (CDA) or N2 source capable of delivering up to 1 scfm 

through the system’s Venturi pump. Add a shut-off valve and high pressure gauge 

(capable of reading 30–100 psig) to easily control sample flow and shut-off or 

activation of the pump. 

3. Attach a length of tubing of appropriate material (PFA Teflon, stainless steel, or monel) 

to the gas fitting at the inlet port on the FC system. Attach the other end to the source to 

be sampled. The FC system is now ready for continuous monitoring. 

4. Power the FC system and allow its PMT (or other light detection device) to thermally 

stabilize. The dark current (# of photon counts per second) decreases and stabilizes to an 

average baseline value on the order of 500 cts/sec, or less. This “warm up” time is 

typically 10–15 minutes. 

5. After warm up, activate the Venturi pump to begin a sample draw through the inlet port 

(and the chemiluminescence chamber). 
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6. The FC system is usually initially factory-calibrated, but most systems can be (and 

should be) recalibrated at any time. It is strongly recommended that a system calibration 

check be performed immediately before and directly after field testing. The calibration 

check should entail exposing the FC chamber to F2 gas standards at three concentration 

levels: at a low, mid, and high level relative to the expected (or observed) F2 field 

concentrations. Should the calibration check points not agree to within ±30% per point 

with the pre-set calibration curve, a more thorough PMT response to F2 concentration 

curve is in order. Rest the FC system calibration before field testing or appropriately 

adjust field data (if possible) if the post-test calibration check reveals a well behaved 

calibration drift. Therefore, it is advantageous to perform F2 calibration checks while 

on-site. Since this is not always feasible, however, a laboratory gas mixing/delivery 

system (or simply a set of gas standards in cylinders) can be used. 

A.4.4 Sampling and Maintenance Considerations 

The following points should be well understood when sampling with the FC system. These will 

help ensure accurate and reproducible results throughout the lifetime of each chemiluminescence 

substrate. Again, some of these points apply specifically to the FC system described in 

Appendix A.4.2, but must be considered when using other FC methods, as well. 

 O2 Signal Suppression 

Consideration must be taken when the FC system is sampling an air source versus a 

predominantly nitrogen (or some other inert gas, such as argon) stream. The presence of 

oxygen in the sample stream interacts with the substrate surface and will partially quench 

the chemiluminescence. Given the geometry of FC chamber (see Appendix A.4.2), the 

amount of PMT signal suppression has been experimentally characterized to be on the order 

of 65% for any given F2 concentration in dry air (containing 21% O2) vs. the same 

concentration in nitrogen. Because the suppression factor decreases linearly with % O2, and 

has been found to be reproducible and well defined under field conditions, a correction 

factor is included in the system software utility to account for it. Enter the percentage of O2

known to be in the sample stream (e.g., for sampling ambient air, enter 21) before field data 

collection. Alternatively, if field testing is known to entail the monitoring of only ambient 

air exhaust streams, the FC system can be calibrated with zero air gas mixtures. Then, no 

correction factor is necessary. 

 Substrate Aging 

The substrate, consisting of an organic salt in the example FC system described in 

Appendix A.4.2, is known to age over extended periods (many months or years). To 

maintain the substrate’s life, it is recommended that the sensor be purged with a dry gas, like 

house N2, then capped off before extended storage. 

 Protecting the Light Detector 

Never expose the PMT to intense light sources, such as room light, with its power on. The 

PMT is an extremely sensitive light measuring device; intense sources, producing signals 

greater than 30 million cts/sec, will damage its performance. Therefore, do not open the FC 

chamber without shutting down the power to the system beforehand. High concentrations of 

F2, even those exceeding 200,000 ppmv, are known to be safe to the PMT since their signals 

still do not reach the 30 MHz threshold.
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 Cross Interferences 

Very few signals generated by cross interference compounds have been observed from the 

FC system described in Appendix A.4.2. Commonly encountered pollutants, such as HF, 

SiF4, SiH4, NF3, HCl, Cl2, PFCs, VOCs, NOx, SOx, N2O, and O2, do not register a response 

from the system. The only potentially interfering compound seen to date has been OF2, 

which appeared to produce a signal of intensity equivalent to 3% of a F2 signal of similar 

concentration. This is still being investigated, however, because it was unknown whether the 

small signal was due to OF2 or a F2 byproduct in the OF2 gas standard. 

 FC Substrate Lifetime

If the chemiluminescence reaction for a given FC system is known to be irreversible 

(i.e., the substrate material does not regenerate after contact with F2), then the substrate 

within the FC chamber will have a finite lifetime, thus requiring periodic recalibration 

and/or replacement. The FC system described in Appendix A.4.2 still maintains a 

measurable response to F2 beyond 775,000 ppmv  min of exposure, but needs recalibration 

at that point, after which the calibration drift becomes more substantial. Other FC systems 

will require substrate replacement/recalibration at different time intervals. 

A.4.5 Examples of Field Data and Analysis 

The FC method is an excellent complementary measurement tool to FTIR or QMS, as shown in 

Figure A-10. The field data shown below involve the abatement of CVD chamber clean 

compounds and byproducts as a function of water scrubbing and steam injection. As with the 

FTIR (Figure A-10a), the FC system provides real-time emissions profiling (Figure A-10b) at the 

ppmv levels exhibited in this particular exhaust system. 
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a) 

b) 

Note: The color legend corresponding to compound trace in the upper left-hand corner of each plot. Y-axes are in 

ppm, X-axes in time-of-day. Generic abatement conditions are also noted. 

Figure A-10 Example of a) Exhaust Emissions from a CVD Chamber Clean Process 

Chamber Clean Compounds and Byproducts and b) F2 Byproduct 
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Appendix B – Protocol for Characterization of Point-of-Use Abatement Devices 

B.1 Point-of-Use (POU) Abatement Protocol 

Depending on the specific characteristics of the gas stream analyzed, the sampling technique can 

be as important as the analytical instrument used. In many cases, traditional sampling methods 

fail and custom designed techniques are needed to minimize analyte loss or distorted results. The 

following are some techniques used to characterize specific, problematic tool effluent streams. 

They will serve as the first of a compilation of different, application-specific analytical sampling 

methods used to characterize semiconductor processing effluent streams. As additional methods 

are reviewed and qualified, they will be added to this document. 

B.1.1 Representative Sampling 

Collecting gas samples from pipes, especially those with laminar flow characteristics, requires 

special attention. Sampling from a fitting bored into a pipe can result in wall effects that cause 

false or inaccurate results. This is especially true when sampling the outlet of wet scrubbers as 

moisture tends to condensate on the inner walls of exhaust pipes; disproportionate levels of 

moisture and dissolved gases are drawn into analyzers leading to incorrect gas phase 

composition characterization. One way to minimize these effects is to introduce a probe bent at 

90 to collect samples concentrically and concurrent with respect to the direction of the gas flow 

from the center of the pipe (see Figure B-1). 

3-Way Valve

3-Way Valve

3-Way Valve

Filter 1 Filter 2

To FTIR

N2

From

Sampling 

Port

Exhaust Duct

Figure B-1 Sampling Setup to Minimize Particle Clogging 
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B.1.2 Acid Gas Analyses 

This can include measurement of acid gases at the exhaust of a metal etch tool (BCl3, HCl, and 

Cl2) using a QMS or FTIR and in water vapor saturated conditions (HF, HCl, F2, Cl2 after a 

water scrubber) using FTIR spectrometers, QMS, and/or fluorine chemiluminescence. In acid gas 

sampling and analysis, materials compatibility can be a dominant concern. The two main 

materials used for sampling are heated stainless steel and Teflon. The disadvantage with heated 

stainless steel is limited flexibility and evidence of reactions between Cl2 and F2 with the walls of 

the sampling lines when water is present. The disadvantage with Teflon lines is evidence of an 

interaction of HF and F2 with Teflon. Ensure that the choice of sampling lines does not affect the 

accuracy or reproducibility of the emissions measurements. In extreme wet conditions, it is 

recommended that an inline permeation dryer (e.g., PERMA-PURE) be considered, which can 

eliminate 90% of the moisture in the gas stream. Studies of analyzer responses (QMS and FTIR 

spectroscopy) with and without the dryer in line have shown no analyte was lost in the water 

removal process (i.e., the dryer is selective and does not remove any acids). This technique 

proved effective for measuring the acid gases at the outlets of wet scrubbers, and for 

characterizing SiF4 and HF emissions during a wet HF clean of an atmospheric pressure CVD 

tool. Note, however, that before implementing any of these sample conditioning techniques, a 

specific effluent stream needs to be thoroughly tested. For instance, further tests have determined 

that some polar organic compounds, ammonia, and TEOS permeate out of the dryer. 

B.1.3 Sequentially Varied Effluent Streams 

In performing mixed effluent characterization studies, it is helpful to install three-way valves at 

the sampling ports. One end is connected to the tool exhaust duct, the other is connected to 

purging dry nitrogen, and the common port is directed to the analyzer. This setup allows either 

the purging nitrogen or sample stream to be transferred to the FTIR, QMS, or fluorine 

chemiluminescence analyzer. Dry nitrogen is used to collect background or baseline spectra or to 

clean the lines and spectrometer between runs. Whenever the port is remote or inaccessible, the 

three-way valve can include a pneumatic actuator to switch between the sample or nitrogen 

stream collection. This can be useful when characterizing varied exhaust streams (e.g., 

measurements inside an ion implanter processing arsine, phosphine, boron trifluoride, and silicon 

tetrafluoride). 

B.1.4 Solid Particulates Clogging 

Many processes in the semiconductor industry release solid particulates. For example, silane and 

TEOS often generate silicon dioxide (SiO2), TEB and diborane generate boric oxide (B2O3), and 

TEPO and phosphine generate phosphorus pentoxide (P2O5). These solids not only hinder 

material balance calculations but can also obstruct sampling lines, analytical tools, and sampling 

valves. To allow continuous analysis, a sampling system has been designed to minimize particle 

(e.g., SiO2) interference with the analysis. This system has been shown to be very effective in 

characterizing the tool effluent composition and concentration of species released during 

APCVD TEOS/ozone process. The setup (see Figure B-1) includes a 1⁄4-inch Teflon-lined 

stainless steel probe bent at 90 to collect samples concentrically and concurrent with respect to 

the direction of the gas flow. Interference from solid particles is further minimized using a filter 

setup (2 μm pore size). Solid particulates within the gas stream are removed by filter #1 before 

entering the analyzer. When filter #1 becomes saturated with solids, two pneumatically actuated 

three-way valves direct the sample stream to filter #2, allowing the replacement of the clogged 
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filter. This setup can result in trouble-free analysis of particulate-laden streams throughout an 

extended testing period. 

B.1.5 POU Abatement Device Dilution Factor Determination 

This section provides methodologies for determining the POU abatement device inlet and outlet 

total volume flows to calculate the dilution factor. The total process volume flow into the POU 

abatement device can be done by accurately flowing a process gas like NF3 with tool process 

power off, and then measuring the concentration (usually with FTIR) at outlet of pump (inlet to 

POU abatement device). It is important that the location for determining this total volume 

process flow is the same as the location for sampling the process effluent. 

Once the total volume flow for all POU abatement device inlets is known, the POU abatement 

device total outlet (exhaust) volume flow needs to be determined. Three methods can be used: 

1. Using inert gas through POU abatement device 

2. Using a gas at POU abatement device outlet 

3. Using a gas through POU abatement device with a known 0% DRE 

 Using Inert Gas Through POU Abatement Device 

This methodology is to accurately flow an inert gas (e.g., Ar, Kr, Xe) that is not used in the 

process into the process tool effluent and to measure the POU abatement device outlet 

concentration for that specie (usually by QMS). Care must be taken to subtract out any of these 

inert gases that are in the air (e.g., argon) supplied to the POU abatement device. Furthermore, 

the inert gas must not also be supplied as a process gas. The background for the inert gas to be 

used in the POU abatement device inlet and outlet sampling locations must be measured. The 

outlet concentration measurement point for determining total outlet volume flow must be the 

same as the POU abatement device exhaust sampling location. 

 Using a Gas at POU Abatement Device Outlet 

Another methodology is to accurately flow a non-reactive gas (e.g., CF4) into the POU 

abatement device outlet and measure the concentration downstream (usually by FTIR). The 

following criteria must be fulfilled when using this methodology: 

1. The POU abatement device outlet must be sampled to ensure that the non-reactive gas is 

not present. 

2. The non-reactive gas must be injected across the POU abatement device outlet duct. 

This can be done using an injection probe with equally spaced holes. 

3. The location selected for downstream non-reactive gas analysis must be at least eight 

duct diameters downstream from the non-reactive gas injection location. 

4. The location selected for downstream non-reactive gas sampling must also be used for 

POU abatement device outlet sampling. This will ensure that any dilution from POU 

abatement device outlet to this sampling location will be accounted for. 

5. The downstream non-reactive gas analysis location duct should be traversed with the 

sampling probe at a few locations to ensure the non-reactive gas is well mixed. For 

example, if the duct is 10 centimeters, the duct can be traversed in 2 centimeter 

increments to prove that the concentration across the duct is uniform. 
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 Using a Gas Through POU Abatement Device with a Known 0% DRE 

Another possible methodology is to accurately flow a process gas (e.g., CF4) that has 0% 

destruction and removal efficiency (DRE) through the POU abatement device and measure 

(usually by FTIR) the outlet concentration. It is critical to document there is a 0% DRE for the 

process gas being used and no CF4 in the gas stream from other sources (e.g., CF4 is not 

generated as a byproduct in POU abatement device). The outlet concentration measurement point 

for determining total outlet volume flow must be the same as the POU abatement device exhaust 

sampling location. 

The calculation for POU abatement device dilution factor is as follows: 

Dilution Factor = (total POU abatement device outlet flow/total POU abatement device inlet 

flow) 

For example, if the total POU abatement device inlet volume flow is 400 slm and total outlet 

volume flow is 4,000 slm, the dilution factor is 10. 

Using dilution factor, % DRE would be calculated as follows: 

% DRE = {[inlet ppmv – (outlet ppmv  dilution factor)]/(inlet ppmv)}  100% 

Caution is required for the concentration measurement and this DRE calculation when there is 

more than one POU abatement device inlet. 

The POU abatement device inlet flow(s) and total outlet flow can be used to calculate mass rates 

into and out of POU abatement device. In this case, DRE can be calculated as follows: 

% DRE = [(total mass in – total mass out)/(total mass in)]  100% 

The total mass in can be calculated by summing all mass rates from all POU abatement device 

inlets. 
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Appendix C – Standard Methods for Liquid and Solid Waste Sampling and Analysis 

Standard methods for liquid and solid waste sampling should be used whenever determining data 

for mass balances. Personnel should use standard methods as prescribed by local or national 

regulatory agencies, credible standards development organization, etc., for the country where 

these sampling and analytical efforts are being performed. 


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