### Accelerating Sustainable Manufacturing

Copyright ©2010 Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMAT ECH , and the SEMATECH logo are registered servicemarks of SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners. 

# ISMI/SIA Stack Testing Technical Presentation

ISMI/SIA Stack Test Sub

- team November 30, 2011

# Contents

• Proposal & Key Supporting Information



### • Supplemental Information: Summary of Stack Testing:

– Company Z: March vs. August 2011, and minute by minute for 2 gases

– Company A: 5 consecutive days and a Fab over a 10 year time scale

– Company Y: 1 day each at 3 stacks



### – Company B: 1 day each at 3 stacks

• EPA Feedback on Proposal

2 November 30, 2011

# Summary of the Proposed Stack Test Method

• Submit initial test plans, prepared in accordance with EPA Guideline GD

- 042, one month prior to start of testing to regulatory agencies .

– Advance notice provides agencies the opportunity to witness testing and/or split sample.

• Validate the analytical method using EPA Method 320 or alternate validation method.

• Identify fab stacks that exhaust GHG emissions above threshold quantities

• Measure total gas flow rate of stack on the test day using EPA Method 1 or 2.

• Measure designated process GHG emissions from relevant stacks.

• Sample stack for a period of 8 hours.



## • Sample each stack sequentially.

• Document test results using GD

- 043.

3 November 30, 2011

# Summary of the Proposed Stack Test Method

– continued

• Measure gas usage on day of stack testing.

• For each gas determine emission factor (EF) by correlating emissions to gas usage.

• Adjust EF for gases that fall below detection limits due to small quantity 

## usage by process.

• Adjust EF for gases not used in process, but formed as by

- products and detected.

• Determine annual usage of each gas from inventory or purchase 

## records.

• Calculate annual emissions for each GHG by multiplying EF by annual gas usage.

• Track abatement units downtime and adjust annual emissions of each 

## gas accordingly.

• Report annual emissions.

4 November 30, 2011

# F

- gas Emissions Can be Accurately Measured and are Consistent Over Time

• Method 320 validation performed at Company Z and Company Y.

• Detection limits are adequate to detect compounds at relevant emissions levels.

• Stack testing at multiple fabs demonstrates tight Confidence Intervals (CI) on emission concentrations.

• Stack flow rates are constant over the test period.

• Data indicates an 8

- hour sampling period is appropriate.

5 November 30, 2011

# Detection Limits Adequate to Detect GHGs at Relevant Emissions Levels

Results from stack test at Company Y using FTIR

6 

# Conclusion : Detection limits are more than sufficient to accurately measure relevant quantities of GHG emissions

November 30, 2011

# Detection Limits

Conclusion : Influence of detection limits on fab emissions during this 

## test are insignificant.

Example:

• 3 ppbv CF4

• 45,000 cfm

 DL= 3MTCO2e/yr 3 3

12 88

28 144 33 26 MDL, ppb Delta, mtCO2e

15 1212 14 2180 5 474 1 294 26 0 4421

7 MTCO2e/year



### From 2011 Company A Stack Testing

November 30, 2011

# Measured Emissions Are Constant Over Test Period

• At the 95% confidence interval, the difference between the 

# upper and lower concentrations over the duration of the test is quite small; this shows that fab emissions are very constant over time.

• Stack flow, as shown on the next chart, is also constant.

8 November 30, 2011 Material Company A Stack1

(5 days, Aug 2011) Company Y Stack A

(1 day, Oct 2011) Company B

(1 day, May 2011) Company Z Stack 1

(1 day, Aug 2011) CF4 89.8

– 93.0 81.6

- 91.4 120.0

- 132.6 181.3

- 193.3 CHF3 43.9

– 44.4 3.2

- 3.9 46.2

- 49.9 35.4

- 38.3 CH2F2 <28 NA NA ND CH3F <35 NA NA NA C2F6 3.1

– 3.6 3.4

- 3.6 9.8

- 10.4 3.7

- 4.4 C4F8 24.6

– 25.2 5.4

- 5.8 11.9

- 12.7 nd NF3 28.0

– 31.6 6.5

- 9.0 8.6

- 13.3 208.2

- 247.8 SF6 34.4

– 35.8 17.2

- 20.2 3.5

- 5.0 7.0

- 9.5 N2O 3,576

– 3,681 2,537

- 2,886 639

- 1,058 9,644

- 10,754 Upper and lower 95 % CI in ppbv

# Stack Flow Rates are Consistent over Time

9 

### Measured flow rate over 4

- 5 days during 2011 Company A stack testing.



## • 

# Flow only varies by a few percent.

November 30, 201160 64 68 72 76 80

8/1/2011 0:00 8/2/2011 0:00 8/3/2011 0:00 Fan Speed (%) Acid Fan 1 Fan Speed (%) Acid Fan 2 Fan Speed (%) Acid Fan 3 Fan Speed (%) Acid Fan 5 Fan Speed (%) Acid Fan 6 Fan Speed (%) Acid Fan 7

0.00 1.00 2.00 3.00 4.00 5.00

8/1/2011 0:00 8/2/2011 0:00 8/3/2011 0:00 System Header Exhaust Pressure (psig) 

# Exhaust Fan Speed is Constant During Stack Test

• Exhaust flow rate and pressure are very tightly controlled to 

# maintain process control.

• During stack test, fan speed and exhaust pressure were constant.

• Supports testing 

# stacks sequentially.

10 

### From 2011 Company Z Stack Testing

– Fab 1.

10 November 30, 2011

# F

- Gas Emissions Are Correlated to F

- Gas Usage

• Correlations demonstrated over multiple time scales from minutes to years.

• Data demonstrates testing for 8 hours is 

# representative of fab emissions.

• Historical data demonstrates annual stack testing can be used to accurately estimate annual emissions.

11 November 30, 2011

# The Relation Between Gas Usage and 

# Emissions has been Evaluated over Multiple Time Scales

9 consecutive years Correlations Consistent Mar vs. Aug 2011

5 consecutive days

– 24 hour period • Consistent emission factors have 

### been demonstrated at several different time scales

– all data shows good correlation.

.

12 November 30, 2011

# Emissions Track Gas Usage
(15 min. Data Points)

• Unique opportunity at Company Z to track CF4 pressure drop (a high use F



### gas) over short intervals.

• Data demonstrates that usage and emissions are correlated over short time intervals.

13 November 30, 2011 CF4: Mar 2011, Stack S1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0 10 20 30 40 50 60 70 80 90 100 Time (qtr hour increments) CF4 emissions

0.0 0.5 1.0 1.5 2.0 2.5 3.0 CF4 usage (gas P delta)

CF4_FTIR PressDelta

### • Top chart shows measured CF4 stack emissions and recorded CF4 usage (normalized) from 2001 thru 2010.

• Lower chart shows plot of measured CF4 emissions vs. recorded CF4 usage from 2001 thru 

### 2010; data shows a high degree of correlation (R2=0.94).

• Over the period from 2001 thru 2010, Company A fab transitioned from the 180 nm to 45 nm 

### technology node which required several process conversions.

 Emissions as a function of gas usage is very linear.  The relation is robust through multiple technology nodes. 

# Relationship Between Use and Emissions is 

# Steady Over Time

14 November 30, 2011 Company A : Normalized CF4 use, and CF4 emissions

0.0 0.2 0.4 0.6 0.8 1.0 1.2

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 CF4 emissions (lb/hr)

0.0 0.5 1.0 1.5 2.0 2.5 Normalized CF4 use

Normalized CF4 usage CF4 emissions (lb/hr)

## Relationship Between Use and Emissions is Steady Over Time

• Top chart shows measured SF 6 

### stack emissions vs recorded SF 6 

### usage (normalized) from 2003 thru 2011; it shows a high degree of 

### correlation (R 2 

### =0.89).

• Lower chart shows the same for years 2004 thru 2011; during these years the site had no SF6 abatement. Data shows a higher degree of correlation (R 2 

### =0.94).

• With consistent levels of abatement correlation improves.

• Change in number of abatement devices is a key variable to track.

 Historical testing demonstrates that stack testing can be used to accurately estimate annual 

### emissions. SF6 2003

- 2011

SF6 2004

- 2011 Emissions, lbs./hr

Emissions, lbs./hr

15 SF6 Usage (Normalized)

SF6 Usage (Normalized)

November 30, 2011

# 8

- Hour Sample is Representative

Company A tested each stack for 5 days (120 hours). Emissions calculated using 8 hr. of data per stack to develop average lbs./hr. emissions Conclusion: 8 hrs. of testing per stack is representative ; results very similar to 120 hr. averages MTCO2e/yr.

16 

### From 2011 

### Company A Stack Testing

November 30, 2011

# 8

- Hour Sample is Representative

17 • CF4 emissions measured continuously over 24

- hour period in 300mm stack

• The mean CF4 conc. is 167 ppbv , with upper and lower 95 % CI of 162

– 172 ppbv

• The 8

- hour running average ranged between 144 and 186 ppbv

 An 8

- hour sample time yields substantially the same result as a 24

- hour sample time. From 2011 Company Z Stack Testing

November 30, 2011

# Use of Stack Emission Factors to Determine Annual Emissions

• Conduct stack test to measure the emissions rate of each gas (i) over the test period

• Measure the total average gas usage rate over the corresponding period

• Calculate Fab specific emissions factors

Example: A) Measure the CF4 emission rate and gas usage rate to determine an emission factor (EF) for the Fab: 

### 0.5 (kg/day) of CF 4 

### emission @ Stack1, 0.3 (kg/day) @ Stack 2, 0.2 (kg/day) @ Stack 3 4.0 (kg/day) of CF 4 

### used across the fab, over the corresponding period

B) Compute the annual CF 4 

### emissions: Total annual CF 4 

### usage = 400 (kg)

18 November 30, 2011

# Stack Testing Frequency

Changes in POU abatement and F

- gas use as a percentage of total are parameters which will result in emissions changes and should trigger re

testing. Proposal :

• 

## Fabs which use the stack test option will test major F

- gas emitting stacks in the first year.

• Thereafter, testing in the subsequent year is required whenever:

– The weight % makeup of an individual F

- gas changes by more than 10 percentage points from one year to the next year, or

– If the fraction of abated tools decreases by greater than 10 %.



## • If no significant changes occur, the EF determined from the initial testing may be used for 5 years.

• As a minimum, stacks would be re

- tested every 5 years.

19 November 30, 2011

# Re

- Testing Upon Major Process Change as 

# Signaled by Change in Gas Mix

• The Company A site transitioned from both 200 and 300 mm wafer processing to strictly 300mm processing in 2008 with switch from remaining C2F6 chamber cleans to NF3

• The production change is clearly signaled by the NF3 and C2F6 wt %

– The CF4 emission vs. gas use correlation remained unchanged by the production line change

– The C2F6 emission vs. use correlation was good until the change

– The SF6 emission vs. use correlation was affected by the change in abatement, not the production line change 

###  Conclusion : Changes in the wt. % and abatement provide a clear indicator of the need to retest stacks and determine emission factors

20 % of Total F

- Gas Usage by Year for Company A Site
F

- Gas 2003 2004 2005 2006 2007 2008 2009 2010 NF3 44 51 45 45 54 85 79 82 SF6 5 7 7 5 5 5 3 2 CF4 14 12 9 8 6 1 9 8 CH2F2 0 0 1 0 1 1 0 1 CHF3 1 1 1 1 1 0 3 3 C2F6 33 19 23 29 26 0 0 0 C4F6 0 0 0 0 0 1 1 0 C4F8 1 2 4 3 2 6 5 4 C4F8O 2 8 10 8 5 0 0 0

November 30, 2011

# Minimum Threshold Quantities

At what emission level can stack emissions be calculated rather than
measured?

• Proposal:

– Ensure coverage of the vast majority of process gas emissions (e.g., all process GHG stacks with emissions in excess of 10,000 MT CO2e/year or 15% of total emissions ).

– Develop options for reasonable engineering estimates for the emissions of stacks not tested

• Example :

– The site shown below has 14 stacks from which F

- GHG are emitted.

– The total GHG emissions are 20,739 (MTCO2e/yr.)

– Under the above proposal, stack testing would be performed on 10 of 14 stacks.

21 November 30, 2011

# Analytical Methods for Subpart I

Proposal:

• Measure stack process GHG concentrations using EPA Method 320 for FTIR, or any other method that is capable of detecting the analytes of interest at the concentrations of interest; which has been validated using EPA Method 301 or an alternate scientifically sound validation protocol.

– Allow use of quality assured analytical methods for all analyses required by Subpart I.



### • Measure stack flow rates using EPA Method 1 or 2. Similar flexibility provisions are contained in Subpart L :

“ Analytical methods. Use a quality assured analytical measurement technology capable of detecting the analyte of interest at the concentration of interest and use a sampling and analytical procedure validated with the analyte of interest at the concentration of interest.
Where calibration standards for the analyte are not available, a chemically similar surrogate may be used. Acceptable analytical measurement technologies include but are not limited to gas chromatography (GC) with an appropriate detector, infrared (IR), fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR). Acceptable methods for determining fluorinated GHGs include EPA Method 18 in appendix A

– 1 of 40 CFR part 60, EPA Method 320 in appendix A of 40 CFR part 63, EPA 430

– R

– 10

– 003 (incorporated by reference, see § 98.7), ASTM D6348

– 03 (incorporated by reference, see § 98.7), or other analytical methods validated using EPA Method 301 at 40 CFR part 63, appendix A or some other scientifically sound validation protocol .”

22 November 30, 2011

# Key Takeaways

• SIA is proposing a stack testing model as an alternative method under Subpart I



### – Stack testing is a well

- accepted method for quantifying emissions

• Testing and data collected by SIA companies demonstrates:

– Established methods can accurately measure process GHG emissions at semiconductor fabs

.



### – Emissions from one 8 hour test period are representative of emissions at the fab over an extended period of time.

– Results of testing combined with chemical use can be scaled to estimate annual emissions.

• The data and analysis developed by ISMI/SIA establishes a solid foundation for future action by EPA

– Testing was conducted at multiple 200 mm and 300 mm fabs which manufacture a variety of semiconductor devices.

– Stack testing provides a direct measure of a fab’s emissions.



### • Numerous benefits of the SIA proposal

– both to EPA and the industry

– Improved accuracy over current methods, minimizes cost and CBI concerns, potential for expeditious resolution of this matter.

23 November 30, 2011