Accelerating Sustainable Manufacturing

Copyright ©2010 

Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH, and the SEMATECH logo are registered servicemarks of 

SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners.

SIA Alternative to RecipeSpecific Testing

Laurie Beu

Consultant to ISMI

Michael Haslam

Predictum, Consultant to ISMI

August 11, 2011
Contents

• Disclaimer

• Introduction

• F-Gas Usage and 

Emissions

• Data Overview

• Distribution by Process

• Parameters

• Summary of Model 

Effects

• Individual Fits

• Observations

• Emission Factors

• Probability Distributions

• Emissions Factors

• Data Set Coverage vs. 

Industry Gas Usage

• Recommendations

August 11, 2011 2
Disclaimer

• Disclaimer of Liability 

– This presentation has been prepared upon request using preliminary survey results and is subject to change

without notice at the authors’ discretion for reasons including, without limitation, receipt of additional information

and continued analysis of survey results.

– The authors’ and presenters’ intent is to report survey findings and to provide non-partisan analysis to the

intended audience. This presentation is not intended to constitute lobbying, and shall not be interpreted as

lobbying.

– This information is provided "as is". The authors, contributors and presenters of this information disclaim any

and all loss or liability, incurred either directly or indirectly as a consequence of applying or using the information

presented herein. Neither ISMI, nor SIA, nor any of their members, employees or officers, makes any warranty,

express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness

of any information disclosed or discussed herein.

– The estimates, assessments, analyses, views and opinions of document authors and contributors and the

presenters, whether expressed herein or expressed orally during the presentation and related meetings, do not

necessarily state or reflect those of any individual entity or company, including, without limitation, ISMI, the SIA

or any of their member companies.

• Disclaimer of Forward-looking Statements

– Portions of this presentation contain forward-looking statements that are based on the authors’ and contributors’

current expectations, estimates, projections and assumptions. These statements are based on assessment of

uncertain factors and therefore are not guarantees of future events and outcomes. Actual future results may

differ materially from what is forecast. All forward-looking statements speak only as of the date of this

presentation.

– All related written and oral forward-looking statements attributable to the authors, presenters, ISMI, SIA or any

person acting on behalf of those entities are qualified by the cautionary statements in this section.

– The authors, contributors and presenters do not undertake any obligation to update or publicly release any

revisions to forward-looking statements to reflect events, circumstances or changes in expectations after the

date

August 11, 2011 3
4

Key Takeaways

• Data Analysis Indicates that there are two suitable Models to estimate etch 

default emissions factors:

- Wafer diameter, input gas

- Wafer diameter, input gas, film

- Either model avoids the technical feasibility and intellectual property issues associated with the 

Current Subpart I Rule.

• The Etch Default Emissions Factors Adequately Represent the Emissions 

Factor for the Overall Process.

• The Data Set is Sufficiently Robust to Provide Representative Emissions 

Factors For the Gas/Wafer Size and Gas/Wafer Size/Film Models.

– Large Data Sets for Most Primary Gas and Gas/Film Categories

– Gas Emissions Factors can be Used to Augment Gas/Film Categories with no or limited data.

– Large data set representing varied equipment data with good spread of the data over the factors: 

significant improvement over NODA .

• Method Comparisons Need to Be Completed to Inform Conclusions Requiring 

the Preferred Model & Approach:

– Precision and Accuracy Comparison

• Emission Factor Uncertainty

• Apportioning Method Uncertainty

– Sensitivity Analysis of Chosen Categories

– Evaluate the Relative cost and performance benefits of the various models

August 11, 2011
Roadmap

• Etch Emissions in Context

• Process and Definitions

• Data Overview

• Analysis: Models

• Emissions Factors

• Conclusions

August 11, 2011 5
Etch F-Gas Usage in Context

• Compiled data from 2009 ISMI Survey.

• For both 200 mm and 300 mm fabs, CVD chamber 

cleans account for the largest share of F-gas usage.

6

In-situ CVD

(% Total)

Remote CVD 

(% Total)

Thermal

(% Total)

All Chamber Cleans 

(% Total)

200 mm 

(5-150 mm Fabs; 12-

200mm Fabs)

5 3 2 2 0 7 5 23 2

300 mm 

(12 Fabs) 2 5 4 1 0 6 6 33 1

All Fabs 3 7 3 3 0 7 0 29 1

2009 Relative Process F-Gas Usage for 29 U.S. Fabs

Etch

(% Total)

Wafer Cleaning

(% Total)

Chamber Cleans

August 11, 2011
Etch F-gas Emissions in Context

• Industry switch to lower emitting NF3 chamber cleans results in significantly reduced 300 

mm chamber clean emissions.

• CVD chamber cleans are 61% of emissions. 

– EPA allows lower cost compliance using default emission factors.

– 61% of emissions are calculated with same method for both non-large and large fabs and have same precision 

and accuracy.

• Etch is 39% of emissions.

– Subpart I requires costly recipe specific testing; no default emission factors for large facilities.

– This amounts to 0.00312% of U.S. GHGs emissions.

7

Default emission factors applied to 2009 ISMI Survey use data; assumes no abatement.

MTCO2e % All Fabs MTCO2e % All Fabs MTCO2e % Etch

200 mm 

(5-150 mm Fabs; 12-

200mm Fabs)

1006086 5 5 730,218 4 0 271,605 1 5

300 mm 

(12 Fabs) 818,967 4 5 376,163 2 1 430,105 2 4

All Fabs 1825053 100 1,106,380 6 1 701,710 3 9

 * Includes wafer clean process emissions.

Total Emissions* Using Default EF Etch Emissions Using Default EF

2009 Estimated Emissions

Chamber Clean Emissions Using 

Default EF

August 11, 2011
2009 Etch F-gas Usage and 

Emissions in Context

• ISMI 2009 survey had 17 responses from 200mm fabs 

and 12 responses from 300mm fabs.

• F-gas usage in etch is ~29% of total industry usage; CVD 

is the major use in both 200mm fabs and in 300mm fabs.

• Industry efforts to develop lower emitting technologies 

such as NF3 based cleans result in lower chamber clean 

emissions from 300 mm fabs.

• Using Tier 2c default emission factors, etch accounts for 

39% of total F-gas emissions.

– 15% of total industry emissions from 200mm etch; 

– 24% of total industry emissions from 300mm etch.

August 11, 2011 8
9

Process for Developing Etch 

Alternative

• Device manufacturers and etch equipment suppliers were asked to provide 

etch emissions characterization data. Data was input into an Excel 

spreadsheet format.

• Data was compiled and analyzed by Predictum, consultant to ISMI.

• ISMI provided sanitized emissions data to EPA on 10-Aug-2011.

• Refined etch emissions categories and defaults have been developed.

1. Wafer size, input gas

2. Wafer size, principal film, input gas

• Next Steps to be completed by 30-Sep-2011:

– Compare relative errors for IPCC Tier 2b, EPA Tier 2c, Refined etch defaults and Tier 3 etch 

emissions data. 

– Validate refined defaults with precision and accuracy analysis of Tier 2b, 2c, Refined, and Tier 

3 Methods.

– Perform sensitivity analysis of etch emissions based on Refined defaults.

• Compare methodologies from other industry sectors.
Definitions

• Etch Step: Step where a pattern is being etched in a product wafer.

• Non-etch Step: Step run on an etch tool that do not involve etching a patterned wafer. 

Non-etch processing include aging / cleaning / dummy wafers / conditioning / seasoning 

/ dry clean season. Non-etch processing typically occurs infrequently (several times per 

25 wafer lot); whereas etch processing occurs on all 25 wafers in a lot.

• Data set: Measured F-gas emissions factors for a specific input F-gas and associated Fgas byproduct(s). 

• Data point: Each measured emission factor whether for input gas or byproducts. 

• Tier 2c Emission Factors: Default factors listed in Tables I-3 and I-4 of Subpart I.

• Refined Emission Factors: Default factors developed using ISMI 2011 data set.

• Principal film type: The principal film being etched from a patterned wafer, i.e., oxide, 

nitride, silicon or metal.

August 11, 2011 10
Data Overview

• Total Data Sets

– 890 data sets from etch tools and recipe steps.

– Non-etch data sets not included in analysis.

• Input Gas Emission Factor is analyzed vs. 13 possible input 

parameters in this set of data.

• Etch steps are used in the primary analysis.

– 655 Data Sets are etch steps. 

– 235 are for steps in the etch recipe that do not involve etching a patterned 

wafer. 

• Parameters are initially removed based on initial single factor models 

or correlations to other parameters.

• This data set has been transmitted to EPA.

August 11, 2011 11
12

Generic Etch Chamber Gas Flow Illustration

Source: Texas Instruments Inc.

Patterned wafer etch

Etching process involves multiple process types that are difficult to 

separate. 

August 11, 2011
1. Wafer Diameter

2. Power

3. Pressure

4. Flowrate

5. Multiple Gases (Y/N)

6. Stabilization (Y/N)

7. Ratio of Stabilization to Etch 

Time

8. Principal Film Type

9. Feature Type

10.Film Stack (Y/N)

11.Measurement Protocol

12.Process Type (Etch, Non-Etch)

13.Input Gas Name

Analyzed Parameter Set

Little to no data received for these parameters.

August 11, 2011 13
Distribution by Etch Step

• Non-wafer etch step will be discussed in later 

slide.

August 11, 2011 14
Parameters with No Effect

Parameter Notes

Feature Type Missing Data

Multiple Gases No difference

Flowrate No difference

Ratio of Stabilization to Etch

Time

Missing Data

Film Stack Missing Data, No difference

Measurement Protocol Appeared correlated with other 

factors

Stabilization 97% have stabilization

August 11, 2011 15
Parameters with Effect

Parameter Notes

Wafer Diameter 59% is 200mm data

Power 0.2 to 5100 W

Input Gas 11 input gases

Principal Film Type 4 Types

Pressure 0 to 2000 mTorr

Process 2 Types – analyzed separately

August 11, 2011 16
Summary of Models – Etch 

Data sets

Model Parameter(s) Model RSquare

Input Gas 55%

Principal Film Type 5%

Power 18%

Pressure 4%

Wafer Diameter 12%

Wafer Diameter, Input Gas 57%

Wafer Diameter, Input Gas,

Principal Film Type

60%

Wafer Diameter, Input Gas, Power 59%

August 11, 2011 17
Explanation of Fit Y by X plots

• The diamonds show the mean and confidence 

intervals of the fits.

August 11, 2011 18
Wafer Diameter

• 300mm emission factors are significantly lower 

than 200mm.

August 11, 2011 19
Input Gas

• Input gas is the major factor.

• Note: Newer etch chemistries with lower emissions factors 

and lower GWP.

August 11, 2011 20
Principal Film Type

• No difference between Nitride and Oxide.

• Metal and Silicon show a statistical difference.

August 11, 2011 21
Power

• Note low points above 2000W as well as several grouping clusters.

• Data is stratified by gas type and only improves upon a gas type model 

by 1-2% while adding significant complexity.

August 11, 2011 22
Observations

• Input Gas is the single factor with the most effect.

• Other parameters have a small cumulative effect when layered in with 

input gas.

– Wafer diameter has a small effect.

– Principal Film Type has a small effect.

– Power has an effect driven by grouping clusters, typically of gas type, and is 

of limited value in the models.

• F-gases are utilized more efficiently in newer etch processes.

– Wafer diameter is a significant effect, with 300mm emissions being 

lower.

• Pressures above 250 mTorr are almost exclusively in 200 mm.

August 11, 2011 23
Emission Factors – Etch – 200 & 300 mm, 

Input Gas (2 Factors)

• Note major statistically significant reductions for 

CF4, SF6 and CHF3in 300 mm vs. 200 mm.

August 11, 2011 24
Distribution Fit with 80th Percentile 

Using the previous two factor model, can probability 

distributions be fit to the individual categories?

August 11, 2011 25
Distribution Fits

• As with real data, various spikes, clumps and 

clusters will be seen in the distributions.

• There is no one distribution that best fits the 

various categories.

• Decision: Use both mean and 80th percentile of 

the actual data for calculation of potential 

emission factors.

August 11, 2011 26
Emission Factors – Etch – 200 mm,

Film type, Gas (3 factors)

• 3 factor model.

August 11, 2011 27
Emission Factors – Etch – 300 mm, 

Film type, Gas (3 factors)

• 3 factor model.

August 11, 2011 28
Emission Factors – Wafer 

Size, Gas, Film (3 factors)

• 3 factor model.

August 11, 2011 29
Emission Model Summary

• 2 Factor model (Gas, Wafer Size) has 18 

categories and gives a 57% R2.

• 3 Factor model (Gas, Wafer Size, Film) has 39 

categories and gives 60% R2; much more complex 

and impacts only the etch portion of industry’s Fgas emissions estimate.

• Any potential end benefit of a small model 

improvement comes at:

– Higher cost.

– Increased uncertainty due to apportioning.

August 11, 2011 30
31

Generic Etch Chamber Gas Flow Illustration

Source: Texas Instruments Inc.

Patterned wafer etch

Etching process involves multiple process types that are difficult to separate. 

August 11, 2011
Emission Factors – Process Steps 

(Etch vs. Non-etch)

• Non-etch steps typically occur infrequently (several times per 25 wafer lot).

• Only SF6 in 200 mm shows a statistical difference from Etch to Non-Etch Process 

Types. 

• Addition of non-etch data does not materially impact emissions estimate.

August 11, 2011 32
Non-etch Data Conclusions

• Non-etch steps typically represent a small 

percentage of the overall etch process.

• Utilizing the etch emission factors developed from 

the etch data adequately represents the emissions 

from the overall process (etch and non-etch). 

August 11, 2011 33
GAS/WAFER SIZE Default 

Emission Factors (2 factor model)

• Quantile 80 is from actual data points.

• Note that 80% quantile is more conservative than the mean.

August 11, 2011 34
35

SIA Conclusions

• Data Analysis Indicates that there are two suitable Models to estimate etch default 

emissions factors:

- Wafer diameter, input gas

- Wafer diameter, input gas, film

- Either model avoids the technical feasibility and intellectual property issues associated with the Current Subpart I 

Rule.

• The Etch Default Emissions Factors Adequately Represent the Emissions Factor for the 

Overall Process.

– No Significant Statistical Difference in Etch and non-Etch Factors

– Where Differences exist, the Etch Emissions Factor is Typically More Conservative.

• The Data Set is Sufficiently Robust to Provide Representative Emissions Factors For the 

Gas/Wafer Size and Gas/Wafer Size/Film Models.

– Large Data Sets for Most Primary Gas and Gas/Film Categories

– Gas Emissions Factors can be Used to Augment Gas/Film Categories with no or limited data.

– Large data set representing varied equipment data with good spread of the data over the factors: significant 

improvement over NODA .

• Method Comparisons Need to Be Completed to Inform Conclusions Requiring the 

Preferred Model & Approach:

– Precision and Accuracy Comparison

• Emission Factor Uncertainty

• Apportioning Method Uncertainty

– Sensitivity Analysis of Chosen Categories

– Evaluate the Relative cost and performance benefits of the various models

August 11, 2011
36

Next Steps

• Need to calculate byproduct EF for these models.

• 9 Facilities will Allocate Gas Use to Gas Type and Gas Type/Film 

Type categories.

– 2009 and 2010 data. 

– Each Facility will describe allocation process.

• Statistically Compare Refined Methods against other Options:

– Gas Categories: Mean and 80th Percentile Default Emissions Factor

– Gas/Film Categories: Mean and 80th Percentile

– Sensitivity Analysis of Default Factors:

• Overall and Etch Emissions Estimate

• EPA Assesses the ISMI Data set.

August 11, 2011 36
Accelerating Sustainable Manufacturing

Copyright ©2010 

Advanced Materials Research Center, AMRC, International SEMATECH Manufacturing Initiative, and ISMI are servicemarks of SEMATECH, and the SEMATECH logo are registered servicemarks of 

SEMATECH, Inc. All other servicemarks and trademarks are the property of their respective owners.

Appendix – Supplemental Data
38

Transferred Data:

• Redacted parameters:

– Tool Manufacturer (redacted in SEMI data set)

– Tool Model Number (redacted in SEMI data set)

– RF generator frequency (correlated to RF generator type and tool 

model number)

– RF generator type (correlated to RF frequency and tool model)

• Conveyed to EPA (little/no data received; meaningful 

correlations cannot be made):

– Ratio of stabilization to etch time (No data)

– Feature type (Missing data)

– Film stack (Missing data) 

August 11, 2011
39

Transferred Data:

• Although not statistically significant, conveyed for transparency:

– Input Gas Flowrate

– Are multiple gases used? (Y/N)

– Includes stabilization time? (Y/N)

• Conveyed (correlations exists or parameter is required to estimate emissions 

or to demonstrate validity of data set):

– Wafer diameter

– Input gas identity

– Input gas emission factor

– Byproduct identity

– Byproduct emission factor

– Principle film type

– Measurement Protocol Used

– Etch Step? (Y/N)

– Other? (Please identify)

– Power

– Pressure

August 11, 2011
Emission Factors – Process

August 11, 2011 40
GAS/WAFER SIZE Emission 

Factors by Process

Quantile 80 is from actual data points

August 11, 2011 41
GAS/WAFER SIZE Emission 

Factors by process type

Quantile 80 is from actual data points.

80 quantile is more conservative.

August 11, 2011 42