# Presentation: 502979

## Projecting PFC Emissions Using EPA’s PFC Emissions Vintage Model   

**Projecting PFC Emissions Using EPA’s PFC Emissions Vintage Model   **

- Presented at
- 9th Annual ISESH Conference
- June 9 – 13, 2002
- San Diego, CA

-     **C. Shepherd Burton*****	****Scott Bartos**
**    ****Consultant****	****	****	****U. S. Environmental**
**    ****2047 Huckleberry Rd.****	****Protection Agency**
**    ****San Rafael, CA****	****            1200 Pennsylvania Ave.**
**	****	****	****	****Washington, DC****	**

## Outline

- Introduction
- Some considerations
- PEVM: Formulation and structure
- Results: 2010 Projections ...
- Key Uncertainties, limitations and caveats
- Summary of findings

**Notes:**
Both long and short-term exposure to high levels of PM2.5 can cause health problems.  

## Introduction

- Semiconductor manufacturing: At threshold of low to zero emissions future
- Path to threshold well documented
- Recognition of environmental risks of PFC emissions
- Broad industry cooperation
- International government-industry cooperation
- Challenge ahead: Achieving aggressive WSC reduction goal by 2010
- What to do?
- Our aim: Contribute to collective sense of what can be done using emissions modeling

**Notes:**
Both long and short-term exposure to high levels of PM2.5 can cause health problems.  

## Some Considerations

**Some Considerations**

- IPCC vs. PEVM: Bottoms-up and top-down methods
- Are PFC emissions correlated with Si consumption?
- Si demand: Historical and projected patterns
- Trends in complexity and effect of copper on interconnects on emissions

## IPCC vs. PEVM: Bottoms-up and top-down methods

**IPCC estimation method**
- Bottoms-up: Company inventories
- Q(MMTCE) = usage x (1 – UF) x (1 – DE)
- Tiered: Rigor varies
- Arguably impractical for projecting industry emissions

**Si - consumption method**
- Top-down: Not now used
*<*Q(MMTCE)> = Si x *gas-process EF*
- “Global” EF to be developed
- Partner reports and public information
- Arguably practical for projecting PFC emissions

## Partner Reported ‘99 MMTCE’s vs. MSI Si-Layers (2000 WFW SEMI)(Values not shown to preserve Partner confidentiality)

## Correlating Partner PFC Emissions Totals (MMTCE) and MSI Silicon x Nominal Number of Layers

| PFC Emissions,
Year Reported | MSI-Si,
Year WFW Published | r2  |
| --- | --- | --- |
| 1997 | 1998 | 0.976 |
| 1998 | 2000 | 0.972 |
| 1999 | 2000 | 0.991 |

## Historical and Projected Si Demand by Linewidth, 1988 - 2010

## Process Complexity Trend

## Reducing metal layers by switching from Al to Cu: How many?

## Model Formulation, Structure and Operationalization

- Formulation
- Structure, sources of information and operationalization
- Comparison of emissions** **factors

## PEVM: Formulation and Structure

- <*PFC Emissions*(y)> ≡  gas-process avg. PFC emissions in year, y
- <*PFC Emissions*(y)> ≡ Ē(y) x S(y)
- Definition of Ē(y), an emissions factor for _*uncontrolled*_ emissions, MMTCE per unit _*area*_ of Si consumed
- <*PFC Emissions*(y)>, from Partner emission reports
- S(y),from SEMI WFW database and VLSI Research, Inc. world Si consumption figures
- Result: Estimate of Ē(y), does NOT account for complexity

## PEVM Formulation and Structure: Accounting for “Complexity”

- <*PFC Emissions*(y)> = Ē(y) S(y)
- 		= Σi λi(y) si(y) ē(y)
- 			 λi(y) = nominal no. of layers for technology node
- 			 i and year y (from ITRS);
- 			 si(y) = Si consumed (from VLSI Res., Inc.) for 			 node i
- 			 ē(y) = avg. gas-process emissions per unit of area
- 			 of Si consumed per _*average *_layer
- ē(y) = Ē(y)/<λ(y)>; <λ(y)> = (1/ S(y)) Σi λi(y) si(y)
- Result: Est. of gas-process average _*uncontrolled*_ emission factor** **

## PEVM Formulation and Structure:Integrating Concept and Mathematics

- <*PFC Emissions*(y)>* *≡ Ē(y) x S(y)
**	****	****	**= Σi λi(y) si(y) ē(y)
- 			= Σi <*PFC Emissions*(y)>i
- Result: Project _*uncontrolled gas-process average*_* *(BAU) emissions using <ē> = Avg(ē(y)) and projected si(y) and λi(y)** **

## Schematic of EPA’s PFC Vintage Model (v.2.14) for Projecting US PFC Emissions from Semiconductor Manufacturing

**Sources & Types of Information**

**Method for Estimating PFC-Process Average Emission Factors**

**Projecting Si Demand to 2010**

**Projecting Emissions**

**Partners**

**SEMI**

**VLSI Research, Inc.**

**ITRS**

**Industry Reports**

**Annual PFC Emissions Totals, ’95-’99**

**World Fab Watch databases: ownership, location, capacity, geometry, etc. ’95-’99**

**World Si Demand, wafer size, in****2**** , ‘83-’05          **

**World Si Demand, device type,      ’83-’05**

**World Si Demand, linewidth, in****2****,      ’83-’05**

**Specs & outlook for industry**

**Test wafers full processed, Cu effect on layers, industry capacity utilization, etc.**

**Partner PFC-Process      average emission factors    (MMTCE/in****2 ****Si)                  1995, ’96, ’97, ’98 & ‘99 **

**Partner per-average-layer emission factors (MMTCE/in****2****Si*layer)      1995, ’96, ’97, ’98, ‘99**

**Linewidth-specific emission factors (MMTCE/in****2**** Si), Avg. ’95-’99**

**Adj. for full- process test wafers**

**Avg. number of layers/node**

**U. S. Si demand by linewidth, in****2 ****Si, 1988 - 2010**

**World Si demand (in****2****) by linewidth, 1988 - 2010**

**Analysis: Adoption/decay profiles for future technology nodes**

**World CAGR for Si demand, 1988 - 2005**

**U. S. PFC emissions by linewidth 1988 – 2010 MMTCE**

**World PFC emissions by linewidth 1988- 2005 MMTCE**

**U. S. share of world layer-weighted capacity, %,       1995 - 2000**

**Effect of Cu interconnect on number of wiring levels (layers)**

**Compare calc. Partner avg. utilization with available world reports.**

**Schematic of EPA’s PFC Vintage Model (v.2.14) for Projecting US PFC Emissions from Semiconductor Manufacturing**

## Avg. PFC-Process Emission Factors: Formation of Ē(y) , ē(y) and <ē> 

| Emission Factors | 1995 | 1996 | 1997 | 1998 | 1999 |
| --- | --- | --- | --- | --- | --- |
| Ē(y), MMTCE/billion in2 Si | 2.49 | 1.93 | 2.10 | 2.42 | 2.67 |
| ē(y), MMTCE/BSI Si-layer | 0.79 | 0.58 | 0.57 | 0.62 | 0.64 |

## Some Results: Application of PEVM

- Projected U. S. emissions: without and with Cu
- Comparison of PEVM and IPCC-like Method** **

## Projected PEVM PFC U. S. Emissions: With Cu, No Reduction Technology

## Projected PEVM PFC U. S. Emissions: Without Cu, No Reduction Technology

## Comparing PEVM and IPCC-like Method

- IPCC-like Method: Extrap. DataQuest ’90 – ’96 survey figures
- ~18 MMTCEs cf. 15 and 16 MMTCEs PEVM with and without Cu, respectively
- CAGR: 20%, ’95 – ’10 period, IPCC-like
- Partnership CAGR: 13%, ’95 – ’99 period

## Key Assumptions, Uncertainties and Limitations

- Emission factors: *reflect process-gas average*
- Silicon projections: changes by wafer size and technology generation; metal layers across markets (MPUs, memory, logic, etc.)
- Disaggregating *avg. process-gas,* node-specific emissions factors, <ē>λi(y): formation of *process/gas-specific* emission factors
- Reduction cases: Selecting technology DEs and penetration rates for alternative control strategies
- Estimating U. S. share of world emissions

## Findings

- Avg.emissions per unit of Si consumed per average layer appears a robust concept
- BAU projections: PEVM PFC emissions estimates compare favorably with bottoms-up IPCC-like method
- BAU 2010 projections with Cu: PEVM gives ~8 times corresponding 1995 emissions
- PFC reduction technologies: On average >90% DE implemented at 200 mm and 300 mm fabs