### Reduction of Perfluorocompound (PFC) Emissions: 2005 State-ofthe-Technology Report

International SEMATECH Manufacturing Initiative Technology Transfer #05104693A-ENG© 2005 International SEMATECH Manufacturing Initiative, Inc. SEMATECH and the SEMATECH logo are registered service marks of SEMATECH, Inc. International SEMATECH Manufacturing Initiative and the International SEMATECH Manufacturing Initiative logo are registered service marks of International SEMATECH Manufacturing Initiative, Inc., a whollyowned subsidiary of SEMATECH, Inc. Product names and company names used in this publication are for identification purposes only and may be trademarks or service marks of their respective companies.

### Reduction of Perfluor ocompound (PFC) Emissions: 2005 State-of-theTechnology Report Technology Transfer #05104693A-ENG International SEMATECH Manufacturing Initiative December 2, 2005

Abstract: technology development and implementation and describes the semiconductor industry’s efforts to reduction processes and technology obtained from a survey of members of the International SEMATECH Manufacturing Initiative (ISMI); the Semi conductor Industry Association (SIA); the World Semiconductor Council (WSC); and chemical, tool, and abatement device suppliers. The appendix includes details about process optimi zations, alternative processes, and abatement technologies.

Keywords: Emissions Reduction, Perfluorocompounds, Po llution Control Equipment, Global Climate Change, Chamber Cleaning, Process Optimization

Authors : Laurie S. Beu Consulting, Austin, TX

Approvals: Walter Worth, Project Manager Ron Remke, Program Manager Scott Kramer, Director Laurie Modrey, Technology Transfer Team Leader reduce PFC emissions. It documents pre-compet itive information about potential PFC emission This report from the ESHI002M project reviews the current state perfluorocompound (PFC)iii

ISMI Technology Transfer #05104693A-ENG Table of Contents

1 EXECUTIVE SUMMARY .....................................................................................................1 2 INTRODUCTION...................................................................................................................2 3 BACKGROUND..................................................................................................................... 2 4 EMISSIONS REDUCTION TE CHNOLOGY DEVELOPMENT .........................................3 4.1 Process Optimization/Alternative Processing.................................................................3 4.2 Alternative Processing: Remote Clean ...........................................................................4 4.3 Remote Clean Byproduct ESH Concerns .......................................................................4 4.4 Alternative Chemistry .....................................................................................................5 4.4.1 Chamber Clean: ≤ 150 mm and Older 200 mm Process Tools............................5 4.4.2 Chamber Clean: Advanced 200 mm and 300 mm ..............................................6 4.4.3 Chamber Clean: Research and Development......................................................6 4.4.4 Plasma Etch.........................................................................................................7 4.5 Capture/Recovery........................................................................................................... .7 4.6 Abatement .................................................................................................................. .....8 5 INDUSTRY APPLICATION OF EMISSION REDUCTION OPTIONS...............................9 6 IMPACT OF INDUSTRY CHANGES ON EMISSIONS.....................................................10 6.1 Chamber Cleans ............................................................................................................1 0 6.2 Etch ....................................................................................................................... ........11 6.3 Future Technologies That May Impact PFC Emissions ...............................................11 6.4 Changes in Wafer Size..................................................................................................12 7 SIA PROGRESS TOWARDS 10% EM ISSIONS REDUCTION GOAL.............................14 8 PROJECTED WSC EMISSIONS .........................................................................................14 9 DISCUSSION AND ANALYSIS..........................................................................................15 9.1 Applicability of Technologies.......................................................................................15 9.2 Process Optimization/Alternative Processing...............................................................16 9.3 Alternative Chemistries.................................................................................................16 9.4 Capture/Recovery..........................................................................................................1 6 9.5 Abatement .................................................................................................................. ...16 9.6 Impact of New Process Technology .............................................................................17 10 CONCLUSIONS ...................................................................................................................1 8 11 REFERENCES......................................................................................................................18 APPENDIX A – Process Optimiza tion/Alternative Processing.....................................................21 A.1 Process Optimization ....................................................................................................21 A.2 Endpoint Detection........................................................................................................2 2 A.3 Remote Plasma Cleans..................................................................................................23 A.4 Alternative Chemistry ...................................................................................................25 A.4.1 Chamber Clean Alternatives .............................................................................26 A.4.2 Alternative Etch Chemistries ............................................................................34 A.5 Capture/Recovery..........................................................................................................3 6 A.5.1 Air Liquide PFC Ca pture and Recycle..............................................................36 A.6 Abatement .................................................................................................................. ...36 A.6.1 PFC Abatement – POU Fueled Burner – Scrubber Units.................................36iv

Technology Transfer #05104693A-ENG ISMI A.6.2 PFC Abatement – POU Catalytic–Scrubber Units............................................48 A.6.3 PFC Abatement – POU Electrically Heated Thermal – Scrubber Units...........54 A.6.4 PFC Abatement – POU Atmospheric Plasma Units .........................................59 A.6.5 PFC Abatement – POU Foreline Plasma Units ................................................65 A.6.6 PFC Abatement – Centralized Atmospheric Plasma Unit ................................69

List of Figures

Figure 1 Wafer Demand Over Time (1995–2010)..................................................................13 Figure 2 WSC Production Normalized PFC Emissions Over Time .......................................13 Figure 3 Annual SIA PFC Partner Emissions.........................................................................14 Figure 4 WSC Indexed PFC Emissions – Actual and Projected ............................................15

List of Tables
Table 1 Implemented Alternativ e Chamber Clean Chemistries..............................................5 Table 2 PFC Abatement Technologies ....................................................................................8 Table 3 PFC Emissions Reduction Options ............................................................................9v

ISMI Technology Transfer #05104693A-ENG Acknowledgments The author would like to thank and acknowle dge the following for their contributions: Olivier Letessier (Air Liquide) Robert Ridgeway and Peter Maroulis (Air Products & Chemicals, Inc.) Reed Content, Calvin Gabriel and Arturo Ruiz (Advanced Micro Devices) Joseph Van Gompel (BOC Edwards) Volker Kinzig (Centrotherm Clean Solutions GmbH) A. Frenzel and Jim Hughins (DAS GmbH Dresden) Art Liu (Desiccant Technology Corp.) Gary Loh and Michael Mocella (DuPont) Laura Mendicino, Terry Sparks and Vict or Vartanian (Freescale Semiconductor) Robert Parkhurst and Bronwyn Pierce (Hewlett Packard) Seung-Jong Ko (Hynix Semiconductor Co.) Tatsuro Beppu (Kanken Techno Co., Ltd.) Linda Gee (LSI Logic) Chris Lewis (LegacyTek LLC) Rafael Reif and Ajay Somani (Massachusetts Institute of Technology) Sebastien Raoux (Metron/Ecosys) Michelle Atkinson (Micron Technology, Inc.) Richard Banks (National Semiconductor) Gabriele Fetzer, Joachim Stache, Harry Thewissen, and Ton van de Kerkhof (Philips Semiconductors) Wang-Keun Kim (Samsung Electronics) Ricky McGowan, Marilyn Redmond, Robert Ru liffson, Susan Vitkavage, and Walter Worth (SEMATECH) Francesca Illuzzi (S T Microelectronics) Bill Delaney and Cher Liu (TecHarmonic) J.P. Suplita, Tina Gilliland, and Tim Yeakley (Texas Instruments, Inc.) Members of the World Semiconductor C ouncil member associations including: EECA/ESIA – Shane Harte and Francesca Illuzzi JEITA/JSIA – Takayuki Ohgoshi KSIA – Ho-Song Hwang SIA – Chuck Fraust Members of the ISMI ESH PAG1

ISMI Technology Transfer #05104693A-ENG 1 EXECUTIVE SUMMARY This report describes the semiconductor industr y’s efforts to reduce perfluorocompound (PFC) emissions, reviewing the current state of PFC technology development and implementation. It documents pre-competitive information about potential PFC emission reduction processes and technology obtained through a survey of me mbers of the International SEMATECH Manufacturing Initiative (ISMI); the Semiconductor Industry A ssociation (SIA); the World Semiconductor Council (WSC); and chemical, tool, and abatement device suppliers. The appendix includes details about process optimiza tions, alternative processes, and abatement technologies. The industry is steadily decommissioning ≤ 150 mm fabs, eliminating them as a source of PFC emissions. For the majority of operating ≤ 150 mm fabs, process optimization and drop-in alternative chemistries for chemical vapor depos ition (CVD) cleans may be the only alternatives for reducing emissions, although a few ≤ 150 mm fabs have installed abatement on certain CVD processes. The 200 mm fabs can be divided into two distinct categories: older fabs with an installed base of CVD tools us ing perfluorocarbon clean chemistr ies and advanced fabs with lower emission NF 3 -based cleans. In older 200 mm fabs, process optimization, installation of endpoint detection, inst allation of remote NF 3 cleans, and use of alternative clean chemistries are the most prevalent means of reducing emissions. Abatement is also being employed in some older 200 mm fabs. The industry and its suppliers have integrated low emission CVD tools into advanced 200 mm and 300 mm fa bs. Several companies report us ing abatement technologies to reduce etch emissions in their advanced 200 mm and 300 mm fabs, and one company is using a central end-of-pipe (EOP) plasma unit to abate CVD emissions fr om an advanced 200 mm fab. Capture/recovery may be appropriate for specialized high volume PFC applications. The industry has undergone significant changes that impact PFC emissions. These changes include development and implementation of new chamber clean processes and chemistries, increased use of plasma etching and adoption of new etch gases, development of new materials and processes, and the use of larger wafers to manufacture advanced semiconductor devices. The change with the greatest impact on PFC emissi ons over time is increasing wafer size and the corresponding advanced processing technologies. As advanced 200 mm a nd 300 mm wafer fabs began ramping in 2001–2004, the normalized rate of emissions (PFC emitted/cm 2 ) decreased, most likely due to the use of NF 3 -based chamber clean processes. Based on the changes brought about by shifting wafer sizes and the projected ac celeration in the transition from old technology to new, there is strong reason to believe the normalized rate of PFC emissions will continue to decline through 2010:

• The world semiconductor industry has dem onstrated significant commitment to reducing PFC emissions.

• The U.S. semiconductor industry achiev ed the 10% reduction goal in 2003 and surpassed the goal in 2004, despite a significan t increase in wafer demand over time.

• If the current normalized PFC emissions tr end continues and wafe r demand projections are accurate, the world-wide industry will achieve the 2010 goal; however, these trends and projections largely depend on the ra mping up of lower emitting advanced 200 mm and 300 mm fabs and a decrease in the em issions from older, higher emitting fabs.2

Technology Transfer #05104693A-ENG ISMI 2 INTRODUCTION As required by the SIA’s memorandum of unders tanding with the Environmental Protection Agency (EPA), this report describes the semiconductor industry’s efforts to reduce PFC emissions. It describes the current state of PFC technology development and the way the industry is implementing that technology. It reviews the impact of indus try changes on historical and projected future emissions and SIA progress towa rds reducing PFC emissions . Finally, it projects future WSC emissions through 2010. This report is a follow-up to Current State of Technology: Perfluorocompound (PFC) Emissions Reduction [1] , published in 1998.

3 BACKGROUND It has been reported that PFCs have been identified as the most potent greenhouse gases measured due to their strong infrared absorption capacity [2] . PFCs are used in semiconductor manufacturing for plasma cleani ng of CVD chambers and for plasma etching. Examples include tetrafluoromethane (CF 4 ), hexafluoroethane (C 2 F 6 ), octofluoropropane (C 3 F 8 ), octofluorocyclobutane (c-C 4 F 8 ), nitrogen trifluoride (NF 3 ), sulfur hexafluoride (SF 6 ), and hydrofluorcarbons (HFCs) such as trifluoromethane (CHF 3 ). It has been reported that PFCs and the HFCs are referred to collectively by the i ndustry as PFCs. Additionally, PFCs such as CF 4 , C 2 F 6 , c-C 4 F 8 , and SF 6 persist in the atmosphere for thousa nds to tens of thousands of years [1] , making any releases permanent on a human tim escale (on the geologic timescale, human civilization emerged in the Holocene period co vering the past 10,000 years to the present). PFCs have been used in semiconductor fabrication facilities (fabs) becaus e they provide uniquely effective process performance when etching high as pect ratio features and are a safer, reliable source of the fluorine needed for cleani ng certain deposition process chambers. In 1999, the WSC—whose members at the time we re the European Electronic Components Manufacturer Association (now the European Semiconductor Indus try Association [ESIA]), the Electronic Industries Association of Japan (now part of the Ja pan Electronics and Information Technology Industries Association [JEITA], as th e Japanese Semiconductor Industry Association [JSIA]), the Korean Semiconductor Industry Association (KSIA), and the SIA—approved a consensus PFC emissions reduction goal [3] . That goal calls on WSC me mber associations to reduce aggregate absolute emi ssions of PFCs from semiconduc tor manufacturing facilities by 10% or greater from baseline le vels by 2010. The baseline year for the ESIA, JEITA-JSIA, and SIA is 1995 while the KSIA baseline is 1997. Th e Taiwan Semiconductor Industry Association (TSIA) subsequently joined the WSC, which defined the baseline year for TSIA as the average of 1997 and 1999 emissions. It should be noted that the semiconductor industry, through the WSC, was the first industry to coordinate globally and voluntar ily establish a greenhouse gas emissions reduction goal; moreover, the 10% goal exceeds the targets established by the Kyoto Protocol for any of the Annex I countries subj ect to specific greenhouse gas emissions reduction targets. Concurrent with the establishment of the WSC goal, the U.S. semiconduc tor industry negotiated a second voluntary agreement with the EPA. The PFC Reduction/Climate Partnership Memorandum of Understanding (M OU) applies to U.S. semiconductor manufacturing operations only and supports the WSC agreement for a collective 10% reduction in emissions by 2010 [4]

.3

ISMI Technology Transfer #05104693A-ENG Both the WSC consensus paper and the EPA memorandum of understanding call on semiconductor manufacturers to share pre-compe titive information about potential PFC emission reduction processes and technology. The memora ndum of understanding has an additional requirement that WSC partners publish a progress report by December 15, 2005, detailing progress towards achieving the 10% reduction goal. This report documents pre-competitive inform ation about potential PFC emissions reduction processes and technology obtained from ISMI , SIA, and WSC members. Additionally, information was gathered by written surveys of semiconductor manufacturers and suppliers as well as a review of relevant l iterature. Survey responses were received from 18 semiconductor manufacturers in the U.S., Europe, and Korea an d from 14 suppliers based in the U.S., Europe, Japan, and Taiwan. Four WSC trade associations provided specific data while information for the fifth association was gathered from th e 2005 International Semiconductor Environment, Safety, and Health (ISESH) conference procee dings. Emissions projections were developed based on VLSI Research, Inc. wafer demand historical data and projections through 2010. Normalized PFC emissions rates were calcula ted based on wafer demand data from Sage Concepts for Korea and Taiwan, and Data quest for the U.S., Europe, and Japan. This report reflects information available thr ough July 2005. It is not intended to be a comprehensive summary of all PFC emission reducti on activities. While attempts were made to include developments that occurred or were co mmercialized after the 199 8 report, technologies may not be included if the users or developers did not disclose information for competitive or other reasons.

4 EMISSIONS REDUCTION TECHNOLOGY DEVELOPMENT The semiconductor industry continues to employ a hierarchy in development of PFC emission reduction technology structured around the pol lution prevention con cepts of reduction, replacement, re-use/recycle, and abatement. These development areas are as follows: 1. Process optimization/alternative processing—re duces the amount of PFCs that are used and emitted 2. Alternative chemistries—reduces or eliminates emissions 3. Capture/recovery—re-uses or recycles PFCs 4. Abatement—destroys, reduces, or eliminates PFC emissions so they are not emitted Certain technologies that we re in research and development stages when ref. [1] was published have since been widely impleme nted by the industry; some tec hnologies have been rejected because of poor performance or other issues; and new technologies are being developed and evaluated.
4.1 Process Optimization/Alternative Processing Process optimization continues to focus prim arily on CVD chamber cleans because they are historically the greatest source of PFC emissions; furthermore, they occur in the absence of wafers and can be optimized without negatively affec ting product yield [4] . Cleans optimization can also be applied to etch and other process chambers where PFCs are used for in situ dry cleans. The PFC gases used in CVD chamber cleans include C 2 F 6 and CF 4 in older (pre-1999) manufacturing equipment as well as C 3 F 8 , C 4 F 8 , octafluorotetrahydrofuran (C 4 F 8 O), and NF 3 that4

Technology Transfer #05104693A-ENG ISMI are lower emitting C 2 F 6 replacement chemistries. Based on 2004 emissions, C 2 F 6 continues to be the primary chamber clean gas and currently makes up the majority of semiconductor PFC emissions. However, in terms of amounts purchased, NF 3 is fast catching up to C 2 F 6 . In process optimization, endpoint detection or extractive metrology is used to monitor emissions and provide clean endpoint times th at are minimized by adjusting process parameters such as chamber pressure, temperature, plasma power, cleaning gas flow rates, and gas ratios of mixtures. Cleans are optimized to minimize ga s consumption, thereby lowering the cost of ownership (COO) due to decreased gas usage. Process optimization can yield emissions reductions of 10–56% compared to baseline C 2 F 6 processes [5] with a potential benefit in throughput. Because of industry growth, optimizati on by itself has not achieved the levels of emission reduction the industry needs to meet the 10% goal; however, optimization can reduce emissions in older fabs and ensure that new chamber clean processes minimize gas consumption and operate efficiently.
4.2 Alternative Processing: Remote Clean Alternative processing—replacing the original process with a new, lower emitting process—has undergone significant development in the last decad e. The industry has developed remote plasma clean technologies to replace in situ C 2 F 6 chamber cleans and CF 4 used in nitride chamber clean. Remote cleans dissociate NF 3 into fluorine ions (F + ) or atoms in a remote plasma and then feed the F + ions/atoms into the process chamber to remove silicon-based residues. Remote cleans convert NF 3 at 95–99% utiliza tion efficiency [6] . Applied Materials has adopted remote plasma technology for chamber cleans across their adva nced 200 mm and 300 mm CVD equipment line. Other companies have developed re mote plasma technologies using NF 3 or other PFC chemistries that can be retrofitted to certai n older CVD chambers. When compared to the original carbon-based PFC chamber cleans that they replace, retrofitted remote cleans result in >95% PFC emissions reduction [7] . Remote cleans also improve tool utilization by reducing clean times and wet clean frequency, improvi ng mean time between failures (MTBF), and reducing costs of chamber parts. Additionally, they may improv e yield through fewer defects.
4.3 Remote Clean Byproduct ESH Concerns Implementing NF 3 remote cleans generates more fluorine (F 2 ) and hydrogen fluoride (HF) emissions than fluorocarbon-based cleans [8] and may require additional treatment to remove these gases from the exhaust stream, depe nding on the fab. Fabs typically treat F 2 and HF exhaust streams with water sc rubbers; the additional loading on central end-of-pipe (EOP) scrubbers may require modifications to the scru bber systems or installation of point-of-use (POU) scrubbers. Depending on a fab’s wastew ater discharge limits, scrubber effluent may require treatment to decrease the fluoride loading. As noted by Vartanian et al., The existing wastewater and/ or air pollution control approa ch and infrastructure may not be well suited to the increased F 2 load from NF 3 -based chamber cleans. Thorough evaluation of the site's air pollution control strategy, existing wastewater handling/treatment infrastructure and capacity, and F 2 discharge limits should be completed before proliferation of NF 3 -based chamber cleans [9]

. Semiconductor manufacturer surveys indicate that other fabs have responded to similar challenges with remote NF 3 and the F 2 . Many fabs have existing fluoride waste treatment facilities that remove fluoride by precipitation with some form of calcium, generating calcium5

ISMI Technology Transfer #05104693A-ENG fluoride. Because of the signifi cant reduction in PFC emissions a nd the process benefits, remote cleans are a key aspect of the industry’s efforts to reduce PFC emissions; however, semiconductor manufacturers should take into account increased F 2 and HF loadings when developing air and wastewater treatment strategies.
4.4 Alternative Chemistry Significant development has been made in altern ative chemistries. Alternative chemistry, or chemical substitution, is the use of chemicals wi th lower global warming potential (GWP) or no GWP as an alternative to PFCs. Alternative chemistry also includes high GWP gases that are more efficiently used in plasma processes, thereby reducing overall greenhouse gas emissions. When evaluating alternative chemistries, criteria must include process pe rformance, review of ESH risks, material availability and cost, and characterization of process emissions and byproducts. Fluorocarbons will generate CF 4 and possibly C 2 F 6 and C 3 F 8 byproducts when used in plasma processes; the amount of input ch emical converted to a PFC byproduct must be quantified to ensure an accurate accounting of PFC emissions. Additionally, any fluorinecontaining compound used in the presence of carbon in a plasma process, such as cleaning of an organic low-k deposition chamber, will fo rm some quantity of PFC such as CF 4 and, possibly, C 2 F 6 . Since fluorocarbons appear to generate other PFCs and COF 2 while NF 3 increases F 2 , HF, and NO x emissions, focusing solely on reducing PFC emissions may generate additional ESH
concerns. 4.4.1 Chamber Clean: ≤ 150 mm and Older 200 mm Process Tools The predominant semiconductor PFC emission is C 2 F 6 from CVD chamber cleans on ≤ 150 mm and older 200 mm process tools. C 2 F 6 is used at 30% efficiency in typical chamber clean processes, resulting in 70% of the input gas being emitted [10] . Additionally, a typical C 2 F 6 plasma chamber clean process converts ∼ 10% of the input C 2 F 6 into CF 4 on a mass per mass basis. As seen in Table 1 , several replacements for C 2 F 6 have been demonstrated and implemented in manufacturing fabs. Table 1 Implemented Alternative Chamber Clean Chemistries

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction from Baseline C 2 F 6 Process C 3 F 8 30–60 12–30 (CF 4 ) 12–70 c-C 4 F 8 70–90 4–11 (CF 4 ) 50–85 C 4 F 8 O 85–90 10–20 (CF 4 ); 4 (C 3 F 8 ) 70–90

NF 3 60–80 0–4 (CF 4 ) depending on carbon content of film removed 20–90

C 3 F 8 , c-C 4 F 8 , and C 4 F 8 O are drop-in replacements for C 2 F 6 (i.e., new gas lines or additional ESH systems do not need to be installed). As Table 1 shows, significant amounts of CF 4 byproduct can be produced with the drop-in re placements; therefore, the amount of O 2 added to the clean process must be optimized to drive the reaction to COF 2 , a highly toxic but water-scrubbable byproduct, instead of CF 4 . Note that at least one semiconducto r manufacturer has also identified the PFC byproduct C 3 F 8 when using C 4 F 8 O. Whereas decreased COO is reported when using the6

Technology Transfer #05104693A-ENG ISMI drop-in replacement chemis tries in lieu of C 2 F 6 (because of decreased clean gas consumption), the impact on emissions is variable. In addition to determining utilization efficiency, all of the PFC byproducts must be quantified to de termine the total effect on emissions. NF 3 is the most effective alternative chemistr y currently used in manufacturing fabs when viewed in terms of clean time, carbon equivalent emissions (a metric used to compare different greenhouse gases based upon their global warming potential), and gas usage [11] . IBM implemented in situ NF 3 cleans to replace C 2 F 6 at their Burlington, VT, manufacturing facility [12] , and Novellus has developed dilute in situ NF 3 clean processes to replace C 2 F 6 in their advanced 200 and 300 mm tools [13] . However, NF 3 is not a drop-in replacement. Unlike the fluorocarbon alternative chemistries in Table 1 , NF 3 is an oxidizer. The use of NF 3 precludes the generation of fluorocarbon byproduct unless organi cs are present; however, plasma chemistries are complex and use of an in situ NF 3 clean process may increase emissions of HF and F 2 as well as NO x . Additional ESH controls, such as local scrubbing, may be required; additionally, one semiconductor manufacturer recommended instal ling a coated stainles s steel exhaust duct [7]

. On a mass basis, NF 3 has a higher cost pe r kilogram than C 2 F 6 and the other fluorocarbon replacements; however, that cost may be offset by decreased consumption a nd faster clean times. CF 4 is used in certain older plasma enhanced (PE)CVD silane deposition chambers for chamber cleaning. One semiconductor manuf acturer reported using C 2 F 6 as an alternative chemistry, reducing PFC emissions by > 57% from the baseline CF 4 process. 4.4.2 Chamber Clean: Advanced 200 mm and 300 mm Because of significantly lower PFC emissions a nd process benefits, CVD tool supplier Applied Materials has standardized remote NF 3 cleans for their advanced 200 mm and 300 mm tools while Novellus has adopted in situ NF 3 cleans for their corresponding tools. Remote plasmas use NF 3 with 95–99% efficiency, whereas in situ processes use NF 3 with 60–80% efficiency [14]

. The lower utilization efficiency of in situ cl eans may require additional abatement; however, NF 3 is abated with most PFC abatement technologi es. Destruction-removal efficiencies of 95–99.9% have been reported.
4.4.3 Chamber Clean: Research and Development Several chamber clean chemistries are in re search and development. From 1998–2002, Japan’s Research Institute of Innovation Technology for the Earth undertook an effort to identify alternative chamber clean chemistries, ev entually recommending carbonyl fluoride (COF 2 ) as a replacement gas. With a GWP of 1 [15] , COF 2 has a much lower global warming potential than other fluorocarbons used for ch amber cleans, and, although COF 2 is toxic, it is easily removed from the exhaust stream by water scrubbing. At the 12 th ISESH Conference in 2005, JEITA-JSIA members presented results of COF 2 evaluations in manufacturing environments. COF 2 cleans reduced PFC emissions 96% with pro cess performance equivalent to PFCs [16] [17] ; however, at a cost of 20,000Yen/kg (~$175/kg), COF 2 is currently not a cost-effective alternative. Chlorine trifluoride (ClF 3 ) was mentioned in the 1998 report as a potential alte rnative chamber clean gas for polysilicon and nitride chambers. Although ClF 3 has no GWP or ozone depletion potential, it has not been widely adopted in the industry because of its extreme reactivity and the risks and costs associated with safe storage and use. In fact, efforts have been undertaken to replace ClF 3 with alternative chemistries such as NF 3 and fluorine [18]

. Fluorine (F 2 ) has been discussed as a po ssible alternative to PFCs for CVD chamber cleaning but was not considered a serious alte rnative in the past because of the ESH risks associated with7

ISMI Technology Transfer #05104693A-ENG transport, storage, and use of high pressure F 2 cylinders. These problems have been addressed by two companies that have deve loped POU fluorine generators [19] [20] . POU F 2 generators convert anhydrous HF into F 2 by electrolysis. After the F 2 is generated, it is purified to remove residual anhydrous HF and other contaminants. Wh ile anhydrous HF is t oxic and corrosive and F 2 is highly toxic and a strong oxi dizer, neither of these materials are global warming gases. When used to clean organic low-k deposition chambers, F 2 generates a small quantity of PFC byproduct such as CF 4 . 4.4.4 Plasma Etch While replacing high GWP gases with lower or non-GWP gases is generally preferable, it has not proven feasible in most plasma etch applic ations. Processing requirements for high aspect ratio plasma etching continue to become more stringent, requiri ng both fluorine to etch and the right carbon-to-fluorine ratio to ensure anisotropic etching. While a significant amount of research has been done on alternative etchan ts such as iodofluorocarbons, hydrofluorocarbons, and unsaturated fluorocarbons [21]

– [24] , many of these chemicals ar e not feasible alternative etchants in a manufacturing environment because of excess polymerization, lack of etch selectivity, difficulties in delivering gases to the process chamber, and potential increased employee exposure risks. An exceptio n is hexafluoro-1,3-butadiene (C 4 F 6 ) for oxide and low-k etching where high selectivity to si licon is required in the presence of nitride or other films with high aspect ratios, thinner resi sts, and less etch resistant resists. In these cases, C 4 F 6 replaces CF 4 , CHF 3 , and C 4 F 8 [24] . With an atmospheric lifetime <1 year and utilization efficiency >95%, PFC emissions can be reduced by >90% compared to baseline CF 4 , CHF 3 and C 4 F 8 processes [26] ; however, as is the case with a ll higher molecular weight fluor ocarbon compounds used in plasma processes, some CF 4 byproduct is formed and emitted.
4.5 Capture/Recovery Several semiconductor manufacturer s and suppliers conducted alpha and beta evaluations of PFC capture/recovery systems that c ould be installed as a central, building-wide means for handling PFC emissions [26]

– [30] . Technologies evaluated include membrane separation, cryogenic recovery, and pressure swing ad sorption/desorption. No evaluation resulted in successful re-use of PFC; all were deemed to be too costly to implement. Capture/r ecovery technology requires extensive pretreatment of the process tool exha ust stream to remove corrosives, pyrophorics, moisture, and particulate. Historically, cham ber clean PFCs make up the majority of PFC emissions. As NF 3 -based cleans proliferate, large bu ilding-wide capture/recovery systems become less cost-effective due to the reduced volu me of PFCs available for recovery. To date, no semiconductor facility in the world has successfu lly implemented centralized capture/recovery technology. As new, lower emitting chamber cleans are implemented and older fabs are decommissioned, the mix of PFC emissions is expect ed to change. JEITA-JSIA projects that, in 2010, the largest quantity of PFC emitted from Japan’s semiconductor facilities will be SF 6 . In addition to plasma etch processes, SF 6 can be found in specialized processes such as IC testing and wafer thinning where it is used in large volume. Air Liquide pr esented data on a semi-centralized membrane system used to capture and recycle SF 6 [31] . In the Air Liquide application, SF 6 was being used in large volume as a blanket gas, not as a plas ma etchant. Byproducts requiring pre-treatment were not present in the exhaust stream; therefore, SF 6 could be captured and re-used in the process, thus reducing process cost of ownership due to reduced virgin SF 6 purchases. While centralized capture/recovery does not appear to be a cost-effective way to reduce PFC emissions,8

Technology Transfer #05104693A-ENG ISMI smaller capture/recovery systems may be appropriate, as demonstr ated in the Air Liquide case, for niche, single PFC, high volume processes.
4.6 Abatement Since the publication of ref. [1] , many new PFC abatement tec hnologies have been developed and new systems commercialized. The indus try has favored POU over centralized EOP abatement for PFCs, believing that it is more e ffective to abate close to the source and, thus, before dilution; however, one semiconductor comp any has recently installed an EOP abatement system that uses corona discharge plasma technology to destroy PFCs from CVD chamber cleans. Most abatement technologi es can be applied to PFC emi ssions from both etch and CVD processes, although several companies have deve loped plasma abatement systems specifically for etch chamber emissions. These are typically installed before the vacuum pump (i.e., the foreline) to avoid dilution of the stream with pump-purge N 2 . Because it is desired to abate certain CVD processes for deposition gases, some semiconductor manufacturers have elected to install POU abatement technology that can also abate PFC emissions. As noted earlier, fluoroc arbons will generate CF 4 and possibly C 2 F 6 and C 3 F 8 byproducts when used in plasma processes. A dditionally, the use of any fluor ine-containing compound in the presence of carbon in a plasma pro cess will form some quantity of CF 4 . Certain abatement devices sold for PFC applications are not capable of destroying CF 4 effectively. Abatement manufacturers may use different me thods of determining destruction/removal efficiency (DRE) because the industry has not de veloped a standardized method. This can make a direct comparison of abatement technologies difficult. Performance of abatement systems varies greatly depending on a variety of abatem ent device and process parameters such as temperature, PFC inlet concentration, flow ra te, overall inlet stream composition, etc. In addition, consumables, maintenance, and uti lities have a significant impact on COO. Technologies under development or proven to be effective in abating PFC emissions from specific applications are listed in Table 2

. Table 2 PFC Abatement Technologies
Technology Type Description and Applicability POU Fueled Burner – Scrubber Uses a propane, methane, natural gas or hydrogen flame to destroy PFCs and other hazardous substances such as deposition precursors followed by a water scrubber, which may contain a base solution, to remove volatile acid gases from the exhaust stream. May not be effective in abating CF 4 . Burnerscrubber units are installed on the process tool exhaust line after the vacuum pump and, thus, the exhaust stream ent ering the unit contains a large amount of N 2 that can lower the combustion unit temperature and, thus, DRE. Burnerscrubber units can typically abate emissi ons from multiple process chambers. Except for the hydrogen-fueled devices, they all generate additional greenhouse gases in the form of CO 2 . POU Catalytic – Scrubber Uses a catalyst to pr omote the destruction of PFCs and process gases at lower activation energies than would otherwise be needed. Catalytic systems operate at a lower temperature than other PFC abatement systems, are electrically heated, and do not require a fuel. A water scrubber typically follows the catalytic reactor to remove HF byproduct from the exhaust stream. May not be effective in abating CF 4 . Catalytic scrubber units are installed on the process tool exhaust line after the vacuum pump and, thus, the exhaust stream entering the unit contains a large amount of nitrogen. Catalytic scrubber units can typically abate emissi ons from multiple process chambers.9

ISMI Technology Transfer #05104693A-ENG Technology Type Description and Applicability POU Electrically Heated Thermal – Scrubber Uses an electrically heated chamber to destroy PFCs and other hazardous substances such as deposition precursors, followed by a water scrubber to remove volatile acid gases from the exhaust stream. Electrically heated thermal-scrubber units are installed on the process tool exhaust line after the vacuum pump. May not achieve the high temperatures required to effectively abate CF 4 . Electrically heated-scrubber units can typically abate emissions from multiple process chambers. POU Atmospheric Plasma Uses plasma to destroy PFCs and other hazardous substances such as deposition precursors. The plasma chamber can be followed by a water scrubber, which may contain a base solution, to remove volatile acid gases from the exhaust stream. Atmospheri c plasma units are installed on the process tool exhaust line after the vacuum pump and, thus, the exhaust stream entering the unit contains a lar ge amount of nitrogen, which can impact the plasma efficacy. Atmospheric plasma units are typically designed to abate emissions from multiple process chambers. POU Pre-pump Plasma Point-of-use foreline plasma units employ a compact, low-pressure plasma reactor to destroy PFCs from etch processes. Foreline plasma units are installed on the foreline after the turbo pump but before the mechanical vacuum pump, where they can abate concentrated emissions before dilution with N 2 purge from the vacuum pump. One unit is required for each etch process chamber. Centralized Atmospheric Plasma The only centralized PF C abatement system is the corona discharge system jointly developed by FH Co., Ltd and Samsung Electronics in Korea. A separate PFC exhaust line is installed post-vacuum pump to segregate CVD chamber clean emissions from deposition emissions. The PFC exhaust passes through the annular space between co-axial cylindrical electrodes used to sustain a corona discharge at at mospheric pressure. Exhaust from the abatement system then flows to the house scrubber for removal of acid gases.

5 INDUSTRY APPLICATION OF EMISSION REDUCTION OPTIONS The age, size, and infrastructure of a fab are th e factors that have the greatest impact on the applicability of PFC emission re duction technology. For instance, older fabs process smaller wafers, are typically smaller in size, and may have space and infrastructure constraints such as a lack of or undersized utilities required to support specifi c reduction technologies; moreover, manufacturers of the process tools in older fa bs are typically no longe r supporting those tools with new process development. WSC member companies were surveyed to determine the technologies that they are implementing to reduce emissions. Table 3 summarizes the PFC emissions reduction options the industry is appl ying to fabs processing various wafer sizes. Table 3 PFC Emissions Reduction Options

Tool Type ≤ 150 mm Fabs Old Technology 200 mm Advanced 200 mm and 300 mm

CVD Fab Decommission Process Optimization Endpoint Detection Alternative Chemistries Limited Abatement Process Optimization Endpoint Detection Remote NF 3 Cleans Alternative Chemistries Abatement NF 3 -based Cleans F 2 Cleans Endpoint Detection Abatement

Etch Fab Decommission Limited Abatement Limited Capture/Recovery Alternative Chemistries Abatement Limited Capture/Recovery10

Technology Transfer #05104693A-ENG ISMI The industry is steadily decommissioning ≤ 150 mm fabs, eliminating them as a source of PFC emissions. The ≤ 150 mm fabs that continue operations may have few choices of emissions reduction technologies because of space and infrastructure constraints. For ≤ 150 mm fabs, process optimization and drop-in alternative chemistries for CVD cleans may be the only alternatives for reducing emissions, although a few ≤ 150 mm fabs have installed abatement on certain CVD processes. For older 200 mm fabs with CVD tools using C 2 F 6 cleans, the industry has focused their PFC reduction efforts on CVD emissions. Process optim ization, installation of endpoint detection, installation of remote NF 3 cleans, and alternative clean chemis tries are the most prevalent means of reducing emissions. One company reported in stalling abatement in an older 200 mm fab; however, abatement typically requi res floor space that may be limited in an existing fab and could require facilities services th at are not available. If etch em issions abatement is also needed, the small footprint pre-vacuum pump plasma systems may be the only alternative to reduce emissions. Capture/recovery may be appropriate for specialized high volume PFC applications. Based on the survey, the industry and its suppliers have integrat ed low emission CVD tools into advanced 200 mm and 300 mm fabs . If an advanced CVD tool uses silane or other flammable or pyrophoric precursors and in situ NF 3 cleans, burner-scrubber abatement with high DREs for all these emissions is available and in use in so me fabs. Companies also report using endpoint detection to minimize PFC gas consumption. With the advent of low emission clean processes, 300 mm etch is expected to gain an increasing share of the industry’s total PFC emissions. Some companies report using alternative etch chemistries to reduce emissions; however, implementation of alternative etchants as a retrofit is costly and time-consuming. Because etch occurs on the wafer surface, process change s require extensive evaluation and process requalification before implementation. Several co mpanies report using abat ement technologies to reduce etch emissions in their advanced 200 mm and 300 mm fabs, and one company is using a central EOP plasma unit to abate CVD emissions from an advanced 200 mm fab. Additionally, capture/recovery may be appropriate for specialized high volume PFC applications.

6 IMPACT OF INDUSTRY CHANGES ON EMISSIONS Since publication of ref. [1] , the industry has undergone significant changes that impact PFC emissions. These changes include developmen t and implementation of new chamber clean processes and chemistries, incr eased use of plasma etching an d adoption of new etch gases, development of new materials and processes, and larger wafers to manufacture advanced semiconductor devices.
6.1 Chamber Cleans The impact of NF 3 cleans is realized principally in advanced 200 mm and 300 mm fabs; however, in 2004, ∼ 66% of the total silicon demand was processed in older technology fabs ( ≤ 150 mm and older 200 mm) using fluor ocarbon-based cleans. In fact, C 2 F 6 still accounted for

∼ 48–50% of the industry’s total PFC emissions in 2004 [33] . A transition from C 2 F 6 cleans to alternative processes and chemistr ies is evidenced by some associ ations reporting reductions in C 2 F 6 emissions and increasing NF 3 or C 3 F 8 emissions. Note, however, th at the associations that reported increased C 3 F 8 emissions in 2004 also reported incr eases from 2003 levels in overall PFC emissions, despite the transition to C 3 F 8 .11

ISMI Technology Transfer #05104693A-ENG 6.2 Etch In interviews, semiconductor etch professionals [33] provided input on PFC usage in etch over time. They agreed that the m ove from 200 mm to 300 mm equi pment has resulted in a 1.5–2X increase in etch PFC consumption per wafer pass; however, they noted that the increased usage is less than would be expected base d on the 2.25X increase in wafer area. The increase in microprocessor metal levels fr om four in 1995 to 11 in 2004 has led to an increase in back-end etch PFC usage. Due to re quirements for higher selectivity to resist and underlying films, c-C 4 F 8 and C 4 F 6 are now being used more exte nsively for dielectric etching, replacing CHF 3 and CF 4 . Both chemistries generate C 2 F 4 , CF 4 , C 3 F 8 , C 2 F 6 , CHF 3 , and some C 4 F 8 byproducts; however, MIT and Motorola’s Semi conductor Product Sector (now Freescale Semiconductor) demonstrated equivalent pro cess performance and a 65–82% reduction in PFC emissions for organosilicate glass and oxide etching when using C 4 F 6 in lieu of c-C 4 F 8 [34]

. Experts note that as device line and contact sizes are scaled, the aspect ratio remains the same; therefore, films are becoming thinner and etch times shorter, thereby decreasing PFC usage. However, one expert cautioned th at selectivity requirements are becoming more critical with the thinner layers and required process changes may result in increased PFC consumption over time. The impact of ultra low-k dielectrics on PFC emissions cannot be ascertained at this time because it is too early in their development stage. In the front-end, integrations using multiple spacers and sometimes multiple polysilicon layers have increased PFC usage. As high-k dielectric s and gates are implemented, increased etching could further increase PFC consumption. It is too early to quantify the imp act of novel structures such as FinFET on PFC emissions. In recent years, semiconductor tool suppliers have evaluated in situ cleans or dry cleans for etch tools to maximize tool uptime and increase mean time between wet cleans (MTBC) [35] . While oxygen can be used to clean orga nic byproducts of the resist fr om the chamber walls, fluorinecontaining gases are required to re move silicon-based residues. The us e of in situ cleans is likely to increase PFC emissions from etch tools. One etch expert estimates that the industry can anticipate a net 2% increase in PFC consumption and, therefore, emissions each year [36] . With increasing usage of NF 3 -based cleans in 300 mm fabs, etch will become a significan t source of 300 mm PFC emissions.
6.3 Future Technologies That May Impact PFC Emissions Atomic layer deposition (ALD) is used increasingly in the industry to deposit back-end copper barriers and seed layers. In the front-end, ALD is being used to deposit metal gates and high-k dielectrics. These materials re place films that formerly were deposited by diffusion processes that did not have PFC chamber cleans. In situ and remote plasma NF 3 -based chamber cleans are currently in development to replace cleans that require the chamber be taken down to remove parts. Non-PFC chemistries are also being evaluated for in situ or remote plasma chamber cleans. Finished semiconductor wafers contain multiple co mputer chips called dies. The finished dies are cut, packaged, and then sent to manufacturers to integrate in to products such as cell phones, computers, personal music players, and automo biles. The shrinking size of electronic products requires that packaged integrated circuits be reduced in thickness a nd footprint. Thin IC packages require thinner dies; a dditionally, fully depleted silicon on insulator (SOI) used for low power, high speed devices also requires thinning of SOI wafers . The four major methods of reducing die thickness are mechanical grinding, ch emical mechanical plan arization (CMP), wet12

Technology Transfer #05104693A-ENG ISMI etching, and atmospheric downs tream plasma (ADP) etching [37] . ADP etching requires PFCs; however, it is not certain that ADP will be the technology of choice for wafer thinning. 3D interconnect—stacking chips and connecti ng them through vias on the die—is a technology being pursued to shorten inte rconnects and decrease delay time [38] . 3D interconnects will employ wafer and die thinning technology, but thos e are most likely to be wet chemical- or CMP-based. The technology will require an addi tional metal deposition; however, it is hoped that new architecture will eliminate an existing layer of metal and the metals changes will be PFC-neutral. An additional etch step is requir ed, but again chip redesign is anticipated to eliminate levels and reduce etch process steps.
6.4 Changes in Wafer Size The change with the largest impact on PFC emi ssions over time is increasing wafer size and the corresponding advanced processi ng technologies. Older technology ≤ 150 mm wafers constituted the bulk of wafer demand in 1995. Between 1995 and the present, ≤ 150 mm wafer demand has steadily declined. VLSI Research projects that ≤ 150 mm wafer demand will be 54% below 1995 levels in 2005 and 73% below those levels in 2010 [40]. Nine semiconductor manufacturers (1 based in Europe, 2 in Korea, and 6 in the U.S.) provided information on actual and projected PFC emissions per fab type in 1995, 2000, 2005, and 2010 [41] While all nine companies indicated PFC emissions from ≤ 150 mm fabs in 1995, five were emitting PFCs from those fabs in 2005 and only four expect to be emitting PFCs from ≤ 150 mm fabs in 2010. Both the industry survey results and VLSI Research wafer demand projections are clear in dicators of the industry trend to close and decommission older technol ogy fabs. PFC emissions increased between 1995– 2000 as first generation 200 mm fabs using predominantly C 2 F 6 cleans ramped up; 200 mm wafers became the predominant wafer type by 2000. As advanced 200 mm and 300 mm wafer fabs began ramping in 2001–2004, the normalized rate of emissions (PFC emitted/cm 2 ) decreased, most likely due to use of NF 3 -based chamber clean processes. An estimate of the percentage of 200 mm wafer demand attributable to older technol ogy fabs versus advanced fabs can be made by assuming that the additional demand above 1999 levels is due to advanced fabs. Based on these estimates, worldwide, advan ced 200 mm and 300 mm fabs will account for approximately 70% of semiconductor manufacturing wafer demand in 2010 [41] [42] ( Figure 1 ). The semiconductor industry has experienced sign ificant growth from 1995 to 2004 with wafer demand increasing 52% [42] . As seen in Figure 2 , while silicon demand has increased, PFC emissions per square inch of silicon increased from 1995–2000 and then began decreasing from 2001–2004. The decreasing trend can be explained by the transition to advanced 200 mm and 300 mm wafer fabs coupled with a change in chamber cleaning technol ogy between older and newer fabs. Newer fabs employ NF 3 -based cleans that result in much lower PFC emissions than C 2 F 6 cleans. If older manufacturi ng facilities are shut down, C 2 F 6 -based cleans will be reduced. Based on the changes brought about by the shift to larger wafer sizes and the accompanying transition from old technology to new, trends indicate that the normalized rate of PFC emissions will continue to decline through 2010.13

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

199 5 1 9 9 6 1 9 9 7 1 9 9 8 1 99

9 2 0 0 0 2 0 0 1 2 0 0 2 2 00

3 2 0 0 4 2 0 0 5 2 0 0 6 2 007 200 8 2 0 09 20 1 0

TimePercent of Total Wafer Demand

Fraction New Technology Fraction of Total Old 200 mm Fraction of Total (<=150 mm)

Figure 1 Wafer Demand Over Time (1995–2010)

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Time (Year)WSC Emissions/Wafer Demand(mmtce/total wafer area)

Figure 2 WSC Production Normalized PFC Emissions Over Time

ISMI Technology Transfer #05104693A-ENG14

7 SIA PROGRESS TOWARDS 10% EMISSIONS REDUCTION GOAL The SIA partners have achieved significant reductions in PFC from their 1999 peak level emissions, meeting the 10% goal in 2003 and exceeding the goal in 2004 ( Figure 3 ). SIA reductions have been achieved through process optimization, alternative processes, alternative chemistries, and abatement. In addition, some older fabs have been closed while some newer fabs have been built that use lower em ission technologies and more abatement. While much has been written about the shri nking of the U.S. semiconductor industry, SIA reductions are not due solely to fab closures. From 1995–2004, North American fabs increased wafer demand by 55% as measured in wafer area [42] in spite of fab closures.

0.7 0.8 0.9

1 1.1 1.2 1.3 1.4 1.5 1.6

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 YearEmissions (mmtce)

10% Reduction Goal

Figure 3 Annual SIA PFC Partner Emissions

8 PROJECTED WSC EMISSIONS All of the associations are demonstrating a decrease in normalized emissions (million metric tons of carbon equivalent [MMTCE]/square inch of wafer demand); however, absolute emissions in 2004 are 0.5–1.3X for four of the fi ve associations. The industry has consistently reduced PFC emissions per square inch of silicon since 2000 ( Figure 2 ). A linear regression analysis of the 2001–2004 normalized emission data results in an R-squared value of 0.99. Assuming this trend continues, emissions can be projected through 2010 using a lin ear extrapolation. Figure 4 shows historical WSC-indexed emissions, as well as projected WSC-indexed emissions from 2005– 2010, based on this linear extrapolation and VL SI Research, Inc. wafer demand projections. Indexed emissions are actual emissions divided by the WSC 2010 goal. An index value of 1.0 is equivalent to the 2010 goal. Because KSIA and TSIA joined the WSC after 1995, their emissions are not included in 1995 and 1996, resulting in inde xed emissions for those years that are less than the overall WSC goal. While VLSI Resear ch predicts increased wafer demand from 2005– 2009, the predicted demand is expected to decrease from 2009 to 2010. Assuming the normalized emissions rate trend continues and th at VLSI’s projected demands are accurate, WSC emissions are projected to be lo wer than the 2010 reduction goal. Technology Transfer #05104693A-ENG ISMI15

ISMI Technology Transfer #05104693A-ENG 0.60 0.80 1.00 1.20 1.40 1.60 1.80

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 YearWSC Indexed Emissions(Emissions/Target Level)

WSC Target Level Actual Projected

Figure 4 WSC Indexed PFC Emissions – Actual and Projected

9 DISCUSSION AND ANALYSIS Following the pollution prevention hierarchy, many t echnologies have been developed in recent years to reduce PFC emissions. Based on the current state of those technol ogies as described in this report, several factors rela ted to their applicability and im plementation should be considered.
9.1 Applicability of Technologies The applicability of PFC emission reducti on technology depends on the age, size, and infrastructure of a fab. In 2004, the la rgest PFC emission continues to be C 2 F 6 , at 48–50% of total semiconductor PFC emissions. C 2 F 6 emissions are expected to decrease over time as 300 mm fabs with NF 3 - and F 2 -based cleans ramp up and as older fabs shut down. For older fabs that will continue oper ations beyond 2009, companies may want to

• Implement those alternative clean processes and chemistries that achieve the highest levels of emissions reductions, or

• Install abatement, if feasible. Due to projected growth in 300 mm fabs, caref ul monitoring of 300 mm PFC consumption and CVD and etch emissions from those fabs as they ramp up are recommended. If a company’s 300 mm fabs use CVD chamber clean technologies other than remote NF 3 or F 2 cleans, the amount of CVD PFC emissions need to be evaluated to determin e if additional measures should be implemented to further reduce emissions. Etch emissions are expected to grow over time and may become the major source of 300 mm PFC emissions. Because etch processes are alr eady optimized to achieve the required process performance, alternative chem istries and process optimization are typically not feasible. Abatement may be the only option if fu rther emissions reductions are needed.16

Technology Transfer #05104693A-ENG ISMI 9.2 Process Optimization/Alternative Processing By itself, process optimization may not reduce emissions sufficiently to enable industry associations to meet the goal. Because of othe r benefits including cost reduction and pollution prevention, however, it should be used on all CVD chamber cleans to minimize chemical consumption and waste generation. The alternative process remote cleans minimi ze PFC emissions. Additionally, they may offer process, yield, and COO benefits . In older fabs, replacing C 2 F 6 cleans with options such as remote cleans, in situ NF 3 cleans, or alternative chemistries is likely to be the most cost-effective means to minimize PFC emissions. The impact of increased F 2 emissions must be addressed when designing exhaust systems and wastewater treatment systems.
9.3 Alternative Chemistries Alternative chemistries are being used to replace C 2 F 6 /O 2 chamber cleans in ol der process tools. These chemistries must be chosen carefully to ensure tangible benefits. One WSC member association has shown a s ubstantial increase in C 3 F 8 emissions over time with a concurrent reduction in C 2 F 6 emissions; however, total emissions of C 2 F 6 and C 3 F 8 in 2004 exceed the highest historical C 2 F 6 emission. This may indicate the C 3 F 8 does not provide the level of emissions reduction needed to reduce overall emi ssions in line with the growth of wafers processed. When evaluating alternative chemistries, criteria must include the following:

• Process performance

• Review of ESH risks

• Alternative chemistry availability and cost

• Process emissions and byproducts characterization Choosing an alternative based so lely on its utilization effici ency may raise additional ESH concerns. For example, fluorocarbon-based al ternatives generate difficult-to-abate CF 4 byproducts and, potentially, other fl uorocarbon byproducts. The use of NF 3 generates increased F 2 , HF, and NO x emissions. While resulting in minimal PFC emissions, F 2 is highly toxic and reactive, thus requiring significant ESH controls , such as double contained piping, toxic gas monitoring, abatement, and possibl y upgrading of exhaust ducts.
While alternative etchants have been extensively researched, C 4 F 6 appears to be the only alternative evaluated so far that provides the required process performance while reducing emissions.
9.4 Capture/Recovery Although centralized capture/recove ry has not proven cost-effective, smaller capture/recovery units may be appropriate in specialized cases wh en a process uses a sing le PFC in large volume without plasma processing, resulting in emissions of a high volume, relatively clean PFC stream.
9.5 Abatement The number and type of commercially availa ble PFC abatement systems has increased dramatically since the first Current State of Technology: Perfluorocompound (PFC) Emissions17

ISMI Technology Transfer #05104693A-ENG Reduction [1] report was issued. Abatement devices ra nge from those that are commercially available with hundreds installed in semiconductor applications to alpha and beta units. Some abatement devices can be used only in specifi c applications. DRE and COO can vary greatly from one abatement device to another. When using PFC abatement, semiconductor manufacturers should establish performance standards for the following:

• Maximum downtime allowable

• COO

• Minimum DRE Abatement devices typically have consumable pa rts that must be replaced; the parts requiring replacement, frequency of replacement, and eq uipment downtime costs should be understood. Because a standard method to calculate DRE does not currently exist, co mparing the results of one abatement device to another is difficult. Many abatement technologies use additives that dilute the exhaust stream; these additives must be taken into account by determining the total dilution across the system. Semiconductor manufact urers must ensure that a PFC abatement device is capable of performing in the specific application for which it is required. DRE data generated from an abatement device installed on a 200 mm etch process are not likely applicable to the same etch process on a 300 mm tool becaus e of increased PFC gas flows and other process variations. Additionally, the total amount of exhaust flow through an abatement device can vary from one application to another. Fluorocarbons in plasma processes ca n generate a significant amount of CF 4 . When installed on fluorocarbon processes, the ability of an abatement device to abate CF 4 must be understood; moreover, to minimize total PFC emissions, the device must effectively abate CF 4 , the PFC most difficult to abate. Finally, once installed, semiconductor manufactur ers must ensure that PFC abatement devices are operated and maintained according to the abat ement device manufacturer’s specifications to ensure that DRE is maintained over time.
9.6 Impact of New Process Technology It is not anticipated that new processing technologies will ha ve a significant impact on PFC emissions before 2010; however, they do have the potential to impact emissions beyond 2010. Thus, it is recommended that the industry m onitor the development and implementation of manufacturing technologies such as wafer thinning, ALD, and in situ dry cleans as well as new front-end integrations and material s and 3D interconnects. If possi ble, these technologies should be developed without using PFCs or by using thos e PFCs and processes that result in the lowest levels of emissions; however, new manufacturin g technologies may not be possible without PFCs. If new technologies require PFCs, pr ocesses should be developed that

• Minimize the amount of PFC required

• Maximize PFC utilization efficiencies

• Minimize formation of PFC byproducts18

Technology Transfer #05104693A-ENG ISMI If PFC emissions from these new technologies be come significant, efforts should be made to employ capture-recovery (for high volume streams) or to abate emissions.

10 CONCLUSIONS As the first industry to coordi nate globally and establish a vo luntary greenhouse gas emissions reduction goal, the semiconductor industry has estab lished itself as a leader and model for other industrial sectors. The world semiconductor indu stry has demonstrated significant commitment to reducing PFC emissions. The U.S. semiconduc tor industry achieved th e 10% reduction goal in 2003 and surpassed the goal in 2004 , despite a significant increase in wafer demand over time. If the current normalized PFC emissions trend continues and wafer de mand projections are accurate, the world-wide industry will achie ve the 2010 goal; however, these trends and projections largely depend on the ramping up of lower emitting advanced 200 mm and 300 mm fabs and a decrease in the emissions from older, higher emitting fabs.

11 REFERENCES [1] Current State of Technology: Perflu orocompound (PFC) Emissions Reduction , Technology Transfer #98053508A-TR, Inte rnational SEMATECH, June 2, 1998. [2] IPCC Science of Climate Change, 1995. [3] WSC Consensus Paper. [4] PFC Reduction/Climate Partnership Memorandum of Understanding. [5] “C 2 F 6 -based Chamber Clean for Silane PECVD,” A.D. Johnson, R.V. Pierce, M.I. Sistern, M. Kencel, R. Sward, and H. Winzig, Semiconductor International , 27 (3), p.57, March 2004. [6] IPCC Electronics Industry GHG E missions Estimating Draft, 2006. [7] Survey Results of Semiconductor Manufacturers, Laurie Beu, 2005. [8] “Impact of Fluorine from NF 3 -based Chamber Cleaning Processes: Environmental Issues in the Electronics and Semiconductor Industry,” P. Brown, L. Mendicino, and V. Vartanian, The Electrochemical Society , PV 99-8, p. 52. [9] “ Managing Fluorinated Byproduc ts of CVD Chamber Cleans ,” V. Vartanian, B. Goolsby, L. Mendicino, P.T. Brown, J. Vires, S. Rose, D. Babbitt, C. Laush, and T. Huang, Semiconductor International , June 2003. [10] IPCC Good Practice Guidance , Industrial Processes , Chapter 3.6, 2001. [11] “ A Critical Comparison of Chamber Cleaning Pr ocesses in an Applied Materials PECVD Tool ,” C. Allgood, S. Hsu, B. Birmingham, and J. Soucy, Proceedings of the SEMICON Southwest , ‘A Partnership for PFC Emissions Reductions’ Seminar, paper #9, 2000. [12] Project XL Final Project Ag reement: Management of Semi conductor Rinsewaters From A Copper Plating Process , submitted by the IBM Essex Junction Semiconductor Manufacturing Facil ity, December 1998. [13] “Reduced PFC Emission Chamber Clean Processes on Novellus CVD Tools,” K. Aitchison, Proceedings of the SEMICON West 99 'Environmental Impact of Process Tools' Seminar , paper C, 1999. [14] IPCC Electronics Industry GHG Emissions Estimating Draft, 2006.19

ISMI Technology Transfer #05104693A-ENG [15] “Summary of the New Alternative Gas Pro cess Development Project for PFCs Emission Reduction from Semiconductor CVD Chamber Cleaning,” T. Beppu, Y. Mitsui, and K. Sakai, Proceedings of the 10 th ISESH Conference , Session 1600–1800, 2003. [16] “Investigation of an Alternative Gas COF 2 Application for CVD Chamber Cleaning Process,” S. Ueda, K. Takahash i, T. Matsubara, and H. Nikou; Proceedings of 12 th ISESH Conference , 2005. [17] “Evaluation of COF 2 in Mass Production Line,” M. Sakamura, T. Minegishi, and M. Yomoda, Proceedings of 12 th ISESH Conference , 2005. [18] “ClF 3 Alternative Search for ALD TiN in -situ Chamber Cleaning,” B. Raley; Proceedings of the 12 th ISESH Conference , 2005. [19] “ On-Site Generation of High Purity Fluorine as a Safe and Economical Alternative for CVD Chamber Cleaning ,” S. Siegele, D. Hage, and F. Siegele, FutureFab International, Issue 13, July, 2002. [20] Generation-F 80 On-Site Fluorine Generator , BOC-Edwards Product Data Sheet. [21] “ Use of Novel Hydrofluoro carbon and Iodofluorocarbon Chem istries for a High Aspect Ratio Via Etch in a High Density Plasma Etch Tool ,” S. Karecki, L. Pruette, R. Reif, T. Sparks, L. Beu, and V. Vartanian; Journal of the Elect rochemical Society , Vol. 145, No. 12, pp. 4305–4312, December 1998. [22] “ Evaluation of Pentafluoroethan e and 1,1-Difluoroethane for a Di electric Etch Application in a High Density Plasma Etch Tool ,” S. Karecki, R. Chatterjee, L. Pruette, R. Reif, T. Sparks, L. Beu, and V. Vartanian, Japanese Journal of Applied Physics , Part 1: Regular Papers, Short Notes & Review Papersm, Volume 39, Issue 7B, pp. 4666–4686, July 2000. [23] “ Evaluation of Hexafluoroben zene as an Environmentally Benign Dielectric Etch Chemistry ,” R. Chatterjee, S. Karecki, R. Reif, T. Sparks, V. Vartanian, and B. Goolsby, Journal of the Elect rochemical Society , Volume 148, Issue 12, pp. G721–G724, December 2001. [24] “ SiO 2 Etching with Perfluorobutadiene in a Dual Frequency Plasma Reactor ,” R. d’Agostino , E. Fornelli , F. Illuzzi , and T. Shirafuji, Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films , Volume 21, Issue 3, pp. 638–642, May 2003. [25] “ Reduction of PFC Emissions to the Envir onment Through Advances in CVD and Etch Processes ,” A.D. Johnson, R.G. Ridg eway, and P.J. Maroulis, IEEE Transactions on Semiconductor Manufacturing , 17 , p.491, November 2004. [26] Semiconductor Industry and Supplier Su rvey Results, Laurie Beu (2005). [27] “Intel PFC Recovery Project,” K. Hasserjian, Proceedings of the 1998 Monterey Global Semiconductor Industry Conference on Perfluorocompound Emissions Control , Session 6, Paper #3 (1998). [28] Evaluation of Praxair’s Perfluoroc ompound (PFC) Capture/Recovery System , Technology Transfer #98113600A-ENG, T. Gilliland and C. Hoover, International SEMATECH, December 1998. [29] “Process Gas Recycling System,” T. Hashimoto, Y. Kishida, Y. Shirai, T. Ohmi, M. Itano, and H. Aoyama, Proceedings of the Fifth Inter national ESH Conference of the Semiconductor Industry , Session 11, paper #4, 1998.20

Technology Transfer #05104693A-ENG ISMI [30] “Recovery of Perfluorocompounds (PFCs) fr om Semiconductor Manufacturing Processes Using a Membrane-based System,” M. F oder, R. Wimmer, J. Yang, and T. McCay, Proceedings of the Electrochemical Society , 99–8, p.60, 1999. [31] “On-Site PFC Recovery System for Multiple Tool or Fab-wide Emissions Reduction: An Update of Recent Operations,” M. Foder, G. Crossland, E. Bell, T. Booth, K. Christian, R. Ridgeway, and J. Yang, Proceedings of the SEMICON Southwest 99 A Partnership for PFC Emissions Reductions Seminar , oral paper I (1999). [32] “PFC Emissions Reduction Via Membrane Ca pture and Processing in Semiconductor,” C.H. Ly, R. Daniel, and C. Anderson; Proceedings of the 11 th Annual ISESH Conference , PFC13, 2004. [33] Data provided in 2005 by ESIA, Japan Electronics and Information Technology Industries Association, Korean Semiconductor Industry Association, Taiwan Semiconductor Industry Association, and SIA. [34] Calvin Gabriel, AMD; Ricky McGowan, SEMATECH; and Terry Sparks, Freescale Semiconductor; privat e communication (2005). [35] Unsaturated Fluorocarbon Etching of Ox ide and Low-k Films in High Density and Medium Density Toolsets Technology Transfer #02014234A-TR, R. Chatterjee, R. Reif, T. Sparks, V. Vartanian, L. Mendi cino, and B. Goolsby, January 2002. [36] “ Controlling Defectivity in Advanced Silicon Etch Systems ,” B. Richardson, MicroMagazine.com. [37] e-Mail from Calvin Gabriel, AMD, 2005. [38] “ Wafer Thinning: Techniques for Ultra-Thin Wafers ,” M. Reiche, G. Wagner; Advanced Packaging , March 2003. [39] “ SEMATECH Pushes 3D Interconnects ,” J. Chappell, Electronics News , March 26, 2004. [40] VLSI Research Inc., Silicon Demand Forecast , Doc: 327031v5.06.1, May 2005. [41] Identification of old technology vs. ne w over time obtained through semiconductor industry survey conducted by L. Beu in Spring 2005. [42] Gartner Dataquest, August 2004.21

ISMI Technology Transfer #05104693A-ENG APPENDIX A – Process Optimization/Alternative Processing

A.1 Process Optimization Process optimization uses extr active metrology such as mass spectrometry (MS) and Fouriertransform infrared spectroscopy (FTIR) to mon itor emissions and provide clean end point times that are minimized based on process parameters su ch as chamber pressure, temperature, plasma power, cleaning gas flow rates, and ratios in the case of mixtur es. Chamber cleans are optimized to minimize gas consumption, thereby, loweri ng cost of ownershi p (COO) and reducing perfluorocompound (PFC) emissions. Cleans optimiza tion is primarily app licable to chemical vapor deposition (CVD) chambers, but the technol ogy can also be applied to etch and other process chambers where PFC cleans ar e performed on a regular basis.

• Technology Status Process optimization can be completed with inte rnal company resources, if available, or by contract.

• Applicability Chamber cleans optimization is applicable to ≤ 150 mm, 200 mm, and 300 mm CVD reactors and to other proce ss tools using regular PFC chamber cleans. A significant amount of work has been previously published on optimization of Novellus Concept One and Applied Materials P5000 chamber cleans.

• Pros

– In addition to reducing PFC emissions by up to 50%, process optimization requires no capital and results in decreased COO (up to 50%) due to reduced chemical usage and increased throughput.

• Cons

– Process requalification may be necessary.

• Reported Results

Clean Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process C 2 F 6 33–55 7–30 (CF 4 ) 20–50

NF 3 (in situ) 60 → 70 0–4 (CF 4 ) Depending on carbon content of film removed 20–40

NF 3 (remote) > 98 0–4 (CF 4 ) Depending on carbon content of film removed >95–99

• Cost of Ownership COO reductions of 20–50% are achievable.22

Technology Transfer #05104693A-ENG ISMI • Recent Publications on PFC Process Optimization G. Loh, Y. Osaki, and M. Mocella, “P erfluorocompound (PFC) Emission Reduction in Existing Plasma Enhanced Chemical Vapor Deposition (PECVD) Tools,” Proceedings of the 11th ISESH Conference , PFC paper #2, 2004. A.D. Johnson, R.V. Pierce, M.I. Sistern, M. Kencel, R. Sward, and H. Winzig, “ C2F6-based Chamber Clean for Silane Plasma Enhanced Chemical Vapor Deposition (PECVD) , International Semiconductor , 27 (3), p.57, March, 2004. Y-d Yoo, “Perfluorocompound (PFC) (C 3 F 8 ) Emission Reduction by Optimizing Cleaning Process,” Proceedings of the 10 th Annual ISESH Conference , 2003. A.D. Johnson, R.G. Ridgeway, and P.J. Maroulis, “ Reduction of Perfluorocompound (PFC) Emissions to the Environment Through Advances in Chemical Vapor Deposition (CVD) and Etch Processes ," IEEE Transactions on Semiconductor Manufacturing , 17, p.491, 2004. V. Vartanian, B. Goolsby, R. Chatterjee, R. K achmarik, D. Babbitt, R. Reif, E. Tonnis, and D. Graves, “ Reduction of Semiconductor Process Emissions by Reactive Gas Optimization ,” IEEE Transactions on Semiconductor Manufacturing , 17, p.483, 2004.

• Contacts Robert Ridgeway, Air Products and Chemicals, Inc., 610-481-4436, ridgewrg@airproducts.com Gary Loh, DuPont, 302-999-4971, gary.loh@dupont.com

• References Information on process optimization was pr ovided by SIA member companies including Laura Mendicino of Freescale Semiconductor, by Francesca Illuzzi of STMicroelectronics, Robert Ridgeway of Air Products & Chem icals, Inc. and Gary Loh of DuPont.

A.2 Endpoint Detection

• General Technology Description Endpoint detection uses techniqu es such as MS, infrared (IR) spectroscopy, optical emission spectroscopy (OES), and radio frequency (R F) impedance monitoring to monitor changes and provide plasma process end point times. PFC gas consumption and emissions can be minimized by determining chamber clean end points and optimizing process parameters such as chamber pressure, temperature, plasma power, cleaning gas flow rates, and ratios in the case of mixtures. Endpoint detection has been used extensively for CVD chamber cleans, but the technology can also be applied to etch and other PFC plasma processes.

• Technology Status Commercially available for use in ≤ 150 mm, 200 mm, and 300 mm CVD and etch reactors. Many process tool suppliers offer supplier supported endpoint de tection systems and processes. Endpoint detection can al so be installed as a retrofit.

• Applicability Endpoint detection is applicable to ≤ 150 mm, 200 mm, and 300 mm CVD and etch reactors.23

ISMI Technology Transfer #05104693A-ENG • Pros

– Reduced PFC emissions due to decreased process time.

– Decreased COO.

– Possible increase in process throughput.

• Cons

– As a retrofit, endpoint detector must be purchased and installed which could require capital expenditure.

• Reported Results An un-named SIA member company reports 40% PFC emissions reduction from baseline process for ≤ 150 mm and 200 mm Applied Ma terials and Novellus C 2 F 6 -based cleans. Philips reports PFC emission reductions of 29–53% and C 2 F 6 gas usage reductions of 34– 47% on borophosphosilicate glass from a TEOS oxysilane source (BPTEOS), undoped silicate glass (USG), and SiN clean processes

• Recent Publications R. Dam, “Optimization of C 2 F 6 -based Plasma Enhanced Chemical Vapor Deposition (PECVD) Chamber Cleaning Process Minimi zing Perfluorocom pound (PFC) Emissions and Operating Costs on a Novellus C-2 Platform,” Proceedings of the 10th Annual ISESH Conference , (2003).

• References Information provided by Harry Thewissen of Philips and an SIA member company.

A.3 Remote Plasma Cleans

• General Technology Description Remote plasma clean technology was developed as an alternative to in situ CVD chamber cleans to clean the deposition byproducts left in the chamber after wafer processing. With remote chamber clean, a plasma-generating un it is mounted on the lid of a CVD chamber. Remote cleans typically react NF 3 or C 3 F 8 in a plasma. The fluorine radicals and ions generated in the remote plasma unit are ro uted to the processing chamber where they chemically react with deposits. The deposition byproducts are then carried away in gaseous form, e.g., SiF 4 .

• Applicability This technology is commercially available for 200 mm and 300 mm CVD chamber cleans. Remote cleans is the process of record (P OR) for Applied Materials advanced 200 mm and 300 mm PECVD chamber cleans. Se veral suppliers manufacture or integrate remote plasma systems for retrofits to existing proce ss tools to replace in situ PFC cleans.

• Pros

– Commercially available technology from seve ral suppliers that reduce chamber clean PFC emissions by 99%.

– Significantly reduced PFC emissions from CVD chamber cleans.24

Technology Transfer #05104693A-ENG ISMI – Remote cleans result in imp roved tool utilization through reduced clean times, reduced wet clean frequency, improved mean time be tween failures (MTBF), reduced chamber parts costs. Additionally, they improve yi eld through reduced de fects and decrease COO.

– CVD tools not equipped with remote cleans ma y be retrofitted with remote cleans.

• Cons

– Implementing NF 3 remote cleans results in ge neration of much greater F 2 and HF emissions than fluorocarbon-based cleans, and requires additional treatment to remove these gases from the exhaust stream.

– Point-of-use (POU) abatement may be necessary in fabs where house scrubber infrastructure is not sufficient to abate the HF/F 2 generated.

– Coated stainless steel ductwork may be required.

– Little information is publicly available on retrofits to non-Applied Materials tools.

• Typical Remote Plasma Required Utilities Argon, NF 3 , or other PFC, electricity, process c ooling water (PCW), toxic gas monitoring for NF 3 .

• Reported Results

PFC Utilization Efficiency (%) % PFC Emissions Reduction From Baseline Process NF 3 >95–99 >15–99 C 3 F 8 >95 >35

• Byproducts Remote cleans converts NF 3 and other PFC into F+ ions and radicals. Units generate significant emissions of F 2 and HF that must be abated. When using NF 3 to clean carboncontaining low-k chambers, a small amount of CF 4 is generated. No information is available on byproducts when using PFCs other than NF 3 as input gas.

• Cost Contact suppliers for cost information.

• Remote Plasma Unit Manufacturers or Integration Specialists

– New Power Plasma Co., Ltd. produces remote high-density plasma generators that decompose NF 3 or C 3 F 8 for CVD chamber cleaning. http://newpower.co.kr

.

– MKS Instruments, Inc. produces the ASTRON family of integrated remote plasma sources with flow rates of 2.0 slm up to 15 slm for semiconductor and flat panel CVD chamber cleaning. In addition to NF 3 , ASTRON hf-s series generators can dissociate alternative PFC gases such as C 2 F 6 , C 3 F 8 , CF 4 , or SF 6 . http://www.mksinst.com/ PRG1.html

.25

ISMI Technology Transfer #05104693A-ENG – LegacyTek offers a remote clean retrofit integration package to Applied Materials P5000 DxL and Centura DxZ 200 mm chambers ; they are currently seeking beta partners to integrate remote cleans on N ovellus tools. The LegacyTek upgrade package includes an MKS Instruments Astron or As tron-I remote plasma unit, integration package, installation and process startup. http://legacytek.com/index.htm

.

• Recent Publications L. Mendicino, P. T. Brown, S. Filipiak, C. Naue rt, H. Estep, M. Fletcher, A. Atherton, and T. Nowak, “Fab Impacts of Implementation of Remote Clean for CVD Chamber Clean,” Proceedings of the SEMICON Southwest – A Partnership for PFC Emissions Reduction Workshop , oral paper #6 (2001). W. Worth, “Evaluation of Applied Materi al's Remote Clean Technology for Chamber Cleans and its Impact on a Fab’s Wastewater Treatment Facilities,” Proceedings of the 8th ISESH Conference , paper 20.3C.3, ECSv2002-15, p. 127, 2001. S. Bailey, M. Goulding, L. Tousignant, L. Zazzera, and S. Shao, “Evaluation of an MKS ASTRONex and C 3 F 8 for Remote Plasma Chamber Clean,” Proceedings of the SEMICON West 2002 STS Symposium , session 104, paper #2, 2002. ECS v2002-15, p. 144. G. Loh, Y. Osaki, and M. Mocella, “Remot e Plasma Chamber Cleaning with the MKS ASTRONex Unit,” Proceedings of the 11th ISESH Conference , PFC paper #4, 2004.

• References Information on remote cleans provided by La ura Mendicino of Frees cale, Wang-Keun Kim of Samsung, and Chris Lewis of LegacyTek. A dditional information obtained from websites of New Power Plasma Co. and MKS Instruments, Inc.

A.4 Alternative Chemistry Alternative chemistry, or chemical substitution, is the use of chemicals with lower global warming potential (GWP) or no GWP as alternatives to PFCs. Alternative chemistry also includes high GWP gases that are more efficientl y used in plasma processes, resulting in an overall greenhouse gas emissions reduction.

• Technology Status In research and development and commercially available.

• Pros

– Alternative chemistries reduce total PFC emissions.

– Drop-in chamber clean alternatives can be im plemented with little to no additional cost and do not require additional ES H measures to be installed.

– Alternative chemistries may al so provide process benefits.

– Implementing alternative chemistries can result in decreased gas consumption and improved COO.26

Technology Transfer #05104693A-ENG ISMI • Cons

– Implementing an alternative chemistry may re quire process re-qualification, especially for etch processes where the wafer is affected.

– Certain alternatives increase ESH risk a nd require additional e ngineering controls.
A.4.1 Chamber Clean Alternatives a) Hexafluoroethane (C 2 F 6 ) for PECVD Chamber Cleans CF 4 was the original POR for cleaning certa in 150 mm PECVD process chambers. CF 4 utilization efficiency in chamber cleans is reported as 0.2. One semiconductor company has reported replacing CF 4 with hexafluoroethane (C 2 F 6 ), resulting in a >57% emissions reduction due to decreased input gas consum ption and more efficient PFC utilization.

• Applicability and Status
≤ 150 mm and 200 mm CVD chamber clean. Comme rcially available and currently in
use.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of gas input (%) (mass/mass) % PFC Emissions Reduction from Baseline C 2 F 6 Process C 2 F 6 17–24 11–13 (CF 4 ) >57

• Cost No cost to implement unless pr ocess re-qualific ation required.

• Pros

– Significantly reduced PFC emissions from CVD chamber cleans.

• Cons

– May require process re-qualification.

– Other alternative chemistries may results in greater PFC emissions reductions.

• Recent Publications N/A

• References Information received from an SIA member company.27

ISMI Technology Transfer #05104693A-ENG b) Octofluoropropane (C 3 F 8 ) for PECVD Chamber Cleans C 2 F 6 was the original POR used to clean th e majority of 150 mm and early 200 mm PECVD process chambers. Industry memb ers are using octofluoropropane (C 3 F 8 ) as an alternative to C 2 F 6 . C 3 F 8 has a higher destruction removal efficiency (DRE) compared to C 2 F 6 that can result in decreased gas consumption and emi ssions. Recent process optimization has resulted in decreased CF 4 byproduct by optimizing the C 3 F 8 /O 2 ratio.

• Applicability and Status
≤ 150 mm and 200 mm CVD chamber cleans. Comme rcially available and currently in use as a retrofit in manufacturing fabs. Novellus has developed C 3 F 8 chamber clean PORs for Novellus Concept One and C oncept Two SiN, SiON, SiO, and TEOS processes.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process C 3 F 8 30–60 12–30 (CF 4 ) 12–70

• Cost No cost to implement unless process re- qualification required. Pr ocess results in a decreased COO of 20–65%.

• Pros

– No capital cost drop-in replacement.

– Equivalent clean times.

– Reduced PFC emissions from CVD chamber cleans.

– Reduced COO.

• Cons

– May require process requalification.

– Can result in significant CF 4 byproducts.

– Other alternative chemistries may result in greater PFC emission reductions.

• Recent Publications S. Kesari, T. Bach, L. Tousignant, W. Reagen, and L. Zazzera, “Process Optimization and PFC Emission Reduction Using C 3 F 8 Chamber Clean Processes in Applied Materials P-5000 PECVD Tools,” 2 nd International Symposium on Environmental Issues with Materials and Processes for Electronics and Semiconductor Industries, Electrochem. Soc. Proceedings , L. Mendicino, Editor, 1999.

• References Information received from SIA member companies including Bronwyn Pierce of HP.28

Technology Transfer #05104693A-ENG ISMI c) Octofluorocyclobutane (c-C 4 F 8 ) for PECVD Chamber Cleans c-C 4 F 8 is being used to replace C 2 F 6 and other fluorocarbon chamber clean chemistries. c-C 4 F 8 dissociates more clean gas when compared to C 2 F 6 and certain other fluorocarbon chemistries. Clean process uses more O 2 , but reduces CF 4 formation.

• Applicability and Status
≤ 150 mm and 200 mm CVD chamber clean. Comme rcially available and currently in use as a retrofit in manufacturing fabs.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process c-C 4 F 8 70–90 4–11 (CF 4 ) 50–85

• Cost No/low cost to implement unless proce ss re-qualification required. Existing perfluorocarbon gas line can be used; mass flow controller (MFC) size may need to be reduced due to much lower c-C 4 F 8 gas flow.

• Pros

– Drop-in replacement resulting in reduced PECVD chamber clean PFC emissions.

– 20–75% decrease in COO due to decreased gas requirements.

• Cons

– May require process re-qualification.

– Generates CF 4 byproduct.

– Other alternatives may result in greater PFC emission reductions.

• Recent Publications E.M. Chan, G. Loh, and C.C. Allgood, “ Process Optimization and Perfluorocompound (PFC) Emission Reduction Using a c-C4F8 Chamber Cleaning Process on a Novellus Concept 1 Dielectric Plasma Enhanced Chemical Vapor Deposition (PECVD) Tool ,” IEEE Transactions on Semiconductor Manufacturing , 17 , p.497, 2004. K. Avala, L. Liu, D. Brindza, G. Loh, and S.A. Moiyadi, “ Reduced Perfluorocompound (PFC) Emissions and Gas Consumption Us ing a c-C4F8-based Plasma Enhanced Chemical Vapor Deposition (PECVD) Chamber Clean Chemistry ,” IEEE Transactions on Semiconductor Manufacturing , 17 , p.504, 2004. C. Allgood, M. Mocella, H. Chae, and H. Sawin, “ Evaluation of Octafluorocyclobutane as a Chamber Clean Gas in a Silicon Di oxide Plasma Enhanced Chemical Vapor Deposition (PECVD) Reactor ,” J. Electrochem. Soc. , 150 , G122, 2003.29

ISMI Technology Transfer #05104693A-ENG C.H. Oh, N.-E. Lee, J.H. Kim, G.Y. Yeom, S.S. Yoon, and T.K. Kwon, “ Effect of N-containing Additive Gases on Global Warming Gas Emission During Remote Plasma Cleaning Process of Silicon Nitride Plasma Enhanced Chemical Vapor Deposition (PECVD) Chamber Us ing C4F8/O2/Ar Chemistry ,” Surface and Coatings Technology , 171 , p.267, 2003. A. Evans, L. Nevala, M. Sledz, a nd C.C. Allgood, “Advances in Reducing Perfluorocompound (PFC) Emissions and Gas Costs: Qualification of c-C 4 F 8 Chamber Clean in a Novellus Concept-2 Chemical Vapor Deposition (CVD) Tool,” Proceedings of the 9th Internat ional Semiconductor ESH Conference , PFC Session A, Paper #1, 2002. A. Evans, L. Nevala, and C. Allgood, “Advances in Reducing Perfluorocompound (PFC) Emissions and Gas Costs: Qua lification and Impl ementation of c-C 4 F 8 Chamber Clean Gas in a Novellus Concept-2 Chemical Vapor Deposition (CVD) Tool,” Proceedings of the SEMIC ON Southwest PFC Seminar , Session 3, Paper 3, 2002.

• References Information received from an SIA member company, Francesca Illuzzi of STMicroelectronics, and Gary Loh of DuPont. Gary Loh Gary.loh@usa.dupont.com 304-999-4971
d) Octafluorotetrahydrofuran (C 4 F 8 O) for PECVD Chamber Cleans C 4 F 8 O is currently being used to re place perfluorocarbons such as C 2 F 6 and C 3 F 8 in PECVD chamber cleans. C 4 F 8 O is an alternative chamber clean chemistry with higher DRE, resulting in reduced gas consumption. Highe r DRE and reduced consumption lead to reduced PFC emissions and lower COO.

• Applicability and Status
≤ 150 mm and 200 mm CVD chamber clean. Comme rcially available and currently in use as a retrofit in manufacturing fabs.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process
C 4 F 8 O 85–90 10–20 (CF 4 ) 4 (C 3 F 8 ) 70–90

• Cost No cost to implement unless process re- qualification required. Sp ecial attention is required for monitoring corrosion effects of reactor parts. Weight monitoring is recommended for cylinder fill information. Lo w-pressure regulators at gas cabinet are recommended.30

Technology Transfer #05104693A-ENG ISMI • Pros

– Drop-in replacement with significantly reduced PFC emissions from CVD chamber cleans.

– 20–50% reduction in COO.

• Cons

– May require process re-qualification.

– Monitoring of parts for corro sion effects is necessary.

– Generates CF 4 byproduct, although at a lower rate than some alternatives.

• Recent Publications K.J. Kim, C.H. Oh, N.-E. Lee, J.H. Kim, J.W. Bae, G.Y. Yeom, and S.S. Yoon, “Global Warming Gas Emission During Plasma Cleaning Process of Silicon Nitride Using c-C 4 F 8 O Feed Gas with Additive N 2 ,” Han'guk Pyomyon Konghak Hoechi , 34 , 403, 2001; Chem. Abstr. , 138 , 94335, 2003. C.H. Oh, N.-E. Lee, J.H. Kim, G.Y. Ye om, S.S. Yoon, and T.K. Kwon, “Increase in Cleaning Rate and Reduction in Global Warming Effect During C 4 F 8 O/O 2 Remote Plasma Cleaning of Silicon Nitride by Adding NO and N 2 O,” Thin Solid Films , 435 , 264, 2003. D. Harman, J. Flood, and E. Frendberg, “Evaluation of C 4 F 8 O as an Alternative Material in Chemical Vapor De position (CVD) Chamber Cleaning,” Proceedings of the 9th International Semiconductor ESH Conference , PFC Session A, Paper #4, 2002. D. Harman, J. Flood, and E. Frendberg, “Evaluation of C 4 F 8 O for Chemical Vapor Deposition (CVD) Chamber Cleans,” Proceedings of the SEMICON West 2002 STS Symposium , Session 104, Paper #3, 2002. J.H. Kim, J.W. Bae, C.H. Oh, K.J. Kim, N.E. Lee, and G.Y. Yeom, “C 4 F 8 O/O 2 /N-based Additive Gases for Silicon Nitride Plasma Enhanced Chemical Vapor Deposition (PECVD) Chamber Cleaning with Low Global Warming Potentials,” Jpn. J. Appl. Phys. , 41, p. 6570, 2002. R. Van San, S. Kesari, and L. Zazzera, “Evaluation and Qualification of C 4 F 8 O as an in situ Cleaning Gas for Plasma Enha nced Chemical Vapor Deposition (PECVD) Tools,” SEMI Conference Proceedings – A Partnership for PFC Emission Reduction , SEMICON Southwest, October 2000.

• References Information received from Harry Thew issen of Philips Semiconductor, Francesca Illuzzi of STMicroelectronics, and an SIA member company.31

ISMI Technology Transfer #05104693A-ENG e) Nitrogen Trifluoride (NF 3 ) for in situ PECVD Chamber Cleans NF 3 is currently being used in manufacturi ng fabs as a replacement for in situ perfluorocarbon PECVD chamber cleans. Additiona lly, Novellus is using dilute in situ NF 3 cleans for their advanced 200 mm and 300 mm tools. NF 3 has a high DRE when used in plasma; moreover, unlike fluorocarbons, NF 3 does not generate CF 4 byproduct unless it is used to clean carbon-containing films. When compared to C 2 F 6 , NF 3 cleans require less clean gas and result in faster clean times.

• Applicability and Status Commercially available and curren tly in use as a retrofit for ≤ 150 mm and 200 mm CVD chamber clean. POR on advanced 200 mm and 300 mm Novellus tools. NF 3 is also used for thin film transistor liquid crystal display chamber cleans.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process

NF 3 60–80 0–4 (CF 4 ) Depending on carbon content of film removed 20–90

• Cost Toxic gas monitoring and additional safety measures may be necessary. Upgraded exhaust duct and point-of-use fluorine abatement may be needed.

• Pros

– Significantly reduced PFC emissions from CVD chamber cleans.

– Unlike fluorocarbons, NF 3 does not generate CF 4 byproduct unless it is used to clean carbon-containing films.

• Cons

– In situ NF 3 is not a drop-in replacement; NF 3 is an oxidizer and has a lower LD50 than C 2 F 6 .

– Toxic gas monitoring may be necessary.

– Clean process may result in higher emissions of HF and F 2 as well as NO x .

– ESH controls such as local scrubbin g may be required; additionally, one semiconductor manufacturer recommended in stallation of coated stainless steel exhaust duct.

– Monitoring of parts for corro sion effects is necessary.

– May require process requalification.

• References Information received from SIA member companies.32

Technology Transfer #05104693A-ENG ISMI f) Carbonyl Fluoride (COF 2 ) for PECVD Chamber Cleans COF 2 is a toxic gas with low GWP and no ozone depletion potential. From 1998–2002, Japan’s Research Institute of Innovation T echnology for the Earth undertook an effort to identify alternative chamber clean ch emistries, eventually recommending COF 2 as a replacement gas. With a GWP of 1, COF 2 has a much lower global warming potential than PFCs used for chamber cleans. Although COF 2 is toxic, it is easily removed from the exhaust stream by water scrubbing. When us ed in plasma, a small amount of CF 4 byproduct is produced. Recent efforts in Japa n have focused on evaluating COF 2 in manufacturing applications.

• Applicability
≤ 150 mm and 200 mm CVD chamber clean. Currently undergoing evaluation in manufacturing fabs in Japan.

• Reported Results At the 12 th ISESH Conference held in 2005, Japan Electronics and Information Technologies Industries Association members presented results of COF 2 evaluations as alternatives to C 2 F 6 and C 3 F 8 cleans in manufacturing environments. On a 200 mm Novellus Concept Two running PETEOS. Panasonic reports that COF 2 cleans resulted in a 96% PFC emission reduction and equivale nt cleaning performance when compared to C 2 F 6 with no adverse affect to the tool . On a Novellus Concept One depositing silicon nitride film on ei ghty thousand 125 mm and 150 mm bipolar wafers, Sanyo reported a 97% PFC emission reduction and no technical difficulties when compared to the baseline C 3 F 8 process. CF 4 byproduct was between 1.2–1.8%.

• Cost Although not listed in conference proceed ings, a gas cost of 20,000Yen/kg was mentioned at the 12 th Annual ISESH Conference. Additi onal ESH controls are required. Incompatibilities may require re-piping pro cess gases into the chamber. POU scrubbing may be required.

• Pros

– 96–97% reduction in PE-CVD chamber clean PFC emissions.

– Faster clean times.

• Cons

– High gas cost.

– Additional ESH controls required.

– Sanyo notes that, because reactivity with NH 3 is high, separate gas lines into the chamber must be installed to prevent inadvertent mixing.

– May require process requalification.33

ISMI Technology Transfer #05104693A-ENG • References M. Sakamura, T. Minegishi, and M. Yomoda, “Evaluation of COF 2 in Mass Production Line,” 12 th Annual ISESH Conference , June, 2005. S. Ueda, K. Takahashi, T. Matsubara, and H. Nikou, “Investigation of an Alternative Gas COF 2 Application for Chemical Vapor Deposition (CVD) Chamber Cleaning Process,” 12 th Annual ISESH Conference , June, 2005. Y. Mitsui, “Alternative Gas for Chemi cal Vapor Deposition (CVD) Cleaning COF 2 ,” 12 th Annual ISESH Conference , June, 2005.
g) Fluorine (F 2 ) for CVD Chamber Cleaning F 2 has been discussed as a po ssible alternative to PFCs for CVD chamber cleaning but had been discarded as a serious alternative in th e past due to the ESH risks associated with transport, storage, and use of high-pressure F 2 cylinders. BOC-Edwards and Fluorine on Call, Ltd. have each developed onsite fluorine ge nerators that convert anhydrous HF into F 2 by electrolysis. After the F 2 is generated, it is purified to remove residual HF and other contaminants. It can then be fed into PECVD chambers for plasma-enhanced in situ cleans. Samsung reports evaluating in situ generated F 2 to replace NF 3 for low-pressure chemical vapor deposition (LPCVD) or CVD chamber clean ing on 300 mm tools. This evaluation is in the research and development stage.

• Applicability
≤ 150 mm, 200 mm, 300 mm and thin film tr ansistor liquid crystal display CVD chamber cleans. Processes are currently in R&D.

• Cost Contact suppliers for cost of on site F 2 generators. Although additional engineering controls are required, Samsung anticipates that replacing NF 3 with onsite generated fluorine will result in 20% cost savings due to reduced chemical and operational costs.

• Pros

– While anhydrous HF is t oxic and corrosive and F 2 is highly toxic and a strong oxidizer, neither of these gases are global warming gases.

– No PFC emissions will be generate d during CVD chamber cleans unless F 2 is used to remove carbon-containing films.

• Cons

– Fluorine generation and use poses additional ESH risks that must be addressed when designing installation site , piping, and generator system.

– POU abatement may be required to abate F 2 emissions from chamber clean.34

Technology Transfer #05104693A-ENG ISMI • Recent Publications S. Siegele, D. Hage, and F. Siegele, “ On-Site Generation of High Purity Fluorine (F2) as a Safe and Economical Alternative for Chemical Vapor Deposition (CVD) Chamber Cleaning ,” FutureFab International, Issue 13, July, 2002. Generation-F 80 Onsite Fluorine Generator , BOC-Edwards Product Data Sheet.

• References Information received from Wang-Kim Keun of Samsung, Chris Case of BOC-Edwards, and Dan Hage of Fluorine on Call, Ltd. Chris Case Chris.Case@bocedwards.com 908-771-6409 Dan Hage dhage@focltd.com 512-329-8866
A.4.2 Alternative Etch Chemistries While replacement of high GWP gases with lowe r or non-GWP gases is generally preferable, it has not proven feasible in most plasma etch applications. Processing requirements for high aspect ratio plasma etching continue to become more stringent, requiring both fluorine to etch and the right carbon to fluorine ratio to ensure anisotropic etching. A significant amount or research has been done on alternative etchan ts such as iodofluorocarbons, hydrofluorocarbons, and unsaturated fluorocarbons; however, many of these chemicals are not viable alternative etchants in a manufacturing environment due to excess polymerization, lack of etch selectivity, difficulties in delivering gases to the proce ss chamber, and potential increased employee exposure risks. One alternative that is being im plemented in manufacturing is C 4 F 6 , which is being used as a dielectric etch gas for advanced ULSI integration, replacing CF 4 , CHF 3 , and C 4 F 8 .

• Applicability C 4 F 6 is being used in advanced 200 mm and 300 mm manufacturing fabs for oxide and low-k etching where high selectivity for silicon is required in the presence of nitride or other films with high aspect ratios, thinner re sists and less etch resistant resists.

• Reported Results

Replacement

Chemistry Utilization Efficiency (%) PFC Byproduct Generation as % of Gas Input (%) (mass/mass) % PFC Emissions Reduction From Baseline C 2 F 6 Process C 4 F 6 > 95 5–10 (CF 4 ) >90 in some cases

• Pros

– C 4 F 6 is a process enabling technol ogy for CD control and etch selectivity and, with an atmospheric lifetime <1 year and utilizati on efficiency >95%, PFC emission reductions >90% can be achieved.35

ISMI Technology Transfer #05104693A-ENG – C 4 F 6 can be implemented as an alternative chemistry using existing hardware and gas lines; however, toxic gas m onitoring may be needed.

• Cons

– As is the case with all higher molecular weight fluorocarbon compounds used in plasma processes, some CF 4 byproduct is formed and emitted.

• Recent Publications S. Karecki, L. Pruette, R. Reif, T. Sparks, L. Beu, and V. Vartanian, “ Use of Novel Hydrofluorocarbon and Iodofluorocarbon Chemis tries for a High Aspect Ratio Via Etch in a High Density Plasma Etch Tool ,” Journal of the Electrochemical Society , Vol. 145, No. 12, December 1998. S. Karecki, R. Chatterjee, L. Pruette, R. Reif, T. Sparks, L. Beu, and V. Vartanian,

“ Evaluation of Pentafluoroe thane and 1,1-Difluoroethane for a Dielectric Etch Application in a High Density Plasma Etch Tool ,” Jpn. J. Appl. Phys ., 39, Part 1 (7B), 4666–4686, July 2000. R. Chatterjee, S. Karecki, R. Reif, T. Sparks, V. Vartanian, B. Goolsby, “ Evaluation of Hexafluorobenzene as an Environmentall y Benign Dielectric Etch Chemistry ,” Journal of The Electrochemical Society , Volume 148, Issue 12, pp. G721–G724, December 2001. F. Fracassi, R. d'Agostino, E. Fornelli , F. Illuzzi, and T. Shirafuji, “ SiO2 Etching with Perfluorobutadiene in a Dual Frequency Plasma Reactor ,” Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Film s, Volume 21, Issue 3, pp. 638–642, May 2003. A.D. Johnson, R.G. Ridgeway, and P.J. Maroulis, “ Reduction of Perfluorocompound (PFC) Emissions to the Environment Through Advances in Chemical Vapor Deposition (CVD) and Etch Processes ,” IEEE Transactions on Semiconductor Manufacturing , 17, p. 491, November 2004.

• References Information on C 4 F 6 was provided by Ajay Somani of MIT, Laura Mendicino and Victor Vartanian of Freescale Semiconductor, a nd Robert Ridgeway of Air Products and Chemicals, Inc. Robert Ridgeway ridgewrg@airproducts.com 610-481-443636

Technology Transfer #05104693A-ENG ISMI A.5 Capture/Recovery
A.5.1 Air Liquide PFC Capture and Recycle In 2003, Air Liquide installed a compact membra ne capture and recirculation system for SF 6 at a power IC manufacturer. The IC manufacturer uses SF 6 as a blanket gas during IC testing. A mixture of 60% SF 6 and 40% air is exhausted from the te sters. The Air Liquide unit compresses the exhaust stream, which is then fed into two membrane separation units. Because the SF 6 is being used as a blanket gas, not as a plasma etchant, byproducts requiring pre-treatment are not present in the exhaust stream. Air Liquide reports an 89% SF 6 recovery rate at >99% purity. Recovered SF 6 is fed back into the testers.

• Project Status System is in operation and Air Liquide reported in 2004 that the system had paid for itself in related cost savings.

• Applicability The Air Liquide membrane separation system ha s a modular design for a wide range of PFC flow rates. It appears to be most cost eff ective when used for specialized, single PFC, high volume processes. The lack of plasma and ot her process byproducts in this particular application makes capture-recovery relativel y straightforward and cost effective.

• Pros

– Cost effective and environmentally prefe rred method for addressing emissions from clean, high volume, single PFC processes.

• Cons

– Centralized PFC capture/recovery has not been implemented in semiconductor manufacturing because it has been deemed t oo costly to implement due to pretreatment requirements and decreasing PFC concentr ations over time in the exhaust.

• References C-H Ly, R. Daniel, and C. Anderson, “P erfluorocompound (PFC) Emission Reduction Via Membrane Capture Processing in Semiconductor,” 11th Annual ISESH Conference , 2004.

A.6 Abatement
A.6.1 PFC Abatement – POU Fueled Burner – Scrubber Units

• General Technology Description Point-of-use fueled burner-scrubber units use a propane, methane, natural gas or hydrogen flame to destroy PFCs and other hazardous substances such as deposition precursors followed by a water scrubber, which may contai n a base solution, to remove volatile acid gases from the exhaust stream. Burner-scrubbe r units are installed on the process tool exhaust line after the vacuum pump and, thus, th e exhaust stream entering the unit contains a large amount of nitrogen (from pump purge and ballast) that can lower the combustion unit37

ISMI Technology Transfer #05104693A-ENG temperature, thus, typically requiring the addition of oxygen to the reach flame temperatures high enough to destroy the carbon based PFCs and SF 6 . Burner-scrubber units can typically abate emissions from multiple process chambers.

• Applicability Both CVD and etch effluents from ≤ 150 mm, 200 mm, and 300 mm process tools can be treated with the bur ner-scrubber units.

• Pros

– Commercially available from multiple suppliers

– Technology that abates both etch and CVD chamber clean PFC emissions at ≥ 95% DRE and removes HF, generated as a result of burning PFCs, from the exhaust stream.

– Fueled systems destroy F 2 , converting it into HF, and scrub the HF byproduct.

– Units are capable of abating emissions from multiple process chambers.

– Largest installed base of abatement systems in the industry.

• Cons

– Requires H 2 or natural gas (NG) fuel. Generate s HF liquid waste stream which may require further treatment before discharge.

– May generate NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and either H 2 or NG, which may not be inst alled as a service utility.

• Manufacturers of Burner-Scrubber Units Without Detailed Information in this Appendix

– ATTO Co, Ltd., produces modified Centroth erm abatement devices for the Korean market. http://atto.co.kr/2 004e/product/pro_012_04.htm

– Global Standard Technology Co., Ltd., comp any produces modified DAS abatement systems for the Korean market. http://www.gst-in.com/contents/business/product/ product01/0111.asp

– UNI-SEM, Korean manufacturer of UN2000- A thermal oxidizer with wet scrubber using H2 as fuel. The footprint is 750 mm × 870 mm × 2262 mm. http://uni-sem.com/ html/pfcmain.html
a) BOC Edwards Thermal Processor Unit (TPU)

• Description The TPU is a point-of-use abatement devi ce, installed post-vacuum pump, which utilizes an inwardly fired combustor follo wed by a three-stage wet scrubber and using proprietary combustion methods to ensure maximum DRE of PFCs and process gases. The TPU operates in two modes: high fire and low fire. In high fire mode, higher flows of fuel and O 2 are injected to abate PFCs (w ith communication between process equipment and the TPU). The footprint is 1300 mm × 625 mm × 1833 mm. Addition of38

Technology Transfer #05104693A-ENG ISMI the scrubber water recirculati on unit (WRU) increases width to ∼ 1600 mm. The unit is installed downstream of the vacuum pumps and can handle effluent from multiple chambers (up to four) with a maximum flow capacity of 200 slm.

• Technology Status Commercially available.

• Applicability Both CVD and etch effluents can be treated with the TPU. Tool can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities Electricity, water ( ∼ 6 gpm), natural gas, N 2 , O 2 , acid waste drain, acid scrubbed exhaust, and general exhaust. Scrubber wa ter consumption can be reduced to <1 gpm makeup water by installing the WRU. The WRU requires cooling water.

• Reported Results DRE (%) PFC Maximum PFC Input Flow Rate (sccm) * # ^
NF 3 6000# > 95 99.99 99 SF 6 12000# 90 to > 905 99.9 95 C 2 F 6 2500–10000* / 6400# 85 to > 95 99.9 95 CHF 3 6000# 90 99.99 99 C 4 F 8 6000# 95 99.9 99 C 3 F 8 6400# 99.9 99.9 95 CF 4 2000* / 6000# 90–96 93 90 CH 2 F 2 3300 mg/m 3 * > 95* C 5 F 8 900 mg/m 3 * > 90* * Performance reported by semiconductor manufacturers # Supplier reported performance ^ Supplier guaranteed

• Byproducts Byproducts of combustion for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. NO x is emitted at ∼ 75 ppm/inlet while destroying CF 4 due to high operating temperature. NF 3 combustion results in formation of N 2 , HF, and NO x . One semiconductor manufacturer reports CO emissions at ∼ 50 mg/m 3

.

• Cost of Technology (provided by supplier) $120,000 USD per unit.39

ISMI Technology Transfer #05104693A-ENG • Cost of Ownership TPU requires replacement of seals, gaskets, and combustor (depends on process) as needed for annual PM. Consumable costs are variable and can range from ∼ $4000– $8000 USD annually. One semiconductor company noted high cost to operate mainly due to heavy maintenance and consumables. Typical annual facilities costs for operation of the TPU based on Fab Utility Cost Values for Cost of Ownership (COO) Calculations (SEMATECH, Technology Transfer #02034260A-TR) is ∼ $8000 USD.

• Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 93% DRE and removes HF, genera ted as a result of burning PFCs, from the exhaust stream.

– Destroys F 2 and removes the resulting HF.

– Unit is capable of abating emissions from multiple process chambers.

– Established technology with installed base of TPUs in multiple semiconductor facilities in the U.S., Europe, and Asia.

• Cons

– Requires NG, which may not be available as a service utility.

– Generates HF liquid waste stream, which may require further treatment before discharge.

– Abatement of CF 4 and NF 3 generates NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and NG, which may not be in stalled as a service utility.

– Oxygen, which also may not be available as a service utility, or compressed dry air (CDA) may be necessary to abate CF 4 .

• Contact Joe Van Gompel 512-633-5105 joe.vangompel@bocedwards.com

• References Information on the TPU was provided by SIA and ISMI member companies including Bronwyn Pierce of HP, a member of ESIA, and Francesca Illuzzi of STMicroelectronics, and by Joe Van Gompel of BOC-Edwards.40

Technology Transfer #05104693A-ENG ISMI b) BOC Edwards Mini-TPU

• Description The Mini-TPU is a point-of-use abatement device, installed post-vacuum pump, which utilizes an inwardly fired combustor follo wed by a three-stage wet scrubber and using proprietary combustion methods to ensure maximum DRE of PFCs and process gases. It is designed strictly to abate emissions from oxide etch and poly etch processes only and is not suitable for CVD. Maximum exha ust flow rate thr ough the Mini-TPU is 50 slm. The mini-TPU is not sold as a sta ndalone unit but is incorporated with high efficiency vacuum pumps in a package called Zenith Etch that is designed for cost- and space-effective PFC abatement. The total footprint of abatement and pumps is 1300 mm

× 625 mm × 1833 mm.

• Technology Status Commercially available.

• Applicability Oxide and poly etch effluents can be treated with the Mini-TPU. Tool can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities Electricity, water, NG, N 2 , O 2 , acid waste drain, acid scr ubbed exhaust, and general exhaust.

• Supplier Reported Results
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 1000 >99 SF 6 1000 >99 C 4 F 8 1000 >99 CH 2 F 2 1000 >99 C 4 F 6 1000 >99 C 5 F 8 1000 >99 CF 4 1000 93

• Byproducts Byproducts of combustion for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. NO x is negligible for all other PFCs except NF 3 , which realizes about 20% conversion to NO x of NF 3 that actually makes it out of the process chamber and into the abatement device.

• Cost of Technology (provided by supplier) Capital cost as low as $30,000 US D per inlet on etch processes.41

ISMI Technology Transfer #05104693A-ENG • Cost of Ownership TPU requires replacement of seals, gaskets, and combustor (depends on process) as needed for annual PM. Consumable costs ar e typically <$4000 USD annually. Typical annual facilities costs for opera tion of the Mini-TPU based on Fab Utility Cost Values for Cost of Ownership (COO) Calculations (SEMATECH, Technology Transfer #02034260A-TR) is ∼ $4000 USD.

• Pros

– Commercially available technology that ab ates oxide and poly etch emissions at ≥ 93% DRE and removes HF, generated as a result of burning PFCs, from the exhaust stream. It also destroys F 2 and removes the resulting HF.

– Unit is capable of abating emissions from multiple process chambers.

• Cons

– Requires NG, which may not be available as a service utility.

– Generates HF liquid waste stream, which may require further treatment before discharge.

– Abatement of NF 3 generates NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited; and NG, which may not be installed as a service utility.

– May require oxygen or compressed dray air (CDA) to abate CF 4 , which may not be available as a service utility.

• Contact Joe Van Gompel 512-633-5105 joe.vangompel@bocedwards.com

• References Information on the mini-TPU was provided by Joe Van Gompel of BOC Edwards.
c) Centrotherm CT-BW Burner Washer

• Description Centrotherm has developed a modular abatement system whose components can be specified based on the specific requireme nts of the process being abated. The Centrotherm CT-BW contains a cone-shaped burner chamber and a separate high efficiency wet scrubber section. The CT-BW is sold as a single system or a 100% redundancy dual system. The footprint ranges from 650 mm × 800 mm × 1850 mm to 800 mm × 1300 mm × 2000 mm. The unit can handle effl uent from multiple chambers with a maximum flow rate of 600 slm.

• Technology Status Commercially available.42

Technology Transfer #05104693A-ENG ISMI • Applicability Both CVD and etch effluents can be treated w ith the CT-BW. Tool can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities Electricity, cooling water ( ∼ 7 slm), O 2 , NG, or hydrogen, scrubber water (1.5 slm makeup water), KOH, or NaOH for scrubber.

• Supplier Reported Results (no semiconductor manufacturer provided data available)

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 10,000 99 SF 6 7000 99 C 2 F 6 7000 99 CHF 3 99 C 4 F 8 99 CF 4 7000 84–95

• Byproducts Byproducts of combustion for car bon-containing PFCs include CO 2 and HF. Final rinse from scrubber contains KF or NaF. NF 3 combustion results in formation of N 2 , HF, and NO x . Final scrubber rinse contains KF, KNO 2 , and KNO 3 . NO x formation depends on set up of the system and flow of N 2 vs. the set-up of the flame.

• Cost of Technology (provided by supplier) $95,000–$110,000 USD per unit.

• Cost of Ownership No information provided.

• Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 95% DRE and removes HF, genera ted as a result of burning PFCs, from the exhaust stream.

– Unit is capable of abating emissions from multiple process chambers.

– Modular design with 100% redundancy capability.

– Newer burner-washer technology than CT-FLM with installed base of CT-BWs in semiconductor facilities in Europe and Korea.

– Centrotherm’s Asia partner is ATTO, which sells a modified device adapted to the Korean market.43

ISMI Technology Transfer #05104693A-ENG • Cons

– Requires H 2 or NG.

– Generates HF liquid waste stream which may require further treatment before discharge; however, Centrotherm has developed an HF treatment system.

– May generate NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and either H 2 or NG, which may not be installed as a service utility.

• Contact Volker Kinzig Volker.Kinzig@centrotherm.de Phone 0049-7344-918-1801

• References Information provided by Volker Kinzig of Centrotherm.
d) Centrotherm FLM (CT-FLM) Flawamat Burner-Scrubber

• Description The CT-FLM is a point-of-use abatement devi ce, installed post-vacuum pump, in which effluent enters an inner tube where it is burned. Effluent from the burner chamber leaves the bottom of the burner through an out er tube where it is washed from the top by a spray nozzle. The CT-FLM is sold as a single system. The footprint is from 650 mm × 800 mm × 1850 mm. The unit is installed downstream of the vacuum pumps and can handle effluent from multiple chambers with a maximum flow capacity of 300 slm.

• Technology Status Commercially available.

• Applicability Both CVD and etch effluents can be treated with the CT-FLM. Tool can be installed as a retrofit or during new tool installation.

• Required Utilities Electricity, water, oxygen, NG or hydrogen, KOH- or NaOH-s olution for scrubber, HF waste drain.44

Technology Transfer #05104693A-ENG ISMI • Reported Results
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 > 95–99 SF 6 3000# > 95* / 99# C 2 F 6 3000# > 90–98* CHF 3 98* C 4 F 8 99* C 3 F 8 98* CF 4 3000# 90–95* *Performance reported by semiconductor manufacturer(s) # Supplier reported performance

• Byproducts Byproducts of combustion for car bon-containing PFCs include CO 2 and HF. Final rinse from scrubber contains KF or NaF. NF 3 combustion results in formation of N 2 , HF, and NO x . Final scrubber rinse contains KF, KNO 2 , and KNO 3 . NO x formation depends on set up of the system and flow of N 2 vs. the set-up of the flame.

• Cost of Technology (provided by supplier) $95,000–$110,000 USD per unit.

• Cost of Ownership FLM requires regular cleaning of internal parts, resulting in period ic cleaning costs and maintenance effort.

• Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 95% DRE and removes HF, genera ted as a result of burning PFCs, from the exhaust stream.

– Unit is capable of abating emissions from multiple process chambers.

– Established technology with installed base of CT-FLMs in multiple semiconductor facilities in Europe and Korea.

– Centrotherm’s Asia partner is ATTO, which sells a modified device adapted to the Korean market.

• Cons

– Requires H 2 or NG.

– Generates HF liquid waste stream which may require further treatment before discharge; however, Centrotherm has developed an HF treatment system.

– May generate NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and either H 2 or NG, which may not be inst alled as a service utility.45

ISMI Technology Transfer #05104693A-ENG • Contact Volker Kinzig Volker.Kinzig@centrotherm.de Phone 0049-7344-918-1801

• References Information on the FLM was provided by Gabriele Fetzer of Philips Semiconductor, Wang-Keun Kim of Samsung, Francesca Illuzzi of STMicroelectronics, and Volker Kinzig of Centrotherm. e) DAS ESCAPE-INLINE

• Description The ESCAPE INLINE is a point-of-use abat ement device, installed post-vacuum pump, in which effluent from up to four pro cess chambers enters a combustion chamber. Toxic, flammable, or pyrophoric compounds as well as PFCs are decomposed in the flame by pyrolysis, reduction and oxidation reactions. Directly after the combustion chamber the gas is quenched rapidly and pa ssed through a wet scrubber column where acidic compounds and particulate matter ar e retained. The scrubber liquid is recirculated and automatically exchanged without interruption of the abatement process. The footprint is 688 mm × 830 mm × 2070 mm (standard version) and has a maximum flow capacity of 200 slm.

• Technology Status Commercially available w ith >1200 units installed.

• Applicability Both CVD and etch effluents can be tr eated with the ESCAPE-INLINE. Abatement device can be installed as a retrof it or during new tool installation.

• Required Utilities NG, LPG, or hydrogen for fuel; electricit y, water, oxygen, CDA, cooling water, N 2 . KOH- or NaOH-solution for scrubber, HF waste drain.

• Reported Results
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 6000# > 95* 99# SF 6 3000# > 95* 95# C 2 F 6 3000# > 90* 95# CHF 3 6000# 99# CH 2 F 2 10,000# 99# C 3 F 8 2500# 99# CF 4 5000# 90* 95# *Performance reported by semiconductor manufacturer(s) # Supplier reported performance46

Technology Transfer #05104693A-ENG ISMI • Byproducts Byproducts of combustion for car bon-containing PFCs include CO 2 and HF. According to supplier, NO x levels are lower than required by national clean air standards (specific country and standards not cited).

• Cost of Technology (per unit) Not provided. Contact supp lier to obtain a quote.

• Cost of Ownership Consumables are required for proper ope ration and maintenance but specific information not available.

• Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 95% DRE and removes HF, genera ted as a result of burning PFCs, from the exhaust stream.

– Unit is capable of abating emissions from multiple process chambers.

– Established technology with in stalled base in multiple semiconductor facilities.

• Cons

– Requires fuel.

– Generates HF liquid waste stream, which may require further treatment before discharge.

– May generate NO x .

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and either H 2 , LPG, or NG, which may not be installed as a service utility.

• Contact Dr. A. Frenzel frenzel@das-europe.de Phone 49-351-871 8634

• References Information provided by Francesca Illuzzi of STMicroelectronics and A. Frenzel of DAS. S-N Li, et al, “FTIR Spectrometers Measure Scrubber Efficiencies,” Solid State Technology , July 2002.47

ISMI Technology Transfer #05104693A-ENG f) Ecosys Marathon 8500

• Description The Ecosys Marathon 8500 is a point-of-use abatement device, installed post-vacuum pump, which utilizes a staged natural gas or liquid propane gas combustor followed by a wet scrubber to ensure maximum DRE of PFCs and process gases. The footprint is 1168 mm × 637 mm × 2261 mm. The unit is installe d downstream of the vacuum pumps and can handle effluent from multiple process chambers and tools with a maximum flow capacity of 700 slm.

• Technology Status Commercially available.

• Applicability Both CVD and etch effluents can be treated with the Marathon 8500. Device can be installed as a retrofit or dur ing new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities 208/220 VAC; 10 A, 2 kW; 0.3–1.25 gpm fres h water; 2–15 gpm cooling water; 70 scfm CDA; 35 scfm N 2 ; 1.3–3.5 scfm natural gas, acid waste drain, 120 scfm exhaust.

• Supplier Reported Results (no semiconductor manufacturer provided data available)

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 4500 99 SF 6 5000 99
C 2 F 6 > 2400 (not tested at higher flow) > 99.9

C 3 F 8 > 3000 (not test at higher flow) > 99.9
CF 4 8000 97 CF 4 4000 98 CF 4 2000 99

• Byproducts Byproducts of combustion for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. CO and NO x production is below 500 lbs/year/device.

• Cost of Technology (provided by supplier) $ 120,000 USD per unit.

• Cost of Ownership Ecosys indicates cost of parts and labor on an annual basis to be $3700 and COO on an annual basis is $5300.48

Technology Transfer #05104693A-ENG ISMI • Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 97% DRE and removes HF, genera ted as a result of burning PFCs, from the exhaust stream.

– Unit is capable of abating emissions from multiple process chambers and multiple tools.

• Cons

– Requires NG or LPG, which may not be available as a service utility.

– Generates HF liquid waste stream, which may require further treatment before discharge.

– Abatement generates CO and NO x ; the ESH impact of these needs to be assessed.

– To be used as a retrofit in an existing fab requires floor space, which may be limited, and NG or LPG, which may not be installed as a service utility.

• Contact Sebastien Raoux, Ecosys 408-719-4668 Sebastien_Raoux@metrontech.com

• References Information on the Ecosys Marathon 8500 was provided by Sebastien Raoux of Ecosys.

A.6.2 PFC Abatement – POU Catalytic–Scrubber Units

• General Technology Description Point-of-use catalytic-scrubber units use a cata lyst to promote the destruction of PFCs and process gases at lower activa tion energies than would othe rwise be needed. Catalytic systems operate at a lower temperature th an other PFC abatement systems and do not require fuel. A water scrubber typically follo ws the catalytic reac tor to remove HF byproduct from the exhaust stream. Catalytic-scr ubber units are installed on the process tool exhaust line after the vacuum pump and, thus, th e exhaust stream entering the unit contains a large amount of nitrogen. Catalytic-scrubber units can typically abate emissions from multiple process chambers.

• Applicability Both CVD and etch effluents from ≤ 150 mm, 200 mm, and 300 mm process tools can be treated with the bur ner-scrubber units.

• Pros

– Catalytic-scrubber units operate at lower temperatures than other PFC abatement systems and do not utilize a fueled flame.49

ISMI Technology Transfer #05104693A-ENG • Cons

– Pre-scrubbers are required to prevent catalyst poisoning.

– Catalyst has a limited lifetime and must be replaced periodically.

– Cost of ownership needs to be evaluated.
a) Ecosys Trinity

• Description The Ecosys Trinity is a point-of-use abat ement device, installed post-vacuum pump, which uses state of the art catalytic me thods to ensure maximum DRE of PFCs and process gases. The etch exhaust stream first passes through a water scrubber where water soluble gases and particles are remove d, then into the catalytic reactor where PFCs are reacted to form HF, and finally th rough a second water scr ubber to remove the HF. The Trinity has a 686 mm × 914 mm × 2006 mm footprint and can handle multiple chambers with an flow capacity of 200 slm.

• Technology Status Commercially available.

• Applicability The Trinity can abate etch emissions. Tool can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities: Water, air, electricity, acid wa ste drain, process gas exhaust.

• Supplier Reported Results

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) C 3 F 8 1000 99 * Maximum flow indicated is for C 3 F 8 , which is the most challenging PFC for a

catalytic-based abatement device. Greater PFC flows and/or DREs can be obtained for other PFC gases and mixtures. Please contact Ecosys for more details.

• Byproducts Byproducts for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber.

• Cost of Technology (provided by supplier) $100,000 USD per unit.

• Cost of Ownership Catalyst must be replaced periodically; lifetime >1 year.50

Technology Transfer #05104693A-ENG ISMI • Pros

– Commercially available technology that ab ates etch PFC emissions at 99% DRE and removes HF, generated as a result of catalyzing PFCs, from the exhaust stream.

– Lower operating temperature than burne r-scrubber units and no open flame.

• Cons

– Limited applicability.

– Pre-scrubber required to prevent catalyst poisoning.

– To be used as a retrofit in an existing fab requires floor space, which may be limited.

• Contact Brian Kingston brian.kingston@metrontech.com Phone 408-887-6132

• References robin.gardiner@metrontech.com “EM Trinity Local Scrubber Efficiency Evaluation,” ITRI Taiwan , April 2004. “Catalytic Technology for Perfluorocompound (PFC) Emissions Control,” Solid State Technology , July 2001. R.S. Brown and J.A. Rossin, “ Catalytic Process for Control of Perfluorocompound (PFC) Emissions , Semiconductor International , June 2001.
b) Hitachi Super Catalytic Decomposition System (SCDS)

• Description The Hitachi Super Catalytic Decomposition Sy stem (SCDS) is a point-of-use abatement device, installed post-vacuum pump, which us es state of the art catalytic methods to ensure maximum DRE of PFCs and process gase s. The SCDS is available in 60, 120, or 200 slm capacities. Each SCDS consists of a pre-spray and packed bed scrubber to remove particulates and water soluble acids , catalytic reactor a nd cooling section, and post-reactor packed bed scrubber to remove HF from the exhaust stream. The SCDS uses recirculated wastewater for each of th e scrubber units, thus minimizing the amount of fresh water required.

• Technology Status Commercially available.

• Applicability The SCDS can abate CVD and etch emissions. Tool can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.51

ISMI Technology Transfer #05104693A-ENG • Required Utilities

Model CD-60 CD-120 CD-200 Capacity (slm) 60 120 200 Electrical (kW) 4 8 11 Water Usage (gpm) 0.4 0.6 0.9 System Size (W × D × H) (mm) 991 × 559 × 1880 1143 × 635 × 1880 1143 × 635 × 1880

• Reported Results DRE (%) PFC Maximum PFC Input Flow Rate (sccm) * # NF 3 NT 99.9 SF 6 NT 99.9 C 2 F 6 1100 > 99 99.9 CHF 3 2400 > 99 99.9 C 4 F 8 NT 99.9 C 3 F 8 80 > 99 99.5 CF 4 7400 > 99 93 C 5 F 8 NT 99.9 * Performance reported by semiconductor manufacturer for CD-120. # Supplier reported performance from website.

• Byproducts Byproducts for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. The fate of the N from NF 3 is not described.

• Cost of Technology (per unit) Not provided. Contact the supplier to obtain a quote.

• Cost of Ownership Hitachi website states that catalyst replacement is required every 12–24 months; the pre-packed tower and pre-spray, cooling room and wastewater tank require annual cleaning; the packed tower requires cleaning ev ery 2 years. According to a user, various parts are required for quarterly, semi-annua l, annual or “as needed” maintenance.

• Pros

– Commercially available technology that ab ates both etch and CVD chamber clean PFC emissions at ≥ 99% DRE and removes HF, generated as a result of catalyzing PFCs, from the exhaust stream.

– Recirculating scrubber results in low water consumption.

– SCDS comes in three sizes and is capable of abating emissions from multiple process chambers.

– Established technology.52

Technology Transfer #05104693A-ENG ISMI • Cons

– To be used as a retrofit in an existing fab requires floor space, which may be limited.

– Cost of ownership needs to be evaluated.

• References Hitachi America did not respond to requests for additional information submitted by the web and email. SCDS specifications were obtained from: http://www.hitachi-hta.com

. Information on the SCDS was provided by Joachim Stache of Philips.
c) TecHarmonic EHTVS/Alpine S

• Description The TecHarmonic EHTVS/Alpine S catalytic scrubber is a comprehensive point-of-use abatement device for particulates, acid ga ses, flammables and PFCs. The Alpine S utilizes a high temperature, electrically heated thermal oxi dizer chamber to preheat the exhaust stream, followed by a vortex particul ate scrubber and packed bed tower which connects to a catalytic chamber to de stroy PFCs, followed by a second vortex particulate scrubber and packed bed tower. Scrubber water re-circulation is used to minimize the amount of fresh water required by the system. The Alpine S is installed post-vacuum pump and can handle effluent from multiple process chambers and tools with a maximum flow capacity of 300 slm. The footprint is 965 mm × 1194 mm × 1918 mm.

• Technology Status Commercially available and installed in a PFC abatement application on an Applied Materials Centura 4 chambe r SiN/TEOS deposition tool.

• Applicability The Alpine S can abate CVD and etch emissions . The Alpine S is suited to handling all PFCs. Tool can be installed as a retr ofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm pr ocess tools.

• Required Utilities Water (1.5 gpm scrubber makeup water), N 2 , CDA, electricity, acid waste drain, cabinet exhaust, acid process exhaust.53

ISMI Technology Transfer #05104693A-ENG • Reported Results from Manufacturing Installations DRE (%) PFC Maximum PFC Input Flow Rate (sccm) * # NF 3 10,000# > 95 90–99 SF 6 6000# > 95 90–99 C 2 F 6 6000# > 95 90–99 C 3 F 8 6000# 90–99 CF 4 6000# 90 90–99 C 4 F 8 6000# 90–99 CHF 3 6000# 90–99 *Performance reported by semiconductor manufacturer(s) #Supplier reported performance from manufacturing installations

• Byproducts Byproducts for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. Supplier reports that no NO x emissions are formed.

• Cost of Technology (per unit) Not provided. Contact supp lier to obtain a quote.

• Cost of Ownership Periodic replacement of thermocouples and ca talyst required. Frequency not reported. TecHarmonic estimates annual cost to operate the Alpine P to be ∼ $17,000–$20,000 in PFC abatement applications.

• Pros

– Commercially available technol ogy that abates particulates , acid gases, flammables and PFC emissions from etch and CVD chamber clean.

– PFC DREs are 90–99% and device removes HF, generated as a result of PFCs destruction, from the exhaust stream.

– Recirculating scrubber results in low water consumption.

– Alpine S is capable of abating emissions from multiple process chambers.

– The Alpine S has >1 year experien ce abating PFC from production.

• Cons

– To be used as a retrofit in an existing fab requires floor space, which may be limited.

– Cost data must be obtained from supplier.

– Limited performance data from semiconductor manufacturers.54

Technology Transfer #05104693A-ENG ISMI • Contact Bill Delaney bdelaney@techarmonic.com Phone 408-360-8780, x201

• References Information on the Alpine S was provided by Francesca Illuzzi of STMicroelectronics and Bill Delaney of TecHarmonic.

A.6.3 PFC Abatement – POU Electrically Heated Thermal – Scrubber Units

• General Technology Description POU electrically heated thermal-scrubber units us e an electrically heated chamber to destroy PFCs and other hazardous substances such as deposition precursors, followed by a water scrubber to remove volatile acid gases from th e exhaust stream. Electrically heated thermalscrubber units are installed on the process to ol exhaust line after the vacuum pump. Electrically heated-scrubber units can typically abate emissions from multiple process chambers.

• Applicability Both CVD and etch effluents from ≤ 150 mm, 200 mm, and 300 mm process tools can be treated with the bur ner-scrubber units.

• Pros

– If >90% efficiency is obtained for all PFC s, total GHG emissions should be lower with this technology compared to burner-scrubbers.

– By using electricity to heat the unit, a fl ammable fuel and open flame are not required which reduces potential fi re risks for the fab.

– Operating costs should be lower than burne r-scrubber units, assuming units have high MTBF and low maintenance requirements.

• Cons

– High temperatures are required to abate CF 4 , a known byproduct of any plasma process using fluorocarbons or used to etch or clean carbon-based films.

– Many electrically heated therma l-scrubber units cannot abate CF 4 .

• Manufacturers of Electrically Heated-Scrubber Units Without Detailed Information in this Appendix Centrotherm CT-EW: As part of their modular abatement sy stem design, Centrotherm is developing an electrically heated burner to abate pyr ophoric deposition gases, NF 3 , and SF 6 . The unit has 600 slm capacity and uses C DA as the oxidation gas instead of O 2 . For more information on alpha and beta test results and commercial availability, contact Volker Kinzig, Volker.Kinzig@centrotherm.de , Phone 0049-7344-918-1801.55

ISMI Technology Transfer #05104693A-ENG a) TecHarmonic EHTVS/Alpine P

• Description The TecHarmonic EHTVS/Alpine P is a comp rehensive point-of-use abatement device for particulates, acid gases, flammables and certain PFCs using dual high temperature, electrically heated thermal oxidizers followed by vortex part iculate scrubber and twin packed bed towers. Scrubber water re-circulation is used to minimize the amount of fresh water required by the system. The Alpine P is installed post-vacuum pump and can handle effluent from multiple process chambers and tools with a maximum flow capacity of 800 slm. The footprint is 965 mm × 1194 mm × 1918 mm.

• Technology Status Commercially available and installed in PFC abatement applications for >3 years.

• Applicability The Alpine P can abate CVD and etch PFC em issions, but is most effective at abating SF 6 and NF 3 . The Alpine S is better suited to handling carbon-containing PFC exhaust streams. Tool can be installed as a re trofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm pr ocess tools.

• Supplier Reported Results from Manufacturing Installations
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 20,000 95–99 SF 6 6000 95–99 C 2 F 6 * 6000 85–99 C 3 F 8 * 6000 85–99 * CF 4 is a plasma process byproduct; CF 4 abatement efficiency is not reported.

• Byproducts Byproducts for carbon-containing PFCs are CO 2 and HF. HF is removed in the wet scrubber. Supplier reports that no NO x emissions are formed.

• Cost of Technology (per unit) Not provided. Contact supp lier to obtain a quote.

• Cost of Ownership Periodic replacement of thermocouples and ga skets is required. Fr equency not reported. TecHarmonic estimates annual cost to operate the Alpine P to be ∼ $5000.

• Pros

– Commercially available technology that ab ates certain PFC emissions from etch and CVD chamber clean at 85–95% DRE and re moves HF, generated as a result of PFCs, from the exhaust stream.

– Recirculating scrubber results in low water consumption.56

Technology Transfer #05104693A-ENG ISMI – Alpine P is capable of abating emissions from multiple process chambers.

– Established technology.

• Cons

– DRE for CF 4 was not provided.

– To be used as a retrofit in an existing fab requires floor space, which may be limited.

– Cost data must be obtained from supplier.

– No user data provided by semiconductor manufacturers.

• Contact Bill Delaney bdelaney@techarmonic.com Phone 408-360-8780, x201

• References Information on the Alpine P was provided by Bill Delaney of TecHarmonic.
b) Kanken Techno KT1000 Series

• Description Kanken Techno has developed the KT line of electrically heated thermal destruction units with pre-and post-scrubbers for co mprehensive point-of-use abatement of particulates, acid gases, flam mables and PFCs. The inlet scrubber removes hydrolytic effluents from the process such as SiF 4 and WF 6 and provides water to react with PFCs in the electric heater reacto r. Kanken Techno has five diffe rent heater chamber designs which operate at different temperatures or e xhaust flow rates. Sel ection of a particular system is dependent on the anticipated process emissions. The post-scrubber removes HF generated from PFC destruction and part iculate. Scrubber water re-circulation is used to minimize the amount of fresh water required by the system. The KT1000 is installed post-vacuum pump and can handle effluent from multiple process chambers and tools.

• Technology Status Commercially available with multiple inst allations in PFC abatement applications.

• Applicability Tool can be installed as a retrof it or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools. See table below for applicability of specific systems.57

ISMI Technology Transfer #05104693A-ENG • Required Utilities and Consumables

Model KT100MF KT1000F KT1000H KT1000EX
Applicability NF 3 CVD Chamber

Cleans NF 3 CVD Chamber

Cleans Etch and CVD Etch

Total Capacity (slm) 400 250 200–250 120 for CF 4 200 for SF 6 Single Port 1100 × 1050 × 1900 Dimensions (mm) Multi Port 1100 × 1350 × 1900 1050 × 1100 × 1900 1100 × 1350 × 1900 1100 × 1050 × 1900

35 35 35 35 Electrical (kVA) Avg. 7 7 7 7 Water Usage (lpm) 10 10 10 10 Process Gas (slm) NH3: 15 NH3: 6 N/A N/A Exhaust (slm) 1000 500 500 500 Acid Waste Drain (lpm) 10 10 10 10 Electric Heater 1/2 yr 1/2 yr 1/2 yr 1/2 yr
Shower Nozzle 1/yr 1/yr 1/yr 1/yr Consumables Recycle Water Pump 1/yr 1/yr 1/yr 1/yr

• Supplier Reported Results from Manuf acturing Installations: KT1000MF

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 15000 > 99%* *< TLV: 10 ppm.

• Supplier Reported Results from Manuf acturing Installations: KT1000F

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 6000 > 99%* *< TLV: 10 ppm.

• Supplier Reported Results from Manuf acturing Installations: KT1000H
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) C 4 F 8 7500 > 90 C 3 F 8 * 7500 > 90 C 2 F 6 * 6000 > 90 CHF 3 * 7500 > 90 * CF 4 is a plasma process byproduct for this input chemistry; CF 4 abatement efficiency is 16.6%.58

Technology Transfer #05104693A-ENG ISMI • Supplier Reported Results from Manuf acturing Installations: KT1000EX
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) CF 4 3600 > 90 SF 6 6000 > 90

• Byproducts Generates HF byproduct. HF is removed in the wet scrubber. KT1000EX generates SO x emissions, which are removed by a wet sc rubber. Supplier reports that no NO x emissions are formed. KT1000MF and KT1000F introduce NH 3 as a reactant gas to prevent the formation of NO x during NF 3 abatement.

• Cost of Technology (per unit) Not provided. Contact supp lier to obtain a quote.

• Cost of Ownership Operating costs not provided. Required consumables and replacement frequency reported above.

• Pros

– Commercially available technology that abates PFC emissions from specified applications at >90%DRE and remove s HF, generated as a result of PFC destruction, from the exhaust stream.

– Recirculating scrubber results in low water consumption.

– Capable of abating emissions from multiple process chambers.

– Commercially available, established technology with large installed base.

• Cons

– CF 4 is a byproduct of plasma processes using C-F chemistries; KT1000EX is only KT unit capable of abating CF 4 >90% DRE.

– To be used as a retrofit in an existing fab requires floor space, which may be limited.

– Cost data must be obtained from supplier.

– No data provided by semiconductor manufacturers.

• Contact Tatsuro Beppu 81-6-6380-1474 mailto:beppu@kanken-techno.co.jp

• References Information on the KT1000 Series was provided by Tatsuro Beppu of Kanken-Techno.59

ISMI Technology Transfer #05104693A-ENG A.6.4 PFC Abatement – POU Atmospheric Plasma Units

• General Technology Description Point-of-use atmospheric plasma units use plas ma at atmospheric pressure to destroy PFCs and other hazardous substances such as deposi tion precursors. The plasma reactor can be followed by a water scrubber, which may contai n a base solution, to remove volatile acid gases from the exhaust stream. Atmospheric plas ma units are installed on the process tool exhaust line after the vacuum pump and, thus, th e exhaust stream entering the unit contains a large amount of nitrogen, which can impact the plasma efficacy. Atmospheric plasma units are typically designed to abate emissions from multiple process chambers.

• Technology Status Commercially available.

• Applicability Emissions from ≤ 150 mm, 200 mm, and 300 mm proce ss tools can be treated.

• Pros

– By using plasma, a flammable fuel and open flame are not required which reduces potential fire risks for the fab.

– Operating costs should be lower than burne r-scrubber units, assuming units have high MTBF and low maintenance requirements.

– Using post-pump plasma minimizes the risk of fluorine or HF formation in the vacuum pump that could lead to pump corrosion.

– Unlike pre-pump plasma systems, post-pump pl asma units pose no risk of particulates diffusing back into the process chamber.

• Cons

– POU atmospheric plasma units are a relatively new and unproven technology.

– Little data is currently available on DRE, uptime, maintenance requirements, and COO.
a) Air Liquide UPAS

• Description Air Liquide has developed an atmospheric microwave plasma system/dry adsorption system. Integration of universal plasma ab atement system (UPAS) technology into a fab may require installation of pretreatment technology and will require post-UPAS abatement to remove HF from the exhaust stream. Centralized wet scrubbers installed for acid exhaust may be adequate. Air Liqui de makes two versions of the UPAS. The Compact UPAS is 635 mm × 700 mm × 1900 mm while the Integr ated UPAS is 635
mm × 1300 mm × 1900 mm. The UPAS can handle e ffluent from multiple process chambers with maximum flow of 120 slm.

• Technology Status Commercially available with 14 units curre ntly installed in manufacturing fabs.60

Technology Transfer #05104693A-ENG ISMI • Applicability UPAS is marketed for etch process emi ssions; however, a paper was presented at ISESH 2005 on application to CVD chamber cleans. Device can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities Electricity, N 2 , CDA, cooling water, acid exha ust, process heat exhaust.

• Reported Results
PFC Maximum PFC Input Flow Rate (mg/m 3 ) DRE (%) C 4 F 8 6700 > 99 CF 4 7300 > 90 CH 2 F 2 500 > 99 CHF 3 6700 > 95

• Byproducts ESIA member notes NO x is generated at ∼ 250 mg/m 3

.

• Cost of Technology (per unit) Not provided. Contact supp lier to obtain a quote.

• Cost of Ownership Air Liquide notes periodic replacement of ceram ic tube (2 tubes as backup), cooling oil (120L), gaskets and other parts may be re quired. Frequency not reported. ESIA member notes dry cartridges as a consumable.

• Pros

– PFC and fluorinated species abatement with reduced corrosion and safety risk in main exhaust.

– Potentially lower operating cost than fueled burner-scrubber units; however, technology is relatively new a nd little information is publicly available on uptime and COO.

• Cons

– Limited applicability.

– May require installation of separate pretreatment system to remove particulates and acid gases.

– Does not remove HF or other acid s generated in plasma; semiconductor manufacturers must determine if central wet scrubbers can sufficiently abate additional UPAS effluent.

– NO x is generated by the plasma system (cracking of O 2 and N 2 ) and is not treated by dry cartridge.

– Solid deposition in the cartridge is NO x -based.61

ISMI Technology Transfer #05104693A-ENG • Contact Olivier Letessier olivier.letessier@airliquide.com Phone +33 1 40 62 5234

• References Information provided by ESIA members a nd Olivier Letessie r of Air Liquide. H. Yamamoto (Ricoh Electronics Devices ), “Perfluorocompound (PFC) Atmospheric Plasma Abatement for Etch and Chemical Vapor Deposition (CVD),” ISESH , 2004. H. Yamamoto (Ricoh Electronics Devices), M. Tabata (Air Liquide Japan – Tokyo, Japan), M. Sato and C-H. Ly (Air Liquide Laboratories, Ibaraki, Japan), and J.C. Rostaing (Centre de Recherche Cla ude Delorme, Les-Loges-en-Josas, France), “Perfluorocompound (PFC) Atmospheric Plas ma Abatement System for Chemical Vapor Deposition (CVD) at Rico h: A Pertinent Approach,” ISESH , 2005.
b) BOC Edwards Zenith Etch Plasma

• Description BOC Edwards offers the Zenith Etch Plas ma, an atmospheric microwave plasma unit followed by a three-stage wet scrubber inco rporated with high-efficiency vacuum pumps for plasma etch chambers. The Zenith Etch Plasma system is not a standalone abatement device; four vacuum pumps ar e included. The foot print is 1300 mm × 625 mm × 1833 mm, which incl udes the abatement system and pumps.

• Technology Status Zenith Etch Plasma is commercially available only in Europe at this time.

• Applicability Zenith Etch Plasma system is available as a re trofit or as part of a new tool installation for etch systems only.

• Required Utilities Water, electricity, N 2 , O 2 , PCW, acid exhaust, general exhaust.

• Supplier Reported Results
PFC Maximum PFC Input Flow Rate (sccm) DRE (%) NF 3 1000 > 99 SF 6 1000 > 99 C 4 F 6 1000 > 99 C 4 F 8 1000 > 99 CF 4 800 91 CH 2 F 2 1000 > 99

CH 3 1000 > 9962

Technology Transfer #05104693A-ENG ISMI • Byproducts All PFCs are converted to CO 2 and HF. BOC Edwards reports HF is removed by a wet scrubber, and NO x emissions are within desired levels.

• Cost of Technology (provided by supplier) As a package including abatement and 4 vacuum pumps, the Zenith Etch system is between $50,000–$75,000 USD per etch chamber depending on the configuration (all piping between pumps and abatement included).

• Cost of Ownership BOC Edwards lists as consumables electrode, seals, gaskets as needed for annual PM. BOC Edwards reports consumables costs are typically <$3000 USD and typical facilities costs based on Fab Utility Cost Values fo r Cost of Ownership (COO) Calculations (SEMATECH, Technology Transfer #02034260A-TR), the fab utility cost values are ∼ $4000 USD.

• Pros Potentially lower operating cost than fuel ed burner-scrubber units; however, technology is relatively new and little information is publicly available on uptime and COO.

• Cons Limited applicability and availability.

• Contact Joe Van Gompel joe.vangompel@bocedwards.com Phone 512-633-5105

• References M. Radiou, A. Seeley, S. Carss, and J. Van Gompel, “Sixty Percent Utilities Savings on Etch Perfluorocompound (PFC) Abatement,” SEMICON West , July 2003. c) Centrotherm Plasma-Washer

• Description Centrotherm has developed a modular point-of-use abatement system whose components can be specified based on the specific requirements of the process being abated. The Centrotherm plasma-washer combines a microwave plasma stage and a separate high efficiency wet scrubber s ection. Dry bed absorber or catalysts are alternatives to the wet scrubbe r section. The unit is installe d after the vacuum pump and operates at atmospheric pressure. The footpr int is dependent on system configuration. The unit can handle effluent from multiple ch ambers with a maximum flow capacity of 120 slm.

• Technology Status Alpha and beta testing.63

ISMI Technology Transfer #05104693A-ENG • Applicability Centrotherm’s plasma-washer can be installed as part of a new etch tool installation or as a retrofit for etch processes; CVD is problematic due to powder generation.

• Required Utilities Electricity, water or oxygen as reactant, nitrogen; scrubber water, KOH or NaOH for scrubber.

• Supplier Reported Results (no semiconductor manufacturer provided data available)

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) SF 6 2000 80–90* C 2 F 6 2000 80–90* CF 4 2000 80–90* *Depending on set-up.

• Byproducts No information provided on byproducts.

• Cost of Technology (provided by supplier) $115,000–$130,000 USD per unit.

• Cost of Ownership Electrodes for the plasma tube must be repl aced periodically (cont act supplier to obtain additional information).

• Pros

– By using plasma, a flammable fuel and open flame are not required which reduces potential fire risks for the fab.

– Operating costs should be lower than bur ner-scrubber units, assuming units have high MTBF and low maintenance requirements.

– Using post-pump plasma minimizes the risk of fluorine or HF formation in the vacuum pump that could lead to pump corrosion.

– Unlike pre-pump plasma systems, pos t-pump plasma units pose no risk of particulate back diffusion into the process chamber.

• Cons

– Relatively new and unproven techno logy with limited applicability.

– Little data available on DRE, uptime, maintenance requirements, and COO; however, it is not recommended for CVD due to particulates and polymeric buildup in the plasma tube.

– To be used as a retrofit in an existing fab requires floor space, which may be limited.64

Technology Transfer #05104693A-ENG ISMI • Contact Volker Kinzig Volker.Kinzig@centrotherm.de Phone 0049-7344-918-1801

• References Semiconductor contacts are MUT Jena and Innovent (Jena, Germany). Information provided by Volker Kinzig of Centrotherm.
d) Desiccant Technology Corporation (D-Tech) Plasma + Wet Scrubber Model LT-DP200VI

• Description D-Tech has developed an integrated atmos pheric plasma and wet scrubber system to abate PFC and chlorofluorocarbon emissions from etch and CVD processes. The unit also destroys CVD precursors and treats SiF 4 byproducts. The unit is 1200 mm × 1000 mm × 1850 mm and can handle e ffluent from multiple chambers with a maximum flow capacity of 600 slm.

• Technology Status Commercially available.

• Applicability Plasma + Wet Scrubber can be used to abat e both etch and CVD emissions. Device can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm process tools.

• Required Utilities Electricity (220 V, 40 A, 50/60 Hz), N 2 (45 lpm @ 5 kg/cm 2 ), CDA (30 lpm @ 3– 5 kg/cm 2 ), cooling water (40 lpm @ 3–5 kg/cm 2 ), city water (2.5 lpm @ 3 kg/cm 2 ).

• Supplier Reported Results (no semiconductor manufacturer provided data available)

PFC Maximum PFC Input Flow Rate (sccm) DRE (%) CF 4 250 > 99 C 2 F 6 4000 > 99 CHF 3 1000 > 99

• Byproducts HF is formed.

• Cost of Ownership D-Tech reports replacement of torch (1 each /40 days), thermocouple (5 each/year), and O-ring seal (8 each/6 months).65

ISMI Technology Transfer #05104693A-ENG • Pros

– Potentially lower operating cost than fueled burner-scrubber units; however, technology is relatively new a nd little information is publicly available on uptime and COO.

• Cons

– May require installati on of separate pretreatment syst em to remove particulate and acid gases.

– Does not remove HF or other acid s generated in plasma; semiconductor manufacturers must determine if central wet scrubbers can sufficiently abate additional UPAS effluent.

• Contact Art Liu art@dtech.com.tw Phone +886-3-5832511

• References Information provided by Art Liu of D-Tech.

A.6.5 PFC Abatement – POU Foreline Plasma Units

• General Technology Description POU foreline plasma units employ a compact, lo w-pressure plasma reactor to destroy PFCs from etch processes. Foreline plasma units are installed on the foreline after the turbo pump but before the mechanical vacuum pump, where they can abate concentrated emissions before dilution with N 2 purge from the vacuum pump. One unit is required per etch process chamber.

• Technology Status Commercially available.

• Applicability Device can be installed as a retrof it or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm etch process chambers.

• Pros

– Compact footprint and potent ially lower COO solution to abate etch PFC emissions.

• Cons

– Does not remove HF or other acid gases gene rated in plasma that are then fed into the vacuum pump.66

Technology Transfer #05104693A-ENG ISMI – Semiconductor manufacturers must monitor impact of acid gases on vacuum system and determine if central wet sc rubbers have sufficient capac ity to abate additional acid gases generated by the pre-pump plasma units.

– In certain applications, pre-pump plasma units pose a potential risk of particles diffusing back into the etch process chamber.
a) Advanced Energy (AE) PCS (successor to Litmas Blue)

• Description The PCS is a high density, inductively coupled plasma generator that is installed on the foreline between the turbo and mechanical vacuum pumps of an etch chamber to decompose unused PFCs into ions and free ra dicals as they enter the vacuum pump. Water vapor is added to ensure conversion to HF. Placement of the PCS in the foreline results in energy-efficient decomposition of PFC emissions when they are most concentrated (i.e., before dilution with n itrogen purge from the vacuum pump). The PCS operates so that the plasma is ON when PFC gases flow in the process chamber and OFF when the chamber is idle. AE has pa rtnered with CS Clean Systems to sell and service the AE line of PFC abatement pr oducts, including the PCS. AE makes 1500 W and 3000 W models of the PCS. Fo otprint of both units is 398 × 274 × 264 mm.

• Technology Status Commercially available with multiple units currently installed in manufacturing fabs.

• Applicability The PCS is applicable to etch processes. De vice can be installed as a retrofit or during new tool installation on ≤ 150 mm, 200 mm, and 300 mm pr ocess tools. One unit is required per etch process chamber.

• Required Utilities Water, electricity.

• Reported Results
PFC Maximum PFC Input Flow Rate (ppm) DRE (%) CHF 3 700 >> 95 CF 4 850 > 90

• Byproducts HF, NO 2 , and COF 2 at low ppm level.

• Cost of Technology (per unit) Not reported. Contact CS Clean Systems.

• Cost of Ownership Plasma tube requires periodic replacement. 5% increase in COO.67

ISMI Technology Transfer #05104693A-ENG • Pros

– Potentially lower COO solution to abat e etch PFC emissions because PFCs are treated before dilution by pump purge nitrogen.

• Cons

– Does not remove HF or other acid gases gene rated in plasma that then feed into the vacuum pump.

– Semiconductor manufacturers must monitor impact of acid gases on vacuum system and determine if central wet scr ubbers have sufficient capacity to abate additional acid gases generated by the PCS.

– CS Clean Systems makes CLEANSORB dry absorber system to remove HF.

• Contact Contact CS Systems for additional information.

• References Information provided by Ton van de Kerkhof of Philips. Additional information obtained from the CS Clean Systems. http://www.cscleansystems.com/index.asp

. b) Ecosys Barracuda

• Description The Ecosys Barracuda is a low-pressure plasma reactor that is installed on the foreline between the turbo and mechanical vacuum pump s of an etch chamber. Placement of the Barracuda in the foreline results in ener gy-efficient decomposition of PFC emissions when they are most concentrated (i.e., be fore dilution with nitrogen purge from the vacuum pump). The plasma is ON when PFC gases flow in the process chamber and OFF when the chamber is idle. Plasma powe r can be adjusted to achieve appropriate DRE, depending on the PFC gas mixture and flow rate. To ensure PFC byproducts are not formed, Barracuda utilizes water va por as a reactant. Reactor size is 45.7 × 25.4 × 25.4 cm. Dimensions of the controller, which can be located remotely, are 38.1 × 25.4 × 20.3 cm.

• Technology Status Currently undergoing beta testing.

• Applicability Ecosys Barracuda is being developed to ab ate etch process emissions. Device can be installed as a retrofit or dur ing new tool installation on ≤ 150 mm, 200 mm, and 300 mm etch process tools. One unit is required per process chamber.

• Required Utilities Water, electricity.68

Technology Transfer #05104693A-ENG ISMI • Reported Results DRE (%) PFC Maximum PFC Input Flow Rate * # CHF 3 850 ppm* >> 95 CF 4 700 ppm* / 120 sccm# > 90 90 * Performance reported by semiconductor manufacturer # Supplier reported performance – maximum flow indicated is for CF 4 , which is most challenging PFC to abate. Greater flows and DREs can be obtained for other PFCs and gas mixtures. Contact Ecosys for more details.

• Byproducts HF, COF 2 , NO 2 , CO, and CO 2 .

• Cost of Technology (provided by supplier) Target price: $30,000 USD per unit.

• Cost of Ownership Ceramic plasma tube requires periodic replacem ent (lifetime estimated to be >1 year). Pros

– Small footprint and potentially lower COO solution for abating etch PFC emissions.

• Cons

– Because unit is undergoing beta testing, little information is available about longterm reliability and COO.

– Does not remove HF or other acid gases gene rated in plasma that then feed into the vacuum pump.

– Semiconductor manufacturers must monitor impact of acid gases on vacuum system and determine if central wet scr ubbers have sufficient capacity to abate additional acid gases generated by the Barracuda.

– If necessary, dry bed absorber system or wet scrubber can also be installed postpump to abate HF.

• Contact Sebastien Raoux, Ecosys 408-719-4668 Sebastien_Raoux@metrontech.com

• References Information on the Ecosys Barracuda was provided by Ton van de Kerkhof of Philips and Sebastien Raoux of Ecosys.69

ISMI Technology Transfer #05104693A-ENG A.6.6 PFC Abatement – Centralized Atmospheric Plasma Unit

• General Technology Description The only centralized PFC abatement system is a corona discharge system jointly developed by FH Co., Ltd and Samsung Electronics in Korea. The technology is undergoing beta evaluation by Samsung. At the beta site, a sepa rate PFC exhaust is installed post-vacuum pump to segregate CVD chamber clean em issions from deposition emissions. The PFC exhaust passes through the annular space between co-axial cylindrical electrodes used to sustain a corona discharge at atmospheric pre ssure. Exhaust from the abatement system then flows to the house scrubber for removal of aci d gases. The unit has a capacity of 50 cubic meters/minute and dimensions of 1500 × 3330 × 1731 mm. Multiple units can be installed to provide required capacity. Deposition process exhaust goes to separate flammable duct.

• Technology Status Extensive beta testing (20+ months). Multiple units installed in fabs in Korea.

• Applicability PFC emissions from semiconductor and LCD display CVD chamber cleans.

• Pros

– Centralized abatement for CVD chamber clean PFC emissions.

– Modular design allows for installation of multiple units to achieve required flow capacity.

• Cons

– New technology with limited installations.

– Little detailed information available on DRE, maintenance requirements, COO, reliability, and uptime.

– Requirement of separate exhaust system fo r PFCs may make use of this technology as a retrofit difficult due to space limitations in existing fabs.

• Required Utilities Power consumption is 220 V, 6 A.

• Reported Results
PFC Maximum PFC Input Flow Rate (ppm) DRE (%) NF 3 65 91.2 C 3 F 8 110 90.1

• Byproducts Not reported. Exhaust flows to central wet scrubbers.

• Cost of Technology (provided by supplier) $500,000 USD per unit.70

Technology Transfer #05104693A-ENG ISMI • Contact FH Co., Ltd.: Young-Hee Lee master@forhuman.co.kr

• References S-K Chae, “New Large-Scale End-of-Pipe Perfluorocompound (PFC) Abatement System Using a High-Efficiency Atmo spheric Discharge Technology,” SEMICON West 2004 , STS:ISM Program, July 2004. Additional information provided by Wang-Keun Kim of Samsung.International SEMATECH Manufacturing Initiative Technology Transfer 2706 Montopolis Drive Austin, TX 78741 http://ismi.sematech.org e-mail: info@sematech.org