FAB Optima™ ™ FAB Optima The Ultim ate Program for Airborne Quality Victor K.F. Chia, Ph.D. Victor K.F. Chia, Ph.D. victor.chia@balazs.com victor.chia@balazs.com ELECTRONICS
Abstract Fab Optim a TM : The Ultim ate Program for Airborne Quality The Fab airborne quality is an essential building block for clean m anufacturing. The construction materials and all materials within the cleanrooms affect the fab airborne quality. Fab Optima is a Quality Control process that ensures the facility is capable of supporting clean m anufacturing for increased production yields. This can only be achieved through collaboration between facility engineers, contam ination control engineers and process engineers working in concert to lower the risk of contam ination that often results in fab and tool escalations. This presentation reviews the key components of the program with examples of m onitoring program s, Recom m ended Practices and test results. Speaker Biography: Victor Chia is a Director of Air Liquide-Balazs Analytical Verify Root Escalation Services. His responsibilities include advancing surface contamination Cause technologies at Balazs, global sales and international business development. Victor has served in the sem iconductor industry for over 20 years. He received his Ph.D. in Analytical Chemistry from the University of California, Santa Barbara and was a post-doctoral fellow at Lawrence Berkeley Laboratory. Victor has hands-on experience with AAS, Raman Spectroscopy and SI MS. He is the current chair of the I EST WG-031 for organic outgassing and is active with AVS at the National and Chapter level committees, as well as the standard committee of the Contam ination I TRS. Victor has held positions at KLA-Tencor (Contamination Specialist) and at Partitioning Charles Evans and Associates (11 years starting as SI MS analyst to Director). Dr. I dentification Test Chia was also the President of Cascade USA, a branch of Cascade Scientific and worked as a Consultant. Victor has published over 40 papers and co-authored several chapters on SIMS and contamination characterization. Victor is an experienced instructor and has presented several UC Berkeley Ext ension Courses. Reducing Contamination
Outline Introduction � AMC baseline, source and control � • MA, MB, MC, MD, MM • Test methods SMC baseline, source and control � • SMO, SMD.SMM Fab Optima TM (Optimization for Manufacturing) � Star � ALert programs for clean manufacturing � Personal behavior � Cleanroom practice � Cleanroom supplies � Cleanroom housekeeping � Cleanroom cleanliness validation � Cleanroom m onitoring program � Case studies � Reducing Contamination
Airborne Molecular Contam ination ( AMC) � MA Molecular Acids HCl, HF, HNO 3 , H 2 SO 4 � MB Molecular Bases Ammonia, amines, amides � MC Molecular Condensables Organics: silicones, plasticizers (bp > 150°C) � MD Molecular Dopants B, P, As compounds � MM Molecular Metals Al, transition metals, alkali � Volatility (vapor pressure) � AMC can pass through HEPA and ULPA filters into cleanrooms � Boiling points � Typically, < ~ 450 o C organics can eventually pass through ULPA or gas filters � AMC can become SMC (Surface Molecular Contamination) � SMC can form many particles � I f > monolayer, SMC can m ake film s, hom ogeneous or islands � SMC is often < ML ( ~ 5Å) or approximately 10 15 atom s or ions/ cm 2 Reducing Contamination
AMC Sources AMC Effects DUV photoresist T-topping Outside air: autos, power plants, smog, � � industry, roofing, paving, fertilizers, Uncontrolled boron or phosphorus doping � pesticides, farming, sewers, fab exhaust, Surface issues: adhesion, wafer bonding, � ocean/ saline water delamination, electrical conductivity, high Process chemicals (esp. hot), reaction by- contact resistance, shorts, � products, reactor exhaust leakage currents, wetting, cleaning, etch rate shifts, spotting, particle removal, Wet cleaning, wet- and dry-etching, � electroplating defects electroplating baths Wafer hazing: time dependent haze Solvents: lithography, cleaning solutions � � Optics hazing: hazing by adsorption, People: ammonia, sulfides, organics � � reactions, etching or photochemistry on Equipment outgassing: robots, motors, � lenses, lasers, steppers, masks, reticles, pumps, fans, pellicles - especially for 157 and 193 nm electronics, computers, heaters lithograpghy Materials outgassing into air or onto � Corrosion: process wafers (Al, Cu), flat � sealed products panel displays, Disasters, internal or external: � equipment, instruments, wiring and � Spills, leaks (coolants), accidents, facility (over many years) fires, power outages SiC/ Si 3 N 4 formation following pre- � � Failures of air handlers and scrubbers oxidation clean Recirculating air between areas � Threshold voltage shifts � FOUPs, Pods, shippers, carriers, � Nucleation irregularities � minienvironments Reducing Contamination
AMC and SMC Sam pling/ Test Methods AMC-MA: Anion - air sampler/IC AMC-MB: Amines/ammonia - air sampler/IC Fused Silica (8h sampling) AMC-MD: Phosphate ions - air sampler/IC AMC-MD: B and P - air sampler/ICP-MS AMC-MM: Metals - air sampler/ICP-MS Air Bubbler Witness Wafer SMC- SMA: W afer - UPW extraction/ I C SMC- SMB: W afer - UPW extraction/ I C SMC- SMOrg: W afer - FW TD- GC- MS SMC- SMD: W afer - VPD I CP- MS SMC- SMM: W afer - VPD I CP- MS & TXRF Pump/Adsorbent AMC-MD: B and P - wafer/VPD ICP-MS AMC-MC: Amides and organic compounds - AMC-MM: Metals - wafer/VPD ICP-MS absorbent tube and TD GC-MS Reducing Contamination
AMC Monitoring ( I ) � Incoming wafers � Organics, condensables, dopants, and metals on the wafer surface � New cleanroom materials (contruction and consumables) � Organic outgas testing (including organophosphate dopants) � Make-up air (MUA) � Organics, acids, and bases prior to recirculation to check for outside environm ental sources � Stockers, mini-environments, wafer sort and storage areas � Acids and am m onium in air (am ines if used in the fab) � Organics and dopants on wafers Reducing Contamination
AMC Monitoring ( I I ) � Pre-diffusion, oxidation furnace, implant annealing process areas � Dopants, metals, and alkali on witness wafers � Acids in air (cause corrosion) � Lithography process areas � Air and gases including CDA, N 2 , Ar, O 2 and He • Acids, bases, and condensables • Up-stream and down-stream of carbon filters/ purifiers � Wet bench and bath areas � Bases, am ines, am ides and organics in air � Acids and am m onium in air (am ines if in photoresist strippers) Cl-induced corrosion of Al at the bottoms of vias. Reducing Contamination
Molecular Acids ( AMC- MA) � NO x dominant MA and is not removed by filters. Not Baselining Molecular Acids in Cleanroom Air as detrimental as other Typical US SEMI Cleanrooms acids. NO x compounds often “smog” related 100% 90% � Most acids are from SC-2, % of sites within range 80% HF, BOE, SPM), RIE, CVD, 70% Br- dopants (POCl 3 ) 60% Cl- 3- very rare since NO3(-) 50% � PO 4 NO2(-) 40% phosphoric acid not PO4(3-) 30% SO4(2-) volatile. POCl 3 leaks can 20% put P into air. 10% 0% 2- can come from inside � SO 4 < 100 100 to 1000 >1000 air or outside air (SO 2 ) Range (pptM) which can oxidize to sulfates Reducing Contamination
Sources of Molecular Acids � Cleaning and acid etch baths (process lines and wet laboratories in fabs) + PO 4 3- , and H + NO 3 + SO 4 2 -, H + Cl - , H + F - , H 3 - � Vaporization of H 2 � Problems occur when there is insufficient exhaust � I m proper airflow setting of minienvironment used for acid sinks � Typical cleanroom H 2 SO 4 concentrations are < 1 ppb � Leaks in HCl lines � Outside environment � Fab m ay be situated in a heavily industrialized area � MUAH systems with insufficient filtering Reducing Contamination
I onic Haze - Background � Dominion Semiconductor was the first to report yield loss from ammonium sulfate haze around 1997, when the company lost some $25M in one day � Since then, essentially every semiconductor fab has experienced some form of haze contamination � In some cases, the loss actually outstripped revenue, with the largest loss reported to date being $100M � The worst effects have been seen in Taiwan and Shanghai, China, where environmental factors figure prominently � In addition to ionic haze, the surfactants that maskmakers use to clean the photomasks are a significant cause of haze Reducing Contamination
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