표준과학연구소Advanced Semiconductor Cleaning Technologies 2006. 6 ㈜ 아이엠티, 레이저그룹 이종명 www.imt-c.co.kr Contents CFC Cleaning Issue Cleaning overview and issues at Semiconductor industry Wet cleaning overview > RCA, Ozone, Marangoni, Sonic, Scrubber, Single wafer mega. Ref: 이종명의 반도체 기술 핸드북 이종명저, 한림원 2004/04 Dry cleaning overview > Plasma, Dry ice, Ar aerosol, UV lamp, SCF Laser cleaning technology > Overview & Introduction Ref: 레이저와 청정가공 > Applications 이종명저, 한림원 2003/07 Conclusions Jong-Myoung Lee, Laser Engineering Group, IMT Co. Ltd. CFC Cleaning Issues Halogen series Solvent is very effective for cleaning and widely used at industrial fields: ex) CFC-113, TCE However they are all ODS (Ozone Depletion Substance): CFC-113, TCE which is permanently prohibited to use in Korea till 2015 (Vienna Agreement) Needs for Alternative cleaning method is very high recently. Wet alternative on development => Water and Hydrocarbon based cleaning solution >> Fundamental measure for ODS is to develop Dry Cleaning Technique Jong-Myoung Lee, Laser Engineering Group, IMT Co. Ltd. Ltd.Wafer cleaning Definition: To reduce the surface contaminants to a minimum level during semiconductor manufacturing processes in order to achieve higher yield. IMT Co. Around 30 % of total processing steps Photolithography CVD PVD Thermal processing Bare wafer Cleaning Output wafer Etching Ion implantation CMP Jong-Myoung Lee. Laser Engineering Group. . Wet cleaning RCA cleaning Ozone cleaning Marangoni dry and cleaning Sonic cleaning: Ultrasonic & Megasonic Single wafer megasonic cleaning Scrubber cleaning Jong-Myoung Lee. Laser Engineering Group. . IMT Co. Ltd. wax) Native oxide (SiO2) Side effects Al & Cu attack. grease. Ltd. Fe. Mg…) Gross organics (PR. Kern at RCA Co.RCA cleaning Typical wet chemical cleaning method for semiconductors 1970 by W. surface roughness Native oxide Native oxide Reactive surface Jong-Myoung Lee. . USA Based on H2O2 Wet chemicals SC1 (APM: Ammonium Peroxide Mixture) SC2 (HPM: Hydrochloric Peroxide Mixture) Piranha (SPM: Sulfuric Peroxide Mixture) DHF (Dilute Hydrofluoric Acid) Typical Composition NH4OH + H2O2 + H2O = 1:1:5 HCl + H2O2 + H2O = 1:1:5 H2SO4 + H2O2 = 4:1 HF + H2O Effective removal contaminants Particles. Laser Engineering Group. IMT Co. native oxide. Organic residue Metallic impurities (Al.. IMT Co.300 USD Based on 8 inch wafer.136.. Ltd. Laser Engineering Group. .120 Gallon 1.235 Gallon 64.Wet station Batch type: dominant till 200 mm wafer X 1) 2) Advantages: Large throughput (~200 wph) Cleaning performance Disadvantages: Huge footprint Enormous chemical and water use & cost Difficult clustering X 1) 2) 3) Yearly chemical use / wet station Yearly DI water use / wet station Yearly chemical cost / wet station 19.821. 2000 9 Jong-Myoung Lee. 96 run/day 9 Data from Semiconductor international Mar. Ozone cleaning RCA based wet chemical cleaning using O3 Oxidizer H2O2 => O3 replacement H2O2: dissociation => H2O => dilution => reduce cleaning performance Current application: PR & organic removal > Piranha(H2SO4+H2O2) => DI/O3 cleaning Jong-Myoung Lee. . Ltd. Laser Engineering Group. IMT Co. IMT Co. Laser Engineering Group. Ltd. .Marangoni dry and cleaning Surface tension difference of IPA & DI water Marangoni force => dry and cleaning No water mark Patent process: Mattson (USA) Jong-Myoung Lee. Sonic cleaning Ultrasonic & Megasonic Above 20kHz & near 1MHz Cleaning Mechanisms > Cavitation: dominant less 100kHz (ultrasonic cleaning) > Acoustic streaming: sonic acceleration 100. Laser Engineering Group.000G at Mega. Dominant at Megasonic Jong-Myoung Lee. Ltd. IMT Co. . Megasonic cleaning Mechanism: Acoustic streaming => Acoustic boundary layer => Drag force => Rolling removal mechanism Nano-scale particle removal (<100nm) Jong-Myoung Lee. . Laser Engineering Group. Ltd. IMT Co. .: Gold finger) >> Cleaning Mechanism => Chemical reaction + Megasonic force >> Advantages (cf CWC): 1) Controllable and repeatable 2) Low consumption of chemicals & water 3) Double-side cleaning 4) Low cycle time >> Disadvantages: 1) Low throughput (rinse + dry) 2) Still wet chemical process Jong-Myoung Lee. Ltd.Single wafer megasonic cleaning (1) Single wafer processor: dominant more than 300 mm wafer (Verteq Co. IMT Co. Laser Engineering Group. .High Pressure Aerosol Jet Gas Inlet Liquid Inlet Atom izing zone HIGH Pressure Jet Droplet acceleration zone Exit Orifice Chemical dispense Ocean Spray (AMAT): for <100nm gate Jong-Myoung Lee. Laser Engineering Group. Ltd. IMT Co. DI & chemical volumes ¾ Applications: post CMP.Scrubber cleaning Dominant for post CMP cleaning >> Cleaning Mechanism: Hydrodynamic drag force > Adhesion force >> Advantages: 1) Strong cleaning force => good organic & inorganic removal Double side cleaning Low recontamination 2) 3) >> Disadvantages: 1) ¾ Blush material: PVA ¾ Throughput = 55-60 wph ¾ Control factors: blush pressure. IMT Co. Laser Engineering Group. Ltd. post PECVD 2) Pattern damage due to contact process Only flat & hard surface available => contaminants stuck & scratch induced Jong-Myoung Lee. . rotation speed. chemicals) Plasma cleaning Dry ice cleaning Ar aerosol cleaning UV lamp cleaning Super critical fluid cleaning Laser cleaning Laser shock cleaning Laser plasma cleaning Jong-Myoung Lee. IMT Co. . Ltd. trench) > Water mark > Corrosion issues (Cu. low-k) > Cluster tool > Environmental issues (water. Laser Engineering Group.Dry cleaning Limits of wet cleaning > High aspect ratio structure (contact. H2O => 2H+O ¾ O + PR => H2O+CO+CO2 + … Heated plate To the pump Jong-Myoung Lee.Plasma cleaning (1) Remote plasma cleaning > Ashing = PR stripping > in-situ etch/strip processing Direct plasma cleaning : Reactive plasma & Ar plasma > Ar plasma: pre-deposition cleaning by sputtering > Reactive plasma: Microwave Remote chemical reaction plasma chamber => volatile O2 Plasma H 2O byproducts ex) PCB flux cleaning. Laser Engineering Group. Ltd. desmearing. IMT Co. . Process chamber H O deflashing O H H O H O O O H O O Wafer *PR Stripping mechanism : chemical reaction ¾ O2 => O+O. Ltd. IMT Co. Soft dry ice cleaning = CO2 snow cleaning > liquid CO2 => adiabatic expansion at nozzle => dry ice generation and blowing 2. . Laser Engineering Group. Hard dry ice cleaning = CO2 pellet cleaning > Dry ice lump => pellet => high pressure blasting Jong-Myoung Lee.Dry Ice cleaning (1) Cryokinetic source: CO2 >> Cleaning type >> CO2 dry ice pellets 1. Ltd. Laser Engineering Group.Ar aerosol cleaning (1) Cryokinetic source: Ar Ar / N2 mixture => compression => adiabatic expansion from the nozzle => Ar aerosol ejection • Advantages 1) Dry process 2) Excellent particle removal performance Disadvantages 1) Pattern damage => flat surface 2) Thermal shock 3) Expensive maintenance due to high purity Ar 4) Expensive equipment due to Vacuum process • >> IBM patent technology => FSI International commercialized. . IMT Co. Jong-Myoung Lee. IMT Co.UV lamp cleaning UV radiation (Hg lamp) + O2 => O & O3 (O+O2) Mechanisms: Direct bond breaking + Chemical reaction E = hν = hc/λ Organic contamination removal (UV/O3 cleaning) Applications: PR hardening. Ltd. surface activation >> Competition with AP tech Jong-Myoung Lee. Laser Engineering Group. . OELD cleaning. .Super critical fluid cleaning (1) Super critical region SCF characteristics (CO2) > High density (~liquid) > Low viscosity (~gas) > High diffusivity (~gas) > High solubility (CO2) > Easy recycling Organic removal process > PR removal Nano-scale pattern rinse & dry process > Deep penetration Jong-Myoung Lee. IMT Co. Laser Engineering Group. Ltd. 한림원. 3. 2. 이종명저. Laser Engineering Group. IMT Co.What is a laser cleaning? Definition of laser cleaning : A process which removes contaminants from a surface by lasersurface interactions 1. 2002 Jong-Myoung Lee. Ltd. . Cleaning mechanisms Photo-thermal effect Photo-mechanical effect Photo-chemical effect Ref: 레이저와 청정가공. Laser cleaning mechanisms Photo-thermal effect Mechanical effect Photo-chemical effect Jong-Myoung Lee. Ltd. IMT Co. . Laser Engineering Group. Ltd. IMT Co.Process characteristics - Unique characteristics Precise process which ceases shortly after the laser pulse has ended Selective process which can be tuned for the removal of specific substances with a proper selection of wavelength Non-contact process which produces no contact wear Surface relief process without any mechanical loads Controllable process that a specific thickness of materials can be removed Environmentally preferable (or clean) process since it is a dry process - - - Jong-Myoung Lee. . Laser Engineering Group. . Laser Engineering Group. IMT Co. Ltd.Applications Medical applications Conservation of artworks Industrial applications Jong-Myoung Lee. Laser Engineering Group. Ltd. .Artwork conservation First laser cleaning shoot at 1975. Venice Jong-Myoung Lee. IMT Co. . Ltd. Laser Engineering Group.Medical applications ***Applications: Dermatology & Dental Surgery Jong-Myoung Lee. IMT Co. Ltd.Industrial applications Jong-Myoung Lee. . Laser Engineering Group. IMT Co. IMT Co. Ltd. . Laser Engineering Group.Tire-mold cleaning Tyre residue removal (every 2-3 weeks) => blasting methods (glass beads with high pressure) Excimer laser (licensed process: Radiance process) •Other application: tire-marking indicating class (rain tire) or logo Jong-Myoung Lee. Comparison of cleaning processes Media blasting In-situ cleaning (op. Ltd. IMT Co. . Off-line) Labor required No Dry ice cleaning Yes Wet chemical cleaning No Laser cleaning Yes High Medium High Low Level of automation Low Low Low High Noise level Medium High Low Low Substrate wear Environmental hazards Post-cleaning waste Yes No Medium No Medium Medium High Low High Low High Low Jong-Myoung Lee. Laser Engineering Group. LPC. . ISM etc. Ltd. iMT holds diverse laser cleaning techniques and systems. SLC. Laser Engineering Group. A creative idea from industrial fields is most important to implement the new technology successfully. LMC.e. Industry) > Wet & Batch => Hybrid => Dry & Single Laser cleaning has unique characteristics and its industrial applications will be expand rapidly. so fundamental understanding of the cleaning processes is most important for successful applications. Jong-Myoung Lee. Cleaning prospect (Semi.Summary Every cleaning methodologies have their own advantages and drawbacks. LSC. i. IMT Co.