docBeam-Induced Cleaving Technology for Kerf-Free c
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Beam-Induced Cleaving Technology for Kerf-Free c
Beam-Induced Cleaving Technology for Kerf-Free c-Si PV Wafering Francois J. Henley Silicon Genesis Corporation San Jose, California, USA 20μm SiGen 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop 50μm SiGen 120μm SiGen 150μm Agenda SiGen – Introduction Crystalline Silicon (c-Si) PV Wafering - MWSS Dominance Kerf-Free Wafering – Basic Advantages Kerfless Integration in PV Manufacturing PolyMax™ - Beam-Induced Wafering Introduction R&D Development – 2007-2009 Alpha System Development – 2009-2011 GenII Production System Description Wafering Quality Conclusion 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.2 Silicon Genesis at a Glance • Founded in 1997 • Developed Layer-Transfer (LT) process and high-volume manufacturing equipment for use in the semiconductor (SOI) and opto-electronic/display markets (SOQ) • Focused technology on developing PolyMaxTM system for solar wafering 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.3 Plasma-Bond System Cleave System Thin-Film Layer-Transfer @ SiGen • Full LT Fab for SOI, SOG, SOQ and GeOI from ‘2000 • Manufactured 5 production tools specific to LT • Licensed LT technology to SEH, MEMC and others • Full LT cost models developed and tested SiGen SOI LT Facility – Circa 2002 First Generation Bond/Cleave Tools – Circa 2001 Plasma 150mm Implanter SOQ – Circa 1999 2004 Patterned 300mmTFT 100nm Silicon SOIArray – Circa – Circa 20022005 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.4 150mm GeOI –Sensor Circa –2002 Si Film on CMOS Circa 2008 Crystalline Silicon (c-Si) PV Wafering MWSS Dominance 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop SILICON GENESIS CONFIDENTIAL p.5 p.5 Wafering in the PV Value Chain Wiresaw Wafering ~50% Material Loss Gluing Sawing Pre-Cleaning Singulation Cleaning Two essential cost saving potential using kerfless wafering 1. Material savings by cutting kerf: ~2x 2. Material savings by cutting thinner wafers: up to 8x or more 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.6 Current Wafering Method Wafer Thickness Wafer Thickness Wire Thickness Wire Thickness Thickness Wire Kerf Loss Loss Kerf ― 40% - 50% of the ingot lost via kerf loss ― Need for expensive slurry and miles of steel wire ― Inherent barrier to slicing wafers less than 150µm thick ― Lack of thickness consistency due to wire abrasion ― Sawing induces micro fractures, increasing potential for breakage Pitch Distance Pitch Distance Ex. Meyer Burger DS 261 Wire Saw Wafer Thickness Wafer Thickness Wire Thickness Kerf Loss Kerf Loss Loss Kerf Wire Wire Thickness Pitch Distance Wire Thickness Pitch Distance Pitch Distance Thickness Multi-Wire Slurry Saw: ~100% Market Share 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.7 Wiresaw (Kerf) Kerfless Wafering Kerf-Free Wafering Basic Advantages 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.8 p.8 Improved Silicon Utilization Wire Saw – 180um wafer 27 wafers/cm Wire Saw 1m = 2,777 wafers = 12 KW Silicon brick Length: 1m Weight: 100 Kg 120umwafer wafer PolyMax – 50um 83 200wafers/cm wafers/cm 1m = 8,333 20,000wafers wafers==35 88KW KW SiGen SiGen PolyMax approximately triples the productivity of feedstock material Reduced upstream manufacturing costs - Materials and OpEx Savings 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.9 Cost Reduction Potential Source: AEI Consulting – February 2012 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.10 Benefit to the PV Industry Kerf-free benefits are numerous for the PV Industry 1. Lower overall cost through entire PV value chain Poly feedstock savings Upstream equipment savings (CZ pullers, cropping, etc.) Lower Opex costs Thinner & higher strength form factors 2. Green footprint & waste reduction Free of wire and slurry consumables Smaller energy footprint Free of recovery/waste treatment infrastructure 3. New Applications Effective across residential to commercial to utility Enables high-efficiency BIPV Flexible high-efficiency PV 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.11 PolyMax™ - Beam-Induced Wafering Introduction 2012 U.S. U.S. PVMC PVMC c-Si c-Si Feedstock/Wafering Feedstock/Wafering Workshop Workshop 2012 SILICON GENESIS p.12 CONFIDENTIAL p.12 Kerfless Competitive Requirements 1. No lifetime compromise 2. 3. 4. 5. 6. ~1.5% efficiency drop equivalent to cost of wafer Compatibility with next-generation cell designs (IBC, EWT, etc.) Inability will limit adoption or force proprietary cell lines Ability to make ultra-thin to substitutional wafer thicknesses Need long-term roadmap capability to remain competitive Good mechanical strength High cell yields and stable manufacturing Good dimensional repeatability High cell yields and stable manufacturing Use of existing equipment infrastructure Lowered complexity of integration Faster adoption rate 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.13 Selected Kerf-Free Wafering Efforts Company Phase Silicon Source Name PSI Process Special licensed from ISE- CVD Bayern Reactor Special CVD on silicon CVD Reactor Special Hot-wire CVD CVD Reactor Product Substrate Area Reported Film on Substrate 156mm Special Shape Med-High Lifetime >100us 15% Reported Long Film on Substrate Full Wafers Med-High Lifetime >15-30us 15% Reported Long Film on Substrate Full Wafers Med-High Little Information Available None Reported Long High Small Grain Multicrystalline ~15% Closed Small Grain Multicrystalline ~13.5% Module Efficiency In Production 220MW Solexel** Gas Crystal Solar** Gas Ampulse Gas Evergreen Solar Liquid String Ribbon Solivo A.G. Liquid String Ribbon Melt Substrate 1366 Liquid Direct Wafering (Melt on Ceramic Form) Substrate Varian Liquid Floating Silicon Method (FSM) IMEC Solid "Thin" Astrowatt Melt Substrate Proprietary Size 80mm 200um Proprietary Size 80mm 135-200um Throughput Potential >19% (no Texturization) High 156mm Wafer 200um High Melt Substrate None Reported High SLIM-Cut CZ Thin Film 10cm2 Low-Medium Solid "Thin" SOM/BCSOM CZ Silicon on Metal 100mm Diameter High Twin Creeks Solid "Thin" Thin-film cleave on substrate CZ Film on None Reported Substrate (Proprietary) High SiGen Solid Full-Range PolyMax CZ Substrate 156mm Wafer 20-120um High Absorber Material Quality Cell Efficiency Time to Ramp TTV Poor "1.5% less than Short No Other Information mc-Si" [6] Substitutional? N/A Short Substitutional? 10% Long Est. 6-8% from Literature Data Medium-Long None Reported (Proprietary) None Reported Medium-Long Lifetime > 200us Mechanical good TTV Good > 19% Short Substitutional None Reported TTV Poor Low Lifetime? Brittle? TTV Poor Low Lifetime? Brittle? ** Process Restart Mostly in R&D/Development Phase Many companies assume pre-2009 PV economics….. Current cost and performance levels render many uncompetitive 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.14 SiGen Kerfless Wafering Hardware Description and Status 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.15 SiGen PolyMax Process Two Step Process (1) Implant (2) Cleave Eliminates Kerf Loss Eliminates Consumables Silicon Plate SiC, Slurry, Wire Eliminates Other Systems Cleaved Wafers 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.16 Gluing Singulation Cleaning Less Damage Etch 2007-09: R&D Equipment Development 2MeV Implant - 2007 50um Wafer - 2008 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop 1.1MeV Implant - 2008 20um Wafer - 2009 p.17 2007-09: R&D Equipment Development 4MeV Implant - 2009 2-4MeV Prototype - 2010 50-150um Production Prototype 150um Wafer - 2009 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.18 Alpha Tool – DC Accelerator Ion Source HV Acceleration Stack SF6 Pressure Vessel 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.19 Beamline & Endstation Scan Magnet Accelerator Beamline Endstation 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.20 PolyMaxTM GenII Production System Description 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.21 Thickness Specific System Design Alpha System 50-150um 40-120um GENIIb 20-50um GENIIa 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.22 GenII Upgrades & Modifications Alpha System GenII Production System Proton Source ~20mA 100mA Accelerator 2-4MeV, 40mA 1.1-3.5MeV, 100mA max. Beamline 35/125 degree 90-degree Endstation 125/156mm bricks 6x6/8x8 tray 125/156mm bricks 6x6/8x8 trayless Cleaving System Gen3 single-brick Gen3 2x8 brick automated Automation None Brick mount/demount Wafer handling 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.23 Compact Implanter Design – GenII Production Proton Source Accelerator Beamline and Scanner Endstation 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.24 Accelerator is moved up to 2nd floor closer to endstation Long beamline eliminated Vault room has reduced footprint of 1,800 sq. ft. Possible Front In/out design p.24 Wafer Quality 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.25 Wafer Specifications 200-1000usec carrier lifetime Excellent mechanical strength < 1% TTV/dimensional tolerance 20-150um wafer thickness range Recent Improvement Wafer Quality and Cost Comparison Wafer Characteristic Typical Wiresaw Value Lifetime ~Brick Lifetime (>500usec) Surface Roughness Mechanical Strength Thickness Range Thickness Variation Dimensional Accuracy (Surface) 120um Wafer Cost (Includes Poly)* 50um Wafer Cost (Includes Poly) Few Microns PolyMax Value ~Brick Lifetime (>500usec) 0.06um to 0.4um (20-150um thickness) 300-400 Mpa Higher than ~120-140um 800MPa to few GPa 10-30um typical Follows brick cropping accuracy Less than 1% over thickness range Follows brick cropping accuracy $0.50/Wp $0.25/Wp Not Capable * Scenario includes best wiresaw performance 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.26 20-150um $0.15/Wp Conclusions – Kerf-Free Wafering Kerfless wafering cost advantages are compelling and enabling for the industry SiGen’s Kerf-Free wafering technology is poised to go to production SiGen is ready to build next-generation “GenII” systems GenIIa: 20-50um capability GenIIb: 40-120um capability Move to lowest thickness c-Si wafers = Path to lowest installed PV cost … Helping to achieve c-Si efficiencies at thin-film prices..... 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.27 Near-Term Challenges (1-3 Years) 1. Supply Chain Rebalancing to Support Low-Cost c-Si PV 2. Stabilized polysilicon prices/supply Integration and use of low cost CZ (i.e. continuous CZ) Optimization of wiresaw processes Low cost c-Si cell and module processes Move to Thin c-Si Cell and Module Enabled Processes Kerfless wafering in pilot factory production Thin wafer handling (50um+ capable) Thin c-Si cell/module production (singulated 50um+ wafer capable) 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.28 Long-Term Challenges (4+ Years) 1. Move to High-Efficiency c-Si Processes 2. Use of “Best of Breed” PV Cell Structures 3. IBC/EWT for medium/thicker wafer HIT type for 20-50um form factors Absorber: N-type single-crystal silicon Crystallization: Continuous CZ Wafering: Kerfless (50um) Cell: HIT using thin-film a-Si PECVD systems Module: Thin-film large-area module manufacturing Lower BOS Costs to Enable Lowest Cost Installations High-efficiency systems will help here 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop p.29 Thank you! For more information visit www.sigen.com 2012 U.S. PVMC c-Si Feedstock/Wafering Workshop
