c- Si Metrology: Perspec;ves from Across the Supply Chain

Transcription

1 SOLARWORLD AMERICAS 2015 Bjoern Seipel c- Si Metrology: Perspec;ves from Across the Supply Chain Feedstock, crystalliza1on, and wafer PVMC mee;ng 2015, SFO

2 America s largest PV manufacturer since 1975 Hillsboro, Oregon U.S. headquarters and factory 500 MW cell capacity 350 MW module capacity 2

3 The world s largest solar manufacturer outside of Asia Freiberg, Germany Arnstadt, Germany 350 MW cell capacity Former Bosch plant 500 MW module capacity 700 MW cell capacity 200 MW module capacity Total global capacity: 1.50 GW cell, 1.05 GW module MC produc1on capacity 750MW in FBG and Cz Produc1on with 500MW capacity in progress 3

4 Industry growing rapidly amid price drops 49% year a\er year Source: IEA Source: GTM Research 4

5 c - Silicon market & cost dissec;on Silicon substrates con;nues domina;ng the PV market with around 90% share 5

6 Metrology? Adjust your needs to who you are Feedstock Crystal Wafer Cell Module Downstream Ver;cally integrated companies have a good idea about material quality due to Processes of Record and ;ght SPC Know supply chain, inves;gate plan for contamina;on streams. How do I buy my silicon ingots, e.g. as grown, shaped, finished Specifica;on on material LT, O[i], C[s], Shape, Slip, Precipitates? What kind of wafer do I buy, e.g. thinner wafer, diamond wire sawn, resis;vity mix, O[i], bow, hv, wafer- back- to ingot tracking? What cell architecture, reliability, PID, LID Mul;ple Suppliers!!! 6

7 Silicon Feedstock EG-Si 9N: Siemens Process (SiHCl3) / SiH4 Sol-Si 7N,8N FBR: Samsung/Sun Edison & REC (SiH4) MG-Sillicon --- > Upgraded MG silicon, Elkem, Kawasaki, Carbothermic routes 6N/Calisolar/Silicor (18.9% ETA PERC) Source: IRTPV Metrology: GD-MS, ICP-MS, DLTS, DTA, LT Source: IEA 7

8 Crystal - mono MCz does not play a role New Wacker FZ process: Granule recharged FZ crystal growth (GFZ) * W. v. Ammon, Phys. Stat. Sol. A, Vol. 211 (2014) 8

9 Cz - Silicon Reduce Variable Costs Reduce power consumption Reduce consumables cost argon recycling; recharge Improve cycle time Improve Yield Larger charge size Reduce structure loss Improve diameter control variable / W p Body = cells Si / W p / W p = Si + variable + fixed / N cells W p cell Reduce Fixed Costs Improve yield Improve cycle time Lean operations fixed / W p Improve material quality Reduce light induced degradation Reduce oxygen precipitates Reduce contaminants and structural defects W p 9

10 Cast Silicon Reduce Variable Costs Reduce power consumption Reduce consumables costs (graphite, crucibles, etc) Reduce cooling/ar costs Improve cycle time variable / W p Si / W p Reduce Silicon Costs Improve yield (increase high lifetime material percentage) Larger charge size / W p = Si + variable + fixed / N cells W p cell Reduce Fixed Costs Improve yield Improve cycle time Lean operations Increase solidification rate fixed / W p W p Improve material quality Increase lifetime Quasi-mono 10

11 Mono- like, QuasiMono Monocrystalline seeds on crucible bohom to copy single crystal informa;on to block size ingot during crystal growth* Aim: Center bricks are completely monocrystal quality (alkaline texture etched Δη +1%) Edge and corner bricks same or beher quality compared to mc Si ingot Challenges**: Disloca;on mul;plica;on during bulk growth on corners, edges and over seed joints Three type of wafers from one ingot and two ways of cell processing Wide range of cell efficiencies produced *Nathan Stoddard, Bei Wu, Ian Witting, Magnus C. Wagener, Yongkook Park, George A. Rozgonyi, Roger Clark: Casting Single Crystal Silicon: Novel Defect Profiles from BP Solar's Mono2 TM Wafers. Solid State Phenomena (2008)1-8 ** H. Zhang, L. Zheng, B. Zhao, Z. Zheng, X. Huang: Future Trends for High Efficiency and Low Cost Silicon-based Photovoltaic Production st NREL workshop on Silicon Solar Cells & Modules 11

12 Metrology Opportuni;es CZ Lots of metrology on silicon samples already exist. Growth metrology: melt level detec;on, melt temperature, pressure, gas flow Past Growth metrology sampling: O[i], C[s], TD, ICP- MS, LT, X- ray, PL, LPS, Resis;vity Defect etching OpportuniFes: Metrology on as- grown crystal in HVM Photoelastcity X- ray Oxygen/Carbon in Crystal IR Other? Wang et al. Energy Procedia 38 ( 2013 ) SolarWorld internal 12

13 Sawing / Wafer Seigneur et al., Photovoltaics Interna;onal (2015) 13

14 Kerfless Direct solidifica;on: Evergreen Ribbon technology out of business Life;me? Wafer quality in HVM? Vapor deposi;on (EPI): ongoing Solexel - 35-micron-thick, high-performance, low-cost monocrystalline solar cells using a lift-off technology (2014) NexWafer - Just founded. Spin- off from FhG ISE Crystal Solar Epi WaferTM technology start in 2015 Cleaving: SiGen, AstrowaL Companies out of business. Only lihle cleaving ac;vity currently ongoing 14

15 Wafer Metrology Common Metrology: Resis;vity, XYZ dimensions, TTV, cracks, stain, bow, roughness, sawmarks VDP- ICP- MS, GD- MS, Gas Chromatography Breakage tests (4- point, ring- on- ring) Not so common or non- existent in HVM: Oxygen, TD, Defects (Swirls, Stacking faults, Slip) Mechanical wafer screening Subsurface damage PL(LT) Photoelas;city 15

16 Sort Term & Long Term Challenges Short term Challenges Characterize/Collect proper;es of different upcoming technologies Understand what quan;;es do need to be characterized to increase yield & quality Find appropriate metrology partners (ver;cally integrated vs. external supplier) Long term Challenges Integrate appropriate metrology in HVM tools (e.g. reflec;vity a\er saw damage removal, perpendicularity of shaped ingots) Iden;fy & adjust to technology changes, e.g. cell architecture requirements, module technology, etc. Collaborate with metrology partners PV companies are not metrology tool manufacturers! 16

17 Thank you for your kind ahen;on? 17