This document discusses fluidized bed reactor technology for producing polysilicon. It provides background on existing polysilicon production processes and fluidization fundamentals. Key elements of fluidized bed reactor design are outlined. Advantages and challenges of fluidized bed processes for polysilicon production are presented. Literature on previous work and current commercial processes is reviewed. A multi-stage approach to fluidized bed reactor development including modeling, experimentation, and pilot testing is proposed.

1. Fluidized Deposition Reactor for Silicon Production
Paul Ege1, Alireza Abbasi1, Jin-Seok Seo2, Jun-Suk Lee2, Jung-Hyun Lee2
1- Reactech Process Development Inc, Canada
2- KCC Corporation, Republic of Korea

2. Overview
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3. Background
Polysilicon Processes
• Siemens Rod Deposition
• High Energy / High Quality
• SiHCl3(g) +H2 = HCl(g) + Si(s)
• SiH4 = Si(g)+Si(s)+ H2
• Metallurgical Routes
• Low Energy / Low Quality
• Fluid Bed deposition
• Low Energy / Medium-High Quality
• SiH4 = Si(g)+Si(s)+ H2
• SiHCl3(g) +H2 = HCl(g) + Si(s)
• 4 SiHCl3= 2 H2+ 3 SiCl4+ Si(s)
• Silane Freespace
• Low Energy / Medium quality
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4. Background
Fluidization Fundamentals
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5. Background
Fluidized bed design elements
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6.
Polysilicon Fluidized Bed
Process Evaluation
Advantages Challenges
ª Continuous granular production - Complex flow patterns
=> Reduce operation cost - Gas mix in emulsion
ª Excellent contact high surface volume - Gas bypass in bubbles
- Attrition and Erosion
=> compact process - Quality reduction
ª Low DP for high throughput - Dust generation
=> high capacity - Pipe/Internal deterioration
- Entrainment
ª Excellent heat transfer - Powder inherent, less with TCS
=> low energy consumption - Dust from abrasion/attrition
- Fouling
- Wall
ª Near isothermal conditions and large - Nozzles/distributor
thermal reservoir
- Complex reaction kinetics
- TCS, equilibrium limited
- Silane, competing reactions
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7. Polysilicon Fluidized Bed
Literature
Ø JPL work in 1980ʼ’s many references
Ø Furusawa Hom/Het kinetics (1988)
Ø Lai & Dudukovics (MEMC) 1986
• Describes a multi step mechanism
Ø Caussat et. Al. study on FBR (1995-98)
• Bubbling reactor model and exp data
Ø Mlezcko et. Al. Solarworld (2004)
Ø Pina et.al REC process (2006)
• PF/CSTR approach
Ø Ydstie-Balaji independent(2009)
Ø Parker Barracuda (2010)
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8. Polysilicon Fluidized Bed
Prior art (old patents)
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9. Polysilicon Fluidized Bed
Protected designs (current patents)
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10. Polysilicon Fluidized Bed
Commercial Processes
MEMC – SiH4 FBR
• Two stage process; high production with dust, low
production to adsorb dust and anneal
• Seed, quench, el.mag. heat, coating and valves
• Recent – multiple beds for growth, and special distributor
• Appears to be traditional bubbling fluid bed behavior
• Dimensions and capacities not revealed
REC – SiH4 FBR
• Submerged Spouted bed one or more spouts
• Nozzle design with secondary orifice, internal grinding,
annular withdrawal, halogen injection, tapered bed
• Recent radiant heated bed with internal liner and cooling
below injector
Others in development
• Wacker, KRICT, AEP, SILIKEN – TCS based
• Samsung-MEMC, KCC – Silane based
• Independent developers
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11. Polysilicon Fluidized Bed
Commercial design solutions
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12. FBR development
Scope Scale and Objective of stages
① Review stage
ü Review literature/patents for IP/Cost/Risk feasibility analysis
② Lab/Bench Scale (inches diameter)
ü Establish reaction kinetics and flow for basic reactor models
ü Validate process conditions and scale up strategy for pilot/commercial
③ Pilot/Demo Scale (feet diameter)
ü Validate commercial challenges in long term continuous operation
ü Verify scale up predictions and design for commercial
ü Well instrumented small commercial unit with many interruptions
ü Risk in scale best taken here!
④ Commercial Scale (meters diameter)
ü Target uninterrupted production with minimum disturbance
ü Start-up and stabilize, then optimize Yield/Capacity/Quality/Economics
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13. FBR development
Multi Stage Effort
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14. FBR development
Multi Level Modeling
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15. FBR development
CFD and CPFD for flow and scale up analysis
Reactech
Process
Development
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16. FBR development
Reactor Model for design/analysis/control
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17. FBR development
Experimental
OBJECTIVE
Experimental
methods
to
verify
a
wide
range
of
parameters
that
are
important
in
reactor
model
development
and
for
design
purposes
Characteristics Methods
Particle– External Pressure and Temperature
• Fluidization/Entrainment/Reactivity • Global / Time average => Mb, Hb, Void fraction
• Porosity/Density, Size/Shape, Umf, DPf, Ut • Fluctuations => frequency, regime, forces
• Correlations => size, velocity
Gas • Delta T=> Solids mixing
• Fluidization/Entrainment Intrusive probes
• Density, Viscosity • Capacitance/Fiberoptic/DP
Fluid bed • Local bubble and void properties
• Void, Solid Mixing, Gas dispersion, Mass and Non Intrusive probes
Heat transfer • x-ray, γ-ray, capacitance
Entrainment • High speed samples => local bubble properties
• TDH, Freeboard flow/void, Cyclone feed/ • Multiple samples => Tomography
efficiency, Dipleg operation Tracer studies
• Gas dispersion
• Solids mixing (solid tracer, heat pulse)
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18. Conclusions
Ø Polysilicon FBR is promising technology for low cost high quality
production
Ø Prior art allows development of Polysilicon FBR. Challenge will be to
avoid design details already patented
Ø Significant development challenges require serious long-term effort
from lab through pilot to commercial scale.
Ø REC successfully commercialized new technology
Ø Several new projects at different development stages
Ø KCC progressing well with solid foundation from Bench scale efforts
fast approaching demonstration scale pilot production
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