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To do list. add extra slide about the coupling, at pressure level. Burn CD

To do list. add extra slide about the coupling, at pressure level. Burn CD. Wafer transport and gas separation in a contact-less Spatial Atomic Layer Deposition track. Candidate: Gonzalo Ramirez Troxler Committee: Dr. ir . R.A.J van Ostayen Dr. E.H.A Granneman

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To do list. add extra slide about the coupling, at pressure level. Burn CD

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  1. To do list.add extra slide about the coupling, at pressure level.Burn CD

  2. Wafer transport and gas separation in a contact-less Spatial Atomic Layer Deposition track. Candidate: Gonzalo Ramirez Troxler Committee: Dr. ir. R.A.J van Ostayen Dr. E.H.A Granneman Prof.ir. R. MunnigSchmidt Dr. R. Delfos

  3. Outline • Introduction and motivation • Solar Cells Market and challenges. • Solar cells, recombination velocity and passivation. • Atomic Layer Deposition • Levitrack System • Working principle • Thesis goals: fine tuning stage. • Modelling • Thin Film Flow • Concentration of Species • Results • CFD model • Prototype system to measure position of wafer • Conclusions and recommendations

  4. Introduction Solar Cells Market Outlook • 1,600% growth of MW installed last decade. • Resources depletion. • Ecological impact.

  5. Introduction Motivation Challenge: To position Solar Cells as a major actor in the power generation scenario. Cost Reduction and Increase efficiency. Surface Passivation using aluminium oxide - Al2O3

  6. Introduction LEVITECH and LEVITRACK Levitrack: • Contact-less transportation track • Substrates levitate and layers of Al2O3are deposited (ALD). • High Throughput. • Low cost of construction. Levitech BV is a Dutch based company that develops novel solutions for the IC and Solar Cells Industry. Spin-off of ASM International.

  7. Introduction Solar cell and passivation • Surface Passivation increase efficiency of solar cell: • Increase lifetime of charge carriers.

  8. Introduction Atomic Layer Deposition (ALD) Initial surface

  9. Introduction Atomic Layer Deposition (ALD) TMA reacts with hydroxyl groups

  10. Introduction Atomic Layer Deposition (ALD) TMA saturates surface.

  11. Introduction Atomic Layer Deposition (ALD) Purge using N2.

  12. Introduction Atomic Layer Deposition (ALD) H2O reacts with methyl groups and Al.

  13. Introduction Atomic Layer Deposition (ALD) H2O saturates the surface forming Al2O3.

  14. Introduction Atomic Layer Deposition (ALD) Purge using N2.

  15. Introduction Spatial Atomic Layer Deposition (1) Single Reactor N2 Spatial ALD TMA H2O

  16. Introduction Spatial Atomic Layer Deposition (2) Layer height: 10 nm X 5 Single Reactor 12 meter Spatial ALD Track Time: 5 min Time: 5 min

  17. LEVITRACK Working principle (1)

  18. LEVITRACK Working principle (2) 0.5 mm

  19. LEVITRACK Working principle (3) 156 mm 156 mm

  20. LEVITRACK Working principle (4)

  21. LEVITRACK Thesis goal: fine tuning stage. The aim of this thesis is to study and improve this 4-m test setup, in order to demonstrate stable transport, while minimizing the mixing of precursor gases. • Stable transport: no damage on wafers. • Mixing of precursors: TMA and H2O need to be always separated on space.

  22. Modelling CFD Model • Multiphysics • Fluid Flow • Concentration of species • Surface Chemistry • Heat transport • Structural mechanics

  23. Modelling Thin film flow (1) Unknowns: 3 velocities and pressure. Unknown: pressure Navier-Stokes equations + Continuity equation. Reynolds’ equation • Assumptions: • Lubricant isoviscous. • Low Reynolds number. (Negligible Inertia force) • Negligible body forces.

  24. Modelling Concentration of species Thin Film Flow • Height average velocity. • N2-O2 model. • Stationary. One way coupling. Concentration of Species.

  25. Results and discussion CFD Model (1) Top Volume Gap Out Volume Exhaust Bottom Volume Gap

  26. Results and discussion Flat surface track: benchmark Flat surface Mixing requirement not fulfilled.

  27. Results and discussion Flat surface track: improvement to geometry 70% groove 100% groove

  28. Results and discussion 100% grooves 100% grooves. Mixing requirement fulfilled.

  29. Results and discussion 100% grooves: Flying height

  30. Results and discussion 70% grooves 70% grooves. Fh = 140 μm Mixing requirement not fulfilled.

  31. Results and discussion Flat surface vs. 100% grooves

  32. Results and discussion Flat surface vs. 70% grooves

  33. Results and discussion Grooved surface track (5) Mixing Requirement

  34. LEVITRACK Thesis goal: fine tuning stage. The aim of this thesis is to study and improve this 4-m test setup, in order to demonstrate stable transport, while minimizing the mixing of precursor gases.

  35. Results and discussion Lateral gap measurement system (1) • Design system to measure separation of the of the wafer to the lateral wall.

  36. Results and discussion Lateral gap measurement system (2)

  37. Conclusions and recommendations Conclusions It was developed: • Fast and accurate enough CFD model to predict the pressure profile and spread of precursors inside the track. • As reference 3d NS model takes 2 day per model, while the thin film flow model 10-20 minutes. • System to measure the lateral gap. • Submitted to be patented. It was found: • Alternative geometry, which fulfils the mixingrequirement.

  38. Conclusions and recommendations Recommendations • Include dynamics of the wafer in the model. • Implement and study lateral stability with proposed measurement system. • Integration of the deposition process to the model.

  39. Back Up slides

  40. Back up slides Solar cell and passivation (1) 1.- N-type and P-type junction together. - - - - - - - - - - - 2.- Creation of the depletion region. 3.- Light adsorbed by the silicon. + + + + + + + + + + + 4.- Creation of electron-holes pairs. 5.- Hole->p-type. Electron->n-type Electron-hole pair tries to recombine. 6.-Electrones conducted.

  41. P1 system Working principle (4)

  42. Modelling Analytical model • Analytical model developed in Levitech. • Simple approach. • A negative pressure difference decrease the wafer velocity. • 0.1 mbar 20% reduction of expected velocity.

  43. Model Validation Model validation (1) 5 mbar 3 mbar 10 mbar 7 mbar

  44. ModelValidation Model validation (2) 1 10 12 30 8 • Velocity: 0 [m/s]: • Row 8: in front of the wafer. • Row 10: on the edge of the wafer. • Row 12: Below the wafer.

  45. ModelValidation Model validation (3)

  46. Results and discussion Summary of grooved geometry • Channel effect. • Load asymmetry • Variation of the flying height (100μm). • Reduce transportation velocity. • Needs to be further studied in the functional prototype.

  47. Results and discussion Lateral gap measurement system (3)

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