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Aluminum Evaporation

Aluminum will be evaporated onto the surface of the wafer to form low-resistance connections to the active devices.

Equipment

LDS 1820 Thermal Evaporator or Cooke CVE301 Thermal Evaporator

Supplies

LDS 1820

  • Demelloy (2%Si in Al alloy)
  • IPA
  • Blue wipers
  • Hi-vac grease

Cooke 301

  • (1) three inch piece of Al wire
  • IPA
  • Blue wipers
  • Hi-vac grease

Operating parameters

LDS 1820

  • Turbo cross over: 30 mTorr
  • Evaporation pressure: <5e-6 Torr
  • Evaporation recipe: 4
  • Evaporation rate: 10 Å/second
  • Total film thickness: 2000 Å

Cooke 301

  • Diffusion pump cross over: 80 microns
  • Evaporation pressure: 1 x 10-5 Torr
  • Filament current: 40 - 60 A
  • Evaporation time: 3 seconds after evaporation starts

Equipment/controls/tools locations

LDS 1820

  • Located behind diffusion furnace
  • Controls located in the rack to the right of the evaporator

Cooke 301

  • Located behind diffusion furnace

Operating precautions

Implosion Hazard

The Cooke 301 uses a glass bell jar that poses an implosion hazard. The pressure exerted on the bell jar by the atmosphere can be extreme. If the bell jar fails, the glass can potentially cause serious injuries.

Operating procedure

See Appendix B of the Lab Supplement.

IC Process

  1. RCA clean

  2. Initial oxidation

  3. Mask 1

  4. Mask 1 etch

  5. Mask 1 PR removal

  6. Boron predep

  7. BSG etch

  8. Boron drive

  9. Mask 2

10. Mask 2 etch

11. Mask 2 PR removal

12. Phosphorus predep

13. PSG Etch

14. Mask 3

15. Mask 3 etch

16. Mask 3 removal

17. Gate oxidation

18. Mask 4

19. Mask 4 etch

20. Mask 4 removal

21. Mask 5

22. Evaporation

23. Lift off

24. Anneal


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