PECVD Depositon

Note: The silane MFC has been changed (again), so all recipes use different gas flows

Do not use the old recipes - they don't work. (Updated 5/9/08)

1. Flow Rates
   
   1. To determine the flow for each gas, multiply the percentage by the full flow in SCCMs
   2. Gas 1 (NH₃) : 35 SCCM
   3. Gas 2 (SiH₄) : 200 SCCM
   4. Gas 3 (N₂O) : 71 SCCM
   5. Gas 3 (N₂) : 100 SCCM
   6. Gas 4 (CF₄/20% O₂) : 0.57 SLPM
2. Silicon Dioxide, SiO₂ - Low Pressure Recipe
   
   1. Not yet recharacterized
   2. Good film quality and uniformity, no chamber buildup, but not conformal
   3. Gas2 (SiH₄): 54%
   4. Gas3 (N₂O) : 17%
   5. Pressure : 350 mTorr
   6. Power : 100 W
   7. Temp : 300°C
   8. Deposition rate : ~170 Angstroms/minute
   9. Index of refraction = 1.46
3. Silicon Dioxide, SiO₂ - High Pressure Recipe
   
   1. Conformal film growth, poor uniformity and heavy buildup in chamber
   2. Gas2 (SiH₄): 52%
   3. Gas3 (N₂O) : 25%
   4. Pressure : 900 mTorr
   5. Power : 50 W
   6. Temp : 250 to 300°C
   7. Deposition rate : ~210 Angstroms/minute
   8. Index of refraction = 1.46
4. Silicon OxyNitride, SiO_xN_y - Not yet recharacterized
   
   1. This process has not been characterized since the MFC change
   2. Film growth rate, index of refraction, and quality depend heavily on chamber condition.
   3. Gas1 (NH₃): 12.5% (was 2.5%)
   4. Gas2 (SiH₄) : 55% (was 95%)
   5. Gas3 (N₂O) : 2.5-25%
   6. Pressure : 900 mTorr
   7. Power : 100 W
   8. Temp : 250°C
   9. Deposition rate : 56-183 Angstroms/minute
   10. Index of refraction = 1.46-1.79
   11. More Information
5. Silicon Nitride, SiN_x
   Film growth rate, index of refraction, and quality depend heavily on chamber condition.
   
   1. For best results, clean and then season the chamber (see seasoning recipe below)
   2. Gas1 (NH₃): 21% to 23%, higher flow will lower index of refraction (start with 22%)
   3. Gas2 (SiH₄) : 73%, higher flow will increase index
   4. Pressure : 1000 mTorr
   5. Power : 100 W
   6. Temp : 250°C
   7. Deposition rate : ~90 Angstroms/minute
   8. Index of refraction = ~2.05
6. Nitride Seasoning
   
   1. First, perform a full chamber clean.
   2. Gas1 (NH₃): 18%
   3. Gas2 (SiH₄): 47%
   4. Pressure: 800 mTorr
   5. Power: 100 W
   6. Temp: 250°C
   7. Time: At least 1 hour for good film index control
   8. Note: This recipe should have no powdery buildup in the chamber - just a film growth.
7. Amorphous Silicon, Si - High Pressure Recipe - Not yet recharacterized
   
   1. This process has not been characterized since the MFC change
   2. Film growth rate, index of refraction, and quality depend heavily on chamber condition.
   3. Chamber Clean
      
      1. Gas4 (CF₄): 10%
      2. Pressure: 300 mTorr
      3. Power: 100 W
      4. Temp: 250°C
      5. Duration: 30 minutes - 1 hour
      6. Wipe clean.
   4. Chamber Seasoning
      
      1. Gas1 (NH₃): 12.5% (was 2.5%)
      2. Gas2 (SiH₄): 55% (was 90%)
      3. Pressure: 900 mTorr
      4. Power: 100 W
      5. Temp: 250°C
      6. Duration: 20 minutes
      7. Wipe clean.
   5. ASI Growth
      
      1. Gas2 (SiH₄): 55% (was 90%)
      2. Pressure: 900 mTorr
      3. Power: 50 W
      4. Temp: 250°C
      5. Deposition rate: ~45 Angstrom/minute
      6. Index of refraction = ~3.7-4.1
8. CF₄Chamber Clean
   
   1. Remember to close the valve on top of the CF4 tank when done
   2. Gas4 (CF₄): 10%
   3. Pressure: 333 mTorr
   4. Power: 100-120 W
   5. Temp: 250°C
   6. Time: 30 minutes to 1 hour, depending on chamber condition