Solid Source Boron Diffusion

Using Boron Source disks obtained from IBM - Essex Jcn (4" diam):
  1. Load wafers: alternate boron disks with silicon wafers, keeping a silicon wafer on each end. For single sided doping, place two silicon wafers between each disk. Ensure that wafers can not contact source disks. For thin wafers, silicon shim may be required.
  2. Load wafer boat into furnace.
  3. Ramp from 400C to 1150C in nitrogen gas flow (IBM: 500C to 1150C at 10C/min, 6liters/min N2+1%O2)
  4. Hold at 1150C for 60 minutes in nitrogen flow for 2.5 micron membranes.
  5. Ramp to 800C (IBM: 10C/min)
  6. Hold at 800C in 100% dry oxygen flow for 30 minutes
  7. Ramp back to 400C in 100% nitrogen.
  8. Pull wafers
  9. Etch glass in HF.
The post-diffusion oxidation step converts surface SiBx layer into borosilicate glass so that it can be stripped in HF.

Christopher.G.Levey@ dartmouth.edu