(2) Dry 02          5 minutes          02 at 800 cc/minute
           (3) Wet 02         35 minutes          02 at 800 cc/minute
           (4) Dry 02          5 minutes          02 at 800 cc/minute
           (5) N2             15 minutes          N2 at 1000 cc/minute

           (6) Pull-out        5 minutes          N2 at 1000 cc/minute
A.2 Phosphorus Base Diffusion:
     A.2a  Photoresist (PR) Application with Base Mask (NBS-4-lAB):

           (1) Bake at 200 degrees C for 30 minutes to completely dry

                the wafer.
           (2) Apply Waycoat 200 negative PR (do this on both sides of

                the wafer, apply and spin PR on back side first).
           (3) Spin at 5000 RPM for 20 seconds.

           (4) Prebake in 65-degree C oven for 20 minutes.
           (5) Align wafer and mask and expose for 4 seconds under UV
                light. (Both sides of the wafer must be exposed.)
           (6) Develop for 20 seconds in spray of Waycoat developer

                 (undiluted), then clean off developer with 15-second

                 spray of Butyl Acetate.
            (7) Dry with N2 and inspect under the microscope.
            (8) Post bake at 130 degrees C for 25 minutes in N2 or air

                circulating oven.
     A.2b Base Window Etch:

            (1) Etch in buffered HF for 2 minutes, rinse in DI water,
                dry and inspect. Etch for 15 seconds more to see if
                the pattern changes color.