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Hints for the Processing Report

Question #1

• The collector is the epi-layer that was on your wafer when you started. You can find the background doping level from the starting wafer info and GT-1.
• When you use DIFCAD, be sure to include all of the high-temperature steps (>500 C). All it takes to diffuses things is heat!
• DIFCAD will give you two columns: position, and net doping (|Nd-Na|).
  • You can add columns to calculate Ei, Ec, and Ev. Remember that at equillibrium, Ef is constant. You can set it's value at whatever you like. Might as well be zero.
  • The formulas will be slightly different for n and p type. You will need to identify the n and p type regions in the net doping data.
• Approximate depletion region widths can be obtained from the approximate doping level on each side. (You can just assume the doping is constant on each side to make a rough calculation.)

Question #5

• Be sure to look at the tables on the Web, since they have been updated since the manual was printed. The spaces in the table that have no effect on the parameters are filled in.
• "|Nd-Na| in the n-type regions" refers to the net doping in the Phosphorous-diffused regions, not to the background doping of the epi-layer.
• "|Nd-Na| in the p-type regions" refers to the net doping in the Boron-diffused regions.
• For the table in a), consider times and Temperatures. It may make your table more readable (and save space) if you use symbols, like "t" and "T" , as well as up or down arrows to indicate increasing or decreasing. Be sure to indicate whether the increase (or decrease) in time and/or temperature increases or decreases the device parameter.

Question #6

The point here is that you discover some of the trade-offs involved in the process. There are many "right" answers.

Warning! This is the archived 1999 Fabweb site! Here is the latest site