Diffusion practice problems
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Read the Diffusion example calculations class notes.
Phosphorus is diffused into a silicon wafer using a constant-dose (erfc ) process. The dose introduced during the diffusion must be Q = 5x1015 cm–2.
The wafer has a constant background doping of NB = 7x1016 cm–3. Design the diffusion (choose the value for Dt) to meet the requirement. Then, calculate the resulting junction depth.Also, choose a temperature and a time to give the correct Dt. (There are many possible answers. The values given below are one possible combination.)
The surface concentration during the depositon step is determined by the solid-solubility limit.
For this diffusion use Ns = 1x1021 cm–3.