EE 432/532 Semiconductor Fabrication G. Tuttle

Diffusion practice problems
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Read the Diffusion example calculations class notes.


Phosphorus is diffused into a silicon wafer using a two-step process. The process parameters are:

The wafer has a constant background doping of NB = 9x1016 cm–3.

The surface concentration during the depositon step is determined by the solid-solubility limit.
For this diffusion use Ns = 1x1021 cm–3.

Determine the surface concentration, the junction depth, and dose at the end of the diffusion.

Answer