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:

• deposition temperature: T₁ = 850°C
• deposition time: t₁ = 75 min
• drive temperature: T₂ = 1025°C
• drive time: t₂ = 2.83 hr.

The wafer has a constant background doping of N_B = 6x10¹⁶ cm^–3.

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

Answer