Question

3. Doping of Silicon One method of introducing dopant impurities into silicon (so as to control the electronic properties) is to depos a in layer on the surface and allow the impurity to diffuse in at a high temperature. Suppose we vapor deposit a thin layer of boron that has 2 x 1015 atoms/cm2 on the surface of a pure silicon wafer, and anneal the wafer for three hours at 1200 C. To about what depth will the boron concentration be greater than 1018 atoms/cm3? To what depth greater than 1016 atoms/cm3? About what will be the concentration of boron at the surface of the silicon? The diffusion coefficient for boron in silicon is given by: Q # 3.69 eV: Do-14 cm2 /sec.

Answer 1