Dopant Atom Diffusion

Diffusion is the movement of impurity atoms in silicon (or another semiconductor) at high temperature. Basically, diffusion can be described as a "smoothing out" of any localized high concentration of impurity atoms that is driven by the motion of the atoms in the material and by their mobility through the dominant atomic matrix (Figure 1). The impurity concentration gradient, dC/dx, is the driving force for diffusion.