Ion Implantation - If ions are accelerated to high energies ( 10 Kev) and are targeted onto the surface of a semiconductor they become embedded.  This process is called ion implantation.  These ions can lose their energy by interactions with nuclei and electrons.

dE/dx = -N[S_n(E) + S_e(E)]

where N is target atoms/ cm^-3 , S_e(E) is the electronic stopping power, S_n(E) is the nuclear stopping power.

The nuclear stopping power:

S_n^o = 2.8 x 10-15 (Z₁Z₂ / Z ^0.333)(M₁ / M₁+M₂) eV cm2

Where Z ^0.333 = (Z₁ ^0.666+Z₂ ^0.666)^½

The electronic stopping power:

Se(E) = k E^1/2
k_Si = 0.2 x 10^-15 (ev)^1/2 cm²
k_GaAs = 0.52 x 10^-15 (ev)^1/2 cm²

Implantation Technology

An ion implanter is a high-voltage particle accelerator producing a high-velocity beam of impurity ions which can penetrate the surface of Si surface wafers. The basic parts of the system is shown schematically.

erf(x) = 2/(Ö Õ )ò e^-x2dx

erfc(0) = 1

erfc(¥ ) = 0

d/dx[erfc] = (2/P )e^-x2

TO PAGE 2