Can We Not Anneal After Ion Implantation?

What are the effects of ion implantation on silicon wafers?

During ion implantation, high-energy impurity ions accelerate the impact on the surface of the silicon wafer, converting its kinetic energy into thermal energy and displacement energy, causing the migration and rearrangement of silicon atoms, destroying the lattice structure of silicon, resulting in dislocation, vacancy and other defects. In addition, after the impurity ions are injected into the silicon, most of these ions stay in the lattice gap and cannot enter the corresponding lattice position very accurately, so it is difficult to improve the doping effect of silicon conductivity.

Annealing after ion implantation is an essential step, the effects of annealing are: 

1、 repair: The annealing process through high temperature, so that silicon atoms obtain enough energy for diffusion and migration, rearranged into an ordered lattice structure. The atoms gradually move to the lowest energy position during the annealing process, and the dislocation, vacancy, etc., are gradually reduced until they disappear, thereby reducing the defects and stresses in the lattice.

1、Activation: Annealing causes these doped ions (As, P, B) to diffuse in the silicon lattice, enter the lattice lattice position, and form covalent bonds with silicon atoms to form stable doped atoms. The doping concentration is evenly distributed, the electrical activity is improved, and the required conductive characteristics are achieved.