Ion Implantation

Ion implantation is the introduction of atoms into a solid substrate by bombardment with ions in the keV to MeV energy range. It was early recognized that this technique provides the possibility of introducing a wide selection of atomic species and also external control of both the number of atoms per cm² introduced into the semiconductor and the depth distribution of the implanted species. This is in contrast to diffusion processes where temperature governs the surface concentration and time and temperature determine the depth distribution. The initial impact of ion implantation in silicon technology was in charge control. This in combination with the fact that simple masking techniques can be used to define the geometrical area of the implanted region led to extensive to MOS technology. Presently implantation is the most common method of introducing dopant atoms for the fabrication of Si devices.

Advantages

This process provides excellent dose control. Typical 10¹¹ to 10¹⁶ cm^-2. It has been possible to control the number of dopant atoms per cm² to about 1% over the surface of a wafer, and to control the number within 3% from wafer to wafer.