Ion Implant is different from other semiconductor
processes because it does not create a new layer on the wafer.
Instead, ion implant changes the electrical characteristics of precise areas within an existing layer
on the wafer.
An ion implanter uses a high-current accelerator tube and steering and focusing magnets to bombard the surface of the wafer with ions of a particular dopant. These dopant ions are implanted into the top layer of the wafer just below the surface, changing the conductivity of a precise region.
To create an insulating, or p-type, region
an acceptor ion such as boron,
gallium or indium is implanted.
To create a conducting, or n-type, region
a donor ion such as antimony,
arsenic, phosphorus
or bismuth is implanted.
Implanters are generally classified as high-current (a beam current higher than 3 milliamp) and medium-current (less than 3 milliamp).
