Ion Implantation

A summary to aid you in studying for the exam

Agenda• Quick recap

• Stopping

• Projected range

• Implantation damage

• Advantages/disadvantages

Setup

• Figure 1: From http://www.spirecorp.com/spire-biomedical/surface-modification-technology/ion-implantation.php

Stopping

• Coulomb scattering

• Two hard spheres scattering elastically

• Energy loss dependencies

Nuclear stopping

Projected range

Deviations

Deviations continued

Channeling

• Less nuclear stopping and low electron densities

• Produces a tail in the implant distribution

• Largest effect when the incident ion is small

• Avoided by using an implant tilt or preamorphizing.

Lattice damage

• Bonds broken.• Critical dose dependent on energy, species

and temperature.• More damage further in due to nuclear

stopping becoming the dominant mechanism• Anneal used to decrease defect density and to

activate implanted species

Shallow junctions

• Low energy difficult due to beam broadening

• Very low energy implants usually performed using molecules

• Thermal electrons

Advantages and difficulties

• Quite controllable• Low amount of impurities• Lattice damage• Shallow junctions• Channeling