Secondary Electron Emission During Ion Implantation

Secondary electron emission can have a strong effect, usually detrimental, upon ion dose control and uniformity. We have measured secondary electron yields, using a commercially available ion implant machine, for various materials encountered in silicon device technology. Measurements were made for arsenic and boron implants at various implant energies and ion beam currents, and at various bias voltages of the electron collector. We find that tantalum silicide has a higher secondary electron yield than aluminum, which has a higher yield than silicon.