Doping mechanism of helium-based plasma

摘要

The mechanism of helium-based plasma doping (He-PD) was investigated. It is found out for the first time that the mechanism is that dopant atoms are knocked-on by a huge number of helium atoms, born out by the results of experiments of helium plasma irradiation following the ultra-low energy implantations. Boron and phosphorous atoms are knocked-on to the almost same depth. Arsenic ions are also evaluated and deeper depth doping than boron and phosphorous is observed. Additionally, it is not necessarily the case that the profile by the He-PD shows steeper abruptness than conventional ion implantation but it is limited to the low power condition. The moving distance by helium irradiation does not depend on atom mass but it correlates linearly to the atom radius. Large atoms such as arsenic moves more than smaller atoms like boron and phosphorous.