イオン注入中の帯電による酸化膜の劣化機構

抄録

Ion implantation involves problems of wafer charging causing the deterioration of thin gate oxides. We investigated how the thin oxide (25nm) of MOS capacitor devices deteriorates during As⁺ ion implantation. The effect of ion beam density, the distribution of the oxide deterioration on a wafer and the effects of photoresist coverage around a gate electrode were quantitatively analyzed using the generated number of interface state at SiO₂/Si inteface of MOS capacitor. The deterioration of gate oxides was found to be affected by the four charge sources: the irradiated ion beam into a gate electrode, the secondary electrons emitted from the gate electrode, the charges accumulated on the photoresist surface around the gate and the secondary electrons emitted from the surface of a wafer holder. The former three charges accelerate the deterioration of the thin oxide and the latter one reduces it.