Recovery of recombination lifetime by pouring de-ionized water onto a rotating plasma-damaged wafer

Abstract

Pouring de-ionized water onto a rotating wafer increases the recombination lifetime reduced by with plasma-induced damage, and this increase is greatest in the central region of the wafer. This recovery is observed with p-type Si and n-type Si substrates and with dry oxides and wet oxides. Electrostatic measurements reveal that the water induces negative charges on a wafer and that the amount of charge increases with increasing rotation speed. Capacitance-voltage analysis indicates that negative charge builds up in the oxides and that interface states are generated at the Si-SiO2 interface. A model is proposed in which electrons produced through the friction between the water and the SiO2 surface play an important role in the recovery of the recombination lifetime.