Characterization of Plasma-Irradiated SiO2/Si Interface Properties by Photoinduced-Carrier Microwave Absorption Method

We report photoinduced carrier recombination induced by 13.56 MHz radio frequency argon plasma treatment for samples of silicon substrates coated with thermally grown SiO 2 layers. The transmissivity of a 9.35 GHz microwave was measured and analyzed under illumination of 532 nm green light to the top or rear surface. Irradiation of argon plasma at 100 W for 5 min caused substantial carrier recombination. The recombination velocity of the plasma-irradiated surface was estimated to be 6000 cm/s. Investigation of 100 kHz capacitance response characteristics as a function of bias voltage for metal oxide p-type silicon structures revealed that irradiation of argon plasma increased the fixed charge density from $3.2\times 10^{11}$ to $3.0\times 10^{12}$ cm -2 . Those changes were restored completely by heat treatment at 300 °C in air for 60 min.