Effects of ion irradiation on silicon oxidation in electron cyclotron resonance argon and oxygen mixed plasma

Effects of ion irradiation on oxidation of silicon at a temperature as low as 130 degrees C in an argon and oxygen mixed plasma excited by electron cy clotron resonance interaction have been investigated. The growth rate of th e oxide films increases with increasing incident energy and flux of argon i ons, and the thickness increases proportionally to the root square of the o xidation time, which suggests that the growth rate is limited by diffusion of oxidants enhanced by irradiation with argon ions. Effects of substrate b ias on the oxidation characteristics have been also investigated. The growt h rate increases with increasing positive bias, and the growth kinetics dev iate from diffusion limited with increasing thickness. The bias dependence of the growth rate is caused by drift of negative oxidants enhanced by the electric field established in the oxide films. Moreover, it is shown that t he electrical properties of the oxide films are improved by applying positi ve substrate bias. The improvement is due to a reduction of irradiation-dam age in the initial oxidation stage. On the basis of the experimental result s, it is concluded that the reduction of the incident energy and the flux o f argon ions in the initial oxidation stage is essential to improve electri cal properties of the oxide films. (C) 2000 American Institute of Physics. [S0021-8979(00)05715-7].