Arrays of periodic submicron conductive links in Si covered by SiO2 formed by polarized laser irradiation

Abstract

Arrays of periodic submicron conductive links were fabricated in silicon covered by SiO2 when polarized frequency doubled Nd:YAG pulsed laser irradiation is focused on the gap between two highly doped regions. The principle of the process is based on the fact that the laser forms periodic melting in silicon, thus inducing preferential dopant diffusion and creating an array of fine conductive links between the highly doped regions. A scanning capacitance microscopy (SCM) was employed to detect these submicron structures and to measure their electrical properties. It was found that between two and seven submicron conductive links are observed in a focused spot size of 3 µm and their number depends only on the laser intensity ranging from 3.10 W to 3.75 W, while their average width (151–300 nm) and depth (108–147 nm) strongly depends on both the laser intensity and number of laser pulses. The resistances of these links are between 363–493 Ω and the effective average doping levels are from 1.5 × 1018 to 2.4 × 1019 cm−3.