Ion channeling studies of low energy ion bombardment induced crystal damage in silicon

Abstract

Helium ion channeling has been used to measure the amount of crystalline damage produced by low energy(⩽ 1 keV) argon, neon and hydrogen ion bombardment of single crystal Si as a function of dose and energy. Using a glancing exit geometry, with a scattering angle of 98°, has allowed an estimate of the damage depth profile particularly for hydrogen ion bombardment. The total damage expressed as an equivalent amorphous silicon thickness was found to be 65 Å for argon, 80 Å for neon and 275 Å for hydrogen for 1 keV ions after a dose of 2–3 × 10 17 cm −2. Under these conditions, crystalline damage produced by hydrogen ions is detected by ion channeling down to a depth of ⪢475 Å. For argon and neon, the total damage scaled with the square root of the ion energy and reaches a near saturation level after an ion dose of 2–3 × 10 15 cm −2. For hydrogen ion bombardment, damage is still clearly increasing even after a dose of 5 × 10 17 cm −2. These results are compared to the predictions of a model based on a calculation of energy deposition per unit volume using the low energy nuclear stopping power of Wilson, Haggmark and Biersack.