LIGHT-ION AND HEAVY-ION CHANNELING PROFILES IN SILICON

Channeling of 200 keV 11B, 27Al 69Ga and 165Ho ions near the 〈100〉 axis of Si is investigated for tilt angles between 0° an 1.5°, both by experiment and simulation. Implantations are carried out at room temperature in Si(100) wafers, 4 in. in diameter, using an electrostatically scanned beam (angular variation is ± 1°). Alignmeent of the Si 〈100〉 axis parallel to the mean incident beam direction is done by monitoring the backscattering yield of 720 keV protons near the centre of the target. Implantation doses are kept low ((2-5) × 1012 cm-2) to minimize damage buildup. The ion depth distributions are measured with secondary-ion mass spectrometry, at a number of locations distributed over the entire wafer, yielding data for the indicated range of tilt angles. The measured profiles are compared with simulations of implanted depth distributions in crystalline targets using the Monte Carlo code MARLOWE (version 12). Different impact-parameter-dependent electronic stopping models as well as the effect of a small amount of damage 'buildup are discussed. © 1990.