Method to characterize the three-dimensional distribution of focused ion beam induced damage in silicon after 50 keV Ga+ irradiation

Abstract

In this article we report the straggling of long-range implantation damage in silicon in the forefront of a focused ion beam induced amorphization zone. Irradiation was carried out at room temperature at a current density of 0.75 A cm−2 (5×1018 ions/cm2 s) using 50 keV Ga+ ions. A highly sensitive tool for detection, an n-metal–oxide–semiconductor field effect transistor is used to quantify and to characterize the distribution profile of ion beam induced electroactive defects. Scanning the beam over active devices allows the extraction of a three-dimensional profile of defects. In situ monitoring of the drive current and intermitting charge pumping measurements revealed the progressive nature of the damage, the generation of interface states, and the lateral extension of irradiation related defects. Far reaching damage cascades extend at least 300 nm in the beam direction and about 220 nm perpendicular to the beam direction of the substrate and define the region of electrically active defects due to particle beam exposure. The long range of the implantation damage is confirmed by binary collision simulations that take the crystallinity of the target into account.