CoSi 2 nanostructures by writing FIB ion beam synthesis

Abstract

A mass separated focused ion beam (FIB) is a very useful tool to fabricate nanostructures by writing implantation within an ion beam synthesis process. In these investigations the IMSA-OrsayPhysics FIB, equipped with a Co 36Nd 64 alloy liquid metal ion source, was applied. Si(100) and (111) wafers were implanted with 60 keV Co ++ ions in the dose range of 2 · 10 16 to 2 · 10 17 cm − 2 . Implantation parameters were investigated, like pixel dwell time, relaxation time (time between two cycles), dose rate as well as the pixel overlapping factor. The subsequent annealing was done in a two step process, namely 600 °C for 60 min and 1000 °C for 30 min in a N 2 ambient. The results obtained by SEM investigations in terms of continuous nanowire structures following the <110> direction and interrupted CoSi 2 pattern in the <100> direction show a clear dependence on the time scale as well as the scanning mode of the irradiation. Structure sizes as small as 10 nm are demonstrated. The formation of CoSi 2 nanostructures is explained by precipitation, Ostwald ripening and coarsening leading to a shrinking of the initial implanted profile.