High Dose Implantation of Nickel into Silicon

Several silicon wafers were implanted with 58Ni+ at an energy of 170 keV and a current density of 12 μA cm−2 to doses between 5 × 1015 and 1.8 × 1018 ions cm−2. The substrates were phosphorus doped n-type Czochralski grown silicon wafers. The wafers were water cooled during implantation and the surface temperatures was monitored with an infrared pyrometer and controlled to < 70°C. Samples were subsequently furnace annealed at 900°C for 30 min in nitrogen. The as-implanted and annealed samples were analyzed using cross-sectional transmission electron microscopy (XTEM), Rutherford backscattering (RBS) spectroscopy, spreading resistance depth profiling (SRP), and scanning electron microscopy (SEM). Microcrystallites of NiSi2 (2–5 nm) buried within an amorphous matrix formed during the 1.5 × 1017 ions cm−2 dose implantation. For higher doses above 3 × 1017 Ni+ cm−2, ion beam sputtering occurred. After annealing, rapid diffusion of nickel and solid-phase recrystallization of the amorphous regions occurred.