Short pulse plasma immersion ion implantation of oxygen into silicon: determination of the energy distribution

Plasma immersion ion implantation was used to implant
oxygen ions into silicon with applied voltage pulses of 40 kV and 2.5 ms
total lenght. Positive ions from the plasma O2+ and O+, with a continuous
energy distribution between 0 and 40 keV were implanted with nominal doses
between 2x1016 and 2x1017/cm2. The resulting oxygen depth profiles were
measured with elastic recoil detection using 13.4 MeV a particles. The
obtained depth profiles were simulated using a linear superposition of
single-energy profiles calculated with TRIM, in order to determine relevant
parameters of the accelerated ions. The energy distribution of the incident
ions is derived from the results obtained and compared with theoretical
models. The agreement found is very good. The plasma found to be composed
of 35(8)% O2+ and 65(8)% O+ ions. An Fe contamination in the plasma is
observed using Rutherford backscattering.