TITANIUM ION-IMPLANTATION INTO SILICON SUBSTRATE BY PLASMA-BASED METAL-ION IMPLANTATION SYSTEM WITH 100-KV 2.5-A PULSE MODULATOR/

A pulsed, metal-ion implantation system with a pulse modulator with sp ecifications of 100 kV/2.5A/30 mu s has been developed. Titanium ions were implanted into a silicon substrate (n-n(+), [111], 400 mu m in th ickness) using applied voltages of 20-50 kV with a negative polarity a nd repetition rates of 180-1800 Hz for d.c. are current of 60 A. Neith er the implantation profile nor the depth is affected by changes in th e repetition rate. As the applied voltage increases, both the total do se and the ion range increase. The dose can be achieved up to the orde r of 10(17) atoms cm(-2). The dose is proportional to the repetition r ate and linearly related to the applied voltage. Changes in the charac teristics in RES spectra from implanted samples are observed as a resu lt of varying the applied voltage. These changes suggest the existence of the mixing layer of titanium and silicon including a silicide stru cture. By adjusting the applied voltage and repetition rate, the degre e of the mixing of titanium and silicon can be controlled to create ne w material compositions. (C) 1998 Elsevier Science S.A.