Plasma immersion ion implantation using titanium and oxygen ions

A titanium vacuum arc burning in oxygen atmosphere was used as a source for titanium and oxygen ions, which were used for plasma immersion ion implantation (PIII) into silicon at different voltages up to −5 kV and duty cycles up to 18%. Without high voltage pulses a deposition rate of 2.5×1016 atoms/cm2 s was reached at a distance of 39 cm from the cathode. Using high voltage pulses, the same rate was obtained as the increased sputter yield is offset by a larger plasma sheath collecting the ions. No interface mixing was observed as the maximum ion range is approximately 10 nm. Furthermore, due to the low duty cycle only a small number of highly energetic ions can reach the interface before the deposited layer is thicker than these 10 nm. However, the texture of the films observed without pulses is rapidly suppressed even at 1 kV pulse voltage and 9% duty cycle. A Ti/O oxygen ratio of 2:3 was measured with ion beam analyses, indicating a high oxygen uptake from the background gas.