Shallow Si p+-n junctions fabricated by focused ion beam Ga+ implantation through thin Ti and TiSi2 layers

Focused ion beam Ga+ implantation through Ti metal (ITM) and TiSi2 (ITS) layers, followed by rapid thermal annealing (RTA), has been investigated for application in self-aligned silicide technology. The Ga+ energy was varied from 25 to 50 keV at doses of 1×1013 and 1×1015 cm−2 followed by RTA at 600 °C for 30 s. Depth profiles of the Ga implants were obtained by performing secondary-ion mass spectrometry. It was observed that higher-energy and higher-dose implants yielded good quality p+-n junction characteristics. Diodes were fabricated to obtain the electrical properties of these silicided junctions. At higher implant energies (≥40 keV) and all doses, I-V characteristics of ITS diodes showed 100 times lower leakage currents (Ir) than ITM diodes. For low-energy (40 keV)/high-dose implantation the ITS diodes showed a slight improvement in Ir over the ITM diodes, whereas for low-energy/low-dose implantation the same Ir was observed.