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 X 10(13) and 1 X 10(15) cm-2 followed by RTA at 600-degrees-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 (greater-than-or-equal-to 40 keV) and all doses, I-V characteristics of ITS diodes showed 100 times lower leakage currents (I(r)) than ITM diodes. For low-energy ( < 40 keV) /high-dose implantation the ITS diodes showed a slight improvement in I(r) over the ITM diodes, whereas for low-energy/low-dose implantation the same I(r) was observed.