The influence of selective tungsten deposition on shallow n+ (As or P)/p and p+(BF2)/n junction leakage.

We report on the onset of reverse bias diode leakage induced by CVD selective tungsten deposition on (a) shallow n sup + (As)/p diodes made by implantation into silicon and (b) n sup + (As or P)/p or p sup + (BF sub 2))/n diodes made by implantation into CoSi sub 2. Tungsten, nominally 1000angstroms thick, was selectively deposited in a hot wall tubular reactor using either a one-step or a two-step deposition sequence at 290C. The n sup + (As)/p junctions show an increase in leakage population after tungsten deposition, as the junction depth decreases. The two-step process was found to produce greater leakage in shallow n sup + (As)/p junctions than the one-step process.