Characterization of shallow silicided junctions for sub-quarter micron ULSI technology. Extraction of silicidation induced Schottky contact area

The current-voltage (I-V) characteristics of shallow silicided p ⁺-n and n⁺-p junctions are presented. In the former the diode behavior was same as in nonsilicided junction, while drastic change in diode I-V was observed in the latter. The formation of Schottky contact was conclusively shown to be the root cause of the modified I-V behavior of n⁺-p junction in the forward bias region. Poole-Frenkel barrier lowering predominantly influenced the reverse leakage current, masking thereby the effect of Schottky contact. The leakage current in n⁺-p diodes was higher than in nonsilicided diodes by two orders of magnitude and this is consistent with the formation of Schottky contact via titanium or titanium-silicide penetrating into the p-substrate and generating trap sites. There is no increase in the leakage current and no formation of Schottky contact in case of the p⁺-n junction. The Schottky contact amounting to less than 0.01% of the total junction area and not amenable for SEM or TEM observation was extracted for the first time by simultaneous characterization of forward and reverse characteristics of silicided n ⁺-p diode