Novel submicrometer MOS devices by self-aligned nitridation of silicide

A new MOS technology is developed for submicrometer MOS devices. In this new technology, TiSi
2
is formed on the source and drain diffused layers by self-aligned silicidation to reduce the sheet resistance, and TiN is formed in the contact holes by self-aligned nitridation of TiSi
2
. This TiN can be used as an effective barrier metal between Al and Si. TiSi
2
is prepared by a two-step annealing method to prevent a reaction between Ti and the field oxide. PSG cap annealing after TiSi
2
formation provides excellent p-n junction characteristics and relatively low silicide sheet resistance of 4 ω/□ even after annealing at 950°C for 30 min. TiN is formed by direct thermal nitridation of TiSi
2
in N
2
ambient at a temperature higher than 900°C after contact hole formation. The formation of TiN is confirmed by AES, ESCA, and X-ray diffraction analysis. The TiN formed by direct thermal nitridation is found to prevent Al diffusion into the Si substrate even for post-metallization annealing at 500°C for 1 h. The characteristics of devices fabricated by this new technology also are determined.