Effect of Current Crowding on Contact Failure in Heavily Doped n sup + -and p sup + -Silicon-on-Insulator

Stability of sub-micron contacts under high current density has been an outstanding reliability issue in advanced Si devices. Polarity effect of failure was observed in Ni and Ni sub 2 Si contacts to n sup + -Si and P sup + -Si. In this report, we studied the failure due to high current density in contacts to n sup + -and P sup + -silicon-on-insulator (SOI). We found a similar polarity effect below certain current: the p sup + -SOI failed preferentially at the cathode, while the n sup + -SOI failed preferentially at the anode. At higher current, damage occurred at both contacts. The effect of current crowding was evident in both cases.