Analysis of irregular increase in sheet resistance of Ni silicides on transition from NiSi to NiSi2

The annealing conditions causing an irregular peak in sheet resistance of nickel silicides are investigated. It is found that the irregular rise in sheet resistance occurs at a critical temperature of 750-775^oC as a result of agglomeration related to phase transition from NiSi to NiSi"2. Experiments on the effect of temperature, heating rate and annealing duration in rapid thermal annealing revealed that the high-resistance state produced by annealing at the critical temperature could not be changed by subsequent annealing at higher temperature, and that the high-resistance state required 30-40s at the critical temperature to form. Pre-annealing at 600^oC was found to suppress the later formation of the high-resistance state.