Influence of substrate bias on the resistivity and TCR of nanostructured Ta-Si-N films

In this paper, the resistivity and temperature coefficient of resistance (TCR) of nanostructured Ta-Si-N thin films fabricated on silicon substrate by reactively cosputtering have been studied. The substrate bias was controlled from 0 to -200 V at a fixed nitrogen flow ratio of 5 FN₂% (FN₂/ (FN₂+FAr) times 100%) to study the electrical properties of different Ta-Si-N films. The Ta-Si-N films with broad peaks reveal that there are a high content of amorphous material and nanocrystalline grains dispersed in an amorphous matrix which is called amorphous-like microstructure. Experimental results indicated that the electrical resistivity and TCR of Ta-Si-N increases with increasing bias. The resistivity and TCR of all amorphous-like Ta-Si-N at 5 FN2% is small about 264 to 277 muOmega-cm and -291 to -448 ppm/degC, respectively. The variation percentage of resistivity and TCR is about 9.84% -21.66% and 1.37%-10.18% after RTA annealing. In the application of Cu barrier layer, the sample at bias 0 V with the lowest resistivity and most stable TCR value can be the best candidate among four samples.