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% (FN ₂/ (FN₂+FAr) × 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 amorphouslike 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 μΩ-cm and -291 to -448 ppm/°C, 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.