New pH-sensitive TaOxNy membranes prepared by NH3 plasma surface treatment and nitrogen incorporated reactive sputtering

For low cost, easy fabrication and low process temperature, Ta2O5 and TaOxNy pH-sensing membranes were prepared by reactive RF sputtering. To incorporate nitrogen into Ta2O5 layer, two process techniques including NH3 plasma treatment on Ta2O5 surface and TaOxNy layer directly deposited in reactive RF sputtering with various N2 ratios were proposed. With NH3 plasma treatment for 10 min, the sensitivity of Ta2O5-EIS structure can be increased to 54.9 mV/pH. The similar result can be obtained TaOxNy layer directly deposited in the nitrogen incorporated reactive RF sputtering. For the long-term stability, both two process techniques could be applied to minimize the drift coefficient. With proper nitrogen incorporation process, an excellent sensitive membrane can be obtained by low temperature process based on NH3 plasma treatment.