Tantalum nitride thin film resistors by low temperature reactive sputtering for plastic electronics

This article describes the fabrication and characterisation of tantalum nitride (TaN) thin film for applications in plastic electronics. Thin films of comparable thickness (50-60 nm) have been deposited by RF-magnetron-reactive sputtering at low temperature (100 degrees C) and their structure and physical (electrical and mechanical) properties have been correlated by using sheet resistance, stress measurements, atomic force microscopy (AFM), XPS, and SIMS. Different film compositions have been obtained by varying the argon to nitrogen flow ratio in the sputtering chamber. XPS showed that 5:1, 2:1 and 1:1 Ar:N-2 ratios gives Ta-2 N, TaN and Ta3N5 phases, respectively. Sheet resistance revealed an increase in resistivity ongoing from the Ta2N phase to the Ta3N5 one. The electrical properties of these films are comparable to those obtained by high temperature deposition process already reported in literature. Furthermore, a roughness and grain size modulation of the above films can be obtained by applying an RF negative bias during deposition without affecting the electrical resistivity. Copyright (C) 2008 John Wiley & Sons, Ltd.