Deposition and characterization of nichrome thin film over PDMS elastomer

Nichrome (Ni - Cr 80/20 wt.%) is one of the most widely used thin film material for the development of micro heaters in various applications. Present paper discusses the optimized sputtering conditions required for successful deposition of nichrome thin film and fabrication of microheaters over a biocompatible polymer PDMS, for biomedical application. Various sputtering conditions like the base vacuum, working pressure, sputtering power and time were standardized to obtain crack free nichrome thin film deposition over PDMS and glass surface. Microheaters were fabricated using the conventional photolithography technique and the resulting structures were used to measure temperature coefficient of resistance (TCR) of nichrome. Measured sheet resistance and TCR of the crack free deposited nichrome thin film over PDMS surface were 3.62 Ω/□ and 713 ppm/°C respectively.