Composition control and electrical properties of Ni-Cr thin films prepared by co-sputtering method

For thin resistor films with low TCR (temperature coefficient of resistance) and high resistivity, we have prepared the thin films by cosputtering method with pure Ni and Cr targets and studied the effect of the process parameters on the electrical properties. In sputtering process, DC/RF power and pressure are varied as controllable parameters. We have investigated the microstructure and measured the electrical properties. When the Ni/Cr ratios of the deposited thin films were 0.8 ∼ 1.5, the resistivity was 100 ∼ 120 μ Ω·cm. Below a Ni/Cr ratio of 1.5 (above 40[wt%] of Cr), the TCR became negative. The TCR of the thin films decreased from -30 ppm/°C to -75 ppm/°C with increasing Cr content. It is suggested that the composition ratio and electrical properties of thin films can be controlled by variation of sputter process parameters.