Study on the Adjustable Temperature Coefficient of the Resistance of Ni-Cr Alloy/VN Ceramic Bilayer Thin Films

Abstract Ni-Cr/VN bilayer thin films were fabricated by DC magnetron sputtering to achieve tunable and near-zero temperature coefficient of resistance (TCR) characteristics for precision thin-film resistors. The Ni-Cr metallic layer (positive TCR) and VN ceramic layer (negative TCR) were sequentially deposited under the optimized conditions, followed by post-annealing between 300 and 400 °C. Structural analyses by X-ray diffraction and transmission electron microscopy revealed that both layers exhibited face-centered cubic (FCC) phases with a strong 111 orientation and well-defined columnar microstructures. The VN film deposited at 200 W displayed the lowest resistivity of 79 μΩ·cm and a TCR of –450 ppm/°C after annealing at 300 °C. The Ni-Cr film deposited at 100 W displayed a resistivity of 46 μΩ·cm and a TCR of +210 ppm/°C after annealing at 300 °C. When the Ni-Cr base film stacked with a VN film, the bilayer exhibited a combined resistivity of ∼70 μΩ·cm and a nearly zero TCR of –10 ppm/°C, due to the compensation between positive and negative TCR behaviors. Systematic variation of the thickness ratio (T1/T2) between Ni-Cr and VN layers demonstrated a linear correlation with the overall TCR, confirming controllable thermal stability through thickness design. These results suggest that Ni-Cr/VN bilayers are promising candidates for thermally stable thin-film resistors compatible with integrated circuit and microelectronic device applications.