Sputtered tungsten nitride films as pseudocapacitive electrode for on chip micro-supercapacitors

Micro-supercapacitors, a class of miniaturized electrochemical capacitors, are an attractive solution to power smart and connected sensors for Internet of Thing (IoT) applications. Unfortunately, to propose on chip micro-supercapacitors with high technological readiness level, the deposition of electrode materials on large-scale substrate is challenging from microelectronic industry point of view. To fulfill the IoT needs and semiconductor industry requirements, the sputtering deposition of transition metal nitride was investigated in the framework of this paper. Bi-functional tungsten nitride films were sputtered on silicon wafer and were investigated both as a current collector and as an electrode material. Atomic Force Microscopy technique was used to evaluate the specific surface of the sputtered films. 7.9 μm-thick W2N films exhibits a specific surface of 75 cm2 per cm2 footprint area and thus it exhibits capacitance values up to 0.55 F cm−2 and more than 700 F cm−3 in 1 M KOH aqueous electrolyte.