Formation and Properties of Thermistor Chips Based on Semiconductor 3D Metal Oxide Films Obtained by RF-Magnetron Sputtering

Abstract

The formation of oxide semiconductor films of the (Mn,Co,Cu)3O4 type by radio frequency magnetron sputtering is presented. The conditions of deposition and subsequent heat treatment make it possible to obtain films with electrophysical characteristics close to those of the bulk ceramic materials used as a target for magnetron sputtering. Two variants of thermistor geometry were implemented. In the first case, the working layer of oxide semiconductor was deposited directly on the dielectric substrate (planar geometry), and in the second case on the layer with high electrical conductivity (Ni or Al) forming the inner electrode (layered geometry). The lower limit of the nominal resistance of the planar thermistor while maintaining high temperature nonlinearity is ~ 10 kΩ. The layered structure with the inner electrode makes it possible to reduce the lower limit of resistance up to ~ 50 Ω without losing the temperature nonlinearity of the thermistor. In addition, heat treatment above 450 °C or current self-heating with sufficient power output leads to the appearance of a pronounced voltage nonlinearity, which increases the thermal constant B of thermistors from 2400–3400 to 5000–5500 K. The fields of application of oxide-film structures for the correction of linear resistors and the implementation of integration approaches in the construction of linearized sensors are discussed.