Development of sensors on the basis of polycrystalline silicon

Properties of polycrystalline silicon layers that are important for sensor applications were investigated. Layers were deposited from the gaseous phase through atmospheric pressure and low pressure chemical vaccuum deposition onto thermally oxidized single crystalline silicon wasfers; doping was carried out by ion implantation. Electrical properties, temperature behavior, and strain sensitivity were investigated. It is found that the temperature coefficients of polysilicon resistors can be determined within broad limits (negative, positive, zero) through selection of the doping. The layers are characterized by a relatively high piezoresistive effect. Based on experimental results, polysilicon thin film sensors (temperature, pressure, flow) were developed. These sensors clearly demonstrate the advantages of polycrystalline silicon layers as a sensor material.