STRESS SENSOR

PURPOSE:To structure a magnetic circuit formed of a thin film thred-dementionally so as to make a stress sensor of this design high in integration by a method wherein the stress sensor is made to be basically composed of a magnetic material thin film formed out of two manetoconstrictive layers, a thin film electrode constituting a coil so as to make the magnetic thin film serve as a magnetic circuit, and an insulator thin film formed surrounding the thin film electrode. CONSTITUTION:A Fe-Si-O-Zr thin film (magnetic alloy layer) 3a, a SiO2 thin film (insulating film) 2a, an Al electrode 4a, a SiO2 thin film (insulating film) 2b, a Fe-Co-Zr thin film (magnetic alloy film) 3b, a SiO2 thin film (insulating film) 2c, and an Al electrode 4b are laminated on a Ti substrate in this sequence for the formation of a thin film ring-shaped solenoid of a structure as shown in the figure. A detection circuit 5 of a single chip which detects the inductance is provided onto the Ti substrate provided with the coil formed as mentioned above. The magnetic thin film constitutes a closed circuit as mentioned above, so that the stress sensor of this design is able to have a large inductance value. And, as the magnetic thin film has a magnetic anisotropy inside, the stress sensor of this structure can be expected to have a large muvalue.