SEMICONDUCTOR STRAIN GAUGE

PURPOSE:To improve the dielectric strength characteristic by a method wherein a specific resistivity of an n type substrate is regulated, so that an inversion voltage between two p type diffused resistance layers is made equal to a yield voltage of a p-n junction between the resistance layer and the substrate. CONSTITUTION:A voltage E1 is applied to p type resistance layers 7-5 of an n type substrate 2. If E1 is increased gradually, the voltage reaches the yield point finally. The lower the density of the substrate, the higher the yield voltage. On the other hand, a continuous electron layer is finally formed between electrode 12-13 by increasing of the voltage E1, so that an inversion layer in which positive holes 20 exist continuously is formed on the substrate 2 with an oxide film in between and a large leakage current is generated. In this case, contrary to the yield voltage, the lower the density of the substrate, the lower the inversion voltage. And the density of the substrate is inversely proportional to a specific resistivity of the substrate. Then if the specific resitivity of the substrate is specified in such a manner that the inversion voltage between the respective diffused resistance layers and the yield voltage of a p-n junction between the resistance layer and the substrate are made approximately equal, the inversion voltage and the yield voltage are balanced and the dielectric strength characteristic is in the optimum condition, so that it is improved significantly.