Abstract: A high-resistant p-silicon layer is formed on a silicon substrate through a silicon oxide film. N-source and n-drain layers are selectively formed in the surface of the high-resistant p-silicon layer. A gate electrode is formed through a gate insulating film on a channel region between the source and drain layers. To induce an n-inverted layer under the gate electrode, a p-base layer is formed in the high-resistant p-silicon layer. A depletion layer extending from a pn junction between the n-drain layer and the high-resistant p-silicon layer reaches the silicon oxide film in a thermal equilibrium state. Part of the high-resistant p-silicon layer extends into a channel region between the drain and base layers. The drain and base layers are connected to each other through part of the depletion layer in the thermal equilibrium state. A field effect transistor having a high-speed operation is provided.

Abstract: A capacitive pressure sensor includes a set of facing electrodes arranged with a cavity disposed therebetween and having insulation layers respectively formed on the surfaces thereof. The contact area between the facing electrodes varies directly with the applied pressure, and variation in the contact area causes variation in the capacitance which is detected as a pressure measurement. Since the capacitance variation is proportional to the applied pressure, a pressure signal which is substantially linear can be obtained. Therefore, the capacitive pressure sensor of this invention can measure pressure with high precision.

Abstract: Disclosed is a semiconductor flow detector, comprising a semiconductor flow detecting element including a heating element and a pair of temperature-measuring elements formed in the substrate, a detecting element for detecting the temperature of the fluid under measurement, a first driving circuit for heating the heating element to keep the temperature of the semiconductor flow detecting element higher by a prescribed level than the temperature of the fluid under measurement, an electric power detection circuit for detecting the electric power flowing through the heating element so as to generate an electric power detection signal, a second driving circuit for driving the pair of the temperature-measuring elements, a temperature difference detecting circuit for detecting the temperature difference between the pair of the temperature-measuring elements so as to generate a temperature difference signal, and an arithmetic circuit for performing prescribed arithmetic operations among the electric power detection s