Semiconductor acceleration sensor and vehicle control system using the

Abstract

A semiconductor acceleration sensor is formed by a cantilever having a conductive movable electrode of predetermined mass at one end, at least one pair of fixed conductive electrodes which are stationary with respect to the movable electrode located on opposing sides of the movable electrode, and gaps provided between the movable electrode and the fixed electrodes. To prevent the movable electrode becoming fused to the contacted fixed electrode, in a first aspect of this invention, an insulating layer is provided between the movable electrode and fixed electrodes, the layer being either on the movable electrode or on the fixed electrodes and in a second aspect the movable electrode or, preferably, the fixed electrodes, are formed of a high melting point material. In such a second aspect, to improve adhesion between the high melting point material and a substrate to which the fixed electrodes are mounted, a lower melting point material is firstly coated on the substrates. A sensor detector unit processing circuit has the output characteristic of the circuit digitally adjusted by suitable switching of a plurality of resistors, and the sensor chip and the detector unit integrated circuit may be located on a common base and mounted in a hermetically sealed chamber to prevent adverse environmental effects affecting operation of the sensor and detector unit assembly. A gas having a dew point of -40.degree. C. or lower is, advantageously, charged into the hermetically sealed chamber.