Semiconductor acceleration sensor with movable electrode

摘要

Adverse effects due to electrostatic force between a semiconductor substrate and a movable electrode are avoided with a new structure. A movable electrode of beam structure is disposed at a specified interval above a p-type silicon substrate. Fixed electrodes, each composed of an impurity diffusion layer, are disposed on both sides of the movable electrode on the p-type silicon substrate; these fixed electrodes are self-aligningly with respect to the movable electrode. The movable electrode is displaced in accompaniment to the action of acceleration, and acceleration is detected by change (fluctuation) in current between the fixed electrodes generated by means of this displacement. Additionally, an electrode for movable electrode upward-movement use is disposed above the movable electrode, a potential difference is given between the movable electrode and the electrode for movable electrode upward-movement use, and attractive force of the movable electrode to the silicon substrate is alleviated.