Semiconductor device which includes multiple isolated semiconductor

Abstract

Disclosed is a semiconductor device which comprises a substrate, an insulating film formed at a predetermined region in the substrate or on the main surface of the substrate, a polycrystalline semiconductor layer formed on at least the insulating film, a single crystal semiconductor layer formed on at least the polycrystalline semiconductor layer, an isolation region formed to extend from the top main surface of the single crystal semiconductor layer to at least the surface of the insulating film, through the polycrystalline semiconductor layer, to electrically isolate a portion formed in the single crystal semiconductor layer surrounded by the isolation region from another portion formed in the single crystal semiconductor layer and not surrounded by the isolation region, at least a semiconductor device formed within the portion surrounded by the isolation region. This semiconductor device has an additional characteristic in that another semiconductor device using another main surface of the substrate as the electrode is provided on the surface of the substrate and the single crystal semiconductor layer, and the plolycrystalline semiconductor layer serves to terminate the electric line of force emitted from the substrate, and therefore, the single crystal semiconductor layer mounted on the polycrystalline semiconductor layer is not affected by the electric line of force. Consequently, a semiconductor device which can operate effectively without being influenced by variations of the electric potential in the substrate can be obtained, and further, an intelligent type power device can be formed in which the power semiconductor device and the semiconductor device controlling the power device are formed in the same substrate but are completely isolated from each other.