High breakdown voltage semiconductor circuit device and method of manufacturing the same

摘要

In a high breakdown voltage semiconductor element (14) among elements integrated together on an SOI substrate in which its rated voltage is shared between an embedded oxide layer (106) and a drain region (108) formed by an element active layer (108), both high integration and high breakdown voltage are realized while also securing suitability for practical implementation and practical use. The high breakdown voltage is realized without hampering size reduction of the element by forming an electrically floating layer (100) of a conductivity type opposite to that of the drain region at the surface of the drain region. Further, the thickness of the embedded oxide layer is reduced to a level suitable for the practical implementation and practical use by setting the thickness of the element active layer of the SOI substrate at 30 µm or more.