SEMICONDUCTOR DEVICE AND ITS MANUFACTURE

摘要

PURPOSE: To obtain a high speed bipolar transistor having high reliability by suppressing electric field concentration in an end portion of an intrinsic base region. CONSTITUTION: A depth of a recessed portion 20 formed on the surface of epitaxial layer 4 is restricted in such a manner that it will not exceed 0.1μm in order to suppress electric field concentration in an end portion of an intrinsic base region 12 near a junction between the intrinsic base region 12 formed directly below the recessed portion 20 and an external base region 11 formed outside the recessed portion.