METHOD OF MANUFACTURE OF CONDUCTIVITY MODULATION MOS SEMICONDUCTOR POWER DEVICE AND DEVICE OBTAINED BY THE METHOD

摘要

PURPOSE: To shorten turn off time by epitaxially growing a thin semiconductor layer of same conductivity type as a substrate on the substrate in order to form a butter layer and then implanting ion dopant into the thin semiconductor layer or depositing ion dopant thereon in order to perform diffusion. CONSTITUTION: A thin layer 4 of P type silicon is grown epitaxially on a silicon P<++> (100) substrate 1. Antimony is then implanted onto the epitaxial layer 4 and diffused to form a layer N<+> thinner than the epitaxial layer 4. At that moment of time, an N<-> type epitaxial layer 3 having resistivity and thickness dependent on the voltage BVDSS of a device to be formed is grown. Since the residual P type thin layer is absorbed through outward diffusion of boron in the substrate during that fabrication process, a butter layer 2 is formed. After forming the N layer 3, an MOS power device is fabricated by a conventional system. According to the method, a heavily doped buffer layer is formed and an HIMOS device is protected not to actuate a parasitic thyristor.