HIGH DIELECTRIC STRENGTH INSULATED GATE TYPE SEMICONDUCTOR DEVICE

PURPOSE:To widen an ASO in a high voltage region in an MOSFET for high dielectric strength power, and to improve the temperature dependence of drain currents by each specifying the length of a channel section in the high dielectric strength vertical type n-channel type MOSFET, impurity concentration in an n type base body and impurity concentration in a p type region containing the channel section. CONSTITUTION:In a not less than 500V high dielectric strength power vertical type n-channel MOSFET, an n type semiconductor 1 as a drain consists of an Si crystal, and impurity concentration is brought to 3.5X10 or less in atomic numbers per unit cm . A metallic film 3 is evaporated on the surface of an n type layer 2 formed by diffusing a doner to one main surface of the base body 1 in high concentration, and a drain electrode D is formed. p type regions 4 are shaped by selectively diffusing an acceptor to the surface of the n type base body deeply, and one parts 4a of the regions 4 are used as channel sections. Impurity concentration in the sections 4a as the channel sections of the p type regions is brought to 1.2X10 or less in atomic numbers per unit cm . The length lof the channel section is selected to 10mum or more.