PURPOSE: To obtain a MIS type semiconductor device of high withstand voltage where a low-voltage logic circuit or the like is mounted on a similar semiconductor substrate, by using a gate electrode and a field oxide film as masks to perform ion implantation of high-concentration impurities for a source and a drain.

CONSTITUTION: On a Pch transistor region at a logic part, a gate electrode 112 and a field oxide film 110 are used as masks to perform ion implantation of boron 2×1015cm-2 in a P type high-concentration impurity region 113 where a source and a drain are formed with a gate oxide film 111 in between. On another Nch transistor region, ion implantation of phosphorus is similarly performed 3×1015cm-2 in an N type high-concentration impurity region 114, and next heat treatment is performed for activation. In order that a depth of diffusion is suppressed to prevent punch through of a transistor at the logic part when this activation is performed, a temperature is limited in an atmosphere of an inactive gas such as nitrogen or possibly in an oxidative atmosphere to be 800∼1000°C in a heat treatment furnace by heater and 900∼1000°C in an instantaneous annealing furnace by a halogen lamp or the like.