resultant structure is subjected to ion implantation or thermal diffusion to form n type regions 68a and 69a each having an impurity concentration of e g about 10 18 cm 3 to 10 21 cm 3 as described above a polysilicon film and an si 3 n 4 film are selectively removed and selectively oxidized including enhanced oxidization to form an oxide film spacer in a u shaped groove by using this spacer low resistance electrodes consisting of a refractory metal silicide film can be formed on a gate side wall drain and source regions respectively therefore not only the gate series resistance but also the contact resistance can be reduced as compared with a conventional transistor fig7 shows a modification of the step for fabricating the sit according to the third embodiment shown in fig6 that is fig7 shows the step shown in fig6 e and steps before this step are the same as the steps shown in fig6 a to 6d assuming that these previous steps are completed the same reference numerals as in fig6 a to 6d denote the same parts in fig7 and its description will be omitted in the step shown in fig6 e the refractory metal film 66 is deposited on the entire surface of the si substrate on the contrary in the step in fig7 refractory metal films 77 78 and 79 are selectively grown on a gate side wall drain.