lower stepped recess 9 respectively then referring to fig1 f the third resist 10a and 10b and the gate metal 11b and 11c are removed by lift off and an fet having a self aligned t shaped gate electrode 11 formed from the gate metal portions in a on the lower stepped portion of two stepped recess is completed according to the fabricating method shown in fig1 a 1 f a large mask alignment margin can be obtained when the first mask patterns 6a and 6b and the second mask patterns 8a and 8b are formed in addition when the third mask patterns 10a and 10b are formed a mask alignment margin of the sum w 1 w 2 of the first and second side wall films widths can be obtained therefore according to this method those patterns can be easily formed and the size of the upper and lower stepped recesses can achieve a desired value by adjusting the widths of the first and second side wall films regardless of the alignment precision of the exposure apparatus in this case the distance between the ohmic electrode 3 or 4 and the gate electrode 11 is the sum of the first side wall films width w 1 and the second side wall films width w 2 for example when the thickness t 1 of the ohmic electrodes 3 and 4 is 0 4 micron and depths t 2 and t 3 of the upper and lower stepped recesses are 0 1 micron the first and second side wall films widths w 1 and w 2 are approximately 0 3 micron and 0 26 micron respectively therefore when the distances between a position where the gate electrode is in contact with the lower stepped.