mask 20 without exposure to the atmosphere as in the first embodiment thereafter the eb resist 17 and the photoresist 18 are formed to cover the opening the region of the photoresist 18 spaced equally from the source and drain electrodes 8 and 9 is patterned using usual exposure further a portion of the eb resist 17 which is in the center of the portion patterned by the photoresist 18 is patterned using electron beam exposure fig4 c using these as masks the gate electrode 10 is formed in schottky contact with the surface protection film 14 by a vacuum evaporation and lift off technique after removal of the photoresist 18 the eb resist 17 and the dielectric mask 20 the dielectric protection film 11 is formed in the exposed portion of the semiconductor layers on the substrate completing the hemt shown in fig3 in the hemt according to the second embodiment after removal of fluorine the surface protection film 14a preventing fluorine invasion is formed on the exposed portion of the schottky contact layer 6 so that device properties are not deteriorated due to fluorine invasion unlike the prior art hemt shown in fig7 the surface protection film 14a is not formed between the source and drain electrodes 8 and 9 and the channel layer 3 so that the distance between the gate and the channel is not increased and the source resistance rs is not increased as a result device properties are not deteriorated the surface protection film 14a is selectively formed by crystal regrowth the surface of the schottky contact layer 6 which is a regrowth interface is less damaged and the surface protection film 14a can be formed only in a required position as a result device properties and device.