| 摘要 |
PURPOSE:To bring a GaAs FET into the state of high frequency use by a method wherein a short gas length is formed by performing a direct patterning method using an ion beam and also by giving a work on an extremely fine width wiring. CONSTITUTION:Cr is vacuum-deposited on the surface of a GaAs wafer in the same manner as has been done heretofore, and a metal layer 7 is formed. Then, a Ga ion and the like is accelerated, a metal film 7 is partially removed while an electric scanning is being performed, and a window 501 is formed. This window can be narrowered to the degree of 0.1mum and down to 0.05mum or thereabout by sufficiently narrowering the diameter of the ion beam. After the processing with an ion beam has been finished, photoresist 8 is applied, and a window 502 is formed using a photomechanical method and the like. Then, a gate 601 is formed by vapor-depositing Al and performing a lift-off. Subsequently, the metal film 7 is removed by etching, and then ohmic metals 201, 301 and 602 to be used for GaAs are vapor-depsited. Besides, the unnecessary part of an active layer is removed by performing an etching, and at the same time, the ohmic contact of the source 201 and the drain 301 is accomplished by performing a heat treatment. |
