| 摘要 |
PURPOSE:To prevent a photoresist from sagging during a process of evaporating a metal layer by a method wherein undercut portions on both sides of a gate pattern formed during a recessing process are filled up with an insulating layer that is provided by application. CONSTITUTION:An activation layer 2 and an ohmic electrode 3 are formed on a GaAs substrate 1, after which a first photoresist pattern 4 is formed and then the activation layer 2 is subjected to etching for the formation of a recess surface 5. A gate metal layer 6 is formed on the recess surface 5, which is followed by line removal of the photoresist pattern 4 and unnecessary metal. An insulating layer 9 is formed by application, which fills up undercut portions 5a on the sides of the recess surface 5. Next, reactive ion etching 10 is accomplished against the insulating film 9, which continues until the gate metal 6 is affected. Finally, a second photoresist pattern is used in a process wherein a second and subsequent gate metal layers are formed on the gate metal 6.
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