0.2 Micron length mushroom gate fabrication using a new single-level photoresist technique

A new technique has been developed to generate sub-half-micron mushroom gates in GaAs MESFET´s. The technique uses a single-level resist and a two-step evaporation process. By using this technique, mushroom gates with lengths as short as 0.2µm near the Schottky interface have been fabricated. Measured gate resistance from this test structure was 6.1Ω/mm gate width which is the lowest value ever reported for gates of equal length. Using this technique, GaAs single-gate and dual-gate MESFET´s with 0.3µm long mushroom gates have been fabricated. At 18GHz, maximum available gain of 9.5dB in the single-gate FET and 11.5dB in the dual-gate FET have been measured. The technique is potentially suitable for the production of low-noise high-frequency FET´s.