Two-step GaAs/AlGaAs selective dry etching process to control vertical and lateral recess profile

We have developed a new two-step GaAs/AlGaAs selective dry etching process by using SiCl₄/SF₆/N₂ gas in Inductively Coupled Plasma system. This process consists of two etching steps that are the first anisotropic etching and the second isotropic etching. In this process, we can control the vertical and lateral etching of the gate recess independently by turning on and off the N₂ flow. The side-etching length is controlled only by the second etching time. The gate-drain breakdown voltage of fabricated Heterojunction Field Effect Transistors can be varied from 9 to 20 V by controlling the side-etching length of n⁺-GaAs layer keeping the same threshold voltage. The present technique can be applicable to fabricating any kind of device such as low noise amplifier and power amplifier, where different breakdown voltages are required.