Patent ID: 8580627

Claim:
A method for fabricating a compound semiconductor device, comprising: providing a gallium arsenide (GaAs) substrate; forming a first element and a second element over a first portion and a second portion of the GaAs substrate, respectively; forming a first passivation layer over the GaAs substrate, the first element, and the second element; performing a patterning process, simultaneously removing a portion of the first passivation layer formed over the first element, the second element, and the GaAs substrate between the first and second elements and respectively exposing a portion of the first and second elements, and the portion of the GaAs substrate between the first and second elements; performing an etching process, using the first passivation layer as an etching mask, forming a trench in a portion of the GaAs substrate between the first and second elements; forming an electrode over the first and second elements; and forming a second passivation layer, conformably covering the first passivation layer, the electrode, and the GaAs substrate exposed by the trench.