Low Damage Dielectric Etching on GaAs Using a Helicon Wave High Density Source

An RF helicon wave high density plasma source has been used to develop a low damage SiO etch process for fabrication of submicron features on GaAs substrates. Etch rate and damage measurements were made on implanted GaAs substrates, coated with SiO deposited by RF plasma CVD. Increases in post-etch sheet resistance as low as 12 % could be achieved using a CF4/O2 chemistry and 10 % overetch. A 0.36µm gate structure was fabricated yielding a residue free, anisotropic etch, with an increase in critical dimension of 600± 100Å from the photolithography and excellent device characteristics. This represents the first demonstration of this etch technology in the fabrication of submicron GaAs devices for digital and mixed signal applications