IMPROVED METHOD OF ETCHING A GATE RECESS REGION IN EPITAXIAL GaAs MESFETs
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
A technique is described whereby the method of fabrication of epitaxial GaAs MESFETs is improved so as to allow reproducible etching of a gate recess region. Described is the use of buried reflecting material, along with the implementation of laser interferometry, to obtain accurate depth measurements of doped epitaxial layers. In the fabrication of GaAs MESFETs, doped epitaxial layers used to form the device are typically grown in a molecular beam epitaxy (MBE) system and consist of a buffer layer of GaAs on a semi-insulating GaAs substrate and layers of p and n type of doped GaAs, as shown in Fig. 1. In etching the gate recess for the GaAs device, it is essential to be able to reproducibly etch down to a required depth for each layer of material.