Micromachining of three-dimensional GaAs membrane structures using high-energy nitrogen implantation

In this paper we present an alternative technology for micromachining gallium arsenide (GaAs) using deep ion implantation. Energetic nitrogen ions at 630 keV and 4 MeV have been used to implant deeply into an n-type GaAs substrate with doses of 2 x 10(14) and I x 10(15) cm(-2). After annealing at 600 degreesC, the nitrogen implanted n-GaAs top layer was converted to semi-insulating GaAs with a thickness of I mum for 630 keV and 2.5 mum for 4 MeV nitrogen ions. A pulsed electrochemical etching process has been developed to selectively remove n-GaAs and to leave the top patterned semi-insulating GaAs layer as a mechanical membrane structure. Various GaAs microstructures, such as cross-bridge, coiled and corrugated membranes, have been successfully fabricated using this micromachining technology.