Epitaxial regrowth in surface micromachining of GaAs

The authors demonstrate a complete surface micromachining procedure including a several steps of epitaxial regrowth in the fabrication of a laterally mobile GaAs structure (a wheel), as well as a sensor structure (a bridge). The enormous etch selectivity and the lack of internal stresses in the AlGaAs-GaAs system, combined with the excellent thickness control provided by MOCVD, make it possible to manufacture micromechanical structures that are similar to structures previously micromachined in the polysilicon-silica system. However, it is noted that economic factors and processing difficulties make the potential for GaAs micromechanics much more limited than for polysilicon