Hetero-micromachining of epitaxial III/V compound semiconductors

Hetero-micromachining, a novel technique for the fabrication of miniaturize d sensors and actuators is described. It is based on III/V compound semicon ductor layers epitaxially grown on (001) silicon. Cantilevers composed of s ingle indium phosphide or gallium arsenide lavers or a layer sequence of di fferent III/V compound semiconductors were realized exploiting the etching selectivity of the layer against the silicon substrate in KOH solution. Bot h etching and fracture properties of InP cantilevers are dependent on the c oncentration of silicon impurities in the layer. For GaAs, a fracture limit in excess of 1.5 GPa was found. Thermally actuated micromirrors that were fabricated by hetero-micromachining of InP could be deflected to up to 0.07 degrees/mW of electrical input power under quasistatic excitation conditio ns. Typically. an increase of this efficiency by an order magnitude was obs erved at resonance that was in the kHz range. (C) 2000 Elsevier Science S.A . All rights reserved.