Hetero-micromachining of epitaxial III/V compound semiconductors

摘要

Hetero-micromachining, a novel technique for the fabrication of miniaturized sensors and actuators is described. It is based on III/V compound semiconductor layers epitaxially grown on (001) silicon. Cantilevers composed of single indium phosphide or gallium arsenide layers or a layer sequence of different III/V compound semiconductors were realized exploiting the etching selectivity of the layer against the silicon substrate in KOH solution. Both etching and fracture properties of InP cantilevers are dependent on the concentration 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°/mW of electrical input power under quasistatic excitation conditions. Typically, an increase of this efficiency by an order magnitude was observed at resonance that was in the kHz range.