Technology and micro-Raman characterization of thick meso-porous silicon layers for thermal effect microsystems

Thermal effect microsystems (TEMS) need a highly thermally insulated substr ate. Porous silicon (PS) offers promising applications for insulation of th ermal transducers from silicon wafers as its thermal conductivity is close to that of silicon oxide. A thorough investigation of PS thermal conductivi ty has been carried out regarding its technological parameters, i.e., poros ity, thickness and oxidation temperature. by means of micro-Raman spectrosc opy which yielded thermal conductivity values less than 2 W/m K as predicte d by theoretical considerations. For TEMS, a 100-mu m-thick meso-PS layer w ith a porosity of about 50% and oxidized at a moderate temperature (300 deg rees C) presents the best attributes to ensure both an efficient thermal in sulation, as its thermal conductivity value was found to be 0.6 W/m K, and a good mechanical strength. (C) 2000 Elsevier Science S.A. All rights reser ved.