CMOS-compatible high-temperature microheater: Microstructure release and testing

Several practical issues in the fabrication and high-temperature operation of micro suspended hearing structures compatible with standard CMOS technol ogy are reported. Suspended microstructures are fabricated in a standard CM OS process and are released by post-process silicon etching. Addition of 15 vol% of isopropyl alcohol (TPA) to 25-wt% tetra-methyl ammonium hydroxide (TMAH) is found to greatly increase yield of the post-process release etch. Electrothermal properties of the polysilicon are investigated during high- temperature operation. Significant thermally induced drift (reduction) in r esistance at high temperatures is found, and the impact on temperature cont rol is discussed Thermal isolation is found to be about 50 K/mW, and reliab le operation is observed at a temperature estimated to be around 1000 degre es C.