This paper details a post-process technique by which circuitry in an unmodified IC technology is thermally and electrically isolated from the silicon substrate. This method enables new applications for micromachining, including temperature regulation of analog integrated circuits. The process will be discussed in detail, along with improved tetramethyl ammonium hydroxide (TMAH) etching chemistries that use strong oxidizers to eliminate hillock formation. Also presented is an electrochemical biasing method that uses circuitry on the silicon being etched during the micromachining step. Work is currently underway to evaluate the use of these micromachining techniques for commercial analog circuit applications, several of which will be highlighted in this presentation.

Klaassen, E. H., Reay, R. J., Storment, C. W., and Kovacs, G. T. A., "Micromachined Thermally Isolated Circuits," Sensors and Actuators A, vol. 58, no. 1, Jan. 1997, pp. 43 - 50.