Extension of High-Temperature Electronics

Commercial and Sandia fabricated silicon MOSFET´s, thickfill resistors and capacitors, and magnetic components were investigated in an effort to increase the versatility of microelectronics used at 300°C and to form a foundation for a higher temperature technology. Commerical MOSFET´s were found susceptible to parameter drifts and have unacceptable electrical characteristics when tested at 300°C, whereas redesigned low alkali impurity devices were able to maintain stable operation at 300°C for 1000 h with improved characteristics. Thus, although MOSFET´s are prone to aging, it is possible to use fabrication procedures which allow MOSFET use at high temperature. A specially developed ceramic filled, high silica frit dielectric thick-film material exhibited a sufficiently high resistivity to permit development of 300°C, 1.0 muF capacitors. Procedures were developed to make this material compatible with the multilayer brick capacitor format which is necessary for miniaturization. Both this dielectric and a ruthenium-based resistor material were shown useful to 500°C. In addition, a spectrum of magnetic components was qualified for use at 500°C.