Investigations of Metal Systems in a Silicon Ceramic Composite Substrate for Electrical and Thermal Contacts as well as Associated Mounting Aspects

Abstract

Abstract A quasi-monolithic silicon ceramic composite substrate (SiCer), allowing the advantageous combination of silicon MEMS technology with the LTCC technology represents a base substrate for new technology concepts. For the realization of such a substrate an adaptation (e. g. expansion coefficient) of the LTCC base material to silicon is required. Due to the fact that this TCE matched LTCC is not supplied with a metallization system, it is important to identify and evaluate suitable metal pastes. We present a compilation of evaluated silver- and gold-based metal pastes, as well as their characterization in terms of solderability and wire-bondability. With the use of thermal vias in combination with deep reactive ion etching to separate individual areas in the silicon layer [1], it is possible to adjust the thermal behavior of SiCer and of systems made of this substrate technology. Particularly for micro-electro-mechanical systems (MEMS) requiring high temperature gradients within the substrate material, e. g. radiation sensors, dew point sensors, energy harvesting or silicon heatsinks a silicon ceramic composite substrate in combination with thermal vias entails a high application potential. We investigate the thermal behavior of silicon ceramic composite substrates. Manufacturing technologies as well as measuring and simulation results regarding the use of thermal vias in SiCer are presented and discussed. Opportunities for construction and connection techniques for mounting a thermal test chip to SiCer are discussed. Furthermore, a simulation-based model to determine the heat dissipation behavior depending on number and arrangement of thermal vias is presented and compared with the measured values.