Fabrication of Silicon–Ceramic (SiCer) Composite Multilayer Modules With Embedded NTC Thermistor Sensors

Abstract

Silicon–ceramics composite substrates (SiCer) are a new concept for combining MEMS devices and ceramic multilayer substrates, which is based on cofiring silicon and low-temperature cofired ceramic (LTCC) substrates. The thermal expansion coefficient of LTCC tape material BCT6 is matched to silicon's coefficient. One advantage of this technology is the ability to integrate passive electronic functions into the LTCC multilayer architecture. In this study, we present the integration of Zn–Co–Cu modified nickel manganate spinel NTC thermistor layers as temperature sensors into the LTCC multilayer architecture of SiCer composite substrates. A paste of thermistor powder was screen-printed on alumina and LTCC substrates, and sintered at 900°C. The similar sintering behavior of LTCC tape and NTC paste allows for cofiring of the two materials. LTCC-integrated temperature sensors were fabricated by cofiring LTCC multilayers with printed thermistor structures and Ag or Au metallization. The functionality of the thermistor elements is documented. Finally, thermistor structures were embedded into the LTCC layers and cofired with Si to create combined SiCer substrates. The R(T) curves of the integrated thermistor elements exhibit NTC thermistor behavior with a B-constant of 3450 K, demonstrating the potential for integrating functional passive components into complex SiCer architectures and expanding potential application scenarios.