Wide temperature range through silicon vias made of Invar and spin-on glass for interposers and MEMS

Through silicon vias (TSVs) are used e.g. to create electrical connections through MEMS wafers or through silicon interposers used in 2.5D packaging. Currently available technologies do not address situations in which TSVs through unthinned wafers have to withstand large temperature variations. We propose using ferromagnetic Invar metal alloy for this purpose due to its low mismatch in heat induced strain in comparison to silicon. We demonstrate the suitability of a magnetic assembly process for Invar TSV fabrication and the use of spin-on glass as a TSV insulator. We demonstrate TSVs, with contact pads, that tolerate temperature cycling between -50 °C and 190 °C and can withstand elevated temperatures of at least up to 365 °C.