Flipped CMOS-diaphragm capacitive tactile sensor surface mountable on flexible and stretchable bus line

Abstract

The following novel configuration has been developed for a MEMS-CMOS integrated tactile sensor on a flexible and stretchable bus for covering a social robot body: a sensing diaphragm is formed on a CMOS substrate by backside etching, and the CMOS substrate is flip-bonded to a low temperature co-fired ceramic (LTCC) substrate. By this configuration, no through-silicon vias (TSVs) are needed, simplifying the fabrication process. The flipped CMOS substrate and the LTCC substrate were bonded and electrically connected using Au-Au bonding, which also formed differential capacitive gaps. A flexible and stretchable wire was fabricated by metal etching and polyimide laser cutting. The tactile sensors, which were mounted on the surface of the flexible bus, sent coded digital signals according to applied force.