THROUGH SILICON VIAS INTEGRABLE WITH THIN-FILM PIEZOELECTRIC STRUCTURES

Abstract

This paper reports on the design and microfabrication of novel through silicon vias (TSV) that are compatible with high-temperature processing of piezoelectric structures. The present approach uses metal deposition in cavities etched in the SOI handle layer of the wafer and electrically isolated islands in the device layer. This design avoids the shortcomings of previous TSV designs, which either introduce large topologies on the wafer surface, include metals that cannot sustain high-temperature processing or use poor electrical insulators. TSVs microfabricated using this new approach exhibit good performance, specifically small resistance between the front and backside metal pads, isolation from the ground plane and small capacitance between the vias and the ground. These TSVs are eminently suitable for devices requiring high-temperature processing, such as thin-film piezoelectric sensors and actuators.