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2020
Journal Article
Titel
AlScN based MEMS quasi-static mirror matrix with large tilting angle and high linearity
Abstract
This paper presents a piezoelectrically (AlScN) driven 3 à 3 quasi-static mirror matrix, where each MEMS mirror utilizes a three-level-construction comprising a mirror plate (diameter = 0.8 mm), a pillar and four AlScN actuators hidden beneath the mirror plate, reducing the chip size to 1.1 à 1.3 mm2. AlScN as a high performance piezoelectric material is used to deliver large force enabling a mechanical tilting angle of ±14° at 150 VDC, in addition to great linearity, repeatability and long-term stability. For realizing the 3D construction three wafers for mirror plate, actuators and a TSV wafer for the vertical electrical contacts are applied. While first demonstrators have been manufactured by a chip-level hybrid assembly to mount the mirror plates onto the actuators, a BEOL triple-wafer-bonding process has been developed to integrate the mirror plates onto the actuators and TSV wafer. This paper will show the design and process efforts for improving the mechanica l behavior of the MEMS mirrors, the process effort and current result of triple-wafer-bonding. It concludes by discussing the technological achievements, challenges and outlook for improved performance due to the material development of AlScN.