Full wafer integration of shape memory alloy microactuators using adhesive bonding

This paper presents the wafer-scale manufacturing of microactuators based on bulk shape memory alloy material integrated using adhesive bonding. The work addresses key technical challenges related to the wafer-scale fabrication of bulk SMA micro actuators, including wafer-scale integration of patterned SMA sheets to structured Si wafers and the integration of cold state reset layers to the microactuators. Contact printing of an adhesive polymer ensures a selective bonding when transferring full SMA sheets to silicon structures on a patterned wafer. The stressed films deposited on top of the SMA microactuator ensure a built-in reset mechanism of the actuators. The paper reports on the successful wafer-scale integration of wafer-sized SMA sheets and the wafer-scale fabrication of actuator cantilevers. First test cantilevers with a length of 2.5 mm show a stroke of approx. 180 mum.