Abstract: An improved MEMS thermal actuator has a cantilevered beam and a conductive circuit having two driving arms, an inner arm adjacent to the cantilevered beam, and an outer arm adjacent to the inner arm. Current flows through the inner and outer arms to heat the conductive circuit, causing it to expand relative to the cantilevered beam. A tether ties the conductive circuit to the cantilevered beam, so that upon expansion, the conductive circuit causes the cantilevered beam to deflect about its anchor point. However, only the inner arm of the driving beam is coupled to the cantilevered beam. Since the outer arm of the conductive circuit is not coupled to the cantilevered beam, the overall stiffness of the actuator may be decreased. In addition, serpentines may be placed in the outer arm of the conductive circuit, in order to further decrease the stiffness of this beam. The actuator may therefore be made more efficient, in that the deflection of the cantilevered beam may be increased for a given input current.

Abstract: A device and a method are described which hermetically seals at least one microstructure within a cavity. Electrical access to the at least one microstructure is provided by through wafer vias formed through a via substrate which supports the at least one microstructure on its front side. The via substrate and a lid wafer may form a hermetic cavity which encloses the at least one microstructure. The through wafer vias are connected to bond pads located outside the cavity by an interconnect structure formed on the back side of the via substrate. Because they are outside the cavity, the bond pads may be placed inside the perimeter of the bond line forming the cavity, thereby greatly reducing the area occupied by the device. The through wafer vias also shorten the circuit length between the microstructure and the interconnect, thus improving heat transfer and signal loss in the device.