Design and fabrication of wafer-level packaged MEMS Pirani gauge with sorrounded heat sinks

This paper presents a wafer-level packaged MEMS (Micro-electromechanical Systems)Pirani gauge with surrounded heat sinks with improved characteristics during the low limit of the cavity vacuum. Different to the reported gauges in other papers, it has four heat sinks, and one of these is the cap of the wafer-level package. And it utilizes two heaters and two constant resistors to construct an Whetstone Bridge, two meander-shaped suspended silicon coils is set as the heaters and two isolated comb-shaped silicon structures as the dual-lateral heat sinks. In addition, the substrate and capped wafers are used as dual-vertical heat sinks. The gauge is finally realized with the volume 1.4mm×1.2mm×0.5mm using the CMOS (Complementary Metal Oxide Semiconductor)-MEMS compatible process. The gauge was measured twice before and after wafer-level packaging. It denotes that with the introduction of the capped heat sink, the device bears a better sensitivity compared to the intermediate device before packaging. With a hole on the edge of the device, the gauge could be widely and flexibly used for the characterization of vacuum packaged MEMS devices.