A Resonant Differential Pressure Microsensor With a Stress Isolation Layer

This article presents a resonant differential pressure microsensor with a stress isolation layer, which is mainly composed of three parts, an SOI wafer, including a handle layer, an oxide layer and a device layer, a GOS wafer, including a glass layer and a silicon layer and a stress isolation structure, including a two-layer glass. The SOI device layer including the central beam in the central area and the side beam in the side area is bonded to GOS glass wafer for vacuum packaging of the beams. The diaphragm including SOI device layer and the GOS wafer is coupled to the two beams through anchors. In order to realize stress isolation, the glass base is designed as a convex structure, which is bonded to sensor chip by anodic bonding technology and fixed to Kovar pedestal by epoxy glue, respectively. Experimental characterizations were carried out, indicating differential pressure sensitivity of 144.85 Hz/kPa (similar to 2079 ppm/kPa) and static pressure sensitivity of -0.98 Hz/kPa (similar to 14 ppm/kPa) and temperature sensitivity of -2.19 Hz/degrees C (similar to 31 ppm/degrees C). Compared with existing research, the low temperature sensitivity was realized, improving the temperature long-term stability of the sensor.