A high-performance P-in-G sensor with multiple-level 3D micro-structure fabricated from one side of single wafer

This paper reports, for the first time, a single-wafer micromachined P-in-G composite-sensor for automobile tire-pressure monitoring system (TPMS) application. Located inside the proof-mass of the accelerometer, the pressure sensor is freely suspended from the stress-free proof-mass-end, thereby eliminating the influence of acceleration to the pressure sensor. The designed P-in-G composite-sensor tested result is 36-fold better than that of the recently published work. Besides the compact P-in-G architecture, the 1.25mm×1.25mm×0.45mm tiny-sized composite-sensor benefits from the single-wafer front-side fabrication technique. With neither double-side alignment/exposure nor wafer-bonding, the IC-foundry compatible high-yield process has created a 6-level 3D micro-structure for the sensor. The sensors have been tested with satisfactory performance for TPMS application.