On-Chip Integration of Pressure Plus 2-Axis (X/Z) Acceleration Composite TPMS Sensors with a Single-Sided Bulk-Micromachining Technique

Abstract

A novel on-chip integration of pressure plus 2-axis (X/Z) acceleration composite sensors for upgraded production of automobile tire pressure monitoring system (TPMS) is proposed, developed, and characterized. Herein, the X-axis accelerometer is with the cantilever beam-mass structure and is used for automatically identifying and positioning each of the four wheels. The IC-Foundry-Compatible low-cost batch fabrication technique of MIS (i.e., Micro-openings Inter-etch and Sealing) is employed to only fabricate the device from the front side of (111) silicon wafer, without double-sided micromachining, wafer bonding, complex Cavity-SOI (Silicon on Insulator) processing, and expensive SOI-wafer needed. Benefited from the single-wafer front-side fabrication technique on ordinary single-polished wafers, the fabricated composite TPMS sensor has the advantages of a small chip-size of 1.9 mm × 1.9 mm, low cross-talk interference, low-cost, and compatible process with IC-foundries. The fabricated pressure sensors, X-axis accelerometer and Z-axis accelerometer, show linear sensing outputs, with the sensitivities as about 0.102 mV/kPa, 0.132 mV/kPa, and 0.136 mV/kPa, respectively. Fabricated with the low-cost front-side MIS process, the fabricated composite TPMS sensors are promising in automotive electronics and volume production.

Advances in high-performance MEMS pressure sensors: design, fabrication, and packaging

“…The sensitivity of the pressure sensor is 0.020 mV/V/kPa, the nonlinearity is 0.4%FS, the sensitivity of the temperature sensor is 0.56 Ω/°C, and the nonlinearity is 0.48%FS. To decrease the chip size and crosstalk between different sensors in integrated chips, Wang et al 127 , 128 developed pressure/acceleration integrated chips, as shown in Fig. 11c, d .…”

“…b Arrangement of piezoresistors for the three-axis accelerometer in (a) 126 . c Sketch of the on-chip integration of the pressure plus two-axis acceleration composite tire pressure monitoring system (TPMS) sensor 127 . d SEM image of the fabricated sensor 127 .…”

“…c Sketch of the on-chip integration of the pressure plus two-axis acceleration composite tire pressure monitoring system (TPMS) sensor 127 . d SEM image of the fabricated sensor 127 . e X-axis accelerometer output and eliminated cross-sensitivity of the Z-axis accelerometer 127 .…”

Fabrication and Characterization of Monolithic Integrated Three-Axis Acceleration/Pressure/Magnetic Field Sensors

“…Dong et al developed integrated acceleration and pressure multifunction sensors with a glass–silicon–glass sandwich structure based on piezoresistive effect, which can be applied to automobile, aerospace, environmental monitoring, and other application fields [ 13 ]. Wang et al proposed composite sensors with pressure and two-axis acceleration that have potential in the mass production of tire pressure monitoring systems (TPMS) with a sensitivity of 0.136 mV/kPa [ 14 ]. With the recent expansion of the automotive electronic products market, and the increasing demand for sensors in the field of intelligent vehicles, sensors applied to the TPMS and intelligent driving field are developing rapidly.…”

A Road Condition Classification Algorithm for a Tire Acceleration Sensor using an Artificial Neural Network

“…Tires, which are in direct contact with the road surface, greatly affect the stability of the vehicle. As a technology that improves vehicle stability and driver convenience, tire-pressure monitoring systems (TPMSs) measure tire pressure and relay that information to the driver [7]. TPMS has been mandatory for automobiles sold in the United States since 2007, and in Korea since 2015 [8,9].…”