Fabrication and Performance of MEMS-Based Pressure Sensor Packages Using Patterned Ultra-Thick Photoresists

Abstract

A novel plastic packaging of a piezoresistive pressure sensor using a patterned ultra-thick photoresist is experimentally and theoretically investigated. Two pressure sensor packages of the sacrifice-replacement and dam-ring type were used in this study. The characteristics of the packaged pressure sensors were investigated by using a finite-element (FE) model and experimental measurements. The results show that the thermal signal drift of the packaged pressure sensor with a small sensing-channel opening or with a thin silicon membrane for the dam-ring approach had a high packaging induced thermal stress, leading to a high temperature coefficient of span (TCO) response of −0.19% span/°C. The results also show that the thermal signal drift of the packaged pressure sensors with a large sensing-channel opening for sacrifice-replacement approach significantly reduced packaging induced thermal stress, and hence a low TCO response of −0.065% span/°C. However, the packaged pressure sensors of both the sacrifice-replacement and dam-ring type still met the specification −0.2% span/°C of the unpackaged pressure sensor. In addition, the size of proposed packages was 4 × 4 × 1.5 mm3 which was about seven times less than the commercialized packages. With the same packaging requirement, the proposed packaging approaches may provide an adequate solution for use in other open-cavity sensors, such as gas sensors, image sensors, and humidity sensors.

Thermal-Performance Instability in Piezoresistive Sensors: Inducement and Improvement

“…Chen et al conducted a series of simulation and experimental investigations on the optimization of wafer-level chip scale packaging (WL-CSP) for piezoresistive pressure sensors. Two different approaches, sacrifice-replacement and dam-ring, were modeled, simulated and tested [82]. In the sacrifice-replacement approach, WL-CSP with small polyimide thickness and large opening window produced small packaging induced stress [83,84]; in the dam-ring approach, large sensing channel opening was also preferred [85].…”

A Review on Evolution, Current Trends and Future Scope of MEMS Piezoresistive Pressure Sensor

“…Currently 6H-SiC, 4H-SiC and 3C-SiC wafers are commercially available. Paper [21], demonstrates 4H-SiC piezoresistive pressure sensor operating at 800 0 C. SiC films are reported almost 15 times costlier than the conventional silicon. As an alternate, in recent years SOI has been extensively used in the fabrication of piezoresistive pressure sensors.…”

A Polymer-Based Capacitive Sensing Array for Normal and Shear Force Measurement

“…There were many researches on sensor arrays for normal and shear force detection. In [ 1 – 5 ], silicon-based tactile sensors were realized by using micromachining techniques. In general, silicon-based devices are too brittle to sustain large deformation, so these devices do not have enough flexibility to cover curved surfaces.…”