Abstract
In this work, a MEMS piezoresistive micro pressure sensor (1.5 × 1.5 × 0.82 mm) is designed and fabricated with SOI-based micromachining technology and assembled using anodic bonding technology. In order to optimize the linearity and sensitivity over a wide effective pressure range (0–5 MPa) and temperature range (25–125 °C), the diaphragm thickness and the insulation of piezoresistors are precisely controlled by an optimized micromachining process. The consistency of the four piezoresistors is greatly improved by optimizing the structure of the ohmic contact pads. Furthermore, the probability of piezoresistive breakdown during anodic bonding is greatly reduced by conducting the top and bottom silicon of the SOI. At room temperature, the pressure sensor with 40 µm diaphragm demonstrates reliable linearity (0.48% F.S.) and sensitivity (33.04 mV/MPa) over a wide pressure range of 0–5.0 MPa. In addition, a polyimide protection layer is fabricated on the top surface of the sensor to prevent it from corrosion by a moist marine environment. To overcome the linearity drift due to temperature variation in practice, a digital temperature compensation system is developed for the pressure sensor, which shows a maximum error of 0.43% F.S. in a temperature range of 25–125 °C.
Highlights
The piezoresistive effect of a semiconductor was first discovered in the 1950s, which is the theoretical basis of most pressure sensors [1,2,3]
The output characteristic of the pressure sensor was measured by a digital pressure The output characteristic of the pressure sensor was measured by a digital pressure test system consisting of a high-precision piston pressure meter, a hot air gun, and a test system consisting of a high-precision piston pressure meter, a hot air gun, and a control system
Our work aimed to develop a novel solution for micro pressure sensors for harsh
Summary
The piezoresistive effect of a semiconductor was first discovered in the 1950s, which is the theoretical basis of most pressure sensors [1,2,3]. In addition to piezoresistive sensors, several different transduction mechanisms have been applied to convert pressures or strains to signals, such as inductance, capacitance, piezoelectricity, and resonance, which can be detected on circuitry [4,5]. Among these designs, piezoresistive sensors are generally accepted due to their simple construction and low energy consumption [6]. Some intrinsic pitfalls of the silicon piezoresistive pressure sensor, such as inadequate performance in harsh environment, e.g., high pressure or high temperature, and output drift due to temperature variation, have limited its application in marine settings
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