Abstract
In this study, we fabricated a wireless micro FET (field effect transistor) pressure sensor based on the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The wireless micro pressure sensor is composed of a FET pressure sensor, an oscillator, an amplifier and an antenna. The oscillator is adopted to generate an ac signal, and the amplifier is used to amplify the sensing signal of the pressure sensor. The antenna is utilized to transmit the output voltage of the pressure sensor to a receiver. The pressure sensor is constructed by 16 sensing cells in parallel. Each sensing cell contains an MOS (metal oxide semiconductor) and a suspended membrane, which the gate of the MOS is the suspended membrane. The post-process employs etchants to etch the sacrificial layers in the pressure sensor for releasing the suspended membranes, and a LPCVD (low pressure chemical vapor deposition) parylene is adopted to seal the etch holes in the pressure. Experimental results show that the pressure sensor has a sensitivity of 0.08 mV/kPa in the pressure range of 0–500 kPa and a wireless transmission distance of 10 cm.
Highlights
Micro pressure sensors, which are important components, can be used in the biomedical and various other industries [1,2]
The post-process was the use of wet etching to remove the sacrificial layers, and to obtain the suspended membrane and the etch holes in the pressure sensor were sealed by LPCVD parylene
If the FET pressure sensors could integrate with wireless circuits as wireless pressure sensors they would have more applications, so in this work we have developed a wireless FET pressure sensor based on the commercial CMOS process
Summary
Micro pressure sensors, which are important components, can be used in the biomedical and various other industries [1,2]. Lysko et al [5] presented a FET pressure sensor fabricated by a surface micromachining technique, and consisting of gate, source, drain and substrate terminals. Dai et al [6] proposed a FET pressure sensor with the readout circuit on a chip manufactured by the commercial CMOS process and a post-process. FET pressure sensor integrated circuits on a chip had the advantages of low packaging cost and small chip area. The advantages of CMOS-MEMS micro pressure sensors include low cost per unit area, compatible with integrated circuits and mass-production utilizing semiconductor foundries. We employ the CMOS-MEMS technique to manufacture an FET pressure sensor integrated with wireless transmission circuits on a chip. Experimental results show that the FET pressure sensor has a sensitivity of 0.08 mV/kPa in the pressure range of 0-500 kPa and a wireless transmission distance of 10 cm
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