Single-mask fabrication of high-G piezoresistive accelerometers with extended temperature range

• Published in: Journal of micromechanics and microengineering 2007-04, Vol.17 (4), p.730-736
• Main Authors: Eklund, E Jesper, Shkel, Andrei M
• Format: Article
• Language: English
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/17/4/009

This paper presents a fabrication process in which all components of an in-plane piezoresistive accelerometer are fabricated simultaneously using a single mask. By dry-etching a silicon-on-insulator (SOI) wafer that has a specific resistivity, piezoresistors are defined and isolated from each other and from the bulk silicon without the pn-junctions normally required in piezoresistive sensors. In addition to simplifying the fabrication, the temperature range is also extended when compared to conventional piezoresistive accelerometers, due to the absence of pn-junctions. Single-axis accelerometers, designed for an acceleration range of 1 G to 500 G with a sensitivity of 1 mV G-1, were fabricated and tested, and linear output characteristics were demonstrated. The temperature performance was also characterized. The temperature coefficient of sensitivity (TCS) was 0.3% deg C-1 and the temperature coefficient of offset (TCO) was 20 mG deg C-1.