Thin Layer SOI-FETs Used for Stress-Sensing and Its Application in Accelerometers

Abstract

In this paper, double-clamped beam with a mass at the center has been fabricated on substrate of a Silicon-on-Insulator (SOI) wafer. Thin layer SOI Field-Effect Transistors (SOI-FETs) have been integrated at ends of the beam on top layer of the SOI wafer, which can be used for stress-sensing. Such a structure can be used as an accelerometer. The applied acceleration can be detected directly by the changing of the drain current. The measured sensitivity and noise floor of the device are 0.91 mV/g and 13 mg/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1/2</sup> . As expected performance of the SOI-FETs, such an accelerometer can be used in a wide temperature range (-60°C to 200°C) in some special applications, such as military, automobile, nuclear and well-logging industry application. Note to Practitioners - This paper describes the method for stress-sensing using the thin layer Silicon-on-Insulator Field-Effect Transistors (SOI-FETs). This method is characterized with adjustable sensitivity and wide working temperature range and is expected to apply in strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors. In the paper we take the application in accelerometers for example. A structure of double-clamped beam with a mass at the center has been fabricated on the substrate of a SOI wafer. Based on the devices, we have measured the characteristics of the sensitivity, the noise floor and the working temperature, which is critical in some applications such as military, automobile, nuclear, and well-logging industry application.