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

Abstract

Abstract. 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. Singleaxis accelerometers, designed for an acceleration range of 1 G to 500 G with a sensitivity of 1 mV/G, 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%/℃ and the temperature coefficient of offset (TCO) was 20 mG/℃.

Cross-axis sensitivity reduction of a silicon MEMS piezoresistive accelerometer

“…Output voltage of the accelerometer was measured over a temperature range from 25 to 85°C at 10°C intervals with 15 min stability time. There is a variation of 17.26% in output voltage for a boron diffused piezoresistors with its surface doping concentration of 5 9 10 18 atoms/cm 3 and the measured values match the predicted values (Eklund and Shkel 2007).…”

“…MEMS piezoresistive accelerometer realized by bulk micromachining technique has been developed by several research groups (Roylance and Angell 1979;Allen et al 1989;Plaza et al 1998;James et al 1996;Wang et al 2003;Aaron et al 2000;Kwon and Park 1998;Ning et al 1995;Chen et al 1997;Eklund and Shkel 2007;Amarasinghe et al 2006;Kal et al 2006). However, acceleration sensor for single axis measurement with stringent requirements of very low cross-axes sensitivity and very good linearity is still under research.…”

“…There are several mechanisms for acceleration sensing viz., piezoelectric (Okada 1995), piezoresistive (Roylance and Angell 1979;Allen et al 1989;Plaza et al 1998;Pak et al 1996;Wang et al 2003;Patridge et al 2000;Lim et al 1999;Sim et al 1998;Kwon and Park 1998;Ning et al 1995;Chen et al 1997;Eklund and Shkel 2007;Amarasinghe et al 2006;Kal et al 2006), capacitive (Butefisch et al 2000;Yazadi et al 2003;Wang et al 2007;Rödjegård et al 2005;Takao et al 2001), tunneling (Dong et al 2005), vibrating beam/resonant beam (Aikele et al 2001;Tabata and Yamamoto 1999;Burns et al 1996), etc. Even though each of the above acceleration sensing mechanisms has its own advantages and limitations, piezoresistive accelerometers are widely used due to its structural simplicity, simple fabrication process and read out circuit compared to the other accelerometers.…”

High Sensitive Piezoresistive Cantilever MEMS Based Sensor by Introducing Stress Concentration Region (SCR)

“…where ∆ is resistance change, and are the longitudinal and transverse stress components, π is the piezoresistive coefficient, G is gauge factor of piezoresistor (G=121, (Eklund and Shkel, 2007) , ∆ is strain component. From equation (3) above, it shows that resistance change increases by maximizing the differential stress − .…”

Fabrication and characterization of monolithic piezoresistive high-g three-axis accelerometer

“…Silicon microfabrication technique makes it possible to reduce size of the sensor as well as the production cost through batch fabrication, making it suitable for mass production. In previous researches, fabricated high-g accelerometers measure the acceleration in one-axis [1][2][3][4][5][6] or three-axis with three proof masses [7]. Compared with a three-axis accelerometer with multiple proof masses, a monolithic three-axis accelerometer is free from axis-alignment error and has advantages of smaller device size, better uniformity of the measurement signals in three sensing directions [7].…”