Abstract
A three-axis accelerometer with a double L-shaped beams structure was designed and fabricated in this paper, consisting of a supporting body, four double L-shaped beams and intermediate double beams connected to two mass blocks. When applying acceleration to the accelerometer chip, according to the output voltage changes of three Wheatstone bridges constituted by twelve piezoresistors on the roots of the beams, the corresponding acceleration along three axes can be measured based on the elastic force theory and piezoresistive effect. To improve the characteristics of the three-axis accelerometer, we simulated how the width of the intermediate double beams affected the characteristics. Through optimizing the structure size, six chips with different widths of intermediate double beams were fabricated on silicon-on-insulator (SOI) wafers using micro-electromechanical systems (MEMS) technology and were packaged on printed circuit boards (PCB) by using an electrostatic bonding process and inner lead bonding technology. At room temperature and VDD = 5.0 V, the resulting accelerometer with an optimized size (w = 500 μm) realized sensitivities of 0.302 mV/g, 0.235 mV/g and 0.347 mV/g along three axes, with a low cross-axis sensitivity. This result provides a new strategy to further improve the characteristics of the three-axis accelerometer.
Highlights
In recent years, with the rapid development of semiconductor technology, accelerometers have been widely used in many different fields, mainly including vibration detection [1], consumer electronics [2], medical treatment [3,4], vibration detection of wind turbines [5], navigation [6,7], automobile safety [8], and so on
Presented a piezoresistive accelerometer with a low cross-axis sensitivity based on masked-maskless wet etching, realizing sensitivities of 0.069 V/V·g, 0.034 V/V·g and 4.15 V/V·g along the x-axis, y-axis and z-axis, and cross-axis sensitivities of 1.67% and 0.82% along the x-axis and y-axis, respectively [10]
Takahashi et al reported an angular acceleration sensor composed of liquid ring channels and piezoresistive cantilevers as the sensing element, achieving an angular acceleration resolution of 0.01 rad/s2 in the range of 0.1–100 Hz on a target axis about 100 times higher than that of the other axes, a high sensitivity and a low cross-interference [11]
Summary
With the rapid development of semiconductor technology, accelerometers have been widely used in many different fields, mainly including vibration detection [1], consumer electronics [2], medical treatment [3,4], vibration detection of wind turbines [5], navigation [6,7], automobile safety [8], and so on. To overcome the above obstacles, a piezoresistive three-axis accelerometer with double L-shaped consistency and reducing cross-interference, which have limited their further development. The basic structure of the three-axis elastic element consists of four double L-shaped beams, intermediate double beams and two mass accelerometer beams is shown in FigureThe. 1, including a topofview, bottom views, blocks, andwith the double sensitiveL-shaped element has twelve piezoresistors. 1c gives the cross-section view along AA’ for the three-axis accelerometer, in which the thicknesses intermediate double beams are the same as those of the four double L-shaped beams.
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