Three-axes monolithic silicon low-g accelerometer

Abstract

In this paper, four different designs for a new three-axes monolithic low-g acceleration sensor are presented. The silicon spring-mass system of the sensor is fabricated in a single step by anisotropic wet chemical etching in KOH using (111) planes as physical etch stop. The orientation of the supporting beams of the spring-mass systems allows the seismic mass to move in a direction orthogonal to the (111) planes. Four mass-spring systems, each one rotated by 90 , enables the detection of three components of the acceleration vector using capacitive readout. Two alignment structures are presented meeting the high requirements in terms of mask alignment, which are necessary when using the described etch technique. A new space saving compensation structure protecting the convex edges of the seismic masses during the etch process was realized and compared with standard solutions. The sensors performance was characterized and is demonstrated.[578]

Ultrasonic Transducers

“…With (100) wafer, not only flat beams, oblique or even vertical beams are also obtainable [46][47][48]. Fig.…”

“…To minimize the irregular undercut effects, several methods have been proposed [40,48,[54][55]. In one word, these processes utilize a pre-etching step to determine the actual <110> crystal orientation, so that in later photolithography steps, these in advance fabricated patterns can be used for mask alignment.…”

“…With (100) wafer, diverse MEMS devices such as accelerometer [44][45][46][47][48], micro optical clips [49][50], acoustic transducers [51], and scanning micro mirrors [52][53] have been fabricated. The reason that (100) wafer is preferred lies in the orientations of (111) planes in it.…”

Dual-Axis Test Rig for Mems Tilt Sensors

“…prototype sensor, like the one described in [1]),  values of important metrological parameters of a sensor are over-or under-estimated in the related catalog,  a sensor must be calibrated by the user (there exist also some calibration methods with no test rig necessary, described e.g. in [2,3], however their application results in a decrease of the accuracy of the sensor calibrated that way),  results of ageing of a sensor must be determined.…”

Optimising Performance of a Cantilever-type Micro Accelerometer Sensor

“…A piezoresistive-type acceleration (inertial) sensor basically consists of a proof-mass attached to a micro-cantilever (flexure) made out of silicon [1][2][3][4][5][6][7][8] . The flexure gets deflected when the sensor is subjected to inertial force.…”