Abstract
This paper discusses the evaluation and testing of MEMS capacitive accelerometer (z-axis sensitive) fabricated using silicon-on-insulator (SOI) wafer. The accelerometer structure consists of highly conductive (p-type, resistivity: 0.001 Ω-cm) silicon proof mass (1000 μm × 1000 μm × 30 μm) suspended by four crab-like L-shaped beams (1150 μm × 30 μm × 30 μm) over Pyrex (7740) glass cavity (5 μm depth). Rest capacitance of the accelerometer structure is found to be ~ 2.1–2.25 pF range. Qualified accelerometer chips are packaged and sealed in lead less ceramic (LCC) package along with capacitive readout circuitry chip. Packaged accelerometer showed a scale factor sensitivity of ~ 47 mV/g in − 17–42 g acceleration range with 3% non-linearity. Corresponding cross-axis sensitivity also measured (2%) in full-scale range. Frequency response of the accelerometer showed a 3 dB bandwidth of 380 Hz. Resolution of the accelerometer is measured by an innovative technique involving inclinometer. Here, the device output is recorded at near vertical mounting tilt angle (θ ~ 90°) of inclinometer. Present accelerometer output can be resolved at the inclinometer measurement at 90° (output: 2.42662 V) and 89° (output: 2.42780 V) which corresponds to an acceleration resolution of ~ 17 mg.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have