Three axis piezoresistive accelerometer using polysilicon layer

Abstract

The variation of each piezoresistor each piezoresistorThe variation of for Y-axis acceleration for X-axis acceleration t -1 1'Three axis piezoresistive accelerometer was fabricated by polysilicon layer using SDB(si1icon direct bonding) technology and LPCVD. The variations of stress according to each direction were utilized to detect the three dimensional acceleration and eliminate cross-axis sensitivities.TCO (temperature coefficient of offset) shifts for X, Y and Z-axis Wheatstone bridge outputs were only about 0 -0.07[%F.S.], 0.028--0.016[%F.S.] and 0.007--0.004[%F.S.] in the 25 ' C -160°C range respectively. The sensitivities of fabricated sensor for X, Y and Z-axis acceleration were about O.O6[mV/V * g], O.OS[mV/V g] and O.l3[mV/V g] at a room temperature. The cross-axis sensitivity for X, Y and Z-axis acceleration was about O.O093[mV/V * g], which stands for the elimination of crossaxis sensitivities as designed.

Design and analysis of a microelectromagnetic vibration transducer used as an implantable middle ear hearing aid

“…The transducer output characteristics are determined by the constants of elasticity, damping, mass, driving force and frequency as expressed in equation (11). The characteristics of vibration force can be controlled by the applied coil current, which is transferred from the external amplification electronics.…”

“…The presented silicon elastic body will be a fabricated semiconductor process such as lithography, deposition, wet and dry etching, etc. The thickness control ability will be executed in the etching process; it is available for improvement of mass production and reproducibility [11].…”

“…To obtain the natural resonant frequency of 5000 Hz, it should have a beam thickness of 30 µm, a length of 400 µm and a beam width of 200 µm. To make a microstructured silicon elastic body, a semiconductor process, such as thermal oxidation, wet and dry etching of silicon, can be applied [11].…”