Three axis piezoresistive accelerometer using polysilicon layer

A three axis piezoresistive accelerometer was fabricated from a polysilicon layer using SDB (silicon 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 the fabricated sensor for X, Y and Z-axis acceleration were about 0.06[mV/V·g], 0.06[mV/V·g] and 0.13[mV/V·g] at room temperature. The cross-axis sensitivity for X, Y and Z-axis acceleration was about 0.0093[mV/V·g], which corresponds to the elimination of cross-axis sensitivities as designed