Angular accelerometer with dual anchor support

An angular accelerometer is demonstrated in 6 /spl mu/m thick silicon-on-insulator (SOI) with improved cross axis rejection using a dual anchor scheme. Dual anchor distribution is responsible for a 2X increase in the linear Z-Axis proof mass mechanical suspension spring constant while increasing the rotational spring constant by less than 15%. A structural framework of beams connected to the proof mass inner ring forms this floating hub, centrally anchored, cylindrical angular accelerometer. The floating hub significantly stiffens the proof mass structure resulting in a more robust sensor design to both process section and undesirable out of plane bending modes experienced during cross axis acceleration excitation. The open loop sensor angular acceleration sensitivity is 6 mV/r/s/sup 2/ with a resolution of 1 r/s/sup 2/ in a 250 Hz bandwidth for devices fabricated on 6 /spl mu/m thick SOI wafers. Mechanical deflection of the proof mass with reference to the fixed substrate anchor sites in a 1 g acceleration field is measured using a Zygo confocal 3D microscope as less than 0.041 /spl mu/m.