THE EFFECTS OF RADIATION ON MEMS ACCELEROMETERS

Exposing just the mechanical part (sensor) of MEMS accelerometers td p rotons and heavy ions caused large changes in outputs representing the measured acceleration for the ADXL50 and very small changes for the A DXL04. The large voltage shift measured for the ADXL50 is attributed t o charge generated by the ions and trapped in dielectric layers below the moveable mass. The trapped charge alters the electric field distri bution which, in turn, changes the output voltage. The construction of the ADXL04 differs from that of the ADXL50 in that the dielectric lay ers are covered with a conducting polycrystalline silicon layer that e ffectively screens out the trapped charge, leaving the output voltage unchanged