Second-order effects in self-testable accelerometers

The self-testable accelerometer, which is a modification of a piezoresistive, doubly supported cantilever structure, is discussed along with second-order effects. In order to incorporate the self-test function, the overforce stops which limit travel have been enlarged to form electrodes. The cross-section of the device is shown. A metal plate is deposited on the seismic mass and connected across the flexures to an outside bond pad. The top and bottom caps that provide protection against overforce and contamination are processed in such a manner that they are electrically connected to the substrate, thereby surrounding the self-test electrode in an electrically neutral environment.<>