Drift of MEMS Capacitive Accelerometers for One-Year Room-Temperature Storage: A Simulation and Experimental Study

In this study, the drift of microelectromechanical system (MEMS) accelerometers stored at room temperature for one year is investigated by both finite-element analysis (FEA) simulation and experiments. In the simulation, a comprehensive FEA model considering the die-attach adhesive viscoelasticity was established to emulate the deformation of the sensor package structure during storage. Then drift models of the scale factor and bias of the accelerometer were built according to the deformed structure. To validate the simulation results, several accelerometers were packaged and their outputs were tested and recorded once per month. The two parameters displayed a continuous drift owing to the release of the packaging stress in the chip. The scale factor drifts were negative and about 2500 ppm for different types of sensors. However, the bias drifts were positive or negative, and their magnitudes were ranging from 12 to 32 mg in storage. Moreover, they reached a steady state after about ten months (< 50 ppm per month for the scale factor) and six months (< 1 mg per month for bias) of room-temperature storage. The results in this article provide meaningful guidance for the application of MEMS accelerometers.