Generation of electrically induced stimuli for MEMS self-test
Résumé
A major task for the implementation of built-in-self-test (BIST) strategies for MEMS is the generation of the test stimuli. These devices can work in different energy domains and are thus designed to sense signals which are generally not electrical. We describe, for different types of MEMS, how the required nonelectrical test stimuli can be induced on-chip by means of electrical signals. This provides the basis for adding BIST strategies for MEMS parts embedded in the coming generation of integrated systems. The on-chip test signal generation is illustrated for the case of MEMS transducers which exploit such physical principles as time-varying electrostatic capacitance, piezoresistivity effect and Seebeck effect. These principles are used in devices such as accelerometers, infrared imagers, pressure sensors or tactile sensors. We used two major MEMS technologies including CMOS-compatible bulk micromachining and surface micromachining. We illustrate the ability to generate on-chip test stimuli and to implement a self-test strategy for the case of a complete application. This corresponds to an infrared imager that can be used in multiple applications