Test and testability of a monolithic MEMS for magnetic field sensing

This paper addresses MEMS testing through a case study: a micromachined mag netic field sensor with on-chip electronics. The sensor element is based on a cantilever beam that is deflected by means of the Lorentz force. Embedde d piezoresistors are used to detect strain in the cantilever beam and thus to detect the magnetic field. A test approach is presented for the whole sy stem focussing on fault classification, on design for testability and on pr oduction test costs. Fault classification introduces several catastrophic a nd parametric faults on both mechanical and electrical elements. Simple and low-cost design for testability such as test point insertion is then discu ssed for test cost reduction and for fault coverage enhancement.