How to evaluate the reliability of MEMS devices without standards

摘要

The standard methodologies currently used for lifetime estimation of microelectronics products rely on the combination of consolidated best practice experience and the knowledge of the manufacturing technology. Indeed, the core physics involved in most solid state device (e.g. transistors) does not change much from one product to another. On the contrary, the large variety of MEMS devices requires a deep understanding of the specific technology they are based on. As a consequence, the failure mechanisms can be even very different between an accelerometer, a micro-mirror or an RF MEMS switch.The present contribution proposes to apply the Physics of Failure approach to estimate the lifetime of MEMS devices, and RF MEMS switches in particular. This methodology takes advantage of the knowledge of the potential failure mode for accelerating the underlying failure mechanism through proper electrical and environmental stimuli. Acceleration factors could be deduced from a parametric study thanks to in-situ monitoring of the devices performance. To assess the reliability of a given device, which could be provided "as is" by the manufacturer, specific testing routines have to be developed and implemented: electrostatic cycling tests, coupled with environmental stresses (temperature, moisture, vibrations, etc.). This paper will then focus on a physical description of the failures to get to an adapted test plan providing the main reliability figures (Time to failure, acceleration factors for instance).