Reliability assessment of a MEMS microphone under mixed flowing gas environment and shock impact loading

• A MEMS microphone was studied via mixed flowing gas test and shock impact test.
• Wire bond detaching was due to the nickel diffusion through the pad metallization.
• Membrane embrittlement was due to the growth of surface silicon dioxide thin film.
• Failures under shock impact were cracking of the diaphragm, backplate and runner.

In this work the reliability of a Micro-Electro-Mechanical Systems (MEMS) microphone is studied through two accelerated life tests, mixed flowing gas (MFG) testing and shock impact testing. The objective is to identify the associated failure mechanisms and improve the reliability of MEMS devices. Failure analyses are carried out by using various tools, such as optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS). Finite element analysis is also conducted to study the complex contact behaviors among the MEMS elements during shock impact testing. The predicted failure sites are in agreement with the experimental findings.