MEMS ultra low leak detection methods: A review

Purpose - The purpose of this paper is to review traditional hermeticity test methods when applied to typical micro-electro-mechanical systems (MEMS) cavity volumes and to propose potential solutions. Design/methodology/approach - Standards for traditional testing have been applied to typical MEMS cavity volumes and the resulting issues of range and sensitivity discussed. ITIn situ/IT test structures have been designed and fabricated with access to the internal cavities to allow characterisation of the structures as a function of pressure. Findings - The ultra low leak rates necessary to guarantee hermeticity of MEMS cannot be measured using traditional methods. Optical test methods are possible although ITin situ/IT test structures currently provide the greatest sensitivity. A portfolio of test techniques is required to allow accurate hermeticity testing of MEMS. Research limitations/implications - This paper provides a starting point for further investigation into several methods of MEMS hermeticity testing. Originality/value - This paper provides a review of the limitations of traditional testing and proposals for future testing as the trend towards smaller volume packaging continues. Fourier transforms Infra-red devices MEMS Packaging processes Spectroscopy. © Emerald Group Publishing Limited.