Evaluation of a microwave based contact-free testing method for mechanical sensitivity analysis of MEMS for inline integration of on-wafer measurements

Testing of Micro Electro Mechanical Systems is a key issue in high volume batch manufacturing. Deviating process parameters influence the nominal intrinsic stress level of the mechanical components, leading to a variation of the specified sensitivity, hence the system functionality. Focusing on a short test time, inline integration, and contactless excitation and analysis methods, establishing an electrical test for the required sensitivity within the mechanical domain is challenging. Depending on the design and functionality of the specific MEMS device, optical interferometry methods, Impedance or Network Analyzers or even final system level tests are implemented nowadays. This paper presents an alternative contactless testing method for sensitivity analysis of MEMS using microwave reflectometry. Proving the enormous potential of the method for inline integration, measurement results for varying chuck thickness and frequencies within the W-band are shown and evaluated, using a dedicated test setup for on-chip or on-wafer measurements.