The development of a new microelectromechanical system (MEMS) always requires a new production process, unlike with pure semiconductor devices. Process recipes and modules have to be revised at the very least, since at present you still can’t fall back on standard recipes for new micromechanical components, as is otherwise customary in semiconductor development.
Both the system design and an optimized process design are essential if a structural element determined primarily by mechanical properties is to work properly. Prototype verification thus not only enables the design to be confirmed, but allows for affirmation of the manufacturing process too. To determine unexpected mechanical behaviour and model deviations, a powerful optical measurement by Laser Vibrometry is often the method of choice.
Due to its high frequency bandwidth, high lateral resolution and excellent amplitude resolution, a laser vibrometer from Polytec should be the first tool you reach for so that you can reliably determine modal properties of MEMS such as transfer functions, resonance frequencies, damping and deflection shapes. The topographical analysis is also important for component development and process optimization. Surface data such as step heights and other dimensions provide you with valuable information about current process parameters, so you can reliably control the MEMS component manufacturing process.
The figure illustrates the a characterization of the topography of a CMOS / MEMS co-integrated flow microsensor carried out using the surface topography option of the MSA Micro System Analyzer from Polytec. The flow microsensor had been realized using silicon-on-insulator (SOI) technology.