Vertical scanning white-light interferometry for dimensional characterization of microelectromechanical system devices

As microelectromechanical systems developed rapidly, the issue of mechanical characterization had emerged as a major consideration in device design and fabrication. Scanning white-light interferometry surface profiling for geometrical characterization and device inspection was proposed. The measurement system was based on a Mirau microscopic interferometer, using a piezo objective nano-positioner to realize accurate scanning in vertical direction in the range of 100 μm. The envelope peak position was extracted by fast Fourier transform processing method, and the whole information of device was obtained . Compared with phase shifting interferometry, it had a large measurement range. The measurement accuracy of the system is calibrated by a step height standard, then measuring repeatability was sub-nanometers level. A micro resonator and a micro pressure sensor are employed to illustrate the capabilities of scanning white-light interferometry as a measurement and process characterization tool.