Abstract

Temporal Phase Shifting Interferometry is the most common method for characterization of surface, profile and displacement properties of micro devices. Common methods of phase shifting require PZT based devices that have inherent errors due to non-linearity. To avoid these errors during phase shifting, a new phase shifting technique is presented in this work. A detailed analysis of the temporal phase shifting technique was performed and an optimized methodology for phase shifting was also established. This technique utilizes the advantage of stroboscopic interferometry to create phase shifted images without requiring any component for phase shifting. The feasibility of the proposed method of phase shifting was demonstrated using the developed Acoustic-Optic Modulated Stroboscopic Interferometer (AOMSI) on simple 1D and 2D micro structures designed specifically for this purpose. The proposed method was used for surface profiling and static characterization of the microstructures. Experiments were performed on microcantilevers in order to extract the curvature of the device due to residual stress on it. The same device was tested under a commercial surface profiler with 1Å resolution and the results were found to be in good agreement with the results from the proposed technique. Static characterization was performed to identify the tip deflection and profile variation of the microcantilever in response to various DC voltages. A capacitor-based cantilever was tested under varied electrostatic loads and the deflection of the cantilever was extracted using the proposed method. The deflection of the cantilever was predicted using a theoretical model based on energy method. Static characterization results from the proposed technique were found to be in good agreement with the predicted results. To extend the applicability of this technique without affecting the spatial resolution for micro devices larger than the field of view of the interferometer, stitching method was proposed and three different stitching configurations were also presented. The same device was tested in full-field of view under the commercial profiler. Good agreement between the result of presented stitching methods and commercial profiler demonstrates the reliability of the presented methods for stitching large structures.