Reconstruction of planar periodic structures based on Fourier analysis of moiré patterns

In recent years, inverse moire methods have been developed to reconstruct micro/nano-scale planar periodic structures with a larger field of view than those constructed using conventional methods. In these methods, moire fringes generated by superposition of the periodic structure and a reference grating are analyzed to reconstruct the periodic structure. There are two approaches to inverse moire methods: the fringe-centerlines method and the phase-shifting method. The former has lower accuracy and is difficult to automate, while the latter requires at least three moire images with complicated processing. A reconstruction method for planar periodic structures using Fourier analysis is proposed. This method can be used to characterize the micro/nano periodic structure from a single microscope moire pattern. At the same time, when combined with a linewidth characterization method, the period and linewidth of the microstructure can be obtained simultaneously. As practical examples, the period and linewidth of a scanning electron microscopy raster are calibrated. Then the microstructures of a micro-electroformed grating and a butterfly wing are reconstructed using the calibrated system. The proposed method provides a tool for the characterization of large area micro/nano periodic structures. Further, this is a promising approach to detect defects in periodic structures.