A novel raster-scanning method to fabricate ultra-fine cross-gratings for the generation of electron beam moire fringe patterns

The resolution of the electron beam moire method depends on the line frequency of the grating. Recently, more and more effort has been devoted to increase the frequency, and a novel method for producing high-resolution electron beam gratings is presented in this work. Cross-gratings with a frequency up to 14,832 lines/mm (67 nm pitch) were successfully fabricated using a common scanning electron microscope without a dedicated pattern generation system. The quality of the grating was high enough to produce high-quality moire fringe patterns. In this method, the ultra-fine cross-grating can be fabricated only through one-directional scanning on the resist, which can improve the grating quality and significantly reduces the fabrication time. The number of control parameters for grating fabrication could be reduced to two compared to the six parameters required by conventional methods, which facilitates the use of the electron beam moire method. The frequency of the fabricated grating is linearly proportional to the exposure magnification. Thus, the frequency of the grating can be accurately predetermined, and the null field can be easily obtained in the electron beam moire method. The quality of the fabricated gratings was illustrated by the obtained micrographs and moire fringe patterns. The full-field local strain near an induced crack was studied to verify the application potential of this method. (C) 2016 Elsevier Ltd. All rights reserved.