Advances in scanning electron microscope moire

The scanning electron microscope (SEM) moire method for microscopic measurements based on electron beam lithography and an SEM has been well developed. Although it has been a reliable method, some drawbacks exist: reinforcement effects, complicated processing and low sensitivity. To improve the SEM moire method, new grating-casting techniques and a fringe-viewing technique must be developed. In this study, a carbonaceous grating technique and a total imaging technique are introduced. Accordingly, there are two techniques available for grating-casting (i.e., the carbonaceous grating technique and the existing lithography grating technique) and three techniques available for fringe viewing (i.e., the total imaging technique, the existing monitor viewing technique and the existing photographic viewing technique). A total of six new imaging techniques of SEM moire methods are available for microscopic measurements by combining one technique from each of the two groups. This study demonstrates the feasibility of the individual techniques and discusses the characteristics and limitations of each. Based on the presented total imaging technique, the sensitivity of the moire method is only dependent on the frequency of specimen grating. Because it can be made as high as 10,000 lines/mm, the SEM moire method can achieve sensitivity as high as 0.01 percent.