Evaluation of Image Shortening for Rectangular Array Patterns in X-Ray Lithography

The image shortening of rectangular array patterns replicated by proximity X-ray lithography was investigated. The shorter pattern width was 100 to 200 nm, and shortening on the longer side was studied. Either a negative or positive tone of the mask was used. The experimental results were compared with the absorbed dose distribution calculated using ToolSet developed at the Center for X-ray Lithography (CXrL). The geometrical features of mask patterns, such as absorber side-wall angle, corner rounding, and pattern resize were taken into account. It was found that image shortening is greater with negative tone masks, while negative tone masks provide higher resolution than positive tone masks. It was also found that the slope of the absorber side wall plays an important role in image shortening. The results suggest that the use of negative tone masks, careful tailoring of the absorber side wall, and proper pattern resizing will provide required dimensions for rectangular array patterns.