Resist pattern inspection for defect reduction in sub-15 nm templates

An essential element of sub-15 nm nanoimprint lithography is to create fine patterns on a template. However, it is challenging to create sub-15 nm half-pitch patterns on a template by direct drawing with a resist, owing to poor resolution and low sensitivity. We are currently researching the development of sub-15 nm half-pitch patterns by applying self-aligned double patterning on a template. The defect density of the template has not yet reached a high-volume manufacturing level. The aim of our study is to achieve a defect density of less than 1 pcs/cm² for sub-15 nm templates. To achieve this, we need to overcome stochastics-induced resist defects. We aim to determine the mechanism of defect formation by observing the details of the defects. We challenged resist-pattern inspections using a grazing-incidence coherent scatterometry microscope, which illuminated an extreme ultraviolet light to the resist pattern and detected the diffraction signal from the pattern. This study was conducted in collaboration with University of Hyogo and Kioxia Corporation. In this paper, we present the results of damage evaluations and resist-pattern inspections.