Spatial Distribution Imaging of Resist Thin Film with Micrometer Resolution using Reflection Type Soft X-ray Projection Microscope

The spatial distribution observation of resist thin films is important for developing high-performance EUV resists with low line-width roughness property. In our previous study on resist spatial distribution evaluation, aggregation at the micrometer scale was indicated. We developed the reflection-type soft X-ray projection microscope equipped with a capillary mirror optics for focusing. The spatial resolution of this microscope was evaluated in a spatial resolution of a several micrometers. A thin film of a positive-tone chemically amplified resist coated on a glass substrate was observed by this microscope, which had not been patterned. The observation photon energy was around the carbon K-edge absorption region (280 – 300 eV). Non-uniform spatial distribution by reflection mode was observed with a size of several-ten micrometers, which indicated the carbon material aggregation. The micrometer-scale aggregation observation in the resist thin film was very significant to achieve low line-width roughness (LWR).