Study on EUV mask defect inspection with hp 16nm node using simulated projection electron microscope images

Abstract

According to an ITRS2012-Update the sensitivity requirement for EUV mask pattern inspection system is to be less than 18 nm for half pitch (hp) 16 nm node devices. The inspection sensitivity of extrusion and intrusion defects on hp 64 line-and-space patterned EUV mask was investigated using simulated projection electron microscope (PEM) image. The obtained defect images showed optimization of current density and image processing techniques were essential for the detection of defects. Extrusion and intrusion defects with 16 nm in size were detected on images formed by 3000 electrons per pixel. The landing energy also greatly influenced the defect detection efficiency. These influences were different for extrusion and intrusion defects. These results were in good agreement with experimentally obtained yield curves of the mask materials and the elevation angles of the defects. These results suggest that PEM technique has a potential to detect 16 nm size defects on hp 64 nm patterned EUV mask.