Applying advanced surface analysis techniques to small defect characterization on EUV ML blanks

Abstract

Developing capability in detection, review, and characterization of sub-100 nm defects on EUV multilayer blanks has become critical in enabling the defect root-cause analysis and the eventual elimination of all defects. We have developed a functional method to apply surface analytical techniques (AES, SEM, EDX, and AFM) to characterize individual defects on EUV multilayer blanks. Optical defect inspection is first done with the Lasertec M1350 which does defect scanning, mapping, image review, and fiducial marking. A defect map is then used to navigate defect search on other tools. Those surface analysis techniques and tools are complementary in uncovering defect elemental as well as morphological data. Our experimental results demonstrated that Auger spectroscopy provides the best lateral resolution and surface-specific elemental information. It is capable of detecting and analyzing compositions of sub-100nm defects, either embedded in or on the surface of the multilayer blanks. The composition defect data serve as the crucial “fingerprints” of the blank fabrication process. SEM provides the morphological shape and size data, which are also critical in the identification of defects. AFM gives the precise defect height data, important for defect smoothing and printability analysis. The EDX/FIB tool provides capability of cross sections of embedded defects.