Development of an EUV Microscope with Focused Coherent EUV Based on Coherent Diffraction Imaging Method for Defect Evaluation on an EUV Mask

Abstract

SUMMARY For evaluation of defects on extreme ultraviolet (EUV) masks at the blank state of manufacturing, we developed a microcoherent EUV scatterometry microscope (micro‐CSM). The illumination source is coherent EUV light with a 140‐nm focus diameter on the defect using a Fresnel zoneplate. This system directly observes the reflection and diffraction signals from a phase defect. The phase and the intensity image of the defect is reconstructed with the diffraction images using ptychography, which is an algorithm of the coherent diffraction imaging. We observed programmed phase defect on a blank EUV mask. Phase distributions of these programmed defects were well reconstructed quantitatively. We also observed actual defects which were inspected by the ABI tool. Actual amplitude defect and phase defect images were reconstructed with intensity and phase contrast. The reconstructed image indicated the defect type of these defect. The micro‐CSM is very powerful tool to evaluate an EUV phase defect.

Mask Defect Detection by Combining Wiener Deconvolution and Illumination Optimization

“…In order to investigate all kinds of mask defects comprehensively, various mask detection techniques were proposed for different types of defects. Mask microscopy is one of the important measurement equipment [16][17][18][19][20] . SHARP in ALS is a typical EUV microscopy device [16,19] , which successfully realized the EUV mask detection system with a resolution of up to 22 nm by means of offaxis zone plate imaging.…”

“…SHARP in ALS is a typical EUV microscopy device [16,19] , which successfully realized the EUV mask detection system with a resolution of up to 22 nm by means of offaxis zone plate imaging. NewSUBARU light source also carried out research such as micro-CSM [18] for mask imaging and defect assessment, and successfully converted the technology into Lasertec corporation, forming an EUV pattern mask detection device (ACTIS A150) [10] .…”

Mask Defect Detection by Combining Wiener Deconvolution and Illumination Optimization

“…In order to investigate all kinds of mask defects comprehensively, various mask detection techniques were proposed for different types of defects. Mask microscopy is one of the important measurement equipment [16][17][18][19][20] . SHARP in ALS is a typical EUV microscopy device [16,19] , which successfully realized the EUV mask detection system with a resolution of up to 22 nm by means of offaxis zone plate imaging.…”

“…SHARP in ALS is a typical EUV microscopy device [16,19] , which successfully realized the EUV mask detection system with a resolution of up to 22 nm by means of offaxis zone plate imaging. NewSUBARU light source also carried out research such as micro-CSM [18] for mask imaging and defect assessment, and successfully converted the technology into Lasertec corporation, forming an EUV pattern mask detection device (ACTIS A150) [10] .…”

An abrasive-free chemical polishing method assisted by nickel catalyst generated by in situ electrochemical plating

“…7,8 This damaged layer significantly reduces the optical reflectance, especially in the short wavelength regime. [9][10][11] In addition, abrasives remaining on the surface after CMP processing are difficult to remove and cause yield reductions in the products.…”