Reflective mask blank for euv lithography, and process for its inspection and process for its production

Abstract

To provide a process for inspecting an EUV mask blank capable of distinguishing phase defects and amplitude defects and capable of detecting even amplitude defects of small sizes, a process for producing an EUV mask blank using the inspection process, and an EUV mask blank obtainable by such a process. A process for inspecting a reflective mask blank for EUV lithography having a multilayer reflective film for reflecting EUV light and an absorber layer for absorbing EUV light formed in this order on a substrate, which comprises a first defect distribution storing step of detecting an in-plane distribution of defects in the multilayer reflective film by, at a stage where the multilayer reflective film is formed on the substrate, applying EUV light to the surface of the multilayer reflective film and storing the detected first defect in-plane distribution data, a second defect distribution storing step of detecting an in-plane distribution of defects from the absorber layer by, at a stage where the absorber layer is formed on the multilayer reflective film, applying light having a wavelength of from 150 to 600 nm to the surface of the absorber layer and storing the detected second defect in-plane distribution data, and a defect distinguishing step of distinguishing phase defects and amplitude defects in the reflective mask blank for EUV lithography by comparison between the first defect in-plane distribution data and the second defect in-plane distribution data.

Dependencies are inferred from the claim text.