Shin-Etsu Chemical Co., Ltd.

Shin-Etsu Polymer Co., Ltd.

Hiroshi Fukuda

Hideo Nakagawa

Ryuji Koitabashi

Tsuneo Terasawa

Tsutomu Suzuki

Daisuke Iwai

Takahiro Kishita

Shinichi Ohori

Atsushi Yokohata

Takahiro Kinoshita

Takuro Takasaka

A defect classification method in accordance with the present invention uses two types of images output from the defect inspection device(i.e., the first inspection image generated from a luminance signal sequentially output from a detector SE and the second inspection image generated from a difference of the signals from an adjacent portion in a region where the defect exists). The first inspection image includes information for discriminating unevenness of the defective shape. Also, while it is difficult to discriminate unevenness of the defective shape by the second inspection image, the second inspection image includes information on a luminance distribution emphasizing a defective section. The region of the defective section is extracted from the second inspection image to be applied to the first inspection image and thereby define an arithmetic processing area, and the image processing is performed within the arithmetic processing area to compute a feature amount.

Defect classification method, method of sorting photomask blanks, and method of manufacturing mask blank

A photomask blank having a thin film on a transparent substrate is inspected for defects by irradiating inspection light to a surface region of the blank, collecting the reflected light from the irradiated region via an inspection optical system to form a magnified image of the region, extracting a feature parameter of light intensity distribution from the magnified image, and identifying the bump/pit shape of the defect based on the feature parameter combined with the structure of the thin film. The defect inspection method is effective for discriminating defects of bump or pit shape in a highly reliable manner. On application of the defect inspection method, photomask blanks having no pinhole defects are available at lower costs and higher yields.

Methods for defect inspection, sorting, and manufacturing photomask blank

Disclosed is a method of inspecting a defect present at a surface portion of a photomask blank which includes an optical film, and a thin film. The method includes: selecting and designating an inspection treatment procedure and a criterion for determination of rugged shape of the defect which correspond to modes of the optical film and the thin film of the photomask blank; applying inspection light to a region including the defect while maintaining a distance between the defect and an objective lens of an inspecting optical system, based on the designated inspection treatment procedure, and collecting reflected light from the region irradiated with the inspection light, as a magnified image of the region, through the inspecting optical system; and determining the rugged shape of the defect, from light intensity distribution of the magnified image, based on the designated criterion for determination.

Defect inspecting method, sorting method and producing method for photomask blank

A method of inspecting a defect present at a surface portion of a photomask blank having at least one thin film formed on a substrate by use of the inspecting optical system. The method includes setting the distance between the defect and an objective lens of an inspecting optical system to a defocus distance, applying inspection light to the defect through the objective lens, collecting reflected light from the region irradiated with the inspection light, through the objective lens, as a magnified image, identifying a light intensity variation portion of the magnified image, and determining the rugged shape of the defect on the basis of a variation in light intensity of the light intensity variation portion of the magnified image.

Defect inspecting method, sorting method, and producing method for photomask blank

The defect size of a photomask blank is evaluated. An inspection-target photomask blank is irradiated with inspection light and reflected light of the region of the inspection-target photomask blank irradiated with the inspection light is collected through an objective lens of an inspection optical system as a magnified image of the region. Then, an intensity change part in the light intensity distribution profile of the magnified image is identified. Next, a difference in the light intensity of the intensity change part is obtained and the width of the intensity change part is obtained as the apparent width of the defect. Then, the width of the defect is calculated on the basis of a predetermined conversion expression showing the relationship among the difference in the light intensity, the apparent width of the defect, and the actual width of the defect, and the width of the defect is estimated.

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Joetsu, Japan

Hiroshi Fukuda