Mask inspection

About: Mask inspection is a research topic. Over the lifetime, 1072 publications have been published within this topic receiving 8696 citations.

Defect Extraction in Photomask Image Using High Order Moment

Abstract: This paper describes an automated technique to extract defects in photomask images. Conventional approaches to photomask inspection rely on difference based techniques which are susceptible to distortion from image ‘noise’. We propose a robust method based on high order moment (HOM) between reference and test images. In comparison to difference based methods, HOM reveals a wide distribution range of pixel values. This result implies that we can specify pixel value thresholds, and use these thresholds as a basis for distinguishing defects from the background. Our proposed algorithm guarantees the accurate extraction of defects. In this paper, we compare and contrast the transmitted reference image with the test image and reflected image pairs.

Mask for defect inspection and method for manufacturing mask for defect inspection

Abstract: PROBLEM TO BE SOLVED: To evaluate defect detection sensitivity in inspection of a defect of a mask pattern. SOLUTION: The defect detection sensitivity is inspected by using a mask for defect inspection having a photomask pattern which includes a basic pattern and a pattern defect comprising a resist pattern at a specified position of the basic pattern. The mask for defect inspection is produced by forming the basic pattern on a photomask substrate, applying a resist on the basic pattern, and exposing and developing the resist to form a specified pattern defect. COPYRIGHT: (C)2005,JPO&NCIPI

Checking method for lithography mask used for IC manufacture using comparison of checked mask structure with reference structure after transfer of both structures to a semiconductor material

Abstract: The checking method has the structure of a reference mask and the structure of the mask being checked each transferred to a semiconductor material, with scanning of the structures via a device for examination of the semiconductor material, e.g. a microscope and comparison of the structures for indicating differences between the reference mask and the checked mask.

Photomask inspection method and photomask inspection apparatus

Abstract: PROBLEM TO BE SOLVED: To stably detect CD error defects regardless of a chip size. SOLUTION: A photomask formed with a light shielding film pattern is irradiated with laser, and the image of the light shielding film pattern is acquired by changing the relative position of a laser and the photomask while reciprocating an irradiation spot of the laser within a micro range. The light shielding film pattern is inspected based on the acquired image. At this time, a direction to reciprocate the irradiation spot of the laser within the micro range is, for example, orthogonal to a main direction in which the light shielding film pattern is extended (step S1, inspection in a 0° direction). After acquiring images for the whole surface of the photomask in the orthogonal state, the photomask is rotated by 90° (step S2), and a direction to reciprocate the irradiation spot of the laser within the micro range is set parallel to the main direction of the pattern to acquire an image (step S3, inspection in a 90° direction). COPYRIGHT: (C)2009,JPO&INPIT

Identification of multilayer structures using secondary electron yield curves: effect of native oxide films on EUV-patterned mask inspection

Abstract: The impact of EUV mask surface conditions on the patterned mask inspection process was investigated. The results of simulations show that the defect detection capability is degraded by the formation of a native oxide film on the surface of a Ru capped multilayer. This effect was assessed by constructing the secondary electron yield (SEY) curves of the EUV mask materials. These experimentally-obtained SEY curves were examined using semi-empirical Monte Carlo simulations. The simulation results demonstrated that a native oxide film increased the SEY, and that this effect varied with film thickness. The results suggest that defect detection capability will vary according to the thickness of the native oxide when employing an inspection system using an electron beam technique. Also of interest is the finding that the thickness of the native oxide film can be ascertained by fitting the SEY curves.