Mask inspection

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

Development of next-generation mask inspection method by using the feature of mask image captured with 199-nm inspection optics

Abstract: We have developed a mask inspection system using 199nm inspection light wavelength. This system performs transmission and reflection inspection processes concurrently within two hours per plate. By the evaluation result of mask images and inspection sensitivity, it is confirmed that the 199nm inspection system has the advantage over the system using 257nm and has the possibility corresponding to next generation mask inspection. Furthermore, advanced die-to-database (D-DB) inspection, which can generate high-fidelity of a reference image based on the CAD data for alternating phase shift mask (PSM) or tri-tone, is required for next generation inspection system, too. Therefore, a reference image generation method using two-layer CAD data has been developed. In this paper, the effectiveness of this method is described.

A highly reliable mask inspection system

Abstract: An automatic system for inspecting micro mask defects with 1-µm minimum detectable size has been developed. An outline of the system is as follows: The pattern image obtained with a pickup tube is converted into binary video signals which are transferred into two parallel logic circuits for detecting pattern defects. One is based on the pattern-analyzing method, for which one of four algorithms for detecting micro defects is presented in detail. The other is based on the design-pattern data-comparing method, where the data compression scheme and a new idea for avoiding mask alignment errors are adopted. A software system outline, very important in assisting the hardware functions in this system, is also presented. The results of experiments for determining system performance indicate that the system can detect ≥1-µm diameter defects or loss patterns with high probability by complimentary use of the two methods. A 4-in by 4-in mask can be inspected within 100 rain.

Pattern transfer mask, mask inspection method and a mask inspection apparatus

Abstract: A mask inspection apparatus of the present invention includes an electron gun for irradiating an electron beam onto a mask with a pattern formed thereon, an electron lens for magnifying an electro-optic mask image passed through the mask, a fluorescent screen for converting the magnified electro-optic mask image to an optical mask image, an optical lens for optically magnifying the optical mask image, a detector for detecting the magnified optical mask image, and a comparator for inspection a defect in the pattern on the basis of the image. By doing so, it is possible to suppress aberrations resulting from the electro-optic magnification and, in addition, inspect the pattern with a high resolution through optical magnification. It is also possible to inspect the mask at its area and to inspect a defect at high speeds.

Investigation of the performance of state-of-the-art defect inspection tools within EUV lithography

Abstract: Optical bright field wafer inspection followed by repeater analysis is used to find a maximum number of programmed and natural defects on a EUV patterned mask. Each aspect of the inspection methodology affecting the sensitivity of the wafer inspection is optimized individually. A special focus is given to the wafer stack. Simulation is used to predict the optimum stack properties and experimental verification is performed through exposures on the IMEC EUV Alpha Demo Tool. The final result is benchmarked against state-of-the-art patterned mask inspection and blank inspection to evaluate the capabilities and limitations of the optical wafer inspection. In addition, the locations obtained by each inspection technique (wafer and mask) were reviewed on wafer by means of a new automated methodology that is based on a tight stage accuracy of both inspection tool and review SEM.

Advanced non-disruptive manufacturing rule checks (MRC)

Abstract: New advanced mask rule checking (MRC) solutions are required to ensure cost effective, high yield photomask manufacturing processes at 65nm and below and are needed to provide new verification capabilities for mask makers and data prep engineers alike. Traditional MRC, which implements fundamental geometric data checks on limited data formats, is not sufficient for advanced photomask manufacturing. Like recent advances in design rule checking (DRC) software, which includes extensive "manufacturing-aware" rules (or DFM rules), MRC solutions must evolve to include a more comprehensive and intelligent rule checks for the mask manufacturing process. This paper describes the development and testing of an advanced MRC software solution developed within the CATS TM mask data preparation (MDP) solution from Synopsys Inc. The new MRC solution enables the inspection and analysis of mask layout patterns for simple and advanced data verification checks. Proposed applications for mask data prep applications are discussed and include incoming design verification, fracture data correction, inspection tool data tags, mask manufacturing tool or inspection tool selection, and job deck verification.