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<title>New mask evaluation tool: the microlithography simulation microscope aerial image measurement system</title>
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1994
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EngineeringElectron-beam LithographyMicroscopyImage AnalysisBeam LithographyMicroscopy MethodComputational ImagingInstrumentationOptical SystemsFocus SeriesLight MicroscopyNanolithography MethodRadiologyOphthalmologyEvaluation ToolComputer EngineeringImage CaptureAerospace EngineeringMicrofabricationMicroscope Image ProcessingBiomedical ImagingImage ProcessorMedicineMsm Design
The Zeiss MSM100 microlithography simulation microscope can evaluate phase shift and conventional photolithographic masks. In this paper we discuss the MSM design, its operation, image capture and analysis methods, and typical applications. The tool's unique optical system captures `through focus' images of a mask for a selected NA, sigma, and wavelength, thus paralleling the characteristics of a particular optical stepper. The MSM operates at i-line (365 nm) and DUV (248 nm) wavelengths, and handles commonly used 5 or 6 inch reticles. The images obtained are optically equivalent to that incident on resist, but are highly magnified so that they may be recorded using a DUV CCD camera. Typically, features of interest are recorded as a through focus series; image intensity is digitized. Application to the assessment of defect printability, both before and after repair, is presented. Masks have been analyzed to predicted CD values which are in good agreement with subsequent resist work. Unconventional illumination schemes have been studied.