System for actinic inspection of semiconductor masks

An apparatus and method are disclosed for actinic inspection of semiconductor masks intended for extended ultraviolet (EUV) lithography, or similar objects, with feature sizes less than 100 nm. The approach uses a coherent light source with wavelength less than 120 nm. Inside a vacuum system, an opt...

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Bibliographic Details
Main Author Ebstein, Steven M
Format Patent
LanguageEnglish
Published 09.07.2019
Subjects
BASIC ELECTRIC ELEMENTS
CALCULATING
COMPUTING
COUNTING
DEVICES USING STIMULATED EMISSION
ELECTRICITY
IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES
MEASURING
OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
OPTICS
PHYSICS
TESTING
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Summary:An apparatus and method are disclosed for actinic inspection of semiconductor masks intended for extended ultraviolet (EUV) lithography, or similar objects, with feature sizes less than 100 nm. The approach uses a coherent light source with wavelength less than 120 nm. Inside a vacuum system, an optical system directs the light to an object, i.e., the mask or mask blank, and directs the resulting reflected or transmitted light to an imaging sensor. A computational system processes the imaging sensor data to generate phase and amplitude images of the object. The preferred imaging modality, a form of digital holography, produces images of buried structures and phase objects, as well as amplitude or reflectance images, with nanometer resolution less than or equal to the feature size of the mask.
Bibliography:Application Number: US201715423239