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US 2025/0044679 A1Published application
Pupil filter with spatially-varying transmission
AssigneeKLA Corporation
InventorAlexander Pokrovskiy
Life of this patent
Estimating the term…
Abstract
An inspection system includes a pupil filter positioned in an imaging pupil of the inspection system. The pupil filter is configured to provide spatially-varying intensity transmission. The pupil filter is a slab of glass with a patterned layer disposed on a surface of the slab of glass. The inspection system introduces a spatially-varying intensity transmission using the pupil filter.
Claims20
An inspection system comprising:
- a light source that generates a beam of light;
- illumination optics configured to direct the beam of light onto an extreme ultraviolet (EUV) reticle;
- a pupil filter positioned in an imaging pupil of the inspection system, wherein the pupil filter is configured to provide spatially-varying intensity transmission, and wherein the pupil filter is a slab of glass with a patterned layer disposed on a surface of the slab of glass;
- a detector that receives an output beam from the pupil filter and is configured to generate an image for the output beam;
- and
- collection optics for directing the output beam that is reflected and scattered from the EUV reticle in response to the beam of light, wherein the output beam is directed through the pupil filter toward the detector.
3 more elements
A method of inspecting an extreme ultraviolet (EUV) reticle, the method comprising:
- using an inspection system to obtain a test image from an output beam that is reflected and scattered from a test portion of an EUV test reticle, wherein the inspection system is configured to provide a spatially-varying intensity transmission, wherein the inspection system introduces the spatially-varying intensity transmission using a pupil filter that is a slab of glass with a patterned layer disposed on a surface of the slab of glass;
- obtaining a reference image for a reference reticle portion that is designed to be identical to the test reticle portion;
- comparing, using a processor, the test image and the reference image;
- and
- determining, using the processor, whether the test reticle portion has a candidate defect based on the comparing.
2 more elements
Dependencies are inferred from the claim text.