US 10,816,486 B2 · Multilayer targets for calibration and alignment of X-ray based measurement systems

Abstract

Multilayer targets enabling fast and accurate, absolute calibration and alignment of X-ray based measurement systems are described herein. The multilayer calibration targets have very high diffraction efficiency and are manufactured using fast, low cost production techniques. Each target includes a multilayer structure built up with pairs of X-ray transparent and X-ray absorbing materials. The layers of the multilayer target structure is oriented parallel to an incident X-ray beam. Measured diffraction patterns indicate misalignment in position and orientation between the incident X-Ray beam and the multilayer target. In another aspect, a composite multilayer target includes at least two multilayer structures arranged adjacent one another along a direction aligned with the incident X-ray beam, adjacent one another along a direction perpendicular to the incident X-ray beam, or a combination thereof. In some embodiments, the multilayer structures are spatially separated from one another by a gap distance.

Claims28

Dependent claims

An X-ray based measurement system comprising:

an X-ray illumination subsystem configured to generate an X-ray beam;
a specimen positioning system configured to position a specimen with respect to the X-ray beam such that the X-ray beam is incident on the surface of the specimen at any location on the surface of the specimen;
a multilayer calibration target disposed on the specimen positioning system, the multilayer calibration target including a first multilayer structure comprising repeating layers of an X-ray transmissive material and an X-ray absorptive material, wherein the multilayer calibration target is located in a path of the X-ray beam such that the repeating layers are oriented substantially parallel to the incident X-ray beam;
an X-ray detector configured to detect X-ray photons diffracted by the multilayer calibration target in response to the incident X-ray beam over a range of positions of the specimen positioning system;
and
a computing system configured to determine a location of incidence of the X-ray beam with respect to the multilayer calibration target based on the detected X-ray photons.

3 more elements

A method comprising:

generating an X-ray illumination beam by an X-ray illumination subsystem;
positioning a multilayer calibration target in a path of the X-ray beam by a specimen positioning system, the multilayer calibration target including a first multilayer structure comprising repeating layers of an X-ray transmissive material and an X-ray absorptive material, wherein the multilayer calibration target is located in the path of the X-ray beam such that the repeating layers are oriented substantially parallel to the incident X-ray beam;
detecting X-ray photons diffracted by the multilayer calibration target in response to the incident X-ray beam over a range of positions of the specimen positioning system;
and
determining a location of incidence of the X-ray beam with respect to the multilayer calibration target based on the detected X-ray photons.

2 more elements

Dependencies are inferred from the claim text.

Multilayer targets for calibration and alignment of X-ray based measurement systems

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Multilayer targets for calibration and alignment of X-ray based measurement systems

Life of this patent

Abstract

Claims28