Kla Tencor Corporation

Kla Corporation

Rui-Fang Shi

Abdurrahman Sezginer

Haifeng Huang

Yalin Xiong

Damon Floyd Kvamme

Weston L Sousa

Lih-Huah Yiin

Bing Li

John Fielden

Daniel C Wack

Carl Hess

Hawren Fang

Patrick LoPresti

Dmitry Skvortsov

Joe Blecher

Alex Pokrovskiy

Zhengyu Wang

Alexander Bykanov

Gaurav Verma

Mark Wagner

Venkatraman Iyer

Scott A Andrews

Yin Xu

Xin Ye

Qiang Q Zhang

Bo Su

Eric Vella

Zefram Marks

Joseph Walsh

Thomas Vavul

Carlos A Duran

Hong Du

Zhengcheng Lin

Sseunhyeun Jo

Guarav Verma

Dan Wack

Mitchell Lindsay

Zhengyu Guo

Robert Kestner

Nicolas Steven Juliano

Amrish Kelkar

Wenfei Gu

Zhian Guo

Carl E Hess

Lih-Huah Yin

A photomask-inspection system includes a vacuum chamber and a stage, disposed in the vacuum chamber, to support a photomask and to translate the photomask horizontally and vertically. The system also includes an EUV objective, disposed in the vacuum chamber, to collect EUV light from the photomask to inspect the photomask for defects and an optical height sensor, at least partially disposed in the vacuum chamber, to measure heights on a surface of the photomask. The system further includes a stage controller to translate the stage horizontally and vertically in accordance with a focal map for the photomask produced using the measured heights on the surface of the photomask.

Integration of an optical height sensor in mask inspection tools

An extreme ultraviolet (EUV) light source includes a vacuum chamber with a rotating target assembly therein. The rotating target assembly has an annular groove with a distal wall relative to an axis of rotation. The distal wall includes a porous region. The rotating target assembly is rotated to form a target by centrifugal force with a layer of molten metal on a distal wall of an annular groove in the rotating target assembly.

Rotating target for extreme ultraviolet source with liquid metal

An optical system with aberration correction is disclosed. The optical system may include an illumination source. The optical system may include a detector. The optical system may include one or more collection optics configured to image a sample onto the detector based on illumination from the illumination source. The optical system may include two or more aberration correction plates located in one or more pupil planes of the one or more collection optics. The two or more aberration correction plates may provide at least partial correction of two or more linearly-independent aberration terms. Any particular one of the two or more aberration correction plates may have a spatially-varying thickness profile providing a selected amount of correction for a single particular aberration term of the two or more linearly-independent aberration terms.

Correcting aberration and apodization of an optical system using correction plates

Disclosed are methods and apparatus for inspecting a photolithographic reticle. A plurality of reference far field images are simulated by inputting a plurality of reference near field images into a physics-based model, and the plurality of reference near field images are generated by a trained deep learning model from a test portion of the design database that was used to fabricate a test area of a test reticle. The test area of a test reticle, which was fabricated from the design database, is inspected for defects via a die-to-database process that includes comparing the plurality of reference far field reticle images simulated by the physic-based model to a plurality of test images acquired by the inspection system from the test area of the test reticle.

Inspection of reticles using machine learning

To calibrate a TDI photomask inspection tool, a photomask with a plurality of distinctly patterned regions is loaded into the tool. The plurality of distinctly patterned regions is successively illuminated with an EUV beam of light. While illuminating respective distinctly patterned regions, respective instances of imaging of the respective distinctly patterned regions are performed using a TDI sensor in the inspection tool. While performing the respective instances of imaging, a reference intensity detector is used to measure reference intensities of EUV light collected from the photomask. Based on the results of the respective instances of imaging and the measured reference intensities of EUV light, linearity of the TDI sensor is determined.

EUV in-situ linearity calibration for TDI image sensors using test photomasks

An acousto-optic modulator (AOM) laser frequency shifter system includes a laser configured to generate an incident beam, a first optical splitter optically coupled to the laser and configured to split the incident beam into at least one portion of the incident beam, at least one phase-shift channel optically coupled to the first optical splitter and configured to generate at least one frequency-shifted beam with an acousto-optic modulator (AOM) from the at least one portion of the incident beam received from the first optical splitter, and a second optical splitter configured to receive the at least one frequency-shifted beam from the at least one phase-shift channel and configured to direct the at least one frequency-shifted beam to an interferometer configured to acquire an interferogram of a sample with the at least one frequency-shifted beam.

Fast phase-shift interferometry by laser frequency shift

Heights on a surface of a photomask are measured using broadband light interferometry. The heights include heights of patterned areas of the photomask. A focal map is produced from the measured heights on the surface of the photomask. To produce the focal map, the measured heights of the patterned areas are adjusted based on fill factors for the patterned areas. The photomask is inspected for defects, using the focal map.

Broadband light interferometry for focal-map generation in photomask inspection

Reference and test waves are directed in a common path mode in a fiber tip diffraction interferometer. A first fiber can be used to generate the reference wave and a second fiber can be used to generate the test wave. Each fiber can include a single mode fiber tip that defines a wedge at an end without a coating on end surface or a tapered fiber tip. The fiber tip diffraction interferometer can include an aplanatic pupil imaging lens or system disposed to receive both the test wave and the reference wave and a sensor configured to receive both the test wave and the reference wave.

Common path mode fiber tip diffraction interferometer for wavefront measurement

Disclosed are methods and apparatus for inspecting a photolithographic reticle. A near field reticle image is generated via a deep learning process based on a reticle database image produced from a design database, and a far field reticle image is simulated at an image plane of an inspection system via a physics-based process based on the near field reticle image. The deep learning process includes training a deep learning model based on minimizing differences between the far field reticle images and a plurality of corresponding training reticle images acquired by imaging a training reticle fabricated from the design database, and such training reticle images are selected for pattern variety and are defect-free. A test area of a test reticle, which is fabricated from the design database, is inspected for defects via a die-to-database process that includes comparing a plurality of references images from a reference far field reticle image to a plurality of test images acquired by the inspection system from the test reticle. The reference far field reticle image is simulated based on a reference near field reticle image that is generated by the trained deep learning model.

An inspection system includes an illumination source configured to generate extreme ultraviolet (EUV) light, illumination optics to direct the EUV light to a sample within a range of off-axis incidence angles corresponding to an illumination pupil distribution, collection optics to collect light from the sample in response to the incident EUV light within a range of collection angles corresponding to an imaging pupil distribution, and a detector configured to receive at least a portion of the light collected by the collection optics. Further, a center of the illumination pupil distribution corresponds to an off-axis incidence angle along a first direction on the sample, and at least one of the illumination pupil distribution or the imaging pupil distribution is non-circular with a size along the first direction shorter than along a second direction perpendicular to the first direction.

Inspection system with non-circular pupil

Disclosed are methods and apparatus for inspecting an extreme ultraviolet (EUV) reticle using an optical inspection tool. An inspection tool having a pupil filter positioned at an imaging pupil is used to obtain a test image or signal from an output beam that is reflected and scattered from a test portion of an EUV test reticle. The pupil filter is configured to provide phase contrast in the output beam. A reference image or signal is obtained for a reference reticle portion that is designed to be identical to the test reticle portion. The test and reference images or signals are compared and it is determined whether the test reticle portion has any candidate defects based on such comparison. For each of a plurality of test reticle portions of the reticle, the operations for using the inspection tool, obtaining a reference image or signal, comparing, and determining are repeated. A defect report is generated based on any candidate defects that have been determined to be present.

Phase contrast monitoring for extreme ultra-violet (EUV) masks defect inspection

Block-to-block reticle inspection includes acquiring a swath image of a portion of a reticle with a reticle inspection sub-system, identifying a first occurrence of a block in the swatch image and at least a second occurrence of the block in the swath image substantially similar to the first occurrence of the block and determining at least one of a location, one or more geometrical characteristics of the block and a spatial offset between the first occurrence of the block and the at least a second occurrence of the block.

Block-to-block reticle inspection

An optical reticle inspection tool is used during a first inspection to obtain, for each set of one or more patch areas of the reticle, a reference average of multiple reference intensity values corresponding to light measured from sub-areas of each patch area. After using the reticle in photolithography processes, the optical reticle inspection tool is used during a second inspection to obtain, for each set of one or more patch areas, an average of multiple test intensity values corresponding to light measured from the sub-areas. The first and second inspections use the same tool setup recipe. A difference intensity map is generated, and such map comprises map values that each corresponds to a difference between each average of the test and reference intensity values for each set of one or more patches. The difference intensity map indicates whether the reticle has degraded over time more than a predefined level.

Time-varying intensity map generation for reticles

Disclosed are methods and apparatus for qualifying a photolithographic reticle. A reticle inspection tool is used to acquire images at different imaging configurations from each of a plurality of pattern areas of a test reticle. A reticle near field for each of the pattern areas of the test reticle is recovered based on the acquired images from each pattern area of the test reticle. A lithography model is applied to the reticle near field for the test reticle to simulate a plurality of test wafer images, and the simulated test wafer images are analyzed to determine whether the test reticle will likely result in an unstable or defective wafer.

Apparatus and methods for predicting wafer-level defect printability

Disclosed are methods and apparatus for facilitating an inspection of a sample using an inspection tool. An inspection tool is used to obtain an image or signal from an EUV reticle that specifies an intensity variation across the EUV reticle, and this intensity variation is converted to a CD variation that removes a flare correction CD variation so as to generate a critical dimension uniformity (CDU) map without the flare correction CD variation. This removed flare correction CD variation originates from design data for fabricating the EUV reticle, and such flare correction CD variation is generally designed to compensate for flare differences that are present across a field of view (FOV) of a photolithography tool during a photolithography process. The CDU map is stored in one or more memory devices and/or displayed on a display device, for example, of the inspection tool or a photolithography system.

Critical dimension uniformity monitoring for extreme ultra-violet reticles

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Cupertino, CA, United States of America

Rui-Fang Shi