Patents by Inventor David Y. Wang

David Y. Wang has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20250146893
    Abstract: A workpiece is measured using multiple-pass spectroscopic ellipsometry and multi-wavelength Raman spectroscopy, which may be performed in the same system. These measurements are combined to form combined measured data. A stress measurement of the workpiece is determined using the combined measured data. The stress measurement can be determined using a model or a machine learning algorithm.
    Type: Application
    Filed: November 4, 2024
    Publication date: May 8, 2025
    Inventors: Houssam Chouaib, Zhengquan Tan, Shova Subedi, Shankar Krishnan, David Y. Wang, Oleg Shulepov, Kevin Peterlinz, Natalia Malkova, Dawei Hu, Carlos Ygartua, Isvar Cordova, Eric Cheek, Roman Sappey, Anderson Chou
  • Publication number: 20240418635
    Abstract: Methods and systems for performing spectroscopic ellipsometry measurements of semiconductor structures with reflective collection relay optics having demagnification from the spectrometer slit to the detector are presented herein. The demagnification effectively increases the NA at the detector and reduces the measurement spot size at the wafer imaged onto the detector. In this manner, the demagnification maintains high spectral resolution at the detector, particularly in the ultraviolet wavelength range, e.g., 120-400 nanometers, while maintaining a small collection NA at the wafer, e.g., collection NA less than 0.05. The small collection NA enables high fringe contrast, signal fidelity, and sensitivity, when measuring thick, multiple layer stacks, e.g., 200-300 layers.
    Type: Application
    Filed: June 15, 2023
    Publication date: December 19, 2024
    Inventors: David Y. Wang, Shankar Krishnan
  • Patent number: 12164093
    Abstract: A Cassegrain or quasi-Cassegrain structure objective lens is used in a polar MOKE metrology system. The quasi-Cassegrain reflective objective lens includes a primary concave mirror and a secondary mirror. The primary concave mirror has a wider diameter than the secondary mirror and defines an aperture through which the laser beam is configured to be transmitted toward the secondary mirror. The secondary mirror can be convex, concave, or have a flat surface.
    Type: Grant
    Filed: October 19, 2021
    Date of Patent: December 10, 2024
    Inventors: Alex Zheng, Jun Wang, David Y. Wang, Chunxia Li, Changfei Yan, Rui Ni, Lansheng Dong, Yang Zhou, Hai-Yang You, Haijing Peng, Walter H. Johnson, Shankar Krishnan, Jianou Shi
  • Publication number: 20240353321
    Abstract: Methods and systems for combined Spectroscopic Reflectometry (SR) and Pattern Recognition (PR) based image measurements of semiconductor structures at high throughput are presented herein. Measurements of large pitch targets and thick targets through die with improved fringe contrast, resolution, and spectral fidelity are enabled. A PR based imaging subsystem generates illumination light ranging from visible to short infrared wavelengths. A SR subsystem generates illumination light ranging from the deep ultraviolet to short infrared wavelengths. The SR subsystem includes low Numerical Aperture (NA) optics to realize a relatively large size illumination and collection spot. Both the SR subsystem and the PR based imaging subsystem share the same objective and resolve signals from different depths of a structure under measurement. In some embodiments, a combined machine learning based measurement model estimates values of one or more parameters of interest based on both SR and PR image signals.
    Type: Application
    Filed: April 19, 2023
    Publication date: October 24, 2024
    Inventors: David Y. Wang, Shankar Krishnan
  • Publication number: 20240280484
    Abstract: The system includes a light source configured to emit light at one or more wavelengths, one or more angles of incidence (AOI), and one or more azimuths; a polarization assembly configured to produce one or more polarization states of the light; a main objective configured to focus the light in the one or more polarization states onto a target that reflects the light; an analyzer assembly configured to analyze one or more polarization states of the light reflected from the target; a detector configured to detect the light reflected from the target and generate an output signal based on the detected light; and a processor configured to generate a measurement of the target based on the output signal produced at the one or more polarization states, the one or more wavelengths, the one or more AOIs, and the one or more azimuths.
    Type: Application
    Filed: September 14, 2023
    Publication date: August 22, 2024
    Inventors: David Y. Wang, Kevin Peterlinz
  • Patent number: 12013355
    Abstract: Methods and systems for performing measurements of semiconductor structures based on high-brightness, Soft X-Ray (SXR) illumination over a small illumination spot size with a small physical footprint are presented herein. In one aspect, the focusing optics of an SXR based metrology system project an image of the illumination source onto a specimen under measurement with a demagnification of at least 1.25. In a further aspect, an illumination beam path from the x-ray illumination source to the specimen under measurement is less than 2 meters. In another aspect, SXR based measurements are performed with x-ray radiation in the soft x-ray region (i.e., 80-3000 eV). In some embodiments, SXR based measurements are performed at grazing angles of incidence in a range from near zero degrees to 90 degrees. In some embodiments, the illumination optics project an image of an illumination source onto a specimen under measurement with a demagnification of 50, or less.
    Type: Grant
    Filed: August 24, 2021
    Date of Patent: June 18, 2024
    Assignee: KLA Corporation
    Inventors: David Y. Wang, Kerstin Purrucker, Michael Friedmann
  • Patent number: 11913874
    Abstract: The system includes a modulatable illumination source configured to illuminate a surface of a sample disposed on a sample stage, a detector configured to detect illumination emanating from a surface of the sample, illumination optics configured to direct illumination from the modulatable illumination source to the surface of the sample, collection optics configured to direct illumination from the surface of the sample to the detector, and a modulation control system communicatively coupled to the modulatable illumination source, wherein the modulation control system is configured to modulate a drive current of the modulatable illumination source at a selected modulation frequency suitable for generating illumination having a selected coherence feature length. In addition, the present invention includes the time-sequential interleaving of outputs of multiple light sources to generate periodic pulse trains for use in multi-wavelength time-sequential optical metrology.
    Type: Grant
    Filed: April 5, 2021
    Date of Patent: February 27, 2024
    Assignee: KLA Corporation
    Inventors: Andrei V. Shchegrov, Lawrence D. Rotter, David Y. Wang, Andrei Veldman, Kevin Peterlinz, Gregory Brady, Derrick A. Shaughnessy
  • Patent number: 11906770
    Abstract: A monolithic optical retarder formed from a monolithic prism may include an input face for receiving a light beam, an output face aligned with an optical axis of the light beam prior to entering the input face, and three or more reflection faces. The three or more reflection faces may be oriented to provide an optical path for the light beam from the input face to the output face via reflection by the three or more reflection faces, where the monolithic optical retarder imparts a selected optical retardation on the light beam based on total internal reflection on at least one of the reflection faces. Further, the input face, the output face, and the three or more reflection faces may be oriented such that an optical axis of the light beam exiting the output face is equal to the optical axis of the light beam entering the input face.
    Type: Grant
    Filed: December 2, 2021
    Date of Patent: February 20, 2024
    Assignee: KLA Corporal
    Inventors: Shankar Krishnan, David Y. Wang
  • Publication number: 20230341337
    Abstract: The system includes a light source configured to emit light along an illumination path; a projection optical assembly disposed in the illumination path; a target disposed in the illumination path and configured to reflect the light along a collection path; a collection optical assembly disposed in the collection path; a detector disposed in the collection path and configured to detect the light reflected from the target and generate an output signal based on the detected light; and a processor in electronic communication with the detector and configured to generate a measurement of the target based on the output signal. The projection optical assembly defines a first numerical aperture at the target and the collection optical assembly defines a second numerical aperture at the target, and the first numerical aperture is slightly larger than the second numerical aperture for measurements of thick films and high aspect ratio structures.
    Type: Application
    Filed: March 16, 2023
    Publication date: October 26, 2023
    Inventors: David Y. Wang, Shankar Krishnan
  • Publication number: 20230131913
    Abstract: A monolithic optical retarder formed from a monolithic prism may include an input face for receiving a light beam, an output face aligned with an optical axis of the light beam prior to entering the input face, and three or more reflection faces. The three or more reflection faces may be oriented to provide an optical path for the light beam from the input face to the output face via reflection by the three or more reflection faces, where the monolithic optical retarder imparts a selected optical retardation on the light beam based on total internal reflection on at least one of the reflection faces. Further, the input face, the output face, and the three or more reflection faces may be oriented such that an optical axis of the light beam exiting the output face is equal to the optical axis of the light beam entering the input face.
    Type: Application
    Filed: December 2, 2021
    Publication date: April 27, 2023
    Inventors: Shankar Krishnan, David Y. Wang
  • Publication number: 20220196576
    Abstract: Methods and systems for performing measurements of semiconductor structures based on high-brightness, Soft X-Ray (SXR) illumination over a small illumination spot size with a small physical footprint are presented herein. In one aspect, the focusing optics of an SXR based metrology system project an image of the illumination source onto a specimen under measurement with a demagnification of at least 1.25. In a further aspect, an illumination beam path from the x-ray illumination source to the specimen under measurement is less than 2 meters. In another aspect, SXR based measurements are performed with x-ray radiation in the soft x-ray region (i.e., 80-3000 eV). In some embodiments, SXR based measurements are performed at grazing angles of incidence in a range from near zero degrees to 90 degrees. In some embodiments, the illumination optics project an image of an illumination source onto a specimen under measurement with a demagnification of 50, or less.
    Type: Application
    Filed: August 24, 2021
    Publication date: June 23, 2022
    Inventors: David Y. Wang, Kerstin Purrucker, Michael Friedmann
  • Publication number: 20220137380
    Abstract: A Cassegrain or quasi-Cassegrain structure objective lens is used in a polar MOKE metrology system. The quasi-Cassegrain reflective objective lens includes a primary concave mirror and a secondary mirror. The primary concave mirror has a wider diameter than the secondary mirror and defines an aperture through which the laser beam is configured to be transmitted toward the secondary mirror. The secondary mirror can be convex, concave, or have a flat surface.
    Type: Application
    Filed: October 19, 2021
    Publication date: May 5, 2022
    Inventors: Alex ZHENG, Jun WANG, David Y. WANG, Chunxia LI, Changfei YAN, Rui NI, Lansheng DONG, Yang ZHOU, Hai-Yang YOU, Haijing PENG, Walter H. JOHNSON, Shankar KRISHNAN, Jianou SHI
  • Patent number: 11309202
    Abstract: A metrology system for characterizing a sample formed from a first wafer and a second wafer bonded at an interface with a metrology target near the interface may include a metrology tool and a controller. The metrology tool may include one or more illumination sources and an illumination sub-system to direct illumination from the one or more illumination sources to the metrology target, a detector, and a collection sub-system to collect light from the sample. The light collected from the sample may include light from the metrology target and light from a top surface of the first wafer, and the collection sub-system is may direct the light from the metrology target to the detector. The controller may execute program instructions causing the one or more processors to generate estimates of one or more parameters associated with the sample based on data received from the detector.
    Type: Grant
    Filed: September 22, 2020
    Date of Patent: April 19, 2022
    Assignee: KLA Corporation
    Inventors: Shankar Krishnan, David Y. Wang, Johannes D. de Veer
  • Patent number: 11231362
    Abstract: A system includes a light source, a Fourier transform infrared reflectometer (FTIR) spectrometer, and broadband reflectometer optics. The system is configured to measure polarized light and unpolarized reflectivities in a wavelength range from 2 ?m to 20 ?m. The light source can be a laser-driven light source. The spectroscopic reflectometer can include a single channel or two channels.
    Type: Grant
    Filed: December 20, 2019
    Date of Patent: January 25, 2022
    Assignee: KLA Corporation
    Inventors: Guorong V. Zhuang, Shankar Krishnan, David Y. Wang, Xuefeng Liu, Mengmeng Ye, Dawei Hu
  • Patent number: 11137350
    Abstract: Methods and systems for performing high throughput spectroscopic measurements of semiconductor structures at mid-infrared wavelengths are presented herein. A Fourier Transform Infrared (FTIR) spectrometer includes one or more measurement channels spanning a wavelength range between 2.5 micrometers and 12 micrometers. The FTIR spectrometer measures a target at multiple different angles of incidence, azimuth angles, different wavelength ranges, different polarization states, or any combination thereof. In some embodiments, illumination light is provided by a laser sustained plasma (LSP) light source to achieve high brightness and small illumination spot size. In some embodiments, FTIR measurements are performed off-axis from the direction normal to the surface of the wafer. In some embodiments, a Stirling cooler extracts heat from the detector of an FTIR spectrometer.
    Type: Grant
    Filed: January 13, 2020
    Date of Patent: October 5, 2021
    Assignee: KLA Corporation
    Inventors: David Y. Wang, Shankar Krishnan, Guorong V. Zhuang
  • Patent number: 11119050
    Abstract: Methods and systems for performing spectroscopic measurements of semiconductor structures including ultraviolet, visible, and infrared wavelengths greater than two micrometers are presented herein. A spectroscopic measurement system includes a combined illumination source including a first illumination source that generates ultraviolet, visible, and near infrared wavelengths (wavelengths less than two micrometers) and a second illumination source that generates mid infrared and long infrared wavelengths (wavelengths of two micrometers and greater). Furthermore, the spectroscopic measurement system includes one or more measurement channels spanning the range of illumination wavelengths employed to perform measurements of semiconductor structures. In some embodiments, the one or more measurement channels simultaneously measure the sample throughout the wavelength range. In some other embodiments, the one or more measurement channels sequentially measure the sample throughout the wavelength range.
    Type: Grant
    Filed: May 20, 2020
    Date of Patent: September 14, 2021
    Assignee: KLA Corporation
    Inventors: Noam Sapiens, Shankar Krishnan, David Y. Wang, Alexander Buettner, Kerstin Purrucker, Kevin A. Peterlinz
  • Publication number: 20210242060
    Abstract: A metrology system for characterizing a sample formed from a first wafer and a second wafer bonded at an interface with a metrology target near the interface may include a metrology tool and a controller. The metrology tool may include one or more illumination sources and an illumination sub-system to direct illumination from the one or more illumination sources to the metrology target, a detector, and a collection sub-system to collect light from the sample. The light collected from the sample may include light from the metrology target and light from a top surface of the first wafer, and the collection sub-system is may direct the light from the metrology target to the detector. The controller may execute program instructions causing the one or more processors to generate estimates of one or more parameters associated with the sample based on data received from the detector.
    Type: Application
    Filed: September 22, 2020
    Publication date: August 5, 2021
    Inventors: Shankar Krishnan, David Y. Wang, Johannes D. de Veer
  • Publication number: 20210223166
    Abstract: The system includes a modulatable illumination source configured to illuminate a surface of a sample disposed on a sample stage, a detector configured to detect illumination emanating from a surface of the sample, illumination optics configured to direct illumination from the modulatable illumination source to the surface of the sample, collection optics configured to direct illumination from the surface of the sample to the detector, and a modulation control system communicatively coupled to the modulatable illumination source, wherein the modulation control system is configured to modulate a drive current of the modulatable illumination source at a selected modulation frequency suitable for generating illumination having a selected coherence feature length. In addition, the present invention includes the time-sequential interleaving of outputs of multiple light sources to generate periodic pulse trains for use in multi-wavelength time-sequential optical metrology.
    Type: Application
    Filed: April 5, 2021
    Publication date: July 22, 2021
    Inventors: Andrei V. Shchegrov, Lawrence D. Rotter, David Y. Wang, Andrei Veldman, Kevin Peterlinz, Gregory Brady, Derrick A. Shaughnessy
  • Patent number: 11043239
    Abstract: A laser beam is directed through a transmissive axicon telescope or a reflective axicon telescope such as in a magneto-optic Kerr effect metrology system. With the transmissive axicon telescope, a Gaussian beam profile is directed through a first axicon lens and a second axicon lens. The first axicon lens and second axicon lens transfer the Gaussian beam profile of the laser beam to a hollowed laser ring. The laser beam with a hollowed laser ring can be directed through a Schwarzschild reflective objective. With the reflective axicon telescope, the laser beam is directed through two conical mirrors that are fully reflective. One of the conical mirrors defines a central hole that the laser beam passes through.
    Type: Grant
    Filed: March 17, 2020
    Date of Patent: June 22, 2021
    Assignee: KLA Corporation
    Inventors: Jun Wang, Yaolei Zheng, Chunxia Li, Changfei Yan, Lansheng Dong, Yang Zhou, Hai-Yang You, Haijing Peng, Jianou Shi, Rui Ni, Shankar Krishnan, David Y. Wang, Walter H. Johnson
  • Patent number: 10969328
    Abstract: The system includes a modulatable illumination source configured to illuminate a surface of a sample disposed on a sample stage, a detector configured to detect illumination emanating from a surface of the sample, illumination optics configured to direct illumination from the modulatable illumination source to the surface of the sample, collection optics configured to direct illumination from the surface of the sample to the detector, and a modulation control system communicatively coupled to the modulatable illumination source, wherein the modulation control system is configured to modulate a drive current of the modulatable illumination source at a selected modulation frequency suitable for generating illumination having a selected coherence feature length. In addition, the present invention includes the time-sequential interleaving of outputs of multiple light sources to generate periodic pulse trains for use in multi-wavelength time-sequential optical metrology.
    Type: Grant
    Filed: February 25, 2019
    Date of Patent: April 6, 2021
    Assignee: KLA Corporation
    Inventors: Andrei V. Shchegrov, Lawrence D. Rotter, David Y. Wang, Andrei Veldman, Kevin Peterlinz, Gregory Brady, Derrick A. Shaughnessy