Patents by Inventor Shankar Krishnan

Shankar Krishnan 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).

  • Patent number: 11077418
    Abstract: A solar thermochemical processing system is disclosed. The system includes a first unit operation for receiving concentrated solar energy. Heat from the solar energy is used to drive the first unit operation. The first unit operation also receives a first set of reactants and produces a first set of products. A second unit operation receives the first set of products from the first unit operation and produces a second set of products. A third unit operation receives heat from the second unit operation to produce a portion of the first set of reactants.
    Type: Grant
    Filed: April 10, 2018
    Date of Patent: August 3, 2021
    Assignee: Battelle Memorial Institute
    Inventors: Robert S. Wegeng, Paul H. Humble, Shankar Krishnan, Steven D. Leith, Daniel R. Palo, Robert A. Dagle
  • Patent number: 11056366
    Abstract: A metrology system may include one or more casings that fit within an interior cavity of a sample transport device, an illumination source within one of the one or more casings, one or more illumination optics within one of the one or more casings for directing illumination from the illumination source to a sample located in the interior cavity of the sample transport device, one or more collection optics within one of the one or more casings for light from the sample in response to the illumination from the illumination source, and one or more detectors within one of the one or more casings for generating metrology data based on at least a portion of the light collected by the one or more collection optics.
    Type: Grant
    Filed: February 20, 2019
    Date of Patent: July 6, 2021
    Assignee: KLA Corporation
    Inventors: Giampietro Bieli, Robert Tas, Kevin O'Brien, Shankar Krishnan, Joshua Butler
  • 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
  • Publication number: 20200302965
    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: Application
    Filed: March 17, 2020
    Publication date: September 24, 2020
    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, Barry Blasenheim
  • Publication number: 20200284733
    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: Application
    Filed: May 20, 2020
    Publication date: September 10, 2020
    Inventors: Noam Sapiens, Shankar Krishnan, David Y. Wang, Alexander Buettner, Kerstin Purrucker, Kevin A. Peterlinz
  • Publication number: 20200250515
    Abstract: Generally, the present disclosure is directed to systems and methods for improved optimization of machine-learned models. In particular, the present disclosure provides stochastic optimization algorithms that are both faster than widely used algorithms for fixed amounts of computation, and are also able to scale up substantially better as more computational resources become available. The stochastic optimization algorithms can be used with large batch sizes. As an example, in some implementations, the systems and methods of the present disclosure can implicitly compute the inverse hessian of each mini-batch of training data to produce descent directions.
    Type: Application
    Filed: July 6, 2018
    Publication date: August 6, 2020
    Inventors: Ryan Rifkin, Ying Xiao, Shankar Krishnan
  • Publication number: 20200240907
    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: Application
    Filed: January 13, 2020
    Publication date: July 30, 2020
    Inventors: David Y. Wang, Shankar Krishnan, Guorong V. Zhuang
  • Publication number: 20200232909
    Abstract: A metrology system may receive a model for measuring one or more selected attributes of a target including features distributed in a selected pattern based on regression of spectroscopic scatterometry data from a scatterometry tool for a range of wavelengths. The metrology system may further generate a weighting function for the model to de-emphasize portions of the spectroscopic scatterometry data associated with wavelengths at which light captured by the scatterometry tool when measuring the target is predicted to include undesired diffraction orders. The metrology system may further direct the spectroscopic scatterometry tool to generate scatterometry data of one or more measurement targets including fabricated features distributed in the selected pattern. The metrology system may further measure the selected attributes for the one or more measurement targets based on regression of the scatterometry data of the one or more measurement targets to the model weighted by the weighting function.
    Type: Application
    Filed: February 26, 2019
    Publication date: July 23, 2020
    Inventors: Phillip Atkins, Liequan Lee, Shankar Krishnan, David C.S. Wu, Emily Chiu
  • Patent number: 10690602
    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: February 14, 2018
    Date of Patent: June 23, 2020
    Assignee: KLA-Tencor Corporation
    Inventors: Noam Sapiens, Shankar Krishnan, David Y. Wang, Alexander Buettner, Kerstin Purrucker, Kevin A. Peterlinz
  • Patent number: 10612980
    Abstract: An apparatus is provided which comprises: a first circuitry to receive a measurement of a first temperature of a section of a computing device during a first loading condition of the computing device, and to receive a measurement of a second temperature of the section of the computing device during a second loading condition of the computing device; and a second circuitry to detect a potential fault in a cooling system to cool the computing device, based at least in part on the first temperature and the second temperature.
    Type: Grant
    Filed: June 21, 2017
    Date of Patent: April 7, 2020
    Assignee: Intel Corporation
    Inventors: Janusz P. Jurski, Tozer J. Bandorawalla, Ramkumar Nagappan, Mariusz Oriol, Piotr Sawicki, Robin A. Steinbrecher, Shankar Krishnan
  • Patent number: 10612916
    Abstract: Methods and systems for evaluating the performance of multiple patterning processes are presented. Patterned structures are measured and one or more parameter values characterizing geometric errors induced by the multiple patterning process are determined. In some examples, a single patterned target and a multiple patterned target are measured, the collected data fit to a combined measurement model, and the value of a structural parameter indicative of a geometric error induced by the multiple patterning process is determined based on the fit. In some other examples, light having a diffraction order different from zero is collected and analyzed to determine the value of a structural parameter that is indicative of a geometric error induced by a multiple patterning process. In some embodiments, a single diffraction order different from zero is collected. In some examples, a metrology target is designed to enhance light diffracted at an order different from zero.
    Type: Grant
    Filed: October 15, 2017
    Date of Patent: April 7, 2020
    Assignee: KLA-Tencor Corporation
    Inventors: Andrei V. Shchegrov, Shankar Krishnan, Kevin Peterlinz, Thaddeus Gerard Dziura, Noam Sapiens, Stilian Ivanov Pandev
  • Patent number: 10605722
    Abstract: Methods and systems for matching measurement spectra across one or more optical metrology systems are presented. The values of one or more system parameters used to determine the spectral response of a specimen to a measurement performed by a target metrology system are optimized. The system parameter values are optimized such that differences between measurement spectra generated by a reference system and the target system are minimized for measurements of the same metrology targets. Methods and systems for matching spectral errors across one or more optical metrology systems are also presented. A trusted metrology system measures the value of at least one specimen parameter to minimize model errors introduced by differing measurement conditions present at the time of measurement by the reference and target metrology systems. Methods and systems for parameter optimization based on low-order response surfaces are presented to reduce the compute time required to refine system calibration parameters.
    Type: Grant
    Filed: December 8, 2017
    Date of Patent: March 31, 2020
    Assignee: KLA-Tencor Corporation
    Inventors: Hidong Kwak, John Lesoine, Malik Sadiq, Lanhua Wei, Shankar Krishnan, Leonid Poslavsky, Mikhail M. Sushchik
  • Patent number: 10551166
    Abstract: Apparatus and methods for performing optically based film thickness measurements of highly absorbing films (e.g., high-K dielectric films) with improved measurement sensitivity are described herein. A highly absorbing film layer is fabricated on top of a highly reflective film stack. The highly reflective film stack includes one or more nominally identical sets of multiple layers of different, optically contrasting materials. The highly reflective film stack gives rise to optical resonance in particular wavelength ranges. The high reflectance at the interface of the highly absorbing film layer and the highly reflective film stack increases measured light intensity and measurement sensitivity. The thickness and optical dispersion of the different material layers of the highly reflective film stack are selected to induce optical resonance in a desired wavelength range. The desired wavelength range is selected to minimize absorption by the highly absorbing film under measurement.
    Type: Grant
    Filed: October 2, 2018
    Date of Patent: February 4, 2020
    Assignee: KLA-Tencor Corporation
    Inventors: Carlos L. Ygartua, Shankar Krishnan
  • Patent number: 10438825
    Abstract: Methods and systems for performing in-situ, selective spectral reflectometry (SSR) measurements of semiconductor structures disposed on a wafer are presented herein. Illumination light reflected from a wafer surface is spatially imaged. Signals from selected regions of the image are collected and spectrally analyzed, while other portions of the image are discarded. In some embodiments, a SSR includes a dynamic mirror array (DMA) disposed in the optical path at or near a field plane conjugate to the surface of the semiconductor wafer under measurement. The DMA selectively blocks the undesired portion of wafer image. In other embodiments, a SSR includes a hyperspectral imaging system including a plurality of spectrometers each configured to collect light from a spatially distinct area of a field image conjugate to the wafer surface. Selected spectral signals associated with desired regions of the wafer image are selected for analysis.
    Type: Grant
    Filed: August 28, 2017
    Date of Patent: October 8, 2019
    Assignee: KLA-Tencor Corporation
    Inventors: Prateek Jain, Daniel Wack, Kevin A. Peterlinz, Andrei V. Shchegrov, Shankar Krishnan
  • Publication number: 20190295874
    Abstract: A metrology system may include one or more casings that fit within an interior cavity of a sample transport device, an illumination source within one of the one or more casings, one or more illumination optics within one of the one or more casings for directing illumination from the illumination source to a sample located in the interior cavity of the sample transport device, one or more collection optics within one of the one or more casings for light from the sample in response to the illumination from the illumination source, and one or more detectors within one of the one or more casings for generating metrology data based on at least a portion of the light collected by the one or more collection optics.
    Type: Application
    Filed: February 20, 2019
    Publication date: September 26, 2019
    Inventors: Giampietro Bieli, Robert Tas, Kevin O'Brien, Shankar Krishnan, Joshua Butler
  • Patent number: 10402941
    Abstract: A method of increasing resolution of an image includes generating vector contours associated with a first image and scaling the vector contours to a second resolution. The first image has a first resolution, and the second resolution is greater than the first resolution. The vector contours are rendered to generate a guiding image at the second resolution, and a second image is generated from the first image based on the guiding image, by using joint upsampling. The second image is generated at the second resolution. The vector contours can be generated by bitmap tracing binary images at different quantization levels. An apparatus and computer readable device implementing the method of increasing the resolution of an image are also provided.
    Type: Grant
    Filed: July 20, 2017
    Date of Patent: September 3, 2019
    Assignee: AT&T INTELLECTUAL PROPERTY I, L.P.
    Inventors: Shankar Krishnan, James Klosowski
  • Patent number: 10281263
    Abstract: Methods and systems for performing optical measurements of geometric structures filled with an adsorbate by a gaseous adsorption process are presented herein. Measurements are performed while the metrology target under measurement is treated with a flow of purge gas that includes a controlled amount of fill material. A portion of the fill material adsorbs onto the structures under measurement and fills openings in the structural features, spaces between structural features, small volumes such as notches, trenches, slits, contact holes, etc. In one aspect, the desired degree of saturation of vaporized material in the gaseous flow is determined based on the maximum feature size to be filled. In one aspect, measurement data is collected when a structure is unfilled and when the structure is filled by gaseous adsorption. The collected data is combined in a multi-target model based measurement to reduce parameter correlations and improve measurement performance.
    Type: Grant
    Filed: July 7, 2016
    Date of Patent: May 7, 2019
    Assignee: KLA-Tencor Corporation
    Inventor: Shankar Krishnan
  • Publication number: 20190107384
    Abstract: Apparatus and methods for performing optically based film thickness measurements of highly absorbing films (e.g., high-K dielectric films) with improved measurement sensitivity are described herein. A highly absorbing film layer is fabricated on top of a highly reflective film stack. The highly reflective film stack includes one or more nominally identical sets of multiple layers of different, optically contrasting materials. The highly reflective film stack gives rise to optical resonance in particular wavelength ranges. The high reflectance at the interface of the highly absorbing film layer and the highly reflective film stack increases measured light intensity and measurement sensitivity. The thickness and optical dispersion of the different material layers of the highly reflective film stack are selected to induce optical resonance in a desired wavelength range. The desired wavelength range is selected to minimize absorption by the highly absorbing film under measurement.
    Type: Application
    Filed: October 2, 2018
    Publication date: April 11, 2019
    Inventors: Carlos L. Ygartua, Shankar Krishnan
  • Patent number: 10215693
    Abstract: Methods and systems for performing spectroscopic reflectometry measurements of semiconductor structures at infrared wavelengths are presented herein. In some embodiments measurement wavelengths spanning a range from 750 nanometers to 2,600 nanometers, or greater, are employed. In one aspect, reflectometry measurements are performed at oblique angles to reduce the influence of backside reflections on measurement results. In another aspect, a broad range of infrared wavelengths are detected by a detector that includes multiple photosensitive areas having different sensitivity characteristics. Collected light is linearly dispersed across the surface of the detector according to wavelength. Each different photosensitive area is arranged on the detector to sense a different range of incident wavelengths. In this manner, a broad range of wavelengths are detected with high signal to noise ratio by a single detector.
    Type: Grant
    Filed: December 18, 2016
    Date of Patent: February 26, 2019
    Assignee: KLA-Tencor Corporation
    Inventors: Shankar Krishnan, David Y. Wang
  • Publication number: 20180372551
    Abstract: An apparatus is provided which comprises: a first circuitry to receive a measurement of a first temperature of a section of a computing device during a first loading condition of the computing device, and to receive a measurement of a second temperature of the section of the computing device during a second loading condition of the computing device; and a second circuitry to detect a potential fault in a cooling system to cool the computing device, based at least in part on the first temperature and the second temperature.
    Type: Application
    Filed: June 21, 2017
    Publication date: December 27, 2018
    Inventors: Janusz P. Jurski, Tozer J. Bandorawalla, Ramkumar Nagappan, Mariusz Oriol, Piotr Sawicki, Robin A. Steinbrecher, Shankar Krishnan