Patents by Inventor Avijit K. Ray-Chaudhuri
Avijit K. Ray-Chaudhuri 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).
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Patent number: 10127652Abstract: Systems and methods for classifying defects detected on a wafer are provided. One method includes detecting defects on a wafer based on output generated for the wafer by an inspection system. The method also includes determining one or more attributes for at least one of the defects based on portions of a standard reference image corresponding to the at least one of the defects. The method further includes classifying the at least one of the defects based at least in part on the one or more determined attributes.Type: GrantFiled: February 2, 2015Date of Patent: November 13, 2018Assignee: KLA-Tencor Corp.Inventors: Lisheng Gao, Avijit K. Ray-Chaudhuri, Raghav Babulnath, Kenong Wu
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Publication number: 20150221076Abstract: Systems and methods for classifying defects detected on a wafer are provided. One method includes detecting defects on a wafer based on output generated for the wafer by an inspection system. The method also includes determining one or more attributes for at least one of the defects based on portions of a standard reference image corresponding to the at least one of the defects. The method further includes classifying the at least one of the defects based at least in part on the one or more determined attributes.Type: ApplicationFiled: February 2, 2015Publication date: August 6, 2015Inventors: Lisheng Gao, Avijit K. Ray-Chaudhuri, Raghav Babulnath, Kenong Wu
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Patent number: 7345754Abstract: Fourier filters and wafer inspection systems are provided. One embodiment relates to a one-dimensional Fourier filter configured to be included in a bright field inspection system such that the bright field inspection system can be used for broadband dark field inspection of a wafer. The Fourier filter includes an asymmetric illumination aperture configured to be positioned in an illumination path of the inspection system. The Fourier filter also includes an asymmetric imaging aperture complementary to the illumination aperture. The imaging aperture is configured to be positioned in a light collection path of the inspection system such that the imaging aperture blocks light reflected and diffracted from structures on the wafer and allows light scattered from defects on the wafer to pass through the imaging aperture.Type: GrantFiled: September 16, 2005Date of Patent: March 18, 2008Assignee: KLA-Tencor Technologies Corp.Inventors: Guoheng Zhao, Mehdi Vaez-Iravani, Andrew V. Hill, Avijit K. Ray-Chaudhuri
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Publication number: 20020190642Abstract: A device for monitoring radiation flux from a surface. The flux monitor is based on the photoelectric effect that occurs inherently when a reflective metal optic is exposed to a beam of energetic radiation. The incoming beam of energetic radiation is not totally reflected by the optic surface. That portion of the radiation absorbed by the optic generates photoelectrons producing a signal proportional to the incident radiation flux. By measuring this signal, an accurate determination of the radiation reflected by the optic surface can be made.Type: ApplicationFiled: June 19, 2001Publication date: December 19, 2002Inventors: Kurt W. Berger, Avijit K. Ray-Chaudhuri
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Patent number: 6441885Abstract: Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.Type: GrantFiled: July 10, 2001Date of Patent: August 27, 2002Assignee: EUV LLCInventors: Steven E. Gianoulakis, Avijit K. Ray-Chaudhuri
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Patent number: 6395455Abstract: Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.Type: GrantFiled: July 10, 2001Date of Patent: May 28, 2002Assignee: EUV LLCInventors: Steven E. Gianoulakis, Avijit K. Ray-Chaudhuri
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Publication number: 20020006556Abstract: Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.Type: ApplicationFiled: July 10, 2001Publication date: January 17, 2002Inventors: Steven E. Gianoulakis, Avijit K. Ray-Chaudhuri
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Publication number: 20020001760Abstract: Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.Type: ApplicationFiled: July 10, 2001Publication date: January 3, 2002Inventors: Steven E. Gianoulakis, Avijit K. Ray-Chaudhuri
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Patent number: 6316150Abstract: Thermal distortion of reticles or masks can be significantly reduced by emissivity engineering, i.e., the selective placement or omission of coatings on the reticle. Reflective reticles so fabricated exhibit enhanced heat transfer thereby reducing the level of thermal distortion and ultimately improving the quality of the transcription of the reticle pattern onto the wafer. Reflective reticles include a substrate having an active region that defines the mask pattern and non-active region(s) that are characterized by a surface that has a higher emissivity than that of the active region. The non-active regions are not coated with the radiation reflective material.Type: GrantFiled: August 24, 1998Date of Patent: November 13, 2001Assignee: EUV LLCInventors: Steven E. Gianoulakis, Avijit K. Ray-Chaudhuri
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Patent number: 6235434Abstract: A method for repair of amplitude and/or phase defects in lithographic masks. The method involves modifying or altering a portion of the absorber pattern on the surface of the mask blank proximate to the mask defect to compensate for the local disturbance (amplitude or phase) of the optical field due to the defect.Type: GrantFiled: December 8, 1998Date of Patent: May 22, 2001Assignee: EUV LLCInventors: Donald W. Sweeney, Avijit K. Ray-Chaudhuri
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Patent number: 6206528Abstract: A pedestal optical substrate that simultaneously provides high substrate dynamic stiffness, provides low surface figure sensitivity to mechanical mounting hardware inputs, and constrains surface figure changes caused by optical coatings to be primarily spherical in nature. The pedestal optical substrate includes a disk-like optic or substrate section having a top surface that is coated, a disk-like base section that provides location at which the substrate can be mounted, and a connecting cylindrical section between the base and optics or substrate sections. The optic section has an optical section thickness2/optical section diameter ratio of between about 5 to 10 mm, and a thickness variation between front and back surfaces of less than about 10%. The connecting cylindrical section may be attached via three spaced legs or members.Type: GrantFiled: September 30, 1998Date of Patent: March 27, 2001Assignee: EUV LLCInventors: Avijit K. Ray-Chaudhuri, Paul A. Spence, Michael P. Kanouff
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Patent number: 6198792Abstract: An EUVL device includes a wafer chamber that is separated from the upstream optics by a barrier having an aperture that is permeable to the inert gas. Maintaining an inert gas curtain in the proximity of a wafer positioned in a chamber of an extreme ultraviolet lithography device can effectively prevent contaminants from reaching the optics in an extreme ultraviolet photolithography device even though solid window filters are not employed between the source of reflected radiation, e.g., the camera, and the wafer. The inert gas removes the contaminants by entrainment.Type: GrantFiled: November 6, 1998Date of Patent: March 6, 2001Assignee: EUV LLCInventors: Michael P. Kanouff, Avijit K. Ray-Chaudhuri