Patents by Inventor Robert Tyler Leonard
Robert Tyler Leonard 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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Publication number: 20220403552Abstract: Silicon carbide (SiC) crystalline materials and related methods are disclosed that provide SiC crystalline materials with reduced optical absorption. In certain aspects, SiC crystalline materials with reduced absorption coefficients for wavelengths of light within the visible spectrum are disclosed. Various peaks in absorption over a wavelength spectrum may be reduced in SiC crystalline materials to improve overall absorption coefficient uniformity across the visible spectrum. By providing such improvements in absorption coefficients for SiC crystalline materials, reduced reflection and transmission losses of light in corresponding devices may be realized. Related methods are disclosed that include various combinations of crystalline growth, with and without various post-growth thermal conditioning steps.Type: ApplicationFiled: June 17, 2021Publication date: December 22, 2022Inventors: Robert Tyler Leonard, Elif Balkas, Valeri F. Tsvetkov, Yuri Khlebnikov, Kathryn A. O'Hara, Simon Bubel, David P. Malta
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Publication number: 20220189768Abstract: Silicon carbide (SiC) materials including SiC wafers and SiC boules and related methods are disclosed that provide large dimension SiC wafers with reduced crystallographic stress. Growth conditions for SiC materials include maintaining a generally convex growth surface of SiC crystals, adjusting differences in front-side to back-side thermal profiles of growing SiC crystals, supplying sufficient source flux to allow commercially viable growth rates for SiC crystals, and reducing the inclusion of contaminants or non-SiC particles in SiC source materials and corresponding SiC crystals. By forming larger dimension SiC crystals that exhibit lower crystallographic stress, overall dislocation densities that are associated with missing or additional planes of atoms may be reduced, thereby improving crystal quality and usable SiC crystal growth heights.Type: ApplicationFiled: December 15, 2020Publication date: June 16, 2022Inventors: Yuri Khlebnikov, Varad R. Sakhalkar, Caleb A. Kent, Valeri F. Tsvetkov, Michael J. Paisley, Oleksandr Kramarenko, Matthew David Conrad, Eugene Deyneka, Steven Griffiths, Simon Bubel, Adrian R. Powell, Robert Tyler Leonard, Elif Balkas, Curt Progl, Michael Fusco, Alexander Shveyd, Kathy Doverspike, Lukas Nattermann
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Patent number: 11361454Abstract: Wafer images and related alignment methods for crystalline wafers are disclosed. Certain aspects relate to accessing and aligning images of a same or similar crystalline wafer captured from different imaging sources. Alignment may include determining spatial differences between shared crystalline features in various wafer images of the same or similar crystalline wafer and transforming at least one of the images according to the determined spatial differences. With sufficient alignment, information may be associated and/or transferred between the various images, thereby providing the capability of forming a combined wafer image and sub-images thereof with high resolution and spatial coordination between different image sources. Certain aspects relate to development of nondestructive, high fidelity defect characterization and/or dislocation counting methods in crystalline materials based on modern deep convolutional neural networks (DCNN).Type: GrantFiled: February 28, 2020Date of Patent: June 14, 2022Assignee: WOLFSPEED, INC.Inventors: Robert Tyler Leonard, Matthew David Conrad, Edward Robert Van Brunt
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Publication number: 20210272298Abstract: Wafer images and related alignment methods for crystalline wafers are disclosed. Certain aspects relate to accessing and aligning images of a same or similar crystalline wafer captured from different imaging sources. Alignment may include determining spatial differences between shared crystalline features in various wafer images of the same or similar crystalline wafer and transforming at least one of the images according to the determined spatial differences. With sufficient alignment, information may be associated and/or transferred between the various images, thereby providing the capability of forming a combined wafer image and sub-images thereof with high resolution and spatial coordination between different image sources. Certain aspects relate to development of nondestructive, high fidelity defect characterization and/or dislocation counting methods in crystalline materials based on modern deep convolutional neural networks (DCNN).Type: ApplicationFiled: February 28, 2020Publication date: September 2, 2021Inventors: Robert Tyler Leonard, Matthew David Conrad, Edward Robert Van Brunt
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Publication number: 20210198804Abstract: Silicon carbide (SiC) wafers and related methods are disclosed that include large diameter SiC wafers with wafer shape characteristics suitable for semiconductor manufacturing. Large diameter SiC wafers are disclosed that have reduced deformation related to stress and strain effects associated with forming such SiC wafers. As described herein, wafer shape and flatness characteristics may be improved by reducing crystallographic stress profiles during growth of SiC crystal boules or ingots. Wafer shape and flatness characteristics may also be improved after individual SiC wafers have been separated from corresponding SiC crystal boules. In this regard, SiC wafers and related methods are disclosed that include large diameter SiC wafers with suitable crystal quality and wafer shape characteristics including low values for wafer bow, warp, and thickness variation.Type: ApplicationFiled: December 17, 2020Publication date: July 1, 2021Inventors: Yuri Khlebnikov, Varad R. Sakhalkar, Caleb A. Kent, Valeri F. Tsvetkov, Michael J. Paisley, Oleksandr Kramarenko, Matthew David Conrad, Eugene Deyneka, Steven Griffiths, Simon Bubel, Adrian R. Powell, Robert Tyler Leonard, Elif Balkas, Jeffrey C. Seaman
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Publication number: 20200365685Abstract: Nondestructive characterization of crystalline wafers is provided, including defect detection, identification, and counting. Certain aspects relate to development of nondestructive, high fidelity defect characterization and/or dislocation counting methods based on deep neural networks. Certain aspects relate to nondestructive methods for defect characterization of silicon carbide (SiC) wafers. By subjecting SiC wafers to nondestructive defect characterization, SiC wafers in their final state may be characterized and subsequently used for device fabrication, vastly reducing the expense of the characterization process. Nondestructive defect characterization also allows for increased sampling and improved feedback loops between crystalline growth process development and subsequent device production.Type: ApplicationFiled: January 23, 2020Publication date: November 19, 2020Inventors: Robert Tyler Leonard, Matthew David Conrad, Edward Robert Van Brunt
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Patent number: 9790619Abstract: A method is disclosed for producing a high quality bulk single crystal of silicon carbide in a seeded growth system by reducing the separation between a silicon carbide seed crystal and a seed holder until the conductive heat transfer between the seed crystal and the seed holder dominates the radiative heat transfer between the seed crystal and the seed holder over substantially the entire seed crystal surface that is adjacent the seed holder.Type: GrantFiled: July 12, 2011Date of Patent: October 17, 2017Assignee: Cree, Inc.Inventors: Robert Tyler Leonard, Adrian Powell, Valeri F. Tsvetkov
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Patent number: 9200381Abstract: A method is disclosed for producing a high quality bulk single crystal of silicon carbide in a seeded growth system by reducing the separation between a silicon carbide seed crystal and a seed holder until the conductive heat transfer between the seed crystal and the seed holder dominates the radiative heat transfer between the seed crystal and the seed holder over substantially the entire seed crystal surface that is adjacent the seed holder.Type: GrantFiled: October 12, 2005Date of Patent: December 1, 2015Assignee: Cree, Inc.Inventors: Robert Tyler Leonard, Adrian Powell, Valeri F. Tsvetkov
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Patent number: 9048166Abstract: A method for controlled growth of silicon carbide and structures produced by the method are disclosed. A crystal of silicon carbide (SiC) can be grown by placing a sacrificial substrate in a growth zone with a source material. The source material may include a low-solubility impurity. SiC is then grown on the sacrificial substrate to condition the source material. The sacrificial substrate is then replaced with the final substrate, and SiC is grown on the final substrate. A single crystal of silicon carbide is produced, wherein the crystal of silicon carbide has substantially few micropipe defects. Such a crystal may also include a substantially uniform concentration of the low-solubility impurity, and may be used to make wafers and/or SiC die.Type: GrantFiled: February 19, 2013Date of Patent: June 2, 2015Assignee: Cree, Inc.Inventors: Robert Tyler Leonard, Hudson M. Hobgood, William A. Thore
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Patent number: 8866159Abstract: A high quality single crystal wafer of SiC is disclosed having a diameter of at least about 100 mm and a micropipe density of less than about 25 cm?2.Type: GrantFiled: November 22, 2013Date of Patent: October 21, 2014Assignee: Cree, Inc.Inventors: Adrian Powell, Mark Brady, Robert Tyler Leonard
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Publication number: 20140291698Abstract: A high quality single crystal wafer of SiC is disclosed having a diameter of at least about 100 mm and a micropipe density of less than about 25 cm?2.Type: ApplicationFiled: November 22, 2013Publication date: October 2, 2014Applicant: Cree, Inc.Inventors: Adrian Powell, Mark Brady, Robert Tyler Leonard
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Patent number: 8618552Abstract: A high quality single crystal wafer of SiC is disclosed having a diameter of at least about 100 mm and a micropipe density of less than about 25 cm?2.Type: GrantFiled: November 15, 2007Date of Patent: December 31, 2013Assignee: Cree, Inc.Inventors: Adrian Powell, Mark Brady, Robert Tyler Leonard
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Patent number: 8377806Abstract: A method for controlled growth of silicon carbide and structures produced by the method are disclosed. A crystal of silicon carbide (SiC) can be grown by placing a sacrificial substrate in a growth zone with a source material. The source material may include a low-solubility impurity. SiC is then grown on the sacrificial substrate to condition the source material. The sacrificial substrate is then replaced with the final substrate, and SiC is grown on the final substrate. A single crystal of silicon carbide is produced, wherein the crystal of silicon carbide has substantially few micropipe defects. Such a crystal may also include a substantially uniform concentration of the low-solubility impurity, and may be used to make wafers and/or SiC die.Type: GrantFiled: April 28, 2010Date of Patent: February 19, 2013Assignee: Cree, Inc.Inventors: Robert Tyler Leonard, Hudson M. Hobgood, William A. Thore
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Patent number: 8147991Abstract: A method is disclosed for producing a high quality bulk single crystal of silicon carbide in a seeded growth system by reducing the separation between a silicon carbide seed crystal and a seed holder until the conductive heat transfer between the seed crystal and the seed holder dominates the radiative heat transfer between the seed crystal and the seed holder over substantially the entire seed crystal surface that is adjacent the seed holder.Type: GrantFiled: May 3, 2010Date of Patent: April 3, 2012Assignee: Cree, Inc.Inventors: Jason Ronald Jenny, David Phillip Malta, Hudson McDonald Hobgood, Stephan Georg Mueller, Mark Brady, Robert Tyler Leonard, Adrian Powell, Valeri F. Tsvetkov
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Publication number: 20110290174Abstract: A method is disclosed for producing a high quality bulk single crystal of silicon carbide in a seeded growth system by reducing the separation between a silicon carbide seed crystal and a seed holder until the conductive heat transfer between the seed crystal and the seed holder dominates the radiative heat transfer between the seed crystal and the seed holder over substantially the entire seed crystal surface that is adjacent the seed holder.Type: ApplicationFiled: July 12, 2011Publication date: December 1, 2011Applicant: NAVY, SECRETARY OF THE, UNITED STATES OF AMERICAInventors: Robert Tyler Leonard, Adrian Powell, Valeri F. Tsvetkov
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Publication number: 20110266556Abstract: A method for controlled growth of silicon carbide and structures produced by the method are disclosed. A crystal of silicon carbide (SiC) can be grown by placing a sacrificial substrate in a growth zone with a source material. The source material may include a low-solubility impurity. SiC is then grown on the sacrificial substrate to condition the source material. The sacrificial substrate is then replaced with the final substrate, and SiC is grown on the final substrate. A single crystal of silicon carbide is produced, wherein the crystal of silicon carbide has substantially few micropipe defects. Such a crystal may also include a substantially uniform concentration of the low-solubility impurity, and may be used to make wafers and/or SiC die.Type: ApplicationFiled: April 28, 2010Publication date: November 3, 2011Applicant: Cree, Inc.Inventors: Robert Tyler Leonard, Hudson M. Hobgood, William A. Thore
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Publication number: 20110024766Abstract: A method is disclosed for producing a high quality bulk single crystal of silicon carbide in a seeded growth system by reducing the separation between a silicon carbide seed crystal and a seed holder until the conductive heat transfer between the seed crystal and the seed holder dominates the radiative heat transfer between the seed crystal and the seed holder over substantially the entire seed crystal surface that is adjacent the seed holder.Type: ApplicationFiled: May 3, 2010Publication date: February 3, 2011Applicant: Cree, Inc.Inventors: Jason Ronald Jenny, David Phillip Malta, Hudson McDonald Hobgood, Stephan Georg Mueller, Mark Brady, Robert Tyler Leonard, Adrian Powell, Valeri F. Tsvetkov
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Patent number: 7601441Abstract: A single polytype single crystal silicon carbide wafer is disclosed having a diameter greater than three inches and less than five inches, resistivity greater than 10,000 ohm-cm, a micropipe density less than 200 cm?2, and a combined concentration of shallow level dopants less than 5E16 cm?3.Type: GrantFiled: June 25, 2004Date of Patent: October 13, 2009Assignee: Cree, Inc.Inventors: Jason Ronald Jenny, David Phillip Malta, Hudson McDonald Hobgood, Stephan Georg Mueller, Mark Brady, Robert Tyler Leonard, Adrian Powell, Valerl F. Tsvetkov
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Publication number: 20080237609Abstract: A high quality single crystal wafer of SiC is disclosed having a diameter of at least about 100 mm and a micropipe density of less than about 25 cm?2.Type: ApplicationFiled: November 15, 2007Publication date: October 2, 2008Applicant: CREE, INC.Inventors: Adrian Powell, Mark Brady, Robert Tyler Leonard
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Patent number: 7422634Abstract: A high quality single crystal wafer of SiC is disclosed. The wafer has a diameter of at least about 3 inches, a warp of less than about 5 ?m, a bow less than about 5 ?m, and a total thickness variation of less than about 2.0 ?m.Type: GrantFiled: April 7, 2005Date of Patent: September 9, 2008Assignee: Cree, Inc.Inventors: Adrian Powell, William H. Brixius, Robert Tyler Leonard, Davis Andrew McClure, Michael Laughner