Patents by Inventor Narayan Solayappan

Narayan Solayappan 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: 20100190288
    Abstract: Thin semiconductor foils can be formed using light reactive deposition. These foils can have an average thickness of less than 100 microns. In some embodiments, the semiconductor foils can have a large surface area, such as greater than about 900 square centimeters. The foil can be free standing or releasably held on one surface. The semiconductor foil can comprise elemental silicon, elemental germanium, silicon carbide, doped forms thereof, alloys thereof or mixtures thereof. The foils can be formed using a release layer that can release the foil after its deposition. The foils can be patterned, cut and processed in other ways for the formation of devices. Suitable devices that can be formed form the foils include, for example, photovoltaic modules and display control circuits.
    Type: Application
    Filed: March 31, 2010
    Publication date: July 29, 2010
    Inventors: Henry Hieslmair, Ronald J. Mosso, Robert B. Lynch, Shivkumar Chiruvolu, William E. McGovern, Craig R. Horne, Narayan Solayappan, Ronald M. Cornell
  • Publication number: 20090017292
    Abstract: Sub-atmospheric pressure chemical vapor deposition is described with a directed reactant flow and a substrate that moves relative to the flow. Thus, using this CVD configuration a relatively high deposition rate can be achieved while obtaining desired levels of coating uniformity. Deposition approaches are described to place one or more inorganic layers onto a release layer, such as a porous, particulate release layer. In some embodiments, the release layer is formed from a dispersion of submicron particles that are coated onto a substrate. The processes described can be effective for the formation of silicon films that can be separated with the use of a release layer into a silicon foil. The silicon foils can be used for the formation of a range of semiconductor based devices, such as display circuits or solar cells.
    Type: Application
    Filed: June 12, 2008
    Publication date: January 15, 2009
    Inventors: Henry Hieslmair, Ronald J. Mosso, Narayan Solayappan, Shivkumar Chiruvolu, Julio E. Morris
  • Patent number: 7459318
    Abstract: A three-dimensional (“3-D”) memory capacitor comprises a bottom electrode, a ferroelectric thin film, and a top electrode that conform to a 3-D surface of an insulator layer. The capacitance area is greater than the horizontal footprint area of the capacitor. Preferably, the footprint of the capacitor is less than 0.2 nm2, and the corresponding capacitance area is typically in a range of from 0.4 nm2 to 1.0 nm2 The ferroelectric thin film preferably has a thickness not exceeding 60 nm. A capacitor laminate including the bottom electrode, ferroelectric thin film, and the top electrode preferably has a thickness not exceeding 200 nm. A low-thermal-budget MOCVD method for depositing a ferroelectric thin film having a thickness in a range of from 30 nm to 90 nm includes an RTP treatment before depositing the top electrode and an RTP treatment after depositing the top electrode and etching the ferroelectric layer.
    Type: Grant
    Filed: April 26, 2006
    Date of Patent: December 2, 2008
    Assignee: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan, Vikram Joshi
  • Publication number: 20070212510
    Abstract: Thin semiconductor foils can be formed using light reactive deposition. These foils can have an average thickness of less than 100 microns. In some embodiments, the semiconductor foils can have a large surface area, such as greater than about 900 square centimeters. The foil can be free standing or releasably held on one surface. The semiconductor foil can comprise elemental silicon, elemental germanium, silicon carbide, doped forms thereof, alloys thereof or mixtures thereof. The foils can be formed using a release layer that can release the foil after its deposition. The foils can be patterned, cut and processed in other ways for the formation of devices. Suitable devices that can be formed form the foils include, for example, photovoltaic modules and display control circuits.
    Type: Application
    Filed: March 13, 2007
    Publication date: September 13, 2007
    Inventors: Henry Hieslmair, Ronald J. Mosso, Robert B. Lynch, Shivkumar Chiruvolu, William E. McGovern, Craig R. Horne, Narayan Solayappan, Ronald M. Cornell
  • Patent number: 7187079
    Abstract: A nonconductive hydrogen barrier layer is deposited on a substrate and completely covers the surface area over a memory capacitor and a MOSFET switch of an integrated circuit memory cell. A portion of an insulator layer adjacent to the bottom electrode of a memory capacitor is removed by etching to form a moat region. A nonconductive oxygen barrier layer is deposited to cover the sidewall and bottom of the moat. The nonconductive oxygen barrier layer and a conductive diffusion barrier beneath the capacitor together provide a substantially continuous diffusion barrier between the capacitor and a switch. Also, the nonconductive hydrogen barrier layer, the nonconductive oxygen barrier, and the conductive diffusion barrier substantially completely envelop the capacitor, in particular a ferroelectric thin film in the capacitor.
    Type: Grant
    Filed: September 19, 2003
    Date of Patent: March 6, 2007
    Assignee: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20060194348
    Abstract: A three-dimensional (“3-D”) memory capacitor comprises a bottom electrode, a ferroelectric thin film, and a top electrode that conform to a 3-D surface of an insulator layer. The capacitance area is greater than the horizontal footprint area of the capacitor. Preferably, the footprint of the capacitor is less than 0.2 nm2, and the corresponding capacitance area is typically in a range of from 0.4 nm2 to 1.0 nm2 The ferroelectric thin film preferably has a thickness not exceeding 60 nm. A capacitor laminate including the bottom electrode, ferroelectric thin film, and the top electrode preferably has a thickness not exceeding 200 nm. A low-thermal-budget MOCVD method for depositing a ferroelectric thin film having a thickness in a range of from 30 nm to 90 nm includes an RTP treatment before depositing the top electrode and an RTP treatment after depositing the top electrode and etching the ferroelectric layer.
    Type: Application
    Filed: April 26, 2006
    Publication date: August 31, 2006
    Applicant: Symetrix Corporation
    Inventors: Carlos Araujo, Larry McMillan, Narayan Solayappan, Vikram Joshi
  • Patent number: 7075134
    Abstract: A three-dimensional (“3-D”) memory capacitor comprises a bottom electrode, a ferroelectric thin film, and a top electrode that conform to a 3-D surface of an insulator layer. The capacitance area is greater than the horizontal footprint area of the capacitor. Preferably, the footprint of the capacitor is less than 0.2 nm2, and the corresponding capacitance area is typically in a range of from 0.4 nm2 to 1.0 nm2 The ferroelectric thin film preferably has a thickness not exceeding 60 nm. A capacitor laminate including the bottom electrode, ferroelectric thin film, and the top electrode preferably has a thickness not exceeding 200 nm. A low-thermal-budget MOCVD method for depositing a ferroelectric thin film having a thickness in a range of from 30 nm to 90 nm includes an RTP treatment before depositing the top electrode and an RTP treatment after depositing the top electrode and etching the ferroelectric layer.
    Type: Grant
    Filed: July 24, 2003
    Date of Patent: July 11, 2006
    Assignee: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan, Vikram Joshi
  • Patent number: 7064374
    Abstract: A hydrogen diffusion barrier in an integrated circuit is located to inhibit diffusion of hydrogen to a thin film of a metal oxide, such as a ferroelectric layered superlattice material, in an integrated circuit. The hydrogen diffusion barrier comprises at least one of the following chemical compounds: strontium tantalate, bismuth tantalate, tantalum oxide, titanium oxide, zirconium oxide and aluminum oxide. The hydrogen barrier layer is amorphous and is made by a MOCVD process at a temperature of 450° C. or less. A supplemental hydrogen barrier layer comprising a material selected from the group consisting of silicon nitride and a crystalline form of one of said hydrogen barrier layer materials is formed adjacent to said hydrogen diffusion barrier.
    Type: Grant
    Filed: June 21, 2004
    Date of Patent: June 20, 2006
    Assignee: Symetrix Corporation
    Inventors: Narayan Solayappan, Jolanta Celinska, Vikram Joshi, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20050094457
    Abstract: A ferroelectric memory includes a group of memory cells, each cell having a ferroelectric memory element, a drive line on which a voltage for writing information to the group of memory cells is placed, and a bit line on which information to be read out of the group of memory cells is placed. The memory is read by placing a voltage less than the coercive voltage of the ferroelectric memory element across a memory element. A preamplifier is connected between the memory cells and the bit line. A set switch is connected between the drive line and the memory cells, and a reset switch is connected to the memory cells in parallel with the preamplifier. Prior to reading, noise from the group of cells is discharged by grounding both electrodes of the ferroelectric memory element.
    Type: Application
    Filed: April 28, 2003
    Publication date: May 5, 2005
    Applicant: Symetrix Corporation
    Inventors: Zheng Chen, Vikram Joshi, Narayan Solayappan, Carlos Paz de Araujo, Larry McMillan
  • Patent number: 6867452
    Abstract: A high dielectric constant insulator including a thin film of a metal oxide selected from the group consisting of tungsten-bronze-type oxides, pyrochlore-type oxides, and combinations of Bi2O3 with an oxide selected from the group consisting of perovskites and pyrochlore-type oxides. An embodiment contains metal oxides represented by the general stoichiometric formulas AB2O6, A2B2O7 and A2Bi2B2O10, wherein A represents A-site atoms selected from the group of metals consisting of Ba, Bi, Sr, Pb, Ca, K, Na and La; and B represents B-site atoms selected from the group of metals consisting of Ti, Zr, Ta, Hf, Mo, W and Nb. Preferably, the metal oxides are (BaxSr1?x)(TayNb1?y)2O6, where 0?y?1.0 and 0?y?1.0; (BaxSr1?x)2(TayNb1?y)2O7, where 0?x?1.0 and 0?y?1.0; and (BaxSr1?x)2Bi2(TayNb1?y)2O10, where 0?x?1.0 and 0?y?1.0. Thin films according to the invention have a relative dielectric constant ?40, and preferably about 100. The value of Vcc in the metal oxides of the invention is close to zero.
    Type: Grant
    Filed: October 23, 2002
    Date of Patent: March 15, 2005
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Shinichiro Hayashi, Vikram Joshi, Narayan Solayappan, Joseph D. Cuchiaro, Carlos A. Paz de Araujo
  • Patent number: 6831313
    Abstract: A ferroelectric memory (436) includes a plurality of memory cells (73, 82, 100) each containing a ferroelectric thin film (15) including a microscopically composite material having a ferroelectric component (18) and a dielectric component (19), the dielectric component being a different chemical compound than the ferroelectric component. The dielectric component is preferably a fluxor, i.e., a material having a higher crystallization velocity than the ferroelectric component. The addition of the fluxor permits a ferroelectric thin film to be crystallized at a temperature of between 400° C. and 550° C.
    Type: Grant
    Filed: July 22, 2003
    Date of Patent: December 14, 2004
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Carlos A. Paz de Araujo, Vikram Joshi, Narayan Solayappan, Jolanta Celinska, Larry D. McMillan
  • Publication number: 20040232468
    Abstract: A hydrogen diffusion barrier in an integrated circuit is located to inhibit diffusion of hydrogen to a thin film of a metal oxide, such as a ferroelectric layered superlattice material, in an integrated circuit. The hydrogen diffusion barrier comprises at least one of the following chemical compounds: strontium tantalate, bismuth tantalate, tantalum oxide, titanium oxide, zirconium oxide and aluminum oxide. The hydrogen barrier layer is amorphous and is made by a MOCVD process at a temperature of 450° C. or less. A supplemental hydrogen barrier layer comprising a material selected from the group consisting of silicon nitride and a crystalline form of one of said hydrogen barrier layer materials is formed adjacent to said hydrogen diffusion barrier.
    Type: Application
    Filed: June 21, 2004
    Publication date: November 25, 2004
    Applicant: Symetrix Corporation
    Inventors: Narayan Solayappan, Jolanta Celinska, Vikram Joshi, Carlos A. Paz de Araujo, Larry D. McMillan
  • Patent number: 6815223
    Abstract: A precursor for forming a thin film of layered superlattice material is applied to an integrated circuit substrate. The precursor coating is heated using rapid thermal processing (RTP) with a ramping rate of 100° C./second at a hold temperature in a range of from 500° C. to 900° C. for a cumulative heating time not exceeding 30 minutes, and preferably less than 5 minutes. In fabricating a ferroelectric memory cell, the coating is heated in oxygen using RTP, then a top electrode layer is formed, and then the substrate including the coating is heated using RTP in oxygen or in nonreactive gas after forming the top electrode layer. The thin film of layered superlattice material preferably comprises strontium bismuth tantalate or strontium bismuth tantalum niobate, and preferably has a thickness in a range of from 25 nm to 120 nm. The process of fabricating a thin film of layered superlattice material typically has a thermal budget value not exceeding 960,000° C.
    Type: Grant
    Filed: November 22, 2002
    Date of Patent: November 9, 2004
    Assignee: Symetrix Corporation
    Inventors: Jolanta Celinska, Vikram Joshi, Narayan Solayappan, Myoungho Lim, Larry D. McMillan, Carlos A. Paz de Araujo
  • Publication number: 20040211998
    Abstract: An integrated circuit includes a layered superlattice material including one or more of the elements cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. These elements may either be A-site elements or superlattice generator elements in the layered superlattice material. In one embodiment, one or more of these elements substitute for bismuth in a bismuth layered material. They also are preferably used in combination with one or more of the following elements: strontium, calcium, barium, bismuth, cadmium, lead, titanium, tantalum, hafnium, tungsten, niobium, zirconium, bismuth, scandium, yttrium, lanthanum, antimony, chromium, thallium, oxygen, chlorine, and fluorine. Some of these materials are ferroelectrics that crystallize at relatively low temperatures and are applied in ferroelectric non-volatile memories.
    Type: Application
    Filed: May 20, 2004
    Publication date: October 28, 2004
    Applicant: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan
  • Patent number: 6787181
    Abstract: A method of forming a Bi-layered superlattice material on a substrate using chemical vapor deposition of a precursor solution of trimethylbismuth and a metal compound dissolved in an organic solvent. The precursor solution is heated and vaporized prior to deposition of the precursor solution on an integrated circuit substrate by chemical vapor deposition. No heating steps including a temperature of 650° C. or higher are used.
    Type: Grant
    Filed: October 26, 2001
    Date of Patent: September 7, 2004
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Narayan Solayappan, Carlos A. Paz de Araujo
  • Patent number: 6781184
    Abstract: A hydrogen diffusion barrier in an integrated circuit is located to inhibit diffusion of hydrogen to a thin film of a metal oxide, such as a ferroelectric layered superlattice material, in an integrated circuit. The hydrogen diffusion barrier comprises at least one of the following chemical compounds: strontium tantalate, bismuth tantalate, tantalum oxide, titanium oxide, zirconium oxide and aluminum oxide. The hydrogen barrier layer is amorphous and is made by a MOCVD process at a temperature of 450° C. or less. A supplemental hydrogen barrier layer comprising a material selected from the group consisting of silicon nitride and a crystalline form of one of said hydrogen barrier layer materials is formed adjacent to said hydrogen diffusion barrier.
    Type: Grant
    Filed: November 29, 2001
    Date of Patent: August 24, 2004
    Assignee: Symetrix Corporation
    Inventors: Narayan Solayappan, Jolanta Celinska, Vikram Joshi, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20040129987
    Abstract: A ferroelectric memory (436) includes a plurality of memory cells (73, 82, 100) each containing a ferroelectric thin film (15) including a microscopically composite material having a ferroelectric component (18) and a dielectric component (19), the dielectric component being a different chemical compound than the ferroelectric component. The dielectric component is preferably a fluxor, i.e., a material having a higher crystallization velocity than the ferroelectric component. The addition of the fluxor permits a ferroelectric thin film to be crystallized at a temperature of between 400° C. and 550° C.
    Type: Application
    Filed: July 22, 2003
    Publication date: July 8, 2004
    Inventors: Kiyoshi Uchiyama, Carlos A. Paz de Araujo, Vikram Joshi, Narayan Solayappan, Jolanta Celinska, Larry D. McMillan
  • Publication number: 20040129961
    Abstract: A three-dimensional (“3-D”) memory capacitor comprises a bottom electrode, a ferroelectric thin film, and a top electrode that conform to a 3-D surface of an insulator layer. The capacitance area is greater than the horizontal footprint area of the capacitor. Preferably, the footprint of the capacitor is less than 0.2 nm2, and the corresponding capacitance area is typically in a range of from 0.4 nm2 to 1.0 nm2 The ferroelectric thin film preferably has a thickness not exceeding 60 nm. A capacitor laminate including the bottom electrode, ferroelectric thin film, and the top electrode preferably has a thickness not exceeding 200 nm. A low-thermal-budget MOCVD method for depositing a ferroelectric thin film having a thickness in a range of from 30 nm to 90 nm includes an RTP treatment before depositing the top electrode and an RTP treatment after depositing the top electrode and etching the ferroelectric layer.
    Type: Application
    Filed: July 24, 2003
    Publication date: July 8, 2004
    Applicant: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan, Vikram Joshi
  • Patent number: 6743643
    Abstract: A nonconductive hydrogen barrier layer is deposited on a substrate and completely covers the surface area over a memory capacitor and a MOSFET switch of an integrated circuit memory cell. A portion of an insulator layer adjacent to the bottom electrode of a memory capacitor is removed by etching to form a moat region. A nonconductive oxygen barrier layer is deposited to cover the sidewall and bottom of the moat. The nonconductive oxygen barrier layer and a conductive diffusion barrier beneath the capacitor together provide a substantially continuous diffusion barrier between the capacitor and a switch. Also, the nonconductive hydrogen barrier layer, the nonconductive oxygen barrier, and the conductive diffusion barrier substantially completely envelop the capacitor, in particular a ferroelectric thin film in the capacitor.
    Type: Grant
    Filed: January 22, 2003
    Date of Patent: June 1, 2004
    Assignee: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20040101977
    Abstract: A precursor for forming a thin film of layered superlattice material is applied to an integrated circuit substrate. The precursor coating is heated using rapid thermal processing (RTP) with a ramping rate of 100° C./second at a hold temperature in a range of from 500° C. to 900° C. for a cumulative heating time not exceeding 30 minutes, and preferably less than 5 minutes. In fabricating a ferroelectric memory cell, the coating is heated in oxygen using RTP, then a top electrode layer is formed, and then the substrate including the coating is heated using RTP in oxygen or in nonreactive gas after forming the top electrode layer. The thin film of layered superlattice material preferably comprises strontium bismuth tantalate or strontium bismuth tantalum niobate, and preferably has a thickness in a range of from 25 nm to 120 nm. The process of fabricating a thin film of layered superlattice material typically has a thermal budget value not exceeding 960,000° C.
    Type: Application
    Filed: November 22, 2002
    Publication date: May 27, 2004
    Applicant: Symetrix Corporation
    Inventors: Jolanta Celinska, Vikram Joshi, Narayan Solayappan, Myoungho Lim, Larry D. McMillan, Carlos A. Paz de Araujo