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: 20040089920
    Abstract: A nonconductive hydrogen barrier layer completely covers the surface area over a memory capacitor and a MOSFET switch of an integrated circuit memory cell. The nonconductive hydrogen barrier layer and a conductive diffusion barrier beneath the capacitor together provide a continuous diffusion barrier between the capacitor and a switch. Also, the nonconductive hydrogen barrier layer and the conductive diffusion barrier continuously envelop the capacitor, in particular a ferroelectric thin film in the capacitor. Preferably, a nonconductive “buried” diffusion barrier layer is disposed over an extended area, providing a continuous diffusion barrier between the capacitor and the switch. A preferred fabrication method comprises forming a thin stack-electrode layer on a capacitor dielectric layer, and then etching the substrate to form self-aligning capacitor stacks.
    Type: Application
    Filed: October 28, 2003
    Publication date: May 13, 2004
    Applicant: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Patent number: 6706585
    Abstract: A first reactant gas is flowed into a CVD reaction chamber containing a heated integrated circuit substrate. The first reactant gas contains a first precursor compound or a plurality of first precursor compounds, and the first precursor compound or compounds decompose in the CVD reaction chamber to deposit a coating containing metal atoms on the heated integrated circuit substrate. The coating is treated by RTP. Thereafter, a second reactant gas is flowed into a CVD reaction chamber containing the heated substrate. The second reactant gas contains a second precursor compound or a plurality of second precursor compounds, which decompose in the CVD reaction chamber to deposit more metal atoms on the substrate. Heat for reaction and crystallization of the deposited metal atoms to form a thin film of layered superlattice material is provided by heating the substrate during CVD deposition, as well as by selected rapid thermal processing (“RTP”) and furnace annealing steps.
    Type: Grant
    Filed: April 2, 2003
    Date of Patent: March 16, 2004
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Narayan Solayappan, Carlos A. Paz de Araujo
  • Publication number: 20040046198
    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: Application
    Filed: September 19, 2003
    Publication date: March 11, 2004
    Applicant: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20030203513
    Abstract: A first reactant gas is flowed into a CVD reaction chamber containing a heated integrated circuit substrate. The first reactant gas contains a first precursor compound or a plurality of first precursor compounds, and the first precursor compound or compounds decompose in the CVD reaction chamber to deposit a coating containing metal atoms on the heated integrated circuit substrate. The coating is treated by RTP. Thereafter, a second reactant gas is flowed into a CVD reaction chamber containing the heated substrate. The second reactant gas contains a second precursor compound or a plurality of second precursor compounds, which decompose in the CVD reaction chamber to deposit more metal atoms on the substrate. Heat for reaction and crystallization of the deposited metal atoms to form a thin film of layered superlattice material is provided by heating the substrate during CVD deposition, as well as by selected rapid thermal processing (“RTP”) and furnace annealing steps.
    Type: Application
    Filed: April 2, 2003
    Publication date: October 30, 2003
    Applicants: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Narayan Solayappan, Carlos A. Paz de Araujo
  • Publication number: 20030152813
    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: November 29, 2001
    Publication date: August 14, 2003
    Applicant: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan
  • Publication number: 20030132470
    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: Application
    Filed: January 22, 2003
    Publication date: July 17, 2003
    Applicant: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Patent number: 6582972
    Abstract: A thin film of precursor for forming a layered superlattice material is applied to an integrated circuit substrate, then a strong oxidizing agent is applied at low temperature in a range of from 100° C. to 300° C. to the precursor thin film, thereby forming a metal oxide thin film. The strong oxidizing agent may be liquid or gaseous. An example of a liquid strong oxidizing agent is hydrogen peroxide. An example of a gaseous strong oxidizing agent is ozone. The metal oxide thin film is crystallized by annealing at elevated temperature in a range of from 500° C. to 700° C., preferably not exceeding 650° C., for a time period in a range of from 30 minutes to two hours. Annealing is conducted in an oxygen-containing atmosphere, preferably including water vapor. Treatment by ultraviolet (UV) radiation may precede annealing. RTP in a range of from 500° C. to 700° C. may precede annealing.
    Type: Grant
    Filed: April 7, 2000
    Date of Patent: June 24, 2003
    Assignees: Symetrix Corporation, Matsushita Electronics Corporation
    Inventors: Vikram Joshi, Jolanta Celinska, Narayan Solayappan, Larry D. McMillan, Carlos A. Paz de Araujo, Koji Arita
  • Publication number: 20030102531
    Abstract: A nonconductive hydrogen barrier layer completely covers the surface area over a memory capacitor and a MOSFET switch of an integrated circuit memory cell. The nonconductive hydrogen barrier layer and a conductive diffusion barrier beneath the capacitor together provide a continuous diffusion barrier between the capacitor and a switch. Also, the nonconductive hydrogen barrier layer and the conductive diffusion barrier continuously envelop the capacitor, in particular a ferroelectric thin film in the capacitor. Preferably, a nonconductive “buried” diffusion barrier layer is disposed over an extended area, providing a continuous diffusion barrier between the capacitor and the switch. A preferred fabrication method comprises forming a thin stack-electrode layer on a capacitor dielectric layer, and then etching the substrate to form self-aligning capacitor stacks.
    Type: Application
    Filed: November 22, 2002
    Publication date: June 5, 2003
    Applicant: Symetrix Corporation
    Inventors: Vikram Joshi, Narayan Solayappan, Carlos A. Paz de Araujo, Larry D. McMillan
  • Publication number: 20030098497
    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: November 29, 2001
    Publication date: May 29, 2003
    Applicant: Symetrix Corporation
    Inventors: Narayan Solayappan, Jolanta Celinska, Vikram Joshi, Carlos A. Paz de Araujo, Larry D. McMillan
  • Patent number: 6562678
    Abstract: A first reactant gas is flowed into a CVD reaction chamber containing a heated integrated circuit substrate. The first reactant gas contains a first precursor compound or a plurality of first precursor compounds, and the first precursor compound or compounds decompose in the CVD reaction chamber to deposit a coating containing metal atoms on the heated integrated circuit substrate. The coating is treated by RTP. Thereafter, a second reactant gas is flowed into a CVD reaction chamber containing the heated substrate. The second reactant gas contains a second precursor compound or a plurality of second precursor compounds, which decompose in the CVD reaction chamber to deposit more metal atoms on the substrate. Heat for reaction and crystallization of the deposited metal atoms to form a thin film of layered superlattice material is provided by heating the substrate during CVD deposition, as well as by selected rapid thermal processing (“RTP”) and furnace annealing steps.
    Type: Grant
    Filed: March 7, 2000
    Date of Patent: May 13, 2003
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Narayan Solayappan, Carlos A. Paz de Araujo
  • Patent number: 6559469
    Abstract: An integrated circuit includes a layered superlattice material having the formula A1w1+a1A2w2+a2 . . . Ajwj+ajS1x1+s1S2x2+s2 . . . Skxk+skB1y1+b1B2y2+b2 . . . Blyl+blQz−q, where A1, A2 . . . Aj represent A-site elements in a perovskite-like structure, S1, S2 . . . Sk represent superlattice generator elements, B1, B2 . . . B1 represent B-site elements in a perovskite-like structure, Q represents an anion, the superscripts indicate the valences of the respective elements, the subscripts indicate the number of atoms of the element in the unit cell, and at least w1 and y1 are non-zero. Some of these materials are extremely low fatigue ferroelectrics and are applied in ferroelectric FETs in non-volatile memories. Others are high dielectric constant materials that do not degrade or break down over long periods of use and are applied as the gate insulator in volatile memories.
    Type: Grant
    Filed: October 11, 2000
    Date of Patent: May 6, 2003
    Assignee: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Vikram Joshi, Narayan Solayappan, Joseph D. Cuchiaro
  • Publication number: 20030080325
    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: Application
    Filed: October 26, 2001
    Publication date: May 1, 2003
    Applicant: Symetrix Corporation and Matsushita Electric Industrial Co., Ltd.
    Inventors: Kiyoshi Uchiyama, Narayan Solayappan, Carlos A. Paz de Araujo
  • Patent number: 6541279
    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≦x≦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(TayNby−1)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.
    Type: Grant
    Filed: March 2, 2001
    Date of Patent: April 1, 2003
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Shinichiro Hayashi, Vikram Joshi, Narayan Solayappan, Joseph D. Cuchiaro, Carlos A. Paz de Araujo
  • Publication number: 20030052357
    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)2(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.
    Type: Application
    Filed: October 23, 2002
    Publication date: March 20, 2003
    Applicant: Symetrix Corporation
    Inventors: Shinichiro Hayashi, Vikram Joshi, Narayan Solayappan, Joseph D. Cuchiaro, Carlos A. Paz de Araujo
  • Patent number: 6511718
    Abstract: A venturi mist generator creates a mist comprising droplets having a mean diameter less than one micron from liquid precursors containing multi-metal polyalkoxide compounds. The mist is mixed and then passed into a gasifier where the mist droplets are gasified at a temperature of between 100° C. and 250° C., which is lower than the temperature at which the precursor compounds decompose. The gasified precursor compounds are transported by carrier gas through insulated tubing at ambient temperature to prevent both condensation and premature decomposition. The gasified precursors are mixed with oxidant gas, and the gaseous reactant mixture is injected through a showerhead inlet into a deposition reactor in which a substrate is heated at a temperature of from 300° C. to 600 ° C. The gasified precursors decompose at the substrate and form a thin film of solid material on the substrate. The thin film is treated at elevated temperatures of from 500° C. to 900° C.
    Type: Grant
    Filed: December 17, 1999
    Date of Patent: January 28, 2003
    Assignee: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Larry D. McMillan, Narayan Solayappan, Jeffrey W. Bacon
  • Patent number: 6495878
    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≦x≦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.
    Type: Grant
    Filed: August 2, 1999
    Date of Patent: December 17, 2002
    Assignees: Symetrix Corporation, Matsushita Electric Industrial Co., Ltd.
    Inventors: Shinichiro Hayashi, Vikram Joshi, Narayan Solayappan, Joseph D. Cuchiaro, Carlos A. Paz de Araujo
  • Publication number: 20020168785
    Abstract: A ferroelectric memory includes a plurality of memory cells each containing a ferroelectric thin film including a microscopically composite material having a ferroelectric material component and a fluxor material component, the fluxor material being a different chemical compound than the ferroelectric material. The fluxor is a material having a higher crystallization velocity than the ferroelectric material. The addition of the fluxor permits a ferroelectric thin film to be crystalized at a temperature of between 400° C. and 550° C.
    Type: Application
    Filed: May 10, 2001
    Publication date: November 14, 2002
    Applicant: Symetrix Corporation
    Inventors: Carlos A. Paz de Araujo, Vikram Joshi, Narayan Solayappan, Jolanta Celinska, Larry D. McMillan
  • Patent number: 6437380
    Abstract: An integrated circuit device includes a thin film of bismuth-containing layered superlattice material having a thickness not exceeding 100 nm, a capping layer thin film of bismuth tantalate, and an electrode. The capping layer has a thickness in a range of from 3 nm to 30 nm and is deposited between the thin film of layered superlattice material and the electrode to increase dielectric breakdown voltage. Preferably the capping layer contains an excess amount of bismuth relative to the stoichiometrically balanced amount represented by the balanced stoichiometric formula BiTaO4. Preferably, the layered superlattice material is ferroelectric SBT or SBTN. Preferably, the integrated circuit device is a nonvolatile ferroelectric memory. Heating treatments for fabrication of the integrated circuit device containing the bismuth tantalate capping layerare conducted at temperatures not exceeding 700° C., preferably in a range of from 650° C. to 700° C.
    Type: Grant
    Filed: March 28, 2001
    Date of Patent: August 20, 2002
    Assignee: Symetrix Corporation
    Inventors: Myoungho Lim, Vikram Joshi, Narayan Solayappan, Larry D. McMillan, Carlos A. Paz de Araujo
  • Patent number: 6326315
    Abstract: A liquid precursor for forming a layered superlattice material is applied to an integrated circuit substrate. The precursor coating is annealed in oxygen using a rapid ramping anneal (“RRA”) technique with a ramping rate of 50° C./second at a hold temperature of 650° C. for a holding time of 30 minutes.
    Type: Grant
    Filed: March 9, 2000
    Date of Patent: December 4, 2001
    Assignees: Symetrix Corporation, Matsushita Electronics Corporation
    Inventors: Kiyoshi Uchiyama, Koji Arita, Narayan Solayappan, Carlos A. Paz de Araujo
  • Patent number: 6322849
    Abstract: An integrated circuit is formed containing a metal-oxide ferroelectric thin film. An inert-gas recovery anneal is conducted to reverse the degradation of ferroelectric properties caused by hydrogen. The inert-gas recovery anneal is conducted in an unreactive gas atmosphere at a temperature range from 300° to 1000° C. for a time period from one minute to two hours. Preferably, the metal-oxide thin film comprises layered superlattice material. Preferably, the layered superlattice material comprises strontium bismuth tantalate or strontium bismuth tantalum niobate. If the integrated circuit manufacture includes a forming-gas anneal, then the inert-gas recovery anneal is performed after the forming-gas anneal, preferably at or near the same temperature and for the same time duration as the forming-gas anneal.
    Type: Grant
    Filed: November 13, 1998
    Date of Patent: November 27, 2001
    Assignees: Symetrix Corporation, Spemens AG
    Inventors: Vikram Joshi, Narayan Solayappan, Walter Hartner, Günther Schindler