Patents by Inventor Pooran Chandra Joshi

Pooran Chandra Joshi 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: 7807225
    Abstract: A high-density plasma method is provided for forming a SiOXNY thin-film. The method provides a substrate and introduces a silicon (Si) precursor. A thin-film is deposited overlying the substrate, using a high density (HD) plasma-enhanced chemical vapor deposition (PECVD) process. As a result, a SiOXNY thin-film is formed, where (X+Y<2 and Y>0). The SiOXNY thin-film can be stoichiometric or non-stoichiometric. The SiOXNY thin-film can be graded, meaning the values of X and Y vary with the thickness of the SiOXNY thin-film. Further, the process enables the in-situ deposition of a SiOXNY thin-film multilayer structure, where the different layers may be stoichiometric, non-stoichiometric, graded, and combinations of the above-mentioned types of SiOXNY thin-films.
    Type: Grant
    Filed: January 26, 2007
    Date of Patent: October 5, 2010
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas, John W. Hartzell
  • Patent number: 7786021
    Abstract: A thin-film transistor (TFT) with a multilayer gate insulator is provided, along with a method for forming the same. The method comprises: forming a channel, first source/drain (S/D) region, and a second S/D region in a Silicon (Si) active layer; using a high-density plasma (HDP) source, growing a first layer of Silicon oxide (SiOx) from the Si active layer, to a first thickness, where x is less than, or equal to 2; depositing a second layer of SiOx having a second thickness, greater than the first thickness, overlying the first layer of SiOx; using the HDP source, additionally oxidizing the second layer of SiOx, wherein the first and second SiOx layers form a gate insulator; and, forming a gate electrode adjacent the gate insulator. In one aspect, the second Si oxide layer is deposited using a plasma-enhanced chemical vapor deposition (PECVD) process with tetraethylorthosilicate (TEOS) precursors.
    Type: Grant
    Filed: November 2, 2005
    Date of Patent: August 31, 2010
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas
  • Patent number: 7759736
    Abstract: A deposition oxide interface with improved oxygen bonding and a method for bonding oxygen in an oxide layer are provided. The method includes depositing an M oxide layer where M is a first element selected from a group including elements chemically defined as a solid and having an oxidation state in a range of +2 to +5, plasma oxidizing the M oxide layer at a temperature of less than 400° C. using a high density plasma source, and in response to plasma oxidizing the M oxide layer, improving M-oxygen bonding in the M oxide layer. The plasma oxidation process diffuses excited oxygen radicals into the oxide layer. The plasma oxidation is performed at specified parameters including temperature, power density, pressure, process gas composition, and process gas flow. In some aspects of the method, M is silicon, and the oxide interface is incorporated into a thin film transistor.
    Type: Grant
    Filed: September 21, 2006
    Date of Patent: July 20, 2010
    Assignee: Sharp Laboratories of America, Inc.
    Inventor: Pooran Chandra Joshi
  • Patent number: 7723242
    Abstract: A method is provided for additionally oxidizing a thin-film oxide. The method includes: providing a substrate; depositing an MyOx (M oxide) layer overlying the substrate, where M is a solid element having an oxidation state in a range of +2 to +5; treating the MyOx layer to a high density plasma (HDP) source; and, forming an MyOk layer in response to the HDP source, where k>x. In one aspect, the method further includes decreasing the concentration of oxide charge in response to forming the MyOk layer. In another aspect, the MyOx layer is deposited with an impurity N, and the method further includes creating volatile N oxides in response to forming the MyOk layer. For example, the impurity N may be carbon and the method creates a volatile carbon oxide.
    Type: Grant
    Filed: January 6, 2006
    Date of Patent: May 25, 2010
    Assignee: Sharp Laboratories of America, inc.
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas, John W. Hartzell
  • Patent number: 7723781
    Abstract: A method is provided for forming a low-temperature vertical gate insulator in a vertical thin-film transistor (V-TFT) fabrication process. The method comprises: forming a gate, having vertical sidewalls and a top surface, overlying a substrate insulation layer; depositing a silicon oxide thin-film gate insulator overlying the gate; plasma oxidizing the gate insulator at a temperature of less than 400° C., using a high-density plasma source; forming a first source/drain region overlying the gate top surface; forming a second source/drain region overlying the substrate insulation layer, adjacent a first gate sidewall; and, forming a channel region overlying the first gate sidewall, in the gate insulator interposed between the first and second source/drain regions. When the silicon oxide thin-film gate insulator is deposited overlying the gate a Si oxide layer, a low temperature deposition process can be used, so that a step-coverage of greater than 65% can be obtained.
    Type: Grant
    Filed: April 23, 2008
    Date of Patent: May 25, 2010
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas, John W. Hartzell
  • Patent number: 7723913
    Abstract: A silicon (Si) nanocrystal embedded Si oxide electroluminescence (EL) device and associated fabrication process are presented. The method provides a substrate bottom electrode, and forms a plurality of Si nanocrystal embedded SiOx film layers overlying the bottom electrode, where X is less than 2. Each SiOx film layer has a Si excess concentration in a range of about 5 to 30%. The outside film layers sandwich an inner film layer having a lower concentration of Si nanocrystals. Alternately stated, the outside Si nanocrystal embedded SiOx film layers have a higher electrical conductivity than a sandwiched inner film layer. A transparent top electrode is formed over the plurality of Si nanocrystal embedded SiOx film layers. The plurality of Si nanocrystal embedded SiOx film layers are deposited using a high density plasma-enhanced chemical vapor deposition (HD PECVD) process. The HD PECVD process initially deposits SiOx film layers, which are subsequently annealed.
    Type: Grant
    Filed: July 7, 2008
    Date of Patent: May 25, 2010
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Vincenzo Casasanta, Apostolos T. Voutsas, Pooran Chandra Joshi
  • Publication number: 20090294885
    Abstract: A photodetector is provided with a method for fabricating a semiconductor nanoparticle embedded Si insulating film for photo-detection applications. The method provides a bottom electrode and introduces a semiconductor precursor and hydrogen. A thin-film is deposited overlying the substrate, using a high density (HD) plasma-enhanced chemical vapor deposition (PECVD) process. As a result, a semiconductor nanoparticle embedded Si insulating film is formed, where the Si insulating film includes either N or C elements. For example, the Si insulating film may be a non-stoichiometric SiOXNY thin-film, where (X+Y<2 and Y>0), or SiCX, where X<1. The semiconductor nanoparticles are either Si or Ge. Following the formation of the semiconductor nanoparticle embedded Si insulating film, an annealing process is performed.
    Type: Application
    Filed: May 29, 2008
    Publication date: December 3, 2009
    Inventors: Pooran Chandra Joshi, Hao Zhang, Apostolos T. Voutsas
  • Publication number: 20090232449
    Abstract: An erbium (Er)-doped silicon (Si) nanocrystalline embedded silicon oxide (SiOx) waveguide and associated fabrication method are presented. The method provides a bottom layer, and forms an Er-doped Si nanocrystalline embedded SiOx film waveguide overlying the bottom layer, having a minimum optical attenuation at about 1540 nanometers (nm). Then, a top layer is formed overlying the Er-doped SiOx film. The Er-doped SiOx film is formed by depositing a silicon rich silicon oxide (SRSO) film using a high density plasma chemical vapor deposition (HDPCVD) process and annealing the SRSO film. After implanting Er+ ions, the Er-doped SiOx film is annealed again. The Er-doped Si nanocrystalline SiOx film includes has a first refractive index (n) in the range of 1.46 to 2.30. The top and bottom layers have a second refractive index, less than the first refractive index.
    Type: Application
    Filed: April 30, 2008
    Publication date: September 17, 2009
    Inventors: Hao Zhang, Pooran Chandra Joshi, Apostolos T. Voutsas
  • Publication number: 20090217968
    Abstract: A solar call is provided along with a method for forming a semiconductor nanocrystalline silicon insulating thin-film with a tunable bandgap. The method provides a substrate and introduces a silicon (Si) source gas with at least one of the following source gases: germanium (Ge), oxygen, nitrogen, or carbon into a high density (HD) plasma-enhanced chemical vapor deposition (PECVD) process. A SiOxNyCz thin-film embedded with a nanocrystalline semiconductor material is deposited overlying the substrate, where x, y, z?0, and the semiconductor material is Si, Ge, or a combination of Si and Ge. As a result, a bandgap is formed in the SiOxNyCz thin-film, in the range of about 1.9 to 3.0 electron volts (eV). Typically, the semiconductor nanoparticles have a size in a range of 1 to 20 nm.
    Type: Application
    Filed: May 18, 2009
    Publication date: September 3, 2009
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas
  • Patent number: 7544625
    Abstract: A method is provided for forming a silicon oxide (SiOx) thin-film with embedded nanocrystalline silicon (Si). The method deposits SiOx, where x is in the range of 1 to 2, overlying a substrate, using a high-density (HD) plasma-enhanced chemical vapor deposition (PECVD) process. As a result, the SiOx thin-film is embedded with nanocrystalline Si. The HD PECVD process may use an inductively coupled plasma (ICP) source, a substrate temperature of less than about 400° C., and an oxygen source gas with a silicon precursor. In one aspect, a hydrogen source gas and an inert gas are used, where the ratio of oxygen source gas to inert gas is in the range of about 0.02 to 5. The SiOx thin-film with embedded nanocrystalline Si typically has a refractive index in the range of about 1.6 to 2.2, with an extinction coefficient in the range of 0 to 0.5.
    Type: Grant
    Filed: May 4, 2006
    Date of Patent: June 9, 2009
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Pooran Chandra Joshi, Tingkai Li, Yoshi Ono, Apostolos T. Voutsas, John W. Hartzell
  • Publication number: 20090115311
    Abstract: A method is provided for fabricating a semiconductor nanoparticle embedded Si insulating film for electroluminescence (EL) applications. The method provides a bottom electrode, and deposits a semiconductor nanoparticle embedded Si insulating film, including an element selected from a group consisting of N and C, overlying the bottom electrode. After annealing, a semiconductor nanoparticle embedded Si insulating film is formed having an extinction coefficient (k) in a range of 0.01-1.0, as measured at about 632 nanometers (nm), and a current density (J) of greater than 1 Ampere per square centimeter (A/cm2) at an applied electric field lower than 3 MV/cm. In another aspect, the annealed semiconductor nanoparticle embedded Si insulating film has an index of refraction (n) in a range of 1.8-3.0, as measured at 632 nm, with a current density of greater than 1 A/cm2 at an applied electric field lower than 3 MV/cm.
    Type: Application
    Filed: August 7, 2008
    Publication date: May 7, 2009
    Inventors: Pooran Chandra Joshi, Jiandong Huang, Apostolos T. Voutsas
  • Publication number: 20090058266
    Abstract: A method is provided for fabricating a semiconductor nanoparticle embedded Si insulating film for short wavelength luminescence applications. The method provides a bottom electrode, and deposits a semiconductor nanoparticle embedded Si insulating film, including the element of N, O, or C, overlying the bottom electrode. After annealing, a semiconductor nanoparticle embedded Si insulating film has a peak photoluminescence (PL) at a wavelength in the range of 475 to 750 nanometers.
    Type: Application
    Filed: November 10, 2008
    Publication date: March 5, 2009
    Inventors: Pooran Chandra Joshi, Hao Zhang, Jiandong Huang, Apostolos T. Voutsas
  • Publication number: 20090040599
    Abstract: A method is provided for optical amplification using a silicon (Si) nanocrystal embedded silicon oxide (SiOx) waveguide. The method provides a Si nanocrystal embedded SiOx waveguide, where x is less than 2, having a quantum efficiency of greater than 10%. An optical input signal is supplied to the Si nanocrystal embedded SiOx waveguide, having a first power at a first wavelength in the range of 700 to 950 nm. The Si nanocrystal embedded SiOx waveguide is pumped with an optical source having a second power at a second wavelength in a range of 250 to 550 nm. As a result, an optical output signal having a third power is generated, greater than the first power, at the first wavelength. In one aspect, the third power increases in response to the length of the waveguide strip.
    Type: Application
    Filed: October 28, 2008
    Publication date: February 12, 2009
    Inventors: Jiandong Huang, Pooran Chandra Joshi, Hao Zhang, Apostolos T. Voutsas
  • Publication number: 20090033206
    Abstract: A silicon (Si) nanocrystal embedded Si oxide electroluminescence (EL) device and associated fabrication process are presented. The method provides a substrate bottom electrode, and forms a plurality of Si nanocrystal embedded SiOx film layers overlying the bottom electrode, where X is less than 2. Each SiOx film layer has a Si excess concentration in a range of about 5 to 30%. The outside film layers sandwich an inner film layer having a lower concentration of Si nanocrystals. Alternately stated, the outside Si nanocrystal embedded SiOx film layers have a higher electrical conductivity than a sandwiched inner film layer. A transparent top electrode is formed over the plurality of Si nanocrystal embedded SiOx film layers. The plurality of Si nanocrystal embedded SiOx film layers are deposited using a high density plasma-enhanced chemical vapor deposition (HD PECVD) process. The HD PECVD process initially deposits SiOx film layers, which are subsequently annealed.
    Type: Application
    Filed: July 7, 2008
    Publication date: February 5, 2009
    Inventors: Vincenzo Casasanta, Apostolos T. Voutsas, Pooran Chandra Joshi
  • Publication number: 20090033207
    Abstract: A method is provided for fabricating a high quantum efficiency silicon (Si) nanoparticle embedded SiOXNY film for luminescence (electroluminescence—EL and photoluminescence—PL) applications. The method provides a bottom electrode, and deposits a Si nanoparticle embedded non-stoichiometric SiOXNY film, where (X+Y<2 and Y>0), overlying the bottom electrode. The Si nanoparticle embedded SiOXNY film is annealed. The annealed Si nanoparticle embedded SiOXNY film has an extinction coefficient (k) of less than about 0.001 as measured at 632 nanometers (nm), and a PL quantum efficiency (PLQE) of greater than 20%.
    Type: Application
    Filed: October 11, 2008
    Publication date: February 5, 2009
    Inventors: Pooran Chandra Joshi, Jiandong Huang, Apostolos T. Voutsas
  • Publication number: 20080305566
    Abstract: A method is provided for forming a silicon (Si) nanocrystal embedded Si oxide electroluminescence (EL) device with a mid-bandgap transition layer. The method provides a highly doped Si bottom electrode, and forms a mid-bandgap electrically insulating dielectric film overlying the electrode. A Si nanocrystal embedded SiOx film layer is formed overlying the mid-bandgap electrically insulating dielectric film, where X is less than 2, and a transparent top electrode overlies the Si nanocrystal embedded SiOx film layer. The bandgap of the mid-bandgap dielectric film is about half that of the bandgap of the Si nanocrystal embedded SiOx film. In one aspect, the Si nanocrystal embedded SiOx film has a bandgap (Eg) of about 10 electronvolts (eV) and mid-bandgap electrically insulating dielectric film has a bandgap of about 5 eV. By dividing the high-energy tunneling processes into two lower energy tunneling steps, potential damage due to high power hot electrons is reduced.
    Type: Application
    Filed: August 22, 2008
    Publication date: December 11, 2008
    Inventors: Jiandong Huang, Pooran Chandra Joshi, Hao Zhang, Apostolos T. Voutsas
  • Patent number: 7446023
    Abstract: A high-density plasma hydrogenation method is provided. Generally, the method comprises: forming a silicon (Si)/oxide stack layer; plasma oxidizing the Si/oxide stack at a temperature of less than 400° C., using a high density plasma source, such as an inductively coupled plasma (ICP) source; introducing an atmosphere including H2 at a system pressure up to 500 milliTorr; hydrogenating the stack at a temperature of less than 400 degrees C., using the high density plasma source; and forming an electrode overlying the oxide. The electrode may be formed either before or after the hydrogenation. The Si/oxide stack may be formed in a number of ways. In one aspect, a Si layer is formed, and the silicon layer is plasma oxidized at a temperature of less than 400 degrees C., using an ICP source. The oxide formation, additional oxidation, and hydrogenation steps can be conducted in-situ in a common chamber.
    Type: Grant
    Filed: December 15, 2004
    Date of Patent: November 4, 2008
    Assignee: Sharp Laboratories of America, Inc.
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas, John W. Hartzell
  • Publication number: 20080266689
    Abstract: A non-stoichiometric SiOXNY thin-film optical filter is provided. The filter is formed from a substrate and a first non-stoichiometric SiOX1NY1 thin-film overlying the substrate, where (X1+Y1<2 and Y1>0). The first non-stoichiometric SiOX1NY1 thin-film has a refractive index (n1) in the range of about 1.46 to 3, and complex refractive index (N1=n1+ik1), where k1 is an extinction coefficient in a range of about 0 to 0.5. The first non-stoichiometric SiOX1NY1 thin-film may be either intrinsic or doped. In one aspect, the first non-stoichiometric SiOX1NY1 thin-film has nanoparticles with a size in the range of about 1 to 10 nm. A second non-stoichiometric SiOX2NY2 thin-film may overlie the first non-stoichiometric SiOX1NY1 thin-film, where Y1?Y2. The second non-stoichiometric SiOX1NY1 thin-film may be intrinsic and doped. In another variation, a stoichiometric SiOX2NY2 thin-film, intrinsic or doped, overlies the first non-stoichiometric SiOX1NY1 thin-film.
    Type: Application
    Filed: April 26, 2007
    Publication date: October 30, 2008
    Inventors: Pooran Chandra Joshi, Apostolos T. Voutsas, John W. Hartzell
  • Patent number: 7439187
    Abstract: A method of fabricating a grayscale reticule includes preparing a quartz substrate; depositing a layer of silicon-rich oxide on the quartz substrate; depositing a layer of silicon nitride as an oxidation barrier layer on the silicon-rich oxide layer; depositing and patterning a layer of photoresist; etching the silicon nitride layer with a pattern for the silicon nitride layer; removing the photoresist; cleaning the quartz substrate and the remaining layers; oxidizing the quartz substrate and the layers thereon, thereby converting the silicon-rich oxide layer to a transparent silicon dioxide layer; removing the remaining silicon nitride layer; forming the quartz substrate and the silicon dioxide thereon into a reticule; and using the reticule to pattern a microlens array.
    Type: Grant
    Filed: October 27, 2006
    Date of Patent: October 21, 2008
    Assignee: Sharp Laboratories of America
    Inventors: Yoshi Ono, Bruce D. Ulrich, Pooran Chandra Joshi
  • Publication number: 20080224164
    Abstract: A light emitting device using a silicon (Si) nanocrystalline Si insulating film is presented with an associated fabrication method. The method provides a doped semiconductor or metal bottom electrode. Using a high density plasma-enhanced chemical vapor deposition (HDPECVD) process, a Si insulator film is deposited overlying the semiconductor electrode, having a thickness in a range of 30 to 200 nanometers (nm). For example, the film may be SiOx, where X is less than 2, Si3Nx, where X is less than 4, or SiCx, where X is less than 1. The Si insulating film is annealed, and as a result, Si nanocrystals are formed in the film. Then, a transparent metal electrode is formed overlying the Si insulator film. An annealed Si nanocrystalline SiOx film has a turn-on voltage of less than 20 volts, as defined with respect to a surface emission power of greater than 0.03 watt per square meter.
    Type: Application
    Filed: May 23, 2008
    Publication date: September 18, 2008
    Inventors: Jiandong Huang, Pooran Chandra Joshi, Apostolos T. Voutsas, Hao Zhang