Patents by Inventor Solomon Assefa

Solomon Assefa 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: 9134479
    Abstract: An optical demultiplexing device includes a first portion operative to receive an input optical signal having a first polarization, a second polarization and multiple channels, and split the input optical signal into a first optical signal having the first polarization and a second optical signal having the first polarization, and an optical demultiplexing portion communicatively connected to the polarization splitter portion, the optical demultiplexing portion operative to receive a combination of the first optical signal and the second optical signal, and output each channel of the first optical signal and the second optical signal to a photodetector device corresponding to each channel.
    Type: Grant
    Filed: September 5, 2012
    Date of Patent: September 15, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Douglas M. Gill, William M. Green
  • Patent number: 9136303
    Abstract: A method of protecting a CMOS device within an integrated photonic semiconductor structure is provided. The method may include depositing a conformal layer of germanium over the CMOS device and an adjacent area to the CMOS device, depositing a conformal layer of dielectric hardmask over the germanium, and forming, using a mask level, a patterned layer of photoresist for covering the CMOS device and a photonic device formation region within the adjacent area. Openings are etched into areas of the deposited layer of silicon nitride not covered by the patterned photoresist, such that the areas are adjacent to the photonic device formation region. The germanium material is then etched from the conformal layer of germanium at a location underlying the etched openings for forming the photonic device at the photonic device formation region. The conformal layer of germanium deposited over the CMOS device protects the CMOS device.
    Type: Grant
    Filed: August 20, 2013
    Date of Patent: September 15, 2015
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Solomon Assefa, Marwan H. Khater, Edward W. Kiewra, Carol Reinholm, Steven M. Shank
  • Patent number: 9117946
    Abstract: A method of forming an integrated photonic semiconductor structure having a photodetector and a CMOS device may include forming the CMOS device on a first silicon-on-insulator region, forming a silicon optical waveguide on a second silicon-on-insulator region, and forming a shallow trench isolation (STI) region surrounding the silicon optical waveguide such that the shallow trench isolation electrically isolating the first and second silicon-on-insulator region. Within a first region of the STI region, a first germanium material is deposited adjacent a first side wall of the semiconductor optical waveguide. Within a second region of the STI region, a second germanium material is deposited adjacent a second side wall of the semiconductor optical waveguide, whereby the second side wall opposes the first side wall. The first and second germanium material form an active region that evanescently receives propagating optical signals from the first and second side wall of the semiconductor optical waveguide.
    Type: Grant
    Filed: January 15, 2013
    Date of Patent: August 25, 2015
    Assignee: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Solomon Assefa, William M. Green, Steven M. Shank, Yurii A. Vlasov
  • Patent number: 9105686
    Abstract: Photonic devices are created by laterally growing a semiconductor material (i.e., a localized semiconductor-on-insulator layer) over a localized buried oxide (BOX) created in a semiconductor by either a trench isolation process or thermal oxidation. In one embodiment, and after trench formation in a semiconductor substrate, the trench is filled with oxide to create a localized BOX. The top surface of the BOX is recessed to depth below the topmost surface of the semiconductor substrate to expose sidewall surfaces of the semiconductor substrate within each trench. A semiconductor material is then epitaxially grown from the exposed sidewall surfaces of the semiconductor substrate.
    Type: Grant
    Filed: November 2, 2012
    Date of Patent: August 11, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, William M. Green, Marwan H. Khater, Yurri A. Vlasov
  • Patent number: 9086387
    Abstract: A method of determining a parameter of a wafer is disclosed. Light is propagated through a waveguide disposed in the wafer. A first measurement of optical power is obtained at a first optical tap coupled to the waveguide and a second measurement of optical power is obtained at a second optical tap coupled to the waveguide using a photodetector placed at a selected location with respect to the wafer. A difference in optical power is determined between the first optical tap and the second optical tap from the first measurement and the second measurement. The parameter of the wafer is determined from the determined difference in optical power.
    Type: Grant
    Filed: August 20, 2013
    Date of Patent: July 21, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Douglas M. Gill, Jessie C. Rosenberg
  • Patent number: 9087952
    Abstract: A method of forming an integrated photonic semiconductor structure having a photonic device and a CMOS device may include depositing a first silicon nitride layer having a first stress property over the photonic device, depositing an oxide layer having a stress property over the deposited first silicon nitride layer, and depositing a second silicon nitride layer having a second stress property over the oxide layer. The deposited first silicon nitride layer, the oxide layer, and the second silicon nitride layer encapsulate the photonic device.
    Type: Grant
    Filed: April 7, 2014
    Date of Patent: July 21, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Tymon Barwicz, Swetha Kamlapurkar, Marwan H. Khater, Steven M. Shank, Yurii A. Vlasov
  • Publication number: 20150194543
    Abstract: An encapsulated integrated photodetector waveguide structures with alignment tolerance and methods of manufacture are disclosed. The method includes forming a waveguide structure bounded by one or more shallow trench isolation (STI) structure(s). The method further includes forming a photodetector fully landed on the waveguide structure.
    Type: Application
    Filed: January 7, 2014
    Publication date: July 9, 2015
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Solomon ASSEFA, Bruce W. PORTH, Steven M. SHANK
  • Patent number: 9069127
    Abstract: A method for controlling an output of an electro-optical de-multiplexing device, the method including identifying which photodetector of a first array of photodetectors is converting a first channel of an optical signal into a first electrical channel signal, and affecting a communicative connection between the identified photodetector of the first array of photodetectors that is converting the first channel of the optical signal into the first electrical channel signal and a first output node associated with the first electrical channel signal.
    Type: Grant
    Filed: July 31, 2012
    Date of Patent: June 30, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Douglas M. Gill, Jonathan E. Proesel, Alexander V. Rylyakov, Clint L. Schow
  • Patent number: 9059025
    Abstract: A semiconductor chip having a photonics device and a CMOS device which includes a photonics device portion and a CMOS device portion on a semiconductor chip; a metal or polysilicon gate on the CMOS device portion, the metal or polysilicon gate having a gate extension that extends toward the photonics device portion; a germanium gate on the photonics device portion such that the germanium gate is coplanar with the metal or polysilicon gate, the germanium gate having a gate extension that extends toward the CMOS device portion, the germanium gate extension and metal or polysilicon gate extension joined together to form a common gate; spacers formed on the germanium gate and the metal or polysilicon gate; and nitride encapsulation formed on the germanium gate.
    Type: Grant
    Filed: August 30, 2013
    Date of Patent: June 16, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, William M. J. Green, Steven M. Shank, Yurii A. Vlasov
  • Patent number: 9036959
    Abstract: A method of forming an integrated photonic semiconductor structure having a photonic device and adjacent CMOS devices may include depositing a first silicon nitride layer over the adjacent CMOS devices and depositing an oxide layer over the first silicon nitride layer, wherein the oxide layer conformally covers the first silicon nitride layer and the underlying adjacent CMOS devices to form a substantially planarized surface over the adjacent CMOS devices. A second silicon nitride layer is then deposited over the oxide layer and a region corresponding to forming the photonic device. A germanium layer is deposited over the oxide layer and the region corresponding to forming the photonic device. The germanium layer deposited over the adjacent CMOS devices is etched to form a germanium active layer within the photonic region, whereby the oxide layer and the second silicon nitride layer protect the adjacent CMOS devices during the etching of the germanium.
    Type: Grant
    Filed: January 2, 2013
    Date of Patent: May 19, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Marwan H. Khater, Edward W. Kiewra, Steven M. Shank
  • Patent number: 9006049
    Abstract: Disclosed are process enhancements to fully integrate the processing of a photonics device into a CMOS manufacturing process flow. A CMOS wafer may be divided into different portions. One of the portions is for the CMOS devices and one or more other portions are for the photonics devices. The photonics devices include a ridged waveguide and a germanium photodetector. The germanium photodetector may utilize a seeded crystallization from melt process so there is more flexibility in the processing of the germanium photodetector.
    Type: Grant
    Filed: November 20, 2013
    Date of Patent: April 14, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, William M. J. Green, Yurii A. Vlasov, Min Yang
  • Patent number: 9006048
    Abstract: Disclosed are process enhancements to fully integrate the processing of a photonics device into a CMOS manufacturing process flow. A CMOS wafer may be divided into different portions. One of the portions is for the CMOS devices and one or more other portions are for the photonics devices. The photonics devices include a ridged waveguide. One or more process steps may be performed simultaneously on the CMOS devices and the photonics devices.
    Type: Grant
    Filed: November 20, 2013
    Date of Patent: April 14, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, William M. J. Green, Yurii A. Vlasov, Min Yang
  • Publication number: 20150054041
    Abstract: A method of protecting a CMOS device within an integrated photonic semiconductor structure is provided. The method may include depositing a conformal layer of germanium over the CMOS device and an adjacent area to the CMOS device, depositing a conformal layer of dielectric hardmask over the germanium, and forming, using a mask level, a patterned layer of photoresist for covering the CMOS device and a photonic device formation region within the adjacent area. Openings are etched into areas of the deposited layer of silicon nitride not covered by the patterned photoresist, such that the areas are adjacent to the photonic device formation region. The germanium material is then etched from the conformal layer of germanium at a location underlying the etched openings for forming the photonic device at the photonic device formation region. The conformal layer of germanium deposited over the CMOS device protects the CMOS device.
    Type: Application
    Filed: August 20, 2013
    Publication date: February 26, 2015
    Applicant: International Business Machines Corporation
    Inventors: Solomon Assefa, Marwan H. Khater, Edward W. Kiewra, Carol Reinholm, Steven M. Shank
  • Patent number: 8948548
    Abstract: A method for demultiplexing an optical signal includes receiving a multi polarization optical signal, separating the multi polarization optical signal into a first polarization optical signal and a second polarization optical signal, rotating a polarization of the first polarization optical signal to match a polarization of the second polarization optical signal, routing the first polarization optical signal and the second polarization optical signal to a common demultiplexing device, outputting a channel of the first polarization optical signal and the second polarization optical signal to a common photodetector.
    Type: Grant
    Filed: September 12, 2012
    Date of Patent: February 3, 2015
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Douglas M. Gill, William M. Green
  • Patent number: 8912032
    Abstract: Current may be passed through an n-doped semiconductor region, a recessed metal semiconductor alloy portion, and a p-doped semiconductor region so that the diffusion of majority charge carriers in the doped semiconductor regions transfers heat from or into the semiconductor waveguide through Peltier-Seebeck effect. Further, a temperature control device may be configured to include a metal semiconductor alloy region located in proximity to an optoelectronic device, a first semiconductor region having a p-type doping, and a second semiconductor region having an n-type doping. The temperature of the optoelectronic device may thus be controlled to stabilize the performance of the optoelectronic device.
    Type: Grant
    Filed: January 23, 2013
    Date of Patent: December 16, 2014
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, William M. Green, Young-hee Kim, Joris Van Campenhout, Yurii A. Vlasov
  • Patent number: 8884387
    Abstract: A semiconductor device includes a substrate including an M2 patterned area. A VA pillar structure is formed over the M2 patterned area. The VA pillar structure includes a substractively patterned metal layer. The VA pillar structure is a sub-lithographic contact. An MTJ stack is formed over the oxide layer and the metal layer of the VA pillar. A size of the MTJ stack and a shape anisotropy of the MTJ stack are independent of a size and a shape anisotropy of the sub-lithographic contact.
    Type: Grant
    Filed: August 7, 2012
    Date of Patent: November 11, 2014
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Michael C. Gaidis, Eric A. Joseph, Eugene J. O'Sullivan
  • Publication number: 20140312443
    Abstract: A method of forming an integrated photonic semiconductor structure having a photodetector and a CMOS device may include forming the CMOS device on a first silicon-on-insulator region, forming a silicon optical waveguide on a second silicon-on-insulator region, and forming a shallow trench isolation (STI) region surrounding the silicon optical waveguide such that the shallow trench isolation electrically isolates the first and second silicon-on-insulator region. Within the STI region, a germanium material is deposited adjacent an end facet of the semiconductor optical waveguide. The germanium material forms an active region that receives propagating optical signals from the end facet of the semiconductor optical waveguide.
    Type: Application
    Filed: April 23, 2013
    Publication date: October 23, 2014
    Applicant: International Business Machines Corportion
    Inventors: SOLOMON ASSEFA, WILLIAM M. GREEN, STEVEN M. SHANK, YURII A. VLASOV
  • Patent number: 8867920
    Abstract: An electro-optical device includes an optical de-multiplexing portion operative to output a first optical signal having a first wavelength and a second optical signal having a second wavelength, an array of photodetectors, and a switching logic portion communicatively connected to the array of photodetectors, the switching logic portion operative to determine which photodetector of the array of photodetectors is converting the first optical signal into a first electrical signal and output the first electrical signal from a first output node associated with the first optical signal.
    Type: Grant
    Filed: July 24, 2012
    Date of Patent: October 21, 2014
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Douglas M. Gill, Jonathan E. Proesel, Alexander V. Rylyakov, Clint L. Schow
  • Patent number: 8847338
    Abstract: A magnetic memory cell having a self-aligned hard mask for contact to a magnetic tunnel junction is provided. For example, a magnetic memory cell includes a magnetic storage element formed on a semiconductor substrate, and a hard mask that is self-aligned with the magnetic storage element. The hard mask includes a hard mask material layer formed on an upper surface of a magnetic stack in the magnetic storage element, an anti-reflective coating (ARC) layer formed on at least a portion of an upper surface of the hard mask material layer, wherein the ARC layer is selected to be removable by a wet etch, and a photoresist layer formed on at least a portion of an upper surface of the ARC layer. The selected portions of the ARC layer and photoresist layer are removed in a same processing step with wet etch techniques without interference to the magnetic stack.
    Type: Grant
    Filed: March 22, 2012
    Date of Patent: September 30, 2014
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Sivananda K. Kanakasabapathy
  • Patent number: 8846440
    Abstract: A method for forming a photodetector device includes forming an insulator layer on a substrate, forming a germanium (Ge) layer on the insulator layer and a portion of the substrate, forming a second insulator layer on the Ge layer, patterning the Ge layer, forming a capping insulator layer on the second insulator layer and a portion of the first insulator layer, heating the device to crystallize the Ge layer resulting in an single crystalline Ge layer, implanting n-type ions in the single crystalline Ge layer, heating the device to activate n-type ions in the single crystalline Ge layer, and forming electrodes electrically connected to the single crystalline n-type Ge layer.
    Type: Grant
    Filed: December 12, 2013
    Date of Patent: September 30, 2014
    Assignee: International Business Machines Corporation
    Inventors: Solomon Assefa, Jeehwan Kim, Jin-Hong Park, Yurii A. Vlasov