Patents by Inventor Shahin Sharifzadeh

Shahin Sharifzadeh 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: 7773442
    Abstract: A complementary field-effect (CMOS) circuit is provided which includes a current-limiting device arranged along a power-supply bus or a ground bus of the circuit. The current-limiting device is configured to prevent latch up of the CMOS circuit. More specifically, the current-limiting device is configured to maintain a junction of the parasitic pnpn diode structure as reverse-biased. A method is also provided which includes creating a current-voltage plot of a pnpn diode arranged within a first CMOS circuit which is absent of a current-limiting device arranged along a power bus of the circuit. In addition, the method includes determining a holding current level from the current-voltage plot and sizing a current-limiting device to place along a power bus of a second CMOS circuit comprising similar design specifications as the first CMOS circuit such that the current through the second CMOS circuit does not exceed the holding current level.
    Type: Grant
    Filed: June 25, 2004
    Date of Patent: August 10, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventors: Ravindra M. Kapre, Shahin Sharifzadeh
  • Publication number: 20090213677
    Abstract: A complementary field-effect (CMOS) circuit is provided which includes a current-limiting device arranged along a power-supply bus or a ground bus of the circuit The current-limiting device is configured to prevent latch up of the CMOS circuit. More specifically, the current-limiting device is configured to maintain a junction of the parasitic pnpn diode structure as reverse-biased. A method is also provided which includes creating a current-voltage plot of a pnpn diode arranged within a first CMOS circuit which is absent of a current-limiting device arranged along a power bus of the circuit. In addition, the method includes determining a holding current level from the current-voltage plot and sizing a current-limiting device to place along a power bus of a second CMOS circuit comprising similar design specifications as the first CMOS circuit such that the current through the second CMOS circuit does not exceed the holding current level.
    Type: Application
    Filed: May 1, 2009
    Publication date: August 27, 2009
    Inventors: Ravindra M. Kapre, Shahin Sharifzadeh
  • Publication number: 20050286295
    Abstract: A complementary field-effect (CMOS) circuit is provided which includes a current-limiting device arranged along a power-supply bus or a ground bus of the circuit. The current-limiting device is configured to prevent latch up of the CMOS circuit. More specifically, the current-limiting device is configured to maintain a junction of the parasitic pnpn diode structure as reverse-biased. A method is also provided which includes creating a current-voltage plot of a pnpn diode arranged within a first CMOS circuit which is absent of a current-limiting device arranged along a power bus of the circuit. In addition, the method includes determining a holding current level from the current-voltage plot and sizing a current-limiting device to place along a power bus of a second CMOS circuit comprising similar design specifications as the first CMOS circuit such that the current through the second CMOS circuit does not exceed the holding current level.
    Type: Application
    Filed: June 25, 2004
    Publication date: December 29, 2005
    Inventors: Ravindra Kapre, Shahin Sharifzadeh
  • Patent number: 6831346
    Abstract: In an embodiment of an integrated circuit structure having buried layer substrate isolation and a method for forming same, a buried layer having conductivity type opposite to that of an overlying well region is used for wells containing transistors prone to noise generation, where the wells are of the same conductivity type as the substrate. The buried layer may in some embodiments include a first portion underlying the transistor and a second portion spaced apart from and laterally surrounding the first portion. In some embodiments, the circuit may include a doped annular region of the same conductivity type as the buried layer, where the annular region contacts a portion of the buried layer and laterally surrounds the transistor. The circuit may further include metallization adapted to connect the well and annular region to opposite polarities of a power supply voltage, or in some embodiments to preclude such connection.
    Type: Grant
    Filed: May 4, 2001
    Date of Patent: December 14, 2004
    Assignee: Cypress Semiconductor Corp.
    Inventors: Gabriel Li, Kenelm G. D. Murray, Jose Arreola, Shahin Sharifzadeh, K. Nirmal Ratnakumar
  • Patent number: 6773975
    Abstract: In one embodiment, a transistor is fabricated by forming gate materials, such as a gate oxide layer and a gate polysilicon layer, prior to forming a shallow trench isolation (STI) structure. Forming the gate materials early in the process minimizes exposure of the STI structure to processing steps that may expose its corners. Also, to minimize cross-diffusion of dopants and to help lower gate resistance, a metal stack comprising a barrier layer and a metal layer may be employed as a conductive line between gates. In one embodiment, the metal stack comprises a barrier layer of tungsten-nitride and a metal layer of tungsten.
    Type: Grant
    Filed: December 20, 2002
    Date of Patent: August 10, 2004
    Assignee: Cypress Semiconductor Corporation
    Inventors: Krishnaswamy Ramkumar, Sundar Narayanan, Shahin Sharifzadeh
  • Patent number: 6734108
    Abstract: According to one embodiment (300), a method of forming a self-aligned contact can include forming adjacent conducting structures with sidewalls (302). A first insulating layer may then be formed without first forming a liner (304), such as a liner that is conventionally formed to protect underlying conducting structures and/or a substrate. A contact hole may then be etched between adjacent conducting structures (306). Contact structures may then be formed (308).
    Type: Grant
    Filed: September 27, 1999
    Date of Patent: May 11, 2004
    Assignee: Cypress Semiconductor Corporation
    Inventors: Bo Jin, Jianmin Qiao, Shahin Sharifzadeh
  • Patent number: 5897371
    Abstract: The present invention concerns a process that maintains a second (or "replica") set of alignment marks during existing processing steps used in manufacturing a semiconductor device or integrated circuit, including CMP and other planarization methods. The present invention avoids alignment problems encountered in conventional CMP processes, particularly tungsten CMP. All alignment steps can be realized through one or more subsequent second (or "replica") alignment marks, set and preserved throughout the remaining process steps, thus maintaining alignment integrity. The present method and apparatus concerns a new alignment mark that may be "printed" in a metal layer on the wafer, for example, a local interconnect or contact layer. The new alignment mark is generally not subjected to planarization or to an "open frame" process. The new alignment mark may also be used to re-etch other alignment marks directly onto the layer conventionally causing alignment problems, such as those created following CMP.
    Type: Grant
    Filed: December 19, 1996
    Date of Patent: April 27, 1999
    Assignee: Cypress Semiconductor Corp.
    Inventors: Kuantai Yeh, Ahmad Chatila, Shahin Sharifzadeh