Patents by Inventor Aftab Ahmad

Aftab Ahmad 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: 6858507
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the N-LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Grant
    Filed: July 19, 2002
    Date of Patent: February 22, 2005
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Charles Dennison
  • Publication number: 20050017312
    Abstract: A barrier layer comprising silicon mixed with an impurity is disclosed for protection of gate dielectrics in integrated transistors. In particular, the barrier layer comprises silicon incorporating nitrogen. The nitrogen can be incorporated into an upper portion of the gate polysilicon during deposition, or a silicon layer doped with nitrogen after silicon deposition. The layer is of particular utility in conjunction with CVD tungsten silicide straps.
    Type: Application
    Filed: July 27, 2004
    Publication date: January 27, 2005
    Inventors: Nanseng Jeng, Aftab Ahmad
  • Publication number: 20050012158
    Abstract: A semiconductor structure pad oxide layer is enlarged by local oxidation of silicon to form a field oxide. An etchback causes the thinnest portions of the field oxide to recede such that a portion of the semiconductor substrate is exposed. An etch through the exposed portion of the semiconductor substrate forms a microtrench between the field oxide and the nitride layer with a lateral dimension that is less than that currently achievable by conventional photolithography. The microtrench is then filled by oxide or nitride growth or by deposition of a dielectric material. In another embodiment, formation of the microtrench is carried out as set forth above, but the nitride layer is removed immediately following trench formation. Alternatively, the pad oxide layer is stripped and a new oxide layer is regrown that substantially covers all exposed surfaces of active areas of the semiconductor substrate.
    Type: Application
    Filed: July 27, 2004
    Publication date: January 20, 2005
    Inventors: Fernando Gonzalez, Mike Violette, Nanseng Jeng, Aftab Ahmad, Klaus Schuegraf
  • Patent number: 6831347
    Abstract: A shallow trench isolation is disclosed wherein the trench depth is reduced beyond that achieved in prior art processes. The reduced trench depth helps to eliminate the formation of voids during the trench refill process and provides for greater planarity in the final isolation structure. Effective device isolation is achieved with a reduced trench depth by utilizing refilling dielectric materials having low dielectric constant.
    Type: Grant
    Filed: September 17, 1997
    Date of Patent: December 14, 2004
    Assignee: Micron Technology, Inc.
    Inventors: Klaus F. Schuegraf, Aftab Ahmad
  • Patent number: 6809395
    Abstract: A semiconductor structure pad oxide layer is enlarged by local oxidation of silicon to form a field oxide. An etchback causes the thinnest portions of the field oxide to recede such that a portion of the semiconductor substrate is exposed. An etch through the exposed portion of the semiconductor substrate forms a microtrench between the field oxide and the nitride layer with a lateral dimension that is less than that currently achievable by conventional photolithography. The microtrench is then filled by oxide or nitride growth or by deposition of a dielectric material. In another embodiment, formation of the microtrench is carried out as set forth above, but the nitride layer is removed immediately following trench formation. Alternatively, the pad oxide layer is stripped and a new oxide layer is regrown that substantially covers all exposed surfaces of active areas of the semiconductor substrate.
    Type: Grant
    Filed: August 6, 1999
    Date of Patent: October 26, 2004
    Assignee: Micron Technology, Inc.
    Inventors: Fernando Gonzales, Mike Violette, Nanseng Jeng, Aftab Ahmad, Klaus Schuegraf
  • Patent number: 6770571
    Abstract: A barrier layer comprising silicon mixed with an impurity is disclosed for protection of gate dielectrics in integrated transistors. In particular, the barrier layer comprises silicon incorporating nitrogen. The nitrogen can be incorporated into an upper portion of the gate polysilicon during deposition, or a silicon layer doped with nitrogen after silicon deposition. The layer is of particular utility in conjunction with CVD tungsten silicide straps.
    Type: Grant
    Filed: January 8, 2003
    Date of Patent: August 3, 2004
    Assignee: Micron Technology, Inc.
    Inventors: Nanseng Jeng, Aftab Ahmad
  • Patent number: 6743979
    Abstract: An integrated circuit, including a substrate with circuitry formed therein, where the substrate has a peripheral edge. Also included are a top most electrically conductive layer and an underlying electrically conductive layer. Outer bonding pads are disposed in an outer ring, and are formed within the top most layer. Inner bonding pads are disposed in an inner ring, and are formed within the top most layer. Inner connectors electrically connect the inner bonding pads to the circuitry. The inner connectors are formed within the underlying layer, and have a width that is less than the width of the inner bonding pads, thereby defining a gap between the inner connectors. Outer connectors electrically connect the outer bonding pads to the circuitry. The outer connectors are formed within the underlying layer, and have a width that is less than the width of the gap between the inner connectors.
    Type: Grant
    Filed: August 29, 2003
    Date of Patent: June 1, 2004
    Assignee: LSI Logic Corporation
    Inventors: Michael J. Berman, Aftab Ahmad, Qwai H. Low, Chok J. Chia, Ramaswamy Ranganathan
  • Patent number: 6664600
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the N− LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Grant
    Filed: August 27, 2002
    Date of Patent: December 16, 2003
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Charles Dennison
  • Patent number: 6660600
    Abstract: Methods of forming integrated circuitry, methods of forming elevated source/drain regions, and methods of forming field effect transistors are described. In one embodiment, a transistor gate line is formed over a semiconductive substrate. A layer comprising undoped semiconductive material is formed laterally proximate the transistor gate line and joins with semiconductive material of the substrate and comprises elevated source/drain material for a transistor of the line. Subsequently, conductivity-modifying impurity is provided into the elevated source/drain material. In another embodiment, a common step is utilized to provide conductivity enhancing impurity into both elevated source/drain material and material of the gate line. In another embodiment, the undoped semiconductive layer is first patterned and etched to provide elevated source/drain regions prior to provision of the conductivity-modifying impurity.
    Type: Grant
    Filed: August 30, 2002
    Date of Patent: December 9, 2003
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Lyle Jones
  • Publication number: 20030139061
    Abstract: A barrier layer comprising silicon mixed with an impurity is disclosed for protection of gate dielectrics in integrated transistors. In particular, the barrier layer comprises silicon incorporating nitrogen. The nitrogen can be incorporated into an upper portion of the gate polysilicon during deposition, or a silicon layer doped with nitrogen after silicon deposition. The layer is of particular utility in conjunction with CVD tungsten silicide straps.
    Type: Application
    Filed: January 8, 2003
    Publication date: July 24, 2003
    Inventors: Nanseng Jeng, Aftab Ahmad
  • Patent number: 6552394
    Abstract: The invention encompasses a transistor device comprising a region of a semiconductor material, and a transistor gate over a portion of the region. The device comprises a pair of opposing sidewall spacers adjacent sidewalls of the transistor gate and a pair of opposing first conductivity type source/drain regions within the semiconductor material proximate the transistor gate. The entirety of the semiconductor material under one of the sidewall spacers being defined as a first segment, and the entirety of the semiconductor material which is under the other of the sidewall spacers being defined as a second segment. The first and second segments of the semiconductor material are separated from the first and second source/drain regions by first and second gap regions, respectively, of the semiconductor material. The device further comprises a pair of opposing second conductivity type halo regions within the first and second gap regions.
    Type: Grant
    Filed: November 29, 2001
    Date of Patent: April 22, 2003
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, David J. Keller
  • Publication number: 20020197804
    Abstract: Methods of forming integrated circuitry, methods of forming elevated source/drain regions, and methods of forming field effect transistors are described. In one embodiment, a transistor gate line is formed over a semiconductive substrate. A layer comprising undoped semiconductive material is formed laterally proximate the transistor gate line and joins with semiconductive material of the substrate and comprises elevated source/drain material for a transistor of the line. Subsequently, conductivity-modifying impurity is provided into the elevated source/drain material. In another embodiment, a common step is utilized to provide conductivity enhancing impurity into both elevated source/drain material and material of the gate line. In another embodiment, the undoped semiconductive layer is first patterned and etched to provide elevated source/drain regions prior to provision of the conductivity-modifying impurity.
    Type: Application
    Filed: August 30, 2002
    Publication date: December 26, 2002
    Inventors: Aftab Ahmad, Lyle Jones
  • Publication number: 20020190315
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the − LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Application
    Filed: August 27, 2002
    Publication date: December 19, 2002
    Inventors: Aftab Ahmad, Charles Dennison
  • Patent number: 6495885
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the N− LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Grant
    Filed: February 16, 2000
    Date of Patent: December 17, 2002
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Charles Dennison
  • Publication number: 20020182813
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the −LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Application
    Filed: July 19, 2002
    Publication date: December 5, 2002
    Inventors: Aftab Ahmad, Charles Dennison
  • Patent number: 6448141
    Abstract: A process for grading the junctions of a lightly doped drain (LDD) N-channel MOSFET by performing a low dosage phosphorous implant after low and high dosage arsenic implants have been performed during the creation of the N− LDD regions and N+ source and drain electrodes. The phosphorous implant is driven to diffuse across both the electrode/LDD junctions and the LDD/channel junctions.
    Type: Grant
    Filed: August 28, 2000
    Date of Patent: September 10, 2002
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Charles Dennison
  • Patent number: 6444529
    Abstract: Methods of forming integrated circuitry, methods of forming elevated source/drain regions, and methods of forming field effect transistors are described. In one embodiment, a transistor gate line is formed over a semiconductive substrate. A layer comprising undoped semiconductive material is formed laterally proximate the transistor gate line and joins with semiconductive material of the substrate and comprises elevated source/drain material for a transistor of the line. Subsequently, conductivity-modifying impurity is provided into the elevated source/drain material. In another embodiment, a common step is utilized to provide conductivity enhancing impurity into both elevated source/drain material and material of the gate line. In another embodiment, the undoped semiconductive layer is first patterned and etched to provide elevated source/drain regions prior to provision of the conductivity-modifying impurity.
    Type: Grant
    Filed: January 26, 2001
    Date of Patent: September 3, 2002
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, Lyle Jones
  • Publication number: 20020074597
    Abstract: The invention includes a method for forming graded junction regions comprising: a) providing a semiconductor material wafer; b) providing a transistor gate over the semiconductor material wafer, the transistor gate having opposing lateral sidewalls; c) providing sidewall spacers adjacent the sidewalls of the transistor gate, the sidewall spacers having a lateral thickness; d) decreasing the lateral thickness of the sidewall spacers; and e) after decreasing the lateral thickness of the sidewall spacers, implanting a conductivity-enhancing dopant into the semiconductor material to form graded junction regions operatively adjacent the transistor gate.
    Type: Application
    Filed: November 29, 2001
    Publication date: June 20, 2002
    Inventors: Aftab Ahmad, David J. Keller
  • Patent number: 6373114
    Abstract: A barrier layer comprising silicon mixed with an impurity is disclosed for protection of gate dielectrics in integrated transistors. In particular, the barrier layer comprises silicon incorporating nitrogen. The nitrogen can be incorporated into an upper portion of the gate polysilicon during deposition, or a silicon layer doped with nitrogen after silicon deposition. The layer is of particular utility in conjunction with CVD tungsten silicide straps.
    Type: Grant
    Filed: October 23, 1998
    Date of Patent: April 16, 2002
    Assignee: Micron Technology, Inc.
    Inventors: Nanseng Jeng, Aftab Ahmad
  • Patent number: 6346439
    Abstract: The invention includes a method for forming graded junction regions comprising: a) providing a semiconductor material wafer; b) providing a transistor gate over the semiconductor material wafer, the transistor gate having opposing lateral sidewalls; c) providing sidewall spacers adjacent the sidewalls of the transistor gate, the sidewall spacers having a lateral thickness; d) decreasing the lateral thickness of the sidewall spacers; and e) after decreasing the lateral thickness of the sidewall spacers, implanting a conductivity-enhancing dopant into the semiconductor material to form graded junction regions operatively adjacent the transistor gate.
    Type: Grant
    Filed: July 9, 1996
    Date of Patent: February 12, 2002
    Assignee: Micron Technology, Inc.
    Inventors: Aftab Ahmad, David J. Keller