Patents by Inventor Sunil D. Mehta

Sunil D. Mehta 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: 6362527
    Abstract: An improved manufacturing process and an improved device made by the process for forming via interconnects between metal layers in a multilevel metallization structure substantially eliminates trench formation during via overetch and exploding vias during via fill. An insulating multilayer structure comprising a conformal oxide, a spin-on layer, and an etch stop layer for the via etch locally planarizes the region adjacent to metal lines before the ILD is deposited and vias are patterned and etched. Using this process, metal borders around vias can be reduced or eliminated, thereby increasing circuit packing density.
    Type: Grant
    Filed: November 21, 1996
    Date of Patent: March 26, 2002
    Assignee: Advanced Micro Devices, Inc.
    Inventor: Sunil D. Mehta
  • Publication number: 20020019143
    Abstract: The present invention is a method for fabricating high quality oxides on a plurality of semiconductor wafers by proper positioning of those semiconductor wafers with respect to each other within a wafer cassette for processing within a bath. Each of the plurality of semiconductor wafers has a predetermined diameter. The method of the present invention includes a step of placing the plurality of semiconductor wafers in a wafer cassette that holds the plurality of semiconductor wafers in a stack configuration. According to the present invention, the plurality of semiconductor wafers within the wafer cassette are spaced with a respective predetermined distance between any two adjacent semiconductor wafers such that a respective ratio of the respective predetermined distance to the predetermined diameter of a semiconductor wafer is at least 0.12.
    Type: Application
    Filed: March 25, 1999
    Publication date: February 14, 2002
    Inventors: HYEON-SEAG KIM, QXIAO-YU LI, SUNIL D. MEHTA
  • Patent number: 6326663
    Abstract: A non-volatile memory cell, comprising a semiconductor substrate having a first conductivity type. A control region is formed of said first conductivity type in the substrate and a control region oxide formed over the control region. The cell includes a program element having a first active region of a second conductivity type formed in said substrate, a doped or implanted region adjacent to said first active region, and a gate oxide overlying at least the channel region. An active region oxide covers a portion of the first active region. A floating gate is formed over said semiconductor substrate on said active region oxide and said control region oxide.
    Type: Grant
    Filed: March 26, 1999
    Date of Patent: December 4, 2001
    Assignee: Vantis Corporation
    Inventors: Xiao-Yu Li, Steven J. Fong, Sunil D. Mehta
  • Publication number: 20010042883
    Abstract: An improved EEPROM cell with a self-aligned tunneling window is provided which is fabricated by a standard STI process so as to produce a smaller layout size and a reduced cell height. The EEPROM cell includes a floating gate, a programmable junction region, and a tunneling oxide layer separating the programmable junction region and the floating gate. The length dimension of the floating gate is less than the length dimension of the tunneling window so that the tunneling window is overlapping the floating gate. The tunneling window is self-aligned by edges forming the length dimension of the floating gate so as to form a self-aligned tunneling window.
    Type: Application
    Filed: October 9, 1998
    Publication date: November 22, 2001
    Inventors: XIAO YU LI, SUNIL D. MEHTA, CHRISTOPHER O. SCHMIDT
  • Patent number: 6309942
    Abstract: A method of manufacturing a semiconductor device with reduced shallow trench isolation defects and stress is disclosed. The disclosed method begins by providing a silicon substrate including a capping layer. A plurality of isolation trenches are then etched through the capping layer and into the silicon substrate to form a plurality of isolation regions in the silicon substrate. The isolation trenches are then filled with an oxide layer. The oxide layer and the capping layer are then polished back using techniques known in the art. After polishing, the semiconductor device is annealed between a temperature range of about 1150° C. to about 1200° C.
    Type: Grant
    Filed: February 4, 1999
    Date of Patent: October 30, 2001
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Ting Y. Tsui, Robert H. Tu, Xiao-Yu Li, Sunil D. Mehta
  • Patent number: 6297128
    Abstract: This invention provides methods for reducing the mechanical stresses within dielectric layers filling the gaps in shallow trench isolation (STI) regions on semiconductor wafers. The methods include the sequential deposition of alternating layers of dielectric materials having tensile stress and compressive stress, respectively. The invention also provides methods for adjusting the residual stress in a dielectric film by controlling the relative thicknesses of the alternating layers of dielectric material to provide bilayers having minimal overall stress. Additionally, the invention provides semiconductor devices having the reduced stress dielectric materials within the shallow isolation trenches of the semiconductor wafer. The reduction in stress within and between trenches decreases defects in the shallow isolation materials and thereby decreases source-drain and trench—trench short circuiting.
    Type: Grant
    Filed: January 29, 1999
    Date of Patent: October 2, 2001
    Assignee: Vantis Corporation
    Inventors: Hyeon-Seag Kim, Sunil D. Mehta
  • Publication number: 20010022359
    Abstract: A non-volatile memory cell comprises a first well region of a first conductivity type within a second well region of a second conductivity type in a substrate. At least one impurity region of an opposite conductivity type to said first conductivity type is formed in the first well as is a well tap region of said first conductivity type. An isolation gate is formed on the surface of the substrate between said at least one impurity region and said well tap region.
    Type: Application
    Filed: January 8, 2001
    Publication date: September 20, 2001
    Inventor: Sunil D. Mehta
  • Patent number: 6291327
    Abstract: A method for eliminating source/drain shorting generated during the highly-doped source/drain implant steps in a standard STI process is provided. This is achieved by reducing the RTA temperature to be less than 1000° C. so as to minimize enhanced doping diffusion. Further, the energy level for the highly-doped source/drain implant steps is increased so to compensate for poly depletion in the gate electrodes.
    Type: Grant
    Filed: November 13, 1998
    Date of Patent: September 18, 2001
    Assignee: Lattice Semiconductor Corporation
    Inventors: Xiao-Yu Li, Sunil D. Mehta, Christopher O. Schmidt, Robert H. Tu
  • Patent number: 6287916
    Abstract: An improved method of fabricating a non-volatile semiconductor device having a PECVD nitride cap layer formed under a BPTEOS oxide film is provided. The present method utilizes the step of forming a LPCVD nitride film under the PECVD nitride cap layer and over the floating gate so as to protect the floating gate from charge loss.
    Type: Grant
    Filed: December 7, 2000
    Date of Patent: September 11, 2001
    Assignee: Lattice Semiconductor Corporation
    Inventor: Sunil D. Mehta
  • Patent number: 6282123
    Abstract: A non-volatile memory cell is formed in a semiconductor substrate and includes a control gate and a floating gate formed over said semiconductor substrate. A first active region and a second active region formed in said substrate. A first implant region formed in said substrate, said first implant region contiguous to said first active region and a second implant region formed in said substrate, said second implant region contiguous to said second active region. A channel region separates said first implant region and said second implant region. In a further aspect, a method of programming and erasing a non-volatile memory cell is disclosed. Programming of said cell is accomplished by injecting hot carriers into a floating gate through a first area of an oxide layer by capacitively coupling said floating gate to a substrate. Erasing said cell is accomplished by injecting oppositely charged hot carriers into said floating gate through a second area of said oxide layer.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: August 28, 2001
    Assignee: Lattice Semiconductor Corporation
    Inventor: Sunil D. Mehta
  • Patent number: 6274898
    Abstract: A triple-well EEPROM cell is described that is programmed and erased by electron tunneling across an entire portion of separate transistor channels. The EEPROM cell has three transistors formed in a semiconductor substrate. The three transistors are a tunneling transistor (NMOS), a sense transistor (NMOS) and a read transistor (NMOS). The tunneling transistor is formed in a second well (e.g a P conductivity type well) that is separated from the substrate by a first well, having e.g. an N conductivity type. a first well formed in the substrate. Electron tunneling occurs to program the EEPROM cell through a sense tunnel oxide layer upon incurrence of a sufficient voltage potential between a floating gate and the sense channel. Electron tunneling also occurs to erase the EEPROM cell through a tunnel oxide layer upon incurrence of a sufficient voltage potential between the floating gate and the tunneling channel.
    Type: Grant
    Filed: May 21, 1999
    Date of Patent: August 14, 2001
    Assignee: Vantis Corporation
    Inventors: Sunil D. Mehta, Xiao-Yu Li
  • Patent number: 6261944
    Abstract: A semiconductor device having a high reliability passivation includes a planarization layer overlying a multi-level interconnect layer. The passivation layer has a planar surface upon which additional passivation layers are formed. Openings in the overlying passivation layers and the planarization layer expose bonding pads in the multi-level interconnect layer. In a process for fabricating the device, the planarization layer is preferably formed by dispensing a siloxane spin-on-glass (SOG) material onto the surface of the multi-level interconnect layer. The SOG is subsequently planarized to form a substantially planar surface.
    Type: Grant
    Filed: November 24, 1998
    Date of Patent: July 17, 2001
    Assignee: Vantis Corporation
    Inventors: Sunil D. Mehta, Xiao-Yu Li
  • Patent number: 6255169
    Abstract: A process for fabricating a non-volatile memory device includes the step of forming a nitrogen region in a semiconductor substrate prior to carrying out a thermal oxidation process to form a tunnel oxide layer. In a preferred process, nitrogen atoms are ion implanted into a silicon substrate to form a nitrogen region at the substrate surface. Then, a thermal oxidation process is carried out to grow a thin tunnel oxide layer overlying the surface of the nitrogen region. During the oxidation process, nitrogen is incorporated into the growing tunnel oxide layer. A floating-gate electrode is formed overlying the tunnel oxide layer and receives electrical charge transferred from a charge control region of the substrate through the tunnel oxide layer. The tunnel oxide layer is capable of undergoing repeated programming and erasing operations while exhibiting reduced effects from stress induced current leakage.
    Type: Grant
    Filed: February 22, 1999
    Date of Patent: July 3, 2001
    Assignees: Advanced Micro Devices, Inc., Vantis Corporation
    Inventors: Xiao-Yu Li, Qi Xiang, Sunil D. Mehta
  • Patent number: 6232223
    Abstract: High integrity borderless vias are formed with a protective sidewall spacer on the exposed side surface of the underlying metal feature before depositing a barrier layer. Embodiments include depositing a dielectric capping layer on a metal feature having an ARC, e.g., TiN, etching to form a through-hole stopping on the capping layer, and then etching the exposed capping layer to form the protective sidewall spacer. Other embodiments include depositing a hard inorganic mask layer on the upper surface of the metal feature before depositing the capping layer, forming the through-hole, and sequentially etching the exposed capping layer to form the protective sidewall spacer and then the inorganic hard mask layer. Further embodiments include metal features without an ARC and retaining the inorganic mask layer on the upper surface of the metal feature.
    Type: Grant
    Filed: September 28, 1999
    Date of Patent: May 15, 2001
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Khanh Q. Tran, Sunil D. Mehta
  • Patent number: 6232631
    Abstract: A non-volatile memory cell structure includes a floating gate, a reverse breakdown hot carrier injection element and a sense transistor. The reverse breakdown hot carrier injection element is at least partially formed in a first region of a semiconductor substrate under at least a portion of the floating gate. The sense transistor is at least partially formed in a second region of a semiconductor substrate, isolated from the first region, and under at least a portion of the floating gate. A read transistor may be connected to the sense transistor. In one embodiment, the read transistor is at least partially formed in the second region of a semiconductor substrate, and connected to the sense transistor.
    Type: Grant
    Filed: December 21, 1998
    Date of Patent: May 15, 2001
    Assignee: Vantis Corporation
    Inventors: Christopher O. Schmidt, Sunil D. Mehta
  • Patent number: 6221733
    Abstract: A method of minimizing mechanical stress generated during the trench-forming/trench-filling process steps in a standard shallow trench isolation (STI) process is provided. This is achieved by forming trenches with a more sloped and smoother profile, and/or limiting the trench depth to be less than 0.4 &mgr;m, and/or reducing or increasing the trench densification temperature, and/or performing the densification step after the chemical-mechanical polishing step. In addition, a furnace TEOS oxide film is used as the trench-filling material.
    Type: Grant
    Filed: November 13, 1998
    Date of Patent: April 24, 2001
    Assignee: Lattice Semiconductor Corporation
    Inventors: Xiao-Yu Li, Sunil D. Mehta, Robert H. Tu
  • Patent number: 6214666
    Abstract: A method for manufacturing a non-volatile EEPROM memory cell, and a memory cell structure provided by the method. The method comprises the steps of: forming a gate stack on the surface of a substrate; forming a first and a second active regions in the substrate so that the first and second active regions extend to a depth below the surface of the substrate and have a first impurity type and an impurity concentration; and implanting a pocket region of an opposite conductivity type to that of the first or second active region into the surface of the substrate adjacent to the first active region. The step of implanting a pocket region may performed by implanting substantially at an angle non-normal to the surface of the substrate.
    Type: Grant
    Filed: December 18, 1998
    Date of Patent: April 10, 2001
    Assignee: Vantis Corporation
    Inventor: Sunil D. Mehta
  • Patent number: 6215700
    Abstract: A non-volatile memory cell structure which includes a floating gate, a reverse breakdown element and a read transistor. The reverse breakdown element is at least partially formed in a first region of a first conductivity type in a semiconductor substrate, and underlies a portion of the floating gate; and the read transistor is at least partially formed in the first region and connected to the reverse breakdown element. In a further embodiment a control gate is capacitively coupled to the floating gate and is formed in a second region of the substrate, outside the well region.
    Type: Grant
    Filed: January 7, 1999
    Date of Patent: April 10, 2001
    Assignee: Vantis Corporation
    Inventors: Steven J. Fong, Stewart G. Logie, Sunil D. Mehta
  • Patent number: 6207989
    Abstract: A non-volatile memory device includes a floating-gate electrode overlying a tunnel oxide layer. A portion of the floating-gate electrode forms the control gate electrode for a sense transistor that is used to determine the presence of charge on the floating-gate electrode. A composite insulation layer overlies the floating-gate electrode. The composite insulation layer includes a dielectric layer, a doped insulating layer overlying the dielectric layer, and a planarization layer overlying the doped insulating layer. The thicknesses of the dielectric layer and the doped insulating layer are precisely determined, such that the doped insulating layer getters mobile ions, such as hydrogen ions, away from the floating-gate electrode, while not capacitively coupling with the floating-gate electrode.
    Type: Grant
    Filed: March 16, 1999
    Date of Patent: March 27, 2001
    Assignee: Vantis Corporation
    Inventors: Xiao-Yu Li, Sunil D. Mehta
  • Patent number: 6208559
    Abstract: An improved process of programming and erasing an EEPROM memory cell in an array of identical cells uses a reduced voltage on the write transistor of the cell to be programmed or erased and at the same time applies smaller voltages across the relatively thin oxides of the write transistors of the other cells in the array so as to reduce oxide leakage and damage in those cells but without disturbing the information stored in those cells. The result is the ability to scale down the size of the EEPROM memory cell allowing enhanced economies and permitting faster program, erase and reading speeds.
    Type: Grant
    Filed: November 15, 1999
    Date of Patent: March 27, 2001
    Assignee: Lattice Semiconductor Corporation
    Inventors: Robert H. Tu, Sunil D. Mehta