Patents by Inventor Rama Divakaruni

Rama Divakaruni 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).

  • Publication number: 20030186502
    Abstract: A method for processing a semiconductor memory device is disclosed, the memory device including an array area and a support area thereon. In an exemplary embodiment of the invention, the method includes removing, from the array area, an initial pad nitride material formed on the device. The initial pad nitride material in the support area, however, is still maintained. Active device areas are then formed within the array area, wherein the initial pad nitride maintained in the support area helps to protect the support area from wet etch processes implemented during the formation of active device areas within the array area.
    Type: Application
    Filed: May 27, 2003
    Publication date: October 2, 2003
    Applicants: INTERNATIONAL BUSINESS MACHINES CORPORATION, INFINEON TECHNOLOGIES NORTH AMERICA CORP.
    Inventors: Rajeev Malik, Larry Nesbit, Jochen Beintner, Rama Divakaruni
  • Patent number: 6620676
    Abstract: A method for processing a semiconductor memory device is disclosed, the memory device including an array area and a support area thereon. In an exemplary embodiment of the invention, the method includes removing, from the array area, an initial pad nitride material formed on the device. The initial pad nitride material in the support area, however, is still maintained. Active device areas are then formed within the array area, wherein the initial pad nitride maintained in the support area helps to protect the support area from wet etch processes implemented during the formation of active device areas within the array area.
    Type: Grant
    Filed: June 29, 2001
    Date of Patent: September 16, 2003
    Assignee: International Business Machines Corporation
    Inventors: Rajeev Malik, Larry Nesbit, Jochen Beintner, Rama Divakaruni
  • Patent number: 6605838
    Abstract: A trench capacitor memory cell structure is provided with includes a vertical collar region that suppresses current leakage of an adjacent vertical parasitic transistor that exists between the vertical MOSFET and the underlying trench capacitor. The vertical collar isolation, which has a vertical length of about 0.50 &mgr;m or less, includes a first portion that is present partially outside the trench and a second portion that is present inside the trench. The first portion of the collar oxide is thicker than said second portion oxide thereby reducing parasitic current leakage.
    Type: Grant
    Filed: September 30, 2002
    Date of Patent: August 12, 2003
    Assignees: International Business Machines Corporation, Infineon Technologies North America Corporation
    Inventors: Jack A. Mandelman, Rama Divakaruni, Gerd Fehlauer, Stephan Kudelka, Uwe Schroeder, Helmut H. Tews
  • Publication number: 20030116784
    Abstract: The invention provides improved DRAM cells using dual gate transistors, DRAM arrays and devices using DRAM cells as well as improved methods for manufacturing such cells, arrays and devices. The DRAM cells of the invention are characterized by the use of a shared bitline contact for each dual gate transistor. The DRAM arrays and devices of the invention are characterized by use of the DRAM cells of the invention and preferably by the use of a relaxed pitch layout for the bitline contacts. The techniques for manufacturing the DRAM arrays and devices of the invention are preferably characterized by use of a relaxed pitch bitline contact configuration which avoids the need for a critical mask.
    Type: Application
    Filed: December 21, 2001
    Publication date: June 26, 2003
    Applicant: International Business Machines Corporation
    Inventors: Rama Divakaruni, Carl J. Radens
  • Patent number: 6566228
    Abstract: Disclosed is a method of simultaneously supplying trench isolations for array and support areas of a semiconductor substrate made of a substrate material, the method comprising providing a first hard mask layer for the array and support areas, said first hard mask comprising mask openings defining trench isolations in the array and support areas, providing deep array trench isolations in the array areas, providing a blanketing planarized conductive material layer over both support and array areas sufficient to fill said mask openings and deep array trench isolations, etching said conductive material through said first hard mask material down into said semiconductor substrate so as to form support trench isolations, such that both deep array trench isolations and support trench isolations are of equal depth, and wherein a conductive element, comprising a quantity of said conductive material, remains in the bottom of each of said deep array trenches.
    Type: Grant
    Filed: February 26, 2002
    Date of Patent: May 20, 2003
    Assignees: International Business Machines Corporation, Infineon Technologies
    Inventors: Jochen Beintner, Rama Divakaruni, Jack A. Mandelman, Andreas Knorr
  • Patent number: 6509624
    Abstract: A structure and process for semiconductor fuses and antifuses in vertical DRAMS provides fuses and antifuses in trench openings formed within a semiconductor substrate. Vertical transistors may be formed in other of the trench openings formed within the semiconductor substrate. The fuse is formed including a semiconductor plug formed within an upper portion of the trench opening and includes conductive leads contacting the semiconductor plug. The antifuse is formed including a semiconductor plug formed within an upper portion of the trench opening and includes conductive leads formed over the semiconductor plug, at least one conductive lead isolated from the semiconductor plug by an antifuse dielectric. Each of the fuse and antifuse are fabricated using a sequence of process operations also used to simultaneously fabricate vertical transistors according to vertical DRAM technology.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: January 21, 2003
    Assignees: International Business Machines Corporation, Infineon Technologies AG
    Inventors: Carl J. Radens, Wolfgang Bergner, Rama Divakaruni, Larry Nesbit
  • Publication number: 20030003653
    Abstract: A method for processing a semiconductor memory device is disclosed, the memory device including an array area and a support area thereon. In an exemplary embodiment of the invention, the method includes removing, from the array area, an initial pad nitride material formed on the device. The initial pad nitride material in the support area, however, is still maintained. Active device areas are then formed within the array area, wherein the initial pad nitride maintained in the support area helps to protect the support area from wet etch processes implemented during the formation of active device areas within the array area.
    Type: Application
    Filed: June 29, 2001
    Publication date: January 2, 2003
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Rajeev Malik, Larry Nesbit, Jochen Beintner, Rama Divakaruni
  • Patent number: 6501131
    Abstract: The process rules for manufacturing semiconductor devices such as MOSFET's are modified to provide dual work-function doping following the customary gate sidewall oxidation step, greatly reducing thermal budget and boron penetration concerns. The concern of thermal budget is further significantly reduced by a device structure which allows a reduced gap aspect ratio while maintaining low sheet resistance values. A reduced gap aspect ratio also relaxes the need for highly reflowable dielectric materials and also facilitates the use of angled source-drain (S-D) and halo implants. Also provided is a novel structure and process for producing a MOSFET channel, lateral doping profile which suppresses short channel effects while providing low S-D junction capacitance and leakage, as well as immunity to hot-carrier effects. This also affords the potential for reduction in the contact stud-to-gate conductor capacitance, because borderless contacts can be formed with an oxide gate sidewall spacer.
    Type: Grant
    Filed: July 22, 1999
    Date of Patent: December 31, 2002
    Assignees: International Business Machines Corporation, Infineon Technologies AG
    Inventors: Rama Divakaruni, Jeffrey P. Gambino, Jack A. Mandelman, Rajesh Rengarajan
  • Patent number: 6498061
    Abstract: A process for fabricating a single-sided semiconductor deep trench structure filled with polysilicon trench fill material includes the following steps. Form a thin film, silicon nitride, barrier layer over the trench fill material. Deposit a thin film of an amorphous silicon masking layer over the barrier layer. Perform an angled implant into portions of the amorphous silicon masking layer which are not in the shadow of the deep trench. Strip the undoped portions of the amorphous silicon masking layer from the deep trench. Then strip the newly exposed portions of barrier layer exposing a part of the trench fill polysilicon surface and leaving the doped, remainder of the amorphous silicon masking layer exposed. Counterdope the exposed part of the trench fill material. Oxidize exposed portions of the polysilicon trench fill material, and then strip the remainder of the masking layer.
    Type: Grant
    Filed: December 6, 2000
    Date of Patent: December 24, 2002
    Assignees: International Business Machines Corporation, Infineon Technologies AG
    Inventors: Rama Divakaruni, Stephan Kudelka, Helmut Tews, Irene McStay, Kil-Ho Lee, Uwe Schroeder
  • Patent number: 6472258
    Abstract: A field effect transistor is formed with a sub-lithographic conduction channel and a dual gate which is formed by a simple process by starting with a silicon-on-insulator wafer, allowing most etching processes to use the buried oxide as an etch stop. Low resistivity of the gate, source and drain is achieved by silicide sidewalls or liners while low gate to junction capacitance is achieved by recessing the silicide and polysilicon dual gate structure from the source and drain region edges.
    Type: Grant
    Filed: November 13, 2000
    Date of Patent: October 29, 2002
    Assignee: International Business Machines Corporation
    Inventors: James W. Adkisson, Paul D. Agnello, Arne W. Ballantine, Rama Divakaruni, Erin C. Jones, Jed H. Rankin
  • Publication number: 20020149047
    Abstract: A structure and method which enables the deposit of a thin nitride liner just before Trench Top Oxide TTO (High Density Plasma) HDP deposition during the formation of a vertical MOSFET DRAM cell device. This liner is subsequently removed after TTO sidewall etch. One function of this liner is to protect the collar oxide from being etched during the TTO oxide sidewall etch and generally provides lateral etch protection which is not realized in the current processing scheme. The process sequence does not rely on previously deposited films for collar protection, and decouples TTO sidewall etch protection from previous processing steps to provide additional process flexibility, such as allowing a thinner strap Cut Mask nitride and greater nitride etching during node nitride removal and buried strap nitrided interface removal.
    Type: Application
    Filed: April 11, 2001
    Publication date: October 17, 2002
    Applicant: INTERNATIONAL BUSINESS MACHINES COPORATION
    Inventors: Rama Divakaruni, Thomas W. Dyer, Rajeev Malik, Jack A. Mandelman, V.C. Jaiprakash
  • Publication number: 20020140039
    Abstract: A field effect transistor is formed with a sub-lithographic conduction channel and a dual gate which is formed by a simple process by starting with a silicon-on-insulator wafer, allowing most etching processes to use the buried oxide as an etch stop. Low resistivity of the gate, source and drain is achieved by silicide sidewalls or liners while low gate to junction capacitance is achieved by recessing the silicide and polysilicon dual gate structure from the source and drain region edges.
    Type: Application
    Filed: June 18, 2002
    Publication date: October 3, 2002
    Applicant: International Business Machines Corporation
    Inventors: James W. Adkisson, Paul D. Agnello, Arne W. Ballantine, Rama Divakaruni, Erin C. Jones, Jed H. Rankin
  • Patent number: 6441423
    Abstract: The preferred embodiment of the present invention provides an improved capacitor design that overcomes many of the limitations of the prior art. The preferred embodiment of the present invention uses germanium to adjust the work function of the storage node. Specifically, the addition of germanium modifies the fermi level of the storage node, moving the fermi level towards the conduction band. This modification of the fermi level reduces the difference in conduction band-edge potentials between the storage node and the counter electrode, thus reducing the maximum electric potential seen across the capacitor. In the preferred embodiment, p-type doped silicon germanium is formed in the trench capacitor adjacent to the capacitor dielectric layer. A barrier layer is then formed over the doped silicon germanium, and the remaining storage node area is filled with n+-type polysilicon.
    Type: Grant
    Filed: May 31, 2000
    Date of Patent: August 27, 2002
    Assignee: International Business Machines Corporation
    Inventors: Jack A. Mandelman, Rama Divakaruni
  • Patent number: 6433397
    Abstract: An N-channel metal oxide semiconductor (NMOS) driver circuit (and method for making the same), includes a boost gate stack formed on a substrate and having a source and drain formed by a low concentration N-type implantation, and an N-driver coupled to the boost gate stack.
    Type: Grant
    Filed: January 21, 2000
    Date of Patent: August 13, 2002
    Assignee: International Business Machines Corporation
    Inventors: Lawrence A. Clevenger, Rama Divakaruni, Louis Lu-Chen Hsu, Yujun Li
  • Patent number: 6429477
    Abstract: The preferred embodiment overcomes the difficulties found in the background art by providing a body contact and diffusion contact formed in a single shared via for silicon on insulator (SOI) technologies. By forming the body contact and diffusion contact in a single shared via, device size is minimized and performance is improved. Particularly, the formed body contact connects the SOI layer with the underlying substrate to avoid instabilities and leakage resulting from a floating SOI channel region. The formed diffusion contact connects device diffusions to above wiring to facilitate device operation. By providing the body contact and diffusion contact together in a single shared via, the preferred embodiment avoids the area penalty that would result from separate contacts. Additionally, the preferred embodiment provides a body contact that is self aligned with other devices, minimizing tolerances needed while minimizing process complexity.
    Type: Grant
    Filed: October 31, 2000
    Date of Patent: August 6, 2002
    Assignee: International Business Machines Corporation
    Inventors: Jack A. Mandelman, Rama Divakaruni, William R. Tonti
  • Patent number: 6404000
    Abstract: A memory structure having a trenched formed in a substrate. A collar oxide is located in an upper portion of the trench and includes a pedestal portion. A method of forming a memory device having a collar oxide with pedestal collar is also disclosed.
    Type: Grant
    Filed: June 22, 2000
    Date of Patent: June 11, 2002
    Assignees: International Business Machines Corporation, Infineon Technologies North America Corp., Kabushiki Kaisha Toshiba
    Inventors: Rama Divakaruni, Rajarao Jammy, Byeong Y. Kim, Jack A. Mandelman, Akira Sudo, Dirk Tobben
  • Publication number: 20020068399
    Abstract: A process for fabricating a single-sided semiconductor deep trench structure filled with polysilicon trench fill material includes the following steps. Form a thin film, silicon nitride, barrier layer over the trench fill material. Deposit a thin film of an amorphous silicon masking layer over the barrier layer. Perform an angled implant into portions of the amorphous silicon masking layer which are not in the shadow of the deep trench. Strip the undoped portions of the amorphous silicon masking layer from the deep trench. Then strip the newly exposed portions of barrier layer exposing a part of the trench fill polysilicon surface and leaving the doped, remainder of the amorphous silicon masking layer exposed. Counterdope the exposed part of the trench fill material. Oxidize exposed portions of the polysilicon trench fill material, and then strip the remainder of the masking layer.
    Type: Application
    Filed: December 6, 2000
    Publication date: June 6, 2002
    Inventors: Rama Divakaruni, Stephan Kudelka, Helmut Tews, Irene McStay, Kil-Ho Lee, Uwe Schroeder
  • Patent number: 6373086
    Abstract: A deep trench capacitor having a modified sidewall geometry within the collar isolation region such that the threshold voltage of the vertical parasitic MOSFET between a buried-strap out-diffusion and a N+ capacitor plate is significantly increased as compared to a conventional arrangement. By forming a concave notch within the sidewalls of the capacitor, the electrical thickness of the gate dielectric is effectively thicker than its actual physical thickness. Thereby, a reduced amount of gate dielectric and dopant is needed for suppression of vertical parasitic MOSFET conduction.
    Type: Grant
    Filed: June 29, 2000
    Date of Patent: April 16, 2002
    Assignee: International Business Machines Corporation
    Inventors: Jack A. Mandelman, Rama Divakaruni, Byeong Y. Kim
  • Patent number: 6348394
    Abstract: A semiconductor device and method of manufacturing thereof are provided. A trench is formed in a semiconductor substrate. A thin oxide liner is preferably formed on surfaces of the trench. A nitride liner is formed in the trench. Charge is trapped in the nitride liner. In a preferred embodiment, the trench is filled with an oxide by an HDP process to increase the amount of charge trapped in the nitride liner. Preferably, the oxide fill is formed directly on the nitride liner.
    Type: Grant
    Filed: May 18, 2000
    Date of Patent: February 19, 2002
    Assignee: International Business Machines Corporation
    Inventors: Jack A. Mandelman, Rama Divakaruni, Herbert Ho, Giuseppe La Rosa, Yujun Li, Jochen Beintner, Radhika Srinivasan
  • Patent number: 6340615
    Abstract: A method of connecting a trench capacitor in a dynamic random access memory (DRAM) cell. First, trenches are formed in a silicon substrate using a masking layer including a pad nitride layer on a pad oxide layer. Trench capacitors are formed in the trenches. A buried strap is formed in each trench on the capacitor. The nitride pad layer is pulled back from the trench openings, exposing the pad oxide layer and any strap material that may have replaced the pad oxide layer around the trenches. The straps and trench sidewalls are doped to form a resistive connection. During a subsequent shallow trench isolation (STI) process, which involves an oxidation step, the exposed strap material on the surface of the silicon surface layer forms oxide unrestrained by pad nitride without stressing the silicon substrate.
    Type: Grant
    Filed: December 17, 1999
    Date of Patent: January 22, 2002
    Assignee: International Business Machines Corporation
    Inventors: Sundar K. Iyer, Rama Divakaruni, Herbert L. Ho, Subramanian Iyer, Babar A. Khan