Patents by Inventor Vijai Kumar Chhagan

Vijai Kumar Chhagan 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: 20030143828
    Abstract: A method for making low sheet resistance local metal interconnections and improved transistor performance is described. The method involves patterning a polysilicon layer and a silicon nitride (Si3N4) cap layer over device areas to form FET gate electrodes, and the patterned polysilicon extends over the field oxide regions to form portions of the local interconnections. After forming source/drain areas and sidewall spacers on the FET gate electrodes, a silicon oxide (SiO2) insulating layer is deposited and polished back to the Si3N4 cap. The Si3N4 is then selectively removed over the patterned polysilicon layer, leaving recesses in the SiO2 layer. After etching contact openings in the SiO2 layer to the substrate, a high electrically conducting metal layer, having a barrier layer, is deposited and patterned to complete the local interconnections.
    Type: Application
    Filed: January 28, 2003
    Publication date: July 31, 2003
    Applicant: Chartered Semiconductor Manufacturing Ltd.
    Inventors: Mei Sheng Zhou, Vijai Kumar Chhagan, Jian Xun Li
  • Patent number: 6534393
    Abstract: A method for making low sheet resistance local metal interconnections and improved transistor performance is described. The method involves patterning a polysilicon layer and a silicon nitride (Si3N4) cap layer over device areas to form FET gate electrodes, and the patterned polysilicon extends over the field oxide regions to form portions of the local interconnections. After forming source/drain areas and sidewall spacers on the FET gate electrodes, a silicon oxide (SiO2) insulating layer is deposited and polished back to the Si3N4 cap. The Si3N4 is then selectively removed over the patterned polysilicon layer, leaving recesses in the SiO2 layer. After etching contact openings in the SiO2 layer to the substrate, a high electrically conducting metal layer, having a barrier layer, is deposited and patterned to complete the local interconnections.
    Type: Grant
    Filed: January 25, 1999
    Date of Patent: March 18, 2003
    Assignees: Chartered Semiconductor Manufacturing Ltd., National University of Singapore, Nanyang Technological University of Singapore, Institute of Microelectronics
    Inventors: Mei Sheng Zhou, Vijai Kumar Chhagan, Jian Xun Li
  • Publication number: 20020076877
    Abstract: A new method of forming silicon nitride sidewall spacers has been achieved. In addition, a new device profile for a silicon nitride sidewall spacer has been achieved. An isolation region is provided overlying a semiconductor substrate. Polysilicon traces are provided. A liner oxide layer is formed overlying the polysilicon traces and the insulator layer. A silicon nitride layer is formed overlying the liner oxide layer. A polysilicon or amorphous silicon layer is deposited overlying the silicon nitride layer. The polysilicon or amorphous silicon layer is completely oxidized to form a temporary silicon dioxide layer. The temporary silicon dioxide layer is rounded in the corners due to volume expansion during the oxidation step. The temporary silicon dioxide layer is anisotropically etched through to expose horizontal surfaces of the silicon nitride layer while leaving vertical sidewalls of the temporary silicon dioxide layer.
    Type: Application
    Filed: February 19, 2002
    Publication date: June 20, 2002
    Applicant: CHARTERED SEMICONDUCTOR MANUFACTURING LTD.
    Inventors: Subhash Gupta, Yelehanka Ramachandramurthy Pradeep, Vijai Kumar Chhagan
  • Patent number: 6391732
    Abstract: A new method of forming silicon nitride sidewall spacers has been achieved. In addition, a new device profile for a silicon nitride sidewall spacer has been achieved. An isolation region is provided overlying a semiconductor substrate. Polysilicon traces are provided. A liner oxide layer is formed overlying the polysilicon traces and the insulator layer. A silicon nitride layer is formed overlying the liner oxide layer. A polysilicon or amorphous silicon layer is deposited overlying the silicon nitride layer. The polysilicon or amorphous silicon layer is completely oxidized to form a temporary silicon dioxide layer. The temporary silicon dioxide layer is rounded in the corners due to volume expansion during the oxidation step. The temporary silicon dioxide layer is anisotropically etched through to expose horizontal surfaces of the silicon nitride layer while leaving vertical sidewalls of the temporary silicon dioxide layer.
    Type: Grant
    Filed: June 16, 2000
    Date of Patent: May 21, 2002
    Assignee: Chartered Semiconductor Manufacturing Ltd.
    Inventors: Subhash Gupta, Yelehanka Ramachandramurthy, Vijai Kumar Chhagan
  • Patent number: 6387765
    Abstract: A method for forming an extended metal gate without poly wrap around effects. A semiconductor structure is provided having a gate structure thereon. The gate structure comprising a gate dielectric layer, a gate silicon layer, a doped silicon oxide layer, and a disposable gate layer stacked sequentially. Spacers are formed on the sidewalls of the gate structure. A dielectric gapfill layer is formed over the semiconductor structure and the gate structure and planarized, stopping on the disposable gate layer. A first silicon nitride layer is formed over the disposable gate layer, and a dielectric layer is formed over the first silicon nitride layer. The dielectric layer is patterned to form a trench over the gate structure; therein the trench has a width greater than the width of the gate structure. The first silicon nitride layer in the bottom of the trench and the disposable gate layer are removed using one or more selective etching processes.
    Type: Grant
    Filed: September 6, 2001
    Date of Patent: May 14, 2002
    Assignee: Chartered Semiconductor Manufacturing Ltd.
    Inventors: Vijai Kumar Chhagan, Yelehanka Ramachandramurthy Pradeep, Mei Sheng Zhou, Henry Gerung, Simon Chooi
  • Patent number: 6337262
    Abstract: A new method is provided for the integration of the of T-top gate process. Active regions are defined and bounded by STI's on the surface of a substrate. The pad oxide is removed from the substrate and replaced by a layer of SAC oxide. A thin layer of nitride is deposited that covers the surface of the created layer of SAC oxide and the surface of the STI regions. A layer of TEOS is deposited and etched defining the regions where the gate electrodes need to be formed. Gate spacers are next formed on the sidewalls of the openings that have been created in the layer of TEOS. The required implants (such as channel implant and threshold implant) are performed, the gate structure is then grown in the openings that have been created in the layer of TEOS. After the gate structure has been completed, the surface of the created structure is polished and the remaining layer of TEOS is removed. Source and drain regions implants can now be performed, LDD regions are implanted using a tilted implant.
    Type: Grant
    Filed: March 6, 2000
    Date of Patent: January 8, 2002
    Assignee: Chartered Semiconductor Manufacturing Ltd.
    Inventors: Yelehanka Ramachandramurthy Pradeep, Chivukula Subrahmanyam, Vijai Kumar Chhagan, Henry Gerung
  • Patent number: 6228770
    Abstract: A new method of forming metal interconnects with air gaps between adjacent interconnects in the manufacture of an integrated circuit device is achieved. A semiconductor substrate is provided. The metal interconnects are formed overlying the semiconductor substrate. A silicon nitride liner layer is deposited. A gap filling oxide layer is deposited to fill gaps between adjacent metal interconnects. The gap filling oxide layer is polished down to the silicon nitride liner layer. A silicon nitride thin layer is deposited. The silicon nitride thin layer is patterned using an oversized, reverse mask of the metal interconnects. The patterning of the silicon nitride thin layer creates openings to thereby expose a portion of the gap filling oxide. The gap filling oxide layer is etched away. A self-sealing oxide layer is deposited overlying the silicon nitride thin layer and the silicon nitride liner layer.
    Type: Grant
    Filed: March 21, 2000
    Date of Patent: May 8, 2001
    Assignee: Chartered Semiconductor Manufacturing Ltd.
    Inventors: Yelehanka Ramachandramurthy Pradeep, Vijai Kumar Chhagan, Henry Gerung, Madhusudan Mukhopadhyay