Patents by Inventor Ashima B. Chakravarti

Ashima B. Chakravarti 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: 7776624
    Abstract: A semiconductor fabrication method. The method includes providing a semiconductor substrate, wherein the semiconductor substrate includes a semiconductor material. Next, a top portion of the semiconductor substrate is removed. Next, a first semiconductor layer is epitaxially grown on the semiconductor substrate, wherein a first atomic percent of a first semiconductor material in the first semiconductor layer is equal to a substrate atomic percent of the substrate semiconductor material in the semiconductor substrate.
    Type: Grant
    Filed: July 8, 2008
    Date of Patent: August 17, 2010
    Assignee: International Business Machines Corporation
    Inventors: Ashima B. Chakravarti, Judson Robert Holt, Jeremy John Kempisty, Suk Hoon Ku, Woo-Hyeong Lee, Amlan Majumdar, Ryan Matthew Mitchell, Renee Tong Mo, Zhibin Ren, Dinkar Singh
  • Publication number: 20100200937
    Abstract: Various techniques for changing the workfunction of the substrate by using a SiGe channel which, in turn, changes the bandgap favorably for a p-type metal oxide semiconductor field effect transistors (pMOSFETs) are disclosed. In the various techniques, a SiGe film that includes a low doped SiGe region above a more highly doped SiGe region to allow the appropriate threshold voltage (Vt) for pMOSFET devices while preventing pitting, roughness and thinning of the SiGe film during subsequent cleans and processing is provided.
    Type: Application
    Filed: February 9, 2009
    Publication date: August 12, 2010
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Stephen W. Bedell, Ashima B. Chakravarti, Michael P. Chudzik, Judson R. Holt, Dominic J. Schepis
  • Patent number: 7767579
    Abstract: A method of making a semiconductor device includes forming a transistor structure having one of an embedded epitaxial stressed material in a source and drain region and a stressed channel and well, subjecting the transistor structure to plasma oxidation, and removing spacer material from the transistor structure.
    Type: Grant
    Filed: December 12, 2007
    Date of Patent: August 3, 2010
    Assignee: International Business Machines Corporation
    Inventors: Ashima B Chakravarti, Zhijiong Luo, Renee Tong Mo, Shreesh Narasimha, Katsunori Onishi
  • Patent number: 7759213
    Abstract: Trenches are formed in a silicon substrate by etching exposed portions of the silicon substrate. After covering areas on which deposition of Si:C containing material is to be prevented, selective epitaxy is performed in a single wafer chamber at a temperature from about 550° C. to about 600° C. employing a limited carrier gas flow, i.e., at a flow rate less than 12 standard liters per minute to deposit Si:C containing regions at a pattern-independent uniform deposition rate. The inventive selective epitaxy process for Si:C deposition provides a relatively high net deposition rate a high quality Si:C crystal in which the carbon atoms are incorporated into substitutional sites as verified by X-ray diffraction.
    Type: Grant
    Filed: August 11, 2008
    Date of Patent: July 20, 2010
    Assignee: International Business Machines Corporation
    Inventors: Abhishek Dube, Ashima B. Chakravarti, Dominic J. Schepis
  • Publication number: 20100112762
    Abstract: Methods of fabricating a semiconductor structure with a non- epitaxial thin film disposed on a surface of a substrate of the semiconductor structure are disclosed. The methods provide selective non-epitaxial growth (SNEG) or deposition of amorphous and/or polycrystalline materials to form a thin film on the surface thereof. The surface may be a non-crystalline dielectric material or a crystalline material. The SNEG on non-crystalline dielectric further provides selective growth of amorphous/polycrystalline materials on nitride over oxide through careful selection of precursors-carrier-etchant ratio. The non-epitaxial thin film forms resultant and/or intermediate semiconductor structures that may be incorporated into any front-end-of-the-line (FEOL) fabrication process.
    Type: Application
    Filed: January 8, 2010
    Publication date: May 6, 2010
    Inventors: Thomas N. Adam, Ashima B. Chakravarti, Eric C.T. Harley, Judson R. Holt
  • Patent number: 7687804
    Abstract: Methods of fabricating a semiconductor structure with a non-epitaxial thin film disposed on a surface of a substrate of the semiconductor structure; and semiconductor structures formed thereof are disclosed. The methods provide selective non-epitaxial growth (SNEG) or deposition of amorphous and/or polycrystalline materials to form a thin film on the surface thereof. The surface may be a non-crystalline dielectric material or a crystalline material. The SNEG on non-crystalline dielectric further provides selective growth of amorphous/polycrystalline materials on nitride over oxide through careful selection of precursors-carrier-etchant ratio. The non-epitaxial thin film forms resultant and/or intermediate semiconductor structures that may be incorporated into any front-end-of-the-line (FEOL) fabrication process.
    Type: Grant
    Filed: January 8, 2008
    Date of Patent: March 30, 2010
    Assignee: International Business Machines Corporation
    Inventors: Thomas N. Adam, Ashima B. Chakravarti, Eric C. T. Harley, Judson R. Holt
  • Publication number: 20100035419
    Abstract: Trenches are formed in a silicon substrate by etching exposed portions of the silicon substrate. After covering areas on which deposition of Si:C containing material is to be prevented, selective epitaxy is performed in a single wafer chamber at a temperature from about 550° C. to about 600° C. employing a limited carrier gas flow, i.e., at a flow rate less than 12 standard liters per minute to deposit Si:C containing regions at a pattern-independent uniform deposition rate. The inventive selective epitaxy process for Si:C deposition provides a relatively high net deposition rate a high quality Si:C crystal in which the carbon atoms are incorporated into substitutional sites as verified by X-ray diffraction.
    Type: Application
    Filed: August 11, 2008
    Publication date: February 11, 2010
    Applicant: International Business Machines Corporation
    Inventors: ABHISHEK DUBE, Ashima B. Chakravarti, Dominic J. Schepis
  • Publication number: 20100009524
    Abstract: A semiconductor fabrication method. The method includes providing a semiconductor substrate, wherein the semiconductor substrate includes a semiconductor material. Next, a top portion of the semiconductor substrate is removed. Next, a first semiconductor layer is epitaxially grown on the semiconductor substrate, wherein a first atom percent of the semiconductor material in the first semiconductor layer is equal to a certain atom percent of the semiconductor material in the semiconductor substrate.
    Type: Application
    Filed: July 8, 2008
    Publication date: January 14, 2010
    Applicant: INTERNATIONAL BUSINESS MACHINES
    Inventors: Ashima B. Chakravarti, Judson Robert Holt, Jeremy John Kempisty, Suk Hoon Ku, Woo-Hyeong Lee, Amlan Majumdar, Ryan Matthew Mitchell, Renee Tong Mo, Zhibin Ren, Dinkar Singh
  • Publication number: 20090267118
    Abstract: Methods for forming carbon silicon alloy (CSA) and structures thereof are disclosed. The method provides improvement in substitutionality and deposition rate of carbon in epitaxially grown carbon silicon alloy layers (i.e., substituted carbon in Si lattice). In one embodiment of the disclosed method, a carbon silicon alloy layer is epitaxially grown on a substrate at an intermediate temperature with a silicon precursor, a carbon (C) precursor in the presence of an etchant and a trace amount of germanium material (e.g., germane (GeH4)). The intermediate temperature increases the percentage of substitutional carbon in epitaxially grown CSA layer and avoids any tendency for silicon carbide to form. The presence of the trace amount of germanium material, of approximately less than 1% to approximately 5%, in the resulting epitaxial layer, has an effect of stabilizing and enhancing deposition/growth rate without compromising the tensile stress of CSA layer formed thereby.
    Type: Application
    Filed: April 29, 2008
    Publication date: October 29, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Ashima B. Chakravarti, Abhishek Dube, Rainer Loesing, Dominic J. Schepis
  • Publication number: 20090269926
    Abstract: A method of forming at least one gate conductor of a complementary metal oxide semiconductor performs a chemical vapor deposition process of polysilicon over a surface where a polysilicon gate is to be located. This deposition can be performed through a mask to form gate structures directly, or a later patterning process can pattern the polysilicon into gate structures. During the chemical vapor deposition process, the method adds impurities in the chemical vapor deposition process to optimize the grain size of the polysilicon according to a number of different methods.
    Type: Application
    Filed: April 28, 2008
    Publication date: October 29, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Abhishek Dube, Ashima B. Chakravarti, Anthony I. Chou, Wei He, Dominic J. Schepis
  • Patent number: 7595010
    Abstract: Adding at least one non-silicon precursor (such as a germanium precursor, a carbon precursor, etc.) during formation of a silicon nitride, silicon oxide, silicon oxynitride or silicon carbide film improves the deposition rate and/or makes possible tuning of properties of the film, such as tuning of the stress of the film. Also, in a doped silicon oxide or doped silicon nitride or other doped structure, the presence of the dopant may be used for measuring a signal associated with the dopant, as an etch-stop or otherwise for achieving control during etching.
    Type: Grant
    Filed: October 26, 2007
    Date of Patent: September 29, 2009
    Assignee: International Business Machines Corporation
    Inventors: Ashima B. Chakravarti, Judson Holt, Kevin K. Chan, Sadanand V. Deshpande, Rangarajan Jagannathan
  • Publication number: 20090173941
    Abstract: Methods of fabricating a semiconductor structure with a non-epitaxial thin film disposed on a surface of a substrate of the semiconductor structure; and semiconductor structures formed thereof are disclosed. The methods provide selective non-epitaxial growth (SNEG) or deposition of amorphous and/or polycrystalline materials to form a thin film on the surface thereof. The surface may be a non-crystalline dielectric material or a crystalline material. The SNEG on non-crystalline dielectric further provides selective growth of amorphous/polycrystalline materials on nitride over oxide through careful selection of precursors-carrier-etchant ratio. The non-epitaxial thin film forms resultant and/or intermediate semiconductor structures that may be incorporated into any front-end-of-the-line (FEOL) fabrication process.
    Type: Application
    Filed: January 8, 2008
    Publication date: July 9, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Thomas N. Adam, Ashima B. Chakravarti, Eric C. T. Harley, Judson R. Holt
  • Publication number: 20090155969
    Abstract: A method of making a semiconductor device includes forming a transistor structure having one of an embedded epitaxial stressed material in a source and drain region and a stressed channel and well, subjecting the transistor structure to plasma oxidation, and removing spacer material from the transistor structure.
    Type: Application
    Filed: December 12, 2007
    Publication date: June 18, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: ASHIMA B. CHAKRAVARTI, ZHIJIONG LUO, RENEE TONG MO, SHREESH NARASIMHA, KATSUNORI ONISHI
  • Patent number: 7473594
    Abstract: An embedded silicon carbon (Si:C) having a substitutional carbon content in excess of one percent in order to effectively increase electron mobility by application of tension to a channel region of an NFET is achieved by overfilling a gap or trench formed by transistor gate structures with Si:C and polishing an etching the Si:C to or below a surface of a raised gate structure in a super-Damascene process, leaving Si:C only in selected regions above the transistor source and drain, even though processes capable of depositing Si:C with sufficiently high substitutional carbon content are inherently non-selective.
    Type: Grant
    Filed: July 25, 2006
    Date of Patent: January 6, 2009
    Assignee: International Business Machines Corporation
    Inventors: Ashima B. Chakravarti, Dureseti Chidambarrao, Judson R. Holt, Yaocheng Liu, Kern Rim
  • Publication number: 20090001430
    Abstract: A dielectric element, and method of manufacturing the same, is disclosed for a semiconductor structure which comprises a substrate having a gate formed on a top surface of the substrate. The substrate and gate define a gap in a region between the gate and the substrate. A specified amount of dielectric on the substrate, at least a portion of which is in the gap, forms the dielectric element which substantially prevents unwanted electrical connectivity between the gate and the substrate.
    Type: Application
    Filed: June 29, 2007
    Publication date: January 1, 2009
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Ashima B. Chakravarti, Renee T. Mo
  • Publication number: 20080242041
    Abstract: A method of selectively forming a germanium structure within semiconductor manufacturing processes removes the native oxide from a nitride surface in a chemical oxide removal (COR) process and then exposes the heated nitride and oxide surface to a heated germanium containing gas to selectively form germanium only on the nitride surface but not the oxide surface.
    Type: Application
    Filed: June 9, 2008
    Publication date: October 2, 2008
    Applicant: International Business Machines Corporation
    Inventors: Ashima B. Chakravarti, Anthony I. Chou, Toshiharu Furukawa, Steven J. Holmes, Wesley C. Natzle
  • Publication number: 20080128712
    Abstract: An embedded silicon carbon (Si:C) having a substitutional carbon content in excess of one percent in order to effectively increase electron mobility by application of tension to a channel region of an NFET is achieved by overfilling a gap or trench formed by transistor gate structures with Si:C and polishing an etching the Si:C to or below a surface of a raised gate structure in a super-Damascene process, leaving Si:C only in selected regions above the transistor source and drain, even though processes capable of depositing Si:C with sufficiently high substitutional carbon content are inherently non-selective.
    Type: Application
    Filed: February 8, 2008
    Publication date: June 5, 2008
    Inventors: Ashima B. Chakravarti, Dureseti Chidambarrao, Judson R. Holt, Yaocheng Liu, Kern Rim
  • Publication number: 20080121926
    Abstract: An integrated circuit system includes a substrate, a carbon-containing silicon region over the substrate, a non-carbon-containing silicon region over the substrate, and a silicon-carbon region, including the non-carbon-containing silicon region and the carbon-containing silicon region.
    Type: Application
    Filed: August 15, 2006
    Publication date: May 29, 2008
    Applicants: Chartered Semiconductor Manufacturing Ltd., International Business Machines Corporation
    Inventors: Jin Ping Liu, Richard J. Murphy, Anita Madan, Ashima B. Chakravarti
  • Patent number: 7361611
    Abstract: Adding at least one non-silicon precursor (such as a germanium precursor, a carbon precursor, etc.) during formation of a silicon nitride, silicon oxide, silicon oxynitride or silicon carbide film improves the deposition rate and/or makes possible tuning of properties of the film, such as tuning of the stress of the film. Also, in a doped silicon oxide or doped silicon nitride or other doped structure, the presence of the dopant may be used for measuring a signal associated with the dopant, as an etch-stop or otherwise for achieving control during etching.
    Type: Grant
    Filed: February 8, 2006
    Date of Patent: April 22, 2008
    Assignee: International Business Machines Corporation
    Inventors: Ashima B. Chakravarti, Judson Holt, Kevin K. Chan, Sadanand V. Deshpande, Rangarajan Jagannathan
  • Publication number: 20080026516
    Abstract: An embedded silicon carbon (Si:C) having a substitutional carbon content in excess of one percent in order to effectively increase electron mobility by application of tension to a channel region of an NFET is achieved by overfilling a gap or trench formed by transistor gate structures with Si:C and polishing an etching the Si:C to or below a surface of a raised gate structure in a super-Damascene process, leaving Si:C only in selected regions above the transistor source and drain, even though processes capable of depositing Si:C with sufficiently high substitutional carbon content are inherently non-selective.
    Type: Application
    Filed: July 25, 2006
    Publication date: January 31, 2008
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Ashima B. Chakravarti, Dureseti Chidambarrao, Judson R. Holt, Yaocheng Liu, Kern Rim