Patents by Inventor Mohsen Banan
Mohsen Banan 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).
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Patent number: 7404856Abstract: The present invention relates to a process for forming single crystal silicon ingots or wafers that contain an axially symmetric region in which vacancies are the predominant intrinsic point defect, that are substantially free of oxidation induced stacking faults, and are nitrogen doped to stabilize oxygen precipitation nuclei therein.Type: GrantFiled: January 15, 2007Date of Patent: July 29, 2008Assignee: MEMC Electronic Materials, Inc.Inventors: Hiroyo Haga, Takaaki Aoshima, Mohsen Banan
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Publication number: 20070169683Abstract: The present invention relates to a process for forming single crystal silicon ingots or wafers that contain an axially symmetric region in which vacancies are the predominant intrinsic point defect, that are substantially free of oxidation induced stacking faults, and are nitrogen doped to stabilize oxygen precipitation nuclei therein.Type: ApplicationFiled: January 15, 2007Publication date: July 26, 2007Applicant: MEMC ELECTRONIC MATERIALS, INC.Inventors: Hiroyo Haga, Takaaki Aoshima, Mohsen Banan
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Patent number: 7217320Abstract: The present invention relates to a process for preparing a single crystal silicon ingot, as well as to the ingot or wafer resulting therefrom. The process comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, and (iii) a cooling rate of the crystal from solidification to about 750° C., in order to cause the formation of a segment having a first axially symmetric region extending radially inward from the lateral surface of the ingot wherein silicon self-interstitials are the predominant intrinsic point defect, and a second axially symmetric region extending radially inward from the first and toward the central axis of the ingot.Type: GrantFiled: December 7, 2004Date of Patent: May 15, 2007Assignee: MEMC Electronics Materials, Inc.Inventors: Chang Bum Kim, Steven L. Kimbel, Jeffrey L. Libbert, Mohsen Banan
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Patent number: 7201800Abstract: A process for imparting controlled oxygen precipitation behavior to a single crystal silicon wafer. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon, and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing, such as an epitaxial deposition process, while maintaining the ability to dissolve any grown-in nucleation centers.Type: GrantFiled: October 12, 2004Date of Patent: April 10, 2007Assignee: MEMC Electronic Materials, Inc.Inventors: Luciano Mule'Stagno, Jeffrey L. Libbert, Richard J. Phillips, Milind Kulkarni, Mohsen Banan, Stephen J. Brunkhorst
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Publication number: 20070074653Abstract: A crystal pulling apparatus for producing a silicon crystal ingot having a reduced amount of metal contamination. The apparatus includes a growth chamber and a component disposed within the growth chamber having a protective layer of silicon nitride for preventing metal contamination of the crystal.Type: ApplicationFiled: September 30, 2005Publication date: April 5, 2007Applicant: MEMC Electronic Materials, Inc.Inventors: Hariprasad Sreedharamurthy, John Holder, Mohsen Banan
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Patent number: 7182809Abstract: A single crystal silicon, ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect, is substantially free of oxidation induced stacking faults and is nitrogen doped to stabilize oxygen precipitation nuclei therein, and a process for the preparation thereof.Type: GrantFiled: August 30, 2001Date of Patent: February 27, 2007Assignee: MEMC Electronic Materials, Inc.Inventors: Hiroyo Haga, Takaaki Aoshima, Mohsen Banan
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Patent number: 7132091Abstract: A single crystal silicon ingot having a constant diameter portion that contains arsenic dopant atoms at a concentration which results in the silicon having a resistivity that is less than about 0.003 ?·cm.Type: GrantFiled: September 27, 2002Date of Patent: November 7, 2006Assignee: MEMC Electronic Materials, Inc.Inventors: Milind Kulkarni, Mohsen Banan, Christopher V. Luers
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Patent number: 7105050Abstract: A process for the preparation of a silicon single ingot in accordance with the Czochralski method. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C. to initially produce in the constant diameter portion of the ingot a series of predominant intrinsic point defects including vacancy dominated regions and silicon self interstitial dominated regions, alternating along the axis, and cooling the regions from the temperature of solidification at a rate which allows silicon self-interstitial atoms to diffuse radially to the lateral surface and to diffuse axially to vacancy dominated regions to reduce the concentration intrinsic point defects in each region.Type: GrantFiled: February 16, 2005Date of Patent: September 12, 2006Assignee: MEMC Electronic Materials, Inc.Inventors: Vladimir V. Voronkov, Robert J. Falster, Mohsen Banan
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Publication number: 20050150445Abstract: The present invention relates to a process for preparing a single crystal silicon ingot, as well as to the ingot or wafer resulting therefrom. The process comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, and (iii) a cooling rate of the crystal from solidification to about 750° C., in order to cause the formation of a segment having a first axially symmetric region extending radially inward from the lateral surface of the ingot wherein silicon self-interstitials are the predominant intrinsic point defect, and a second axially symmetric region extending radially inward from the first and toward the central axis of the ingot.Type: ApplicationFiled: December 7, 2004Publication date: July 14, 2005Applicant: MEMC Electronic Materials, Inc.Inventors: Chang Kim, Steven Kimbel, Jeffrey Libbert, Mohsen Banan
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Publication number: 20050132948Abstract: A process for the preparation of a silicon single ingot in accordance with the Czochralski method. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C. to initially produce in the constant diameter portion of the ingot a series of predominant intrinsic point defects including vacancy dominated regions and silicon self interstitial dominated regions, alternating along the axis, and cooling the regions from the temperature of solidification at a rate which allows silicon self-interstitial atoms to diffuse radially to the lateral surface and to diffuse axially to vacancy dominated regions to reduce the concentration intrinsic point defects in each region.Type: ApplicationFiled: February 16, 2005Publication date: June 23, 2005Applicant: MEMC Electronic Materials, Inc.Inventors: Vladimir Vornokov, Robert Falster, Mohsen Banan
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Patent number: 6866713Abstract: The present invention provides for a process for preparing a single crystal silicon ingot by the Czochralski method. The process comprises selecting a seed crystal for Czochralski growth wherein the seed crystal comprises vacancy dominated single crystal silicon.Type: GrantFiled: October 28, 2002Date of Patent: March 15, 2005Assignee: MEMC Electronic Materials, Inc.Inventors: Hariprasad Sreedharamurthy, Mohsen Banan
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Publication number: 20050048247Abstract: A process for imparting controlled oxygen precipitation behavior to a single crystal silicon wafer. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon, and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing, such as an epitaxial deposition process, while maintaining the ability to dissolve any grown-in nucleation centers.Type: ApplicationFiled: October 12, 2004Publication date: March 3, 2005Inventors: Luciano Mule'Stagno, Jeffrey Libbert, Richard Phillips, Milind Kulkarni, Mohsen Banan, Stephen Brunkhorst
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Patent number: 6858307Abstract: A process for the preparation of a silicon single ingot in accordance with the Czochralski method. The process for growing the single crystal silicon ingot comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C. to initially produce in the constant diameter portion of the ingot a series of predominant intrinsic point defects including vacancy dominated regions and silicon self interstitial dominated regions, alternating along the axis, and cooling the regions from the temperature of solidification at a rate which allows silicon self-interstitial atoms to diffuse radially to the lateral surface and to diffuse axially to vacancy dominated regions to reduce the concentration intrinsic point defects in each region.Type: GrantFiled: October 5, 2001Date of Patent: February 22, 2005Assignee: MEMC Electronic Materials, Inc.Inventors: Vladimir V. Vornokov, Robert J. Falster, Mohsen Banan
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Patent number: 6846539Abstract: The present invention relates to a process for preparing a single crystal silicon ingot, as well as to the ingot or wafer resulting therefrom. The process comprises controlling (i) a growth velocity, v, (ii) an average axial temperature gradient, G0, and (iii) a cooling rate of the crystal from solidification to about 750° C., in order to cause the formation of a segment having a first axially symmetric region extending radially inward from the lateral surface of the ingot wherein silicon self-interstitials are the predominant intrinsic point defect, and a second axially symmetric region extending radially inward from the first and toward the central axis of the ingot.Type: GrantFiled: January 22, 2002Date of Patent: January 25, 2005Assignee: MEMC Electronic Materials, Inc.Inventors: Chang Bum Kim, Steven L. Kimbel, Jeffrey L. Libbert, Mohsen Banan
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Silicon wafers with stabilized oxygen precipitate nucleation centers and process for making the same
Patent number: 6808781Abstract: A silicon wafer having a controlled oxygen precipitation behavior such that a denuded zone extending inward from the front surface and oxygen precipitates in the wafer bulk sufficient for intrinsic gettering purposes are ultimately formed. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing such as an epitaxial deposition process while maintaining the ability to dissolve any grown-in nucleation centers.Type: GrantFiled: December 23, 2002Date of Patent: October 26, 2004Assignee: MEMC Electronic Materials, Inc.Inventors: Luciano Mule'Stagno, Jeffrey L. Libbert, Richard J. Phillips, Milind Kulkarni, Mohsen Banan, Stephen J. Brunkhorst -
Publication number: 20040009111Abstract: The present invention relates to single crystal silicon, ingot or wafer form, which contains an axially symmetric region in which vacancies are the predominant intrinsic point defect, is substantially free of oxidation induced stacking faults and is nitrogen doped to stabilize oxygen precipitation nuclei therein, and a process for the preparation thereof.Type: ApplicationFiled: July 30, 2003Publication date: January 15, 2004Inventors: Hiroyo Haga, Takaaki Aoshima, Mohsen Banan
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Patent number: 6663709Abstract: A crystal puller and method for growing monocrystalline silicon ingots includes first and second electrical resistance heaters in the crystal puller in longitudinal, closely spaced relationship with each other to radiate heat toward the ingot as the ingot is pulled upward within the housing. In one embodiment, the first heater is powered when the ingot is pulled upward to a first axial position above the surface of the molten silicon and the second heater is powered when the ingot is pulled upward to a second axial position above the first axial position. In another embodiment the first and second heaters are powered until the ingot is separated from the molten silicon and then the heating power output of the first and second heaters is reduced to substantially increase the cooling rate at which the ingot is cooled. An adapter mounting the heaters may also be provided for adapting existing crystal pullers to incorporate the heaters.Type: GrantFiled: June 26, 2001Date of Patent: December 16, 2003Assignee: MEMC Electronic Materials, Inc.Inventors: Zheng Lu, Mohsen Banan, Ying Tao, Lee Ferry, Carl F. Cherko
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Publication number: 20030196587Abstract: The present invention relates to a process for growing a single crystal silicon ingot, which contains an axially symmetric region having a predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects in that region. The process comprising cooling the ingot from the temperature of solidification to a temperature of less than 800° C. and, as part of said cooling step, quench cooling a region of the constant diameter portion of the ingot having a predominant intrinsic point defect through the temperature of nucleation for the agglomerated intrinsic point defects for the intrinsic point defects which predominate in the region.Type: ApplicationFiled: May 6, 2003Publication date: October 23, 2003Applicant: MEMC Electronic Materials, Inc.Inventors: Kirk D. McCallum, W. Brock Alexander, Mohsen Banan, Robert J. Falster, Joseph C. Holzer, Bayard K. Johnson, Chang Bum Kim, Steven L. Kimbel, Zheng Lu, Paolo Mutti, Vladimir V. Voronkov, Luciano Mule'Stagno, Jeffrey L. Libbert
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Publication number: 20030136961Abstract: A silicon wafer having a controlled oxygen precipitation behavior such that a denuded zone extending inward from the front surface and oxygen precipitates in the wafer bulk sufficient for intrinsic gettering purposes are ultimately formed. Specifically, prior to formation of the oxygen precipitates, the wafer bulk comprises dopant stabilized oxygen precipitate nucleation centers. The dopant is selected from a group consisting of nitrogen and carbon and the concentration of the dopant is sufficient to allow the oxygen precipitate nucleation centers to withstand thermal processing such as an epitaxial deposition process while maintaining the ability to dissolve any grown-in nucleation centers.Type: ApplicationFiled: December 23, 2002Publication date: July 24, 2003Applicant: MEMC Electronic Materials, Inc.Inventors: Luciano Mule'Stagno, Jeffrey L. Libbert, Richard J. Phillips, Milind Kulkarni, Mohsen Banan, Stephen J. Brunkhorst
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Patent number: 6579362Abstract: A heat shield assembly for use in a crystal puller has an outer reflector interposed between the ingot and the crucible as the ingot is pulled from the molten source material. A cooling shield is interposed between the ingot and the outer reflector whereby the cooling shield is exposed to heat radiated from the ingot for increasing the rate at which the ingot is cooled, thereby increasing the axial temperature gradient of the ingot. In a further embodiment, an inner shield panel is disposed generally intermediate the cooling shield and the ingot in radially spaced relationship with the cooling shield and is constructed of a material substantially transparent to radiant heat from the ingot.Type: GrantFiled: March 23, 2001Date of Patent: June 17, 2003Assignee: MEMC Electronic Materials, Inc.Inventors: Lee W. Ferry, Richard G. Schrenker, Mohsen Banan