Patents by Inventor Sundar Narayanan
Sundar Narayanan 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: 9741765Abstract: Provided is a monolithic integration of resistive memory with complementary metal oxide semiconductor using integrated circuit foundry processes. A memory device is provided that includes a substrate comprising one or more complementary metal-oxide semiconductor devices, a first insulator layer formed on the substrate; and a monolithic stack. The monolithic stack includes multiple layers fabricated as part of a monolithic process over the first insulator layer. The multiple layers include a first metal layer, a second insulator layer, and a second metal layer. A resistive memory device structure is formed within the second insulator layer and within a thermal budget of the one or more complementary metal-oxide semiconductor devices. The resistive memory device structure is implemented as a pillar device or as a via device. Further, the first metal layer is coupled to the second metal layer.Type: GrantFiled: December 31, 2014Date of Patent: August 22, 2017Assignee: CROSSBAR, INC.Inventors: Sundar Narayanan, Steve Maxwell, Natividad Vasquez, Jr., Harry Yue Gee
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Patent number: 9697874Abstract: Providing for a monolithic memory device comprising a combination of a one-transistor, one-resistor (1T1R) memory array, and a one-transistor, multiple-resistor (1TnR, where n is a suitable integer greater than 1) memory array is described herein. By way of example, the monolithic memory device can be a stand-alone device, configured to perform functions in response to predetermined conditions and generate an output(s), or can be a removable device that can be connected to and operable with another device. In various embodiments, the 1TnR array having high memory density can serve as storage class memory (SCM) for the monolithic memory device, and the 1T1R array having high performance and efficacy can serve as code memory. In addition to the foregoing, the 1T1R array and the 1TnR array can be fabricated from at least one common layer or a common processing step, to simplify and lower cost of fabricating disclosed memory devices.Type: GrantFiled: June 9, 2016Date of Patent: July 4, 2017Assignee: CROSSBAR, INC.Inventors: Mehdi Asnaashari, Sundar Narayanan
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Publication number: 20170162783Abstract: Provision of fabrication, construction, and/or assembly of a two-terminal memory device is described herein. The two-terminal memory device can include an active region with a silicon bearing layer, an interface layer, and an active metal layer. The interface layer can be grown on the silicon bearing layer, and the growth of the interface layer can be regulated with N2O plasma.Type: ApplicationFiled: December 6, 2016Publication date: June 8, 2017Inventors: Sundar Narayanan, Sung Hyun Jo, Liang Zhao
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Patent number: 9595670Abstract: A method includes patterning a layered structure comprising a monolithic stack including a bottom electrode surrounded by a dielectric material, a switching material, a barrier material, a dielectric hardmask, and a patterned photoresist formed above and adjacent to a portion of the dielectric hardmask. The patterning includes patterning the dielectric hardmask using a first etchant and employing the patterned photoresist as a mask, patterning the barrier material using a second etchant and employing a portion of the dielectric hardmask remaining after the patterning the dielectric hardmask as a mask, and patterning the switching material using ion milling or etching and employing the portion of the dielectric hardmask remaining after the patterning the barrier material as a mask.Type: GrantFiled: July 21, 2014Date of Patent: March 14, 2017Assignee: CROSSBAR, INC.Inventors: Harry Yue Gee, Steven Patrick Maxwell, Natividad Vasquez, Jr., Sundar Narayanan
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Publication number: 20160351625Abstract: A recessed high voltage metal oxide semiconductor (MOS) transistor is provided for use in a two-terminal memory cell. The two-terminal memory cell can include a resistive switching device connected to the recessed MOS transistor. The recessed MOS transistor provides for an increased channel length relative to the transistor size in comparison to a traditional MOS transistor. This allows for a decreased memory cell size while maintaining comparable electrical parameters (threshold voltage, channel length, and leakage) than would otherwise be possible. The recessed MOS transistor can be made as either a NMOS or PMOS device using n-type or p-type materials respectively, where the channel, or inversion layer, is formed by electrons (NMOS) or holes (PMOS) between the source and drain in the transistor.Type: ApplicationFiled: May 29, 2015Publication date: December 1, 2016Inventors: Harry Yue Gee, Tanmay Kumar, Natividad Vasquez, JR., Steven Patrick Maxwell, Sundar Narayanan
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Patent number: 9437814Abstract: During fabrication of a two-terminal memory device, a terminal (e.g., bottom terminal) can be formed. After formation of the terminal, a chemical mechanical planarization (CMP) process can be applied that, depending on the composition of the terminal, can cause damage that affect operating characteristics of the finished memory device or cell. In some embodiments, such damage can be removed by one or more post-CMP processes. In some embodiments, such damage can be mitigated so as to prevent the damage from occurring at all, by, e.g., forming a sacrificial layer atop the terminal prior to performing the CMP process. Thus, the sacrificial layer can operate to protect the terminal from damage resulting from the CMP process, with the remainder of the sacrificial layer being removed prior to completing the fabrication of the two-terminal memory device.Type: GrantFiled: August 29, 2014Date of Patent: September 6, 2016Assignee: Crossbar, Inc.Inventors: Harry Yue Gee, Majid Milani, Natividad Vasquez, Jr., Steven Patrick Maxwell, Sundar Narayanan
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Patent number: 9425046Abstract: Techniques for processing silicon germanium (SiGe) thin films to reduce surface roughness thereof are provided herein. In an aspect, a method is disclosed that includes depositing a silicon germanium (SiGe) material upon a surface of a substrate at or below about 450 degrees Celsius, the substrate having a plurality of CMOS devices therein and forming, from the deposited SiGe material, a SiGe material film, wherein the SiGe material film has a jagged surface comprising projections and indentations extended along a direction substantially perpendicular to the surface of the substrate. The method further includes performing a chemical mechanical planarization (CMP) process to the jagged surface of the SiGe material, and reducing variations between the projections and the indentions along the direction substantially perpendicular to the surface of the substrate, and transforming the jagged surface of the SiGe material into a relatively smooth surface, compared to the jagged surface.Type: GrantFiled: July 18, 2014Date of Patent: August 23, 2016Assignee: Crossbar, Inc.Inventors: Harry Yue Gee, Steven Patrick Maxwell, Natividad Vasquez, Jr., Sundar Narayanan
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Patent number: 9343668Abstract: Providing for two-terminal memory cell structures and fabrication that can be achieved with a relatively low temperature process(es) is described herein. By way of example, disclosed two-terminal memory cells can be formed at least in part as a continuous deposition, potentially yielding improved efficiency in manufacturing. Furthermore, various embodiments can be compatible with some existing complementary metal oxide semiconductor fabrication processes, reducing or avoiding retooling overhead that might be associated with modifying existing fabrication processes in favor of other two-terminal memory cell fabrication techniques.Type: GrantFiled: March 14, 2013Date of Patent: May 17, 2016Assignee: CROSSBAR, INC.Inventors: Steve Maxwell, Sundar Narayanan, Sung Hyun Jo, Tanmay Kumar
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Patent number: 9209396Abstract: Provision of fabrication, construction, and/or assembly of a two-terminal memory device is described herein. The two-terminal memory device can include an active region with a silicon bearing layer, an interface layer, and an active metal layer. The interface layer can be grown on the silicon bearing layer, and the growth of the interface layer can be regulated with N2O plasma.Type: GrantFiled: June 6, 2013Date of Patent: December 8, 2015Assignee: Crossbar, Inc.Inventor: Sundar Narayanan
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Publication number: 20150318333Abstract: Providing for a memory device having a resistive switching memory integrated within backend layers of the memory device is described herein. By way of example, the resistive switching memory can be embedded memory such as cache, random access memory, or the like, in various embodiments. The resistive memory can be fabricated between various backend metallization schemes, including backend copper metal layers and in part utilizing one or more damascene processes. In some embodiments, the resistive memory can be fabricated in part with damascene processes and in part with subtractive etch processing, utilizing four or fewer photo-resist masks. Accordingly, the disclosure provides a relatively low cost, high performance embedded memory compatible with a variety of fabrication processes of integrated circuit foundries.Type: ApplicationFiled: March 3, 2015Publication date: November 5, 2015Inventors: Sundar Narayanan, Steve Maxwell, Natividad Vasquez, JR., Harry Yue Gee
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Publication number: 20150243886Abstract: Provided is a monolithic integration of resistive memory with complementary metal oxide semiconductor using integrated circuit foundry processes. A memory device is provided that includes a substrate comprising one or more complementary metal-oxide semiconductor devices, a first insulator layer formed on the substrate; and a monolithic stack. The monolithic stack includes multiple layers fabricated as part of a monolithic process over the first insulator layer. The multiple layers include a first metal layer, a second insulator layer, and a second metal layer. A resistive memory device structure is formed within the second insulator layer and within a thermal budget of the one or more complementary metal-oxide semiconductor devices. The resistive memory device structure is implemented as a pillar device or as a via device. Further, the first metal layer is coupled to the second metal layer.Type: ApplicationFiled: December 31, 2014Publication date: August 27, 2015Inventors: Sundar Narayanan, Steve Maxwell, Natividad Vasquez, JR., Harry Yue Gee
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Publication number: 20150228893Abstract: A memory cell that includes a first metal layer formed over a substrate is provided. The substrate includes one or more complementary metal-oxide semiconductor devices. The memory cell also includes a via device that connects at least a portion of the first metal layer and at least another portion of a second metal layer. The first metal layer has a first thickness having an edge thereof that serves as an electrode for a memory cell formed by the via device. The memory cell scales as a function of the first thickness and at least in part independent of a minimum feature size of the memory device.Type: ApplicationFiled: February 4, 2015Publication date: August 13, 2015Inventors: Sundar Narayanan, Steve Maxwell, Natividad Vasquez, JR., Harry Yue Gee
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Publication number: 20140335675Abstract: Provision of fabrication, construction, and/or assembly of a two-terminal memory device is described herein. The two-terminal memory device can include an active region with a silicon bearing layer, an interface layer, and an active metal layer. The interface layer can be grown on the silicon bearing layer, and the growth of the interface layer can be regulated with N2O plasma.Type: ApplicationFiled: June 6, 2013Publication date: November 13, 2014Inventor: Sundar NARAYANAN
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Patent number: 8445381Abstract: A method of making a semiconductor structure comprises forming an oxide layer on a substrate; forming a silicon nitride layer on the oxide layer; annealing the layers in NO; and annealing the layers in ammonia. The equivalent oxide thickness of the oxide layer and the silicon nitride layer together is at most 25 Angstroms.Type: GrantFiled: December 20, 2007Date of Patent: May 21, 2013Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Sundar Narayanan
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Patent number: 7371637Abstract: A method of making a semiconductor structure comprises forming an oxide layer on a substrate; forming a silicon nitride layer on the oxide layer; annealing the layers in NO; and annealing the layers in ammonia. The equivalent oxide thickness of the oxide layer and the silicon nitride layer together is at most 25 Angstroms.Type: GrantFiled: September 24, 2004Date of Patent: May 13, 2008Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Sundar Narayanan
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Publication number: 20080093680Abstract: A method of making a semiconductor structure comprises forming an oxide layer on a substrate; forming a silicon nitride layer on the oxide layer; annealing the layers in NO; and annealing the layers in ammonia. The equivalent oxide thickness of the oxide layer and the silicon nitride layer together is at most 25 Angstroms.Type: ApplicationFiled: December 20, 2007Publication date: April 24, 2008Inventors: Krishnaswamy Ramkumar, Sundar Narayanan
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Patent number: 7351663Abstract: A method of removing a defect from a gate stack on a substrate, comprises treating the gate stack with a plasma. The plasma comprises fluorine, the gate stack comprises a gate layer and a metallic layer, and substantially no photoresist is present on the substrate.Type: GrantFiled: June 27, 2005Date of Patent: April 1, 2008Assignee: Cypress Semiconductor CorporationInventors: Alex Kabansky, Hean-Cheal Lee, Sundar Narayanan, Prabhuram Gopalan, Vinay Krishna
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Patent number: 7189652Abstract: A method of forming a semiconductor structure comprises oxidizing a stack, to form sidewall oxide in contact with sides of the stack. The stack is on a semiconductor substrate, the stack includes a gate layer, comprising silicon; a metallic layer, on the gate layer; and an etch-stop layer, on the metallic layer. The sidewall oxide in contact with the metallic layer is thinner than the sidewall oxide in contact with the gate layer.Type: GrantFiled: December 6, 2002Date of Patent: March 13, 2007Assignee: Cypress Semiconductor CorporationInventors: Alain Blosse, Sundar Narayanan, Krishnaswamy Ramkumar
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Patent number: 7172914Abstract: A method of forming a semiconductor structure includes forming an isolation region in a semiconductor substrate. A first oxide layer is on the substrate, a first sacrificial layer is on the first oxide layer, and a first nitride layer is on the first sacrificial layer. The first oxide layer may be a screen oxide layer, and the method provides consistency in the thickness of the screen oxide layer.Type: GrantFiled: January 2, 2001Date of Patent: February 6, 2007Assignee: Cypress Semiconductor CorporationInventor: Sundar Narayanan
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Patent number: 7094707Abstract: A method of nitriding a gate oxide layer by annealing a preformed oxide layer with nitric oxide (NO) gas in a hot wall, single wafer furnace is provided. The nitridation process can be carried out rapidly (i.e., at nitridation times of 30 seconds to 2 minutes) while providing acceptable levels of nitridation (i.e., up to 6 at. %) and desirable nitrogen/depth profiles. The nitrided gate oxide layer can optionally be reoxidized in a second oxidation step after the nitridation step. A gate electrode layer (e.g., boron doped polysilicon) can then be deposited on top of the nitrided gate oxide layer or on top of the reoxidized and nitrided gate oxide layer.Type: GrantFiled: May 13, 2002Date of Patent: August 22, 2006Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Sundar Narayanan