Patents by Inventor Krishnaswamy Ramkumar
Krishnaswamy Ramkumar 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: 8940645Abstract: A method for fabricating a nonvolatile charge trap memory device is described. The method includes subjecting a substrate to a first oxidation process to form a tunnel oxide layer overlying a polysilicon channel, and forming over the tunnel oxide layer a multi-layer charge storing layer comprising an oxygen-rich, first layer comprising a nitride, and an oxygen-lean, second layer comprising a nitride on the first layer. The substrate is then subjected to a second oxidation process to consume a portion of the second layer and form a high-temperature-oxide (HTO) layer overlying the multi-layer charge storing layer. The stoichiometric composition of the first layer results in it being substantially trap free, and the stoichiometric composition of the second layer results in it being trap dense. The second oxidation process can comprise a plasma oxidation process or a radical oxidation process using In-Situ Steam Generation.Type: GrantFiled: July 1, 2012Date of Patent: January 27, 2015Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Sagy Levy, Jeong Byun
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Publication number: 20150004718Abstract: Non-volatile memory cells including complimentary metal-oxide-semiconductor transistors and embedded ferroelectric capacitor and methods of forming the same are described. In one embodiment, the method includes forming on a surface of a substrate a gate level including a gate stack of a MOS transistor, a first dielectric layer overlying the MOS transistor and a first contact extending through the first dielectric layer from a top surface thereof to a diffusion region of the MOS transistor. A local interconnect (LI) layer is deposited over the top surface of the first dielectric layer and the first contact, a ferro stack including a bottom electrode, a top electrode and ferroelectric layer there between deposited over the LI layer, and the ferro stack and the LI layer patterned to form a ferroelectric capacitor and a LI through which the bottom electrode is electrically coupled to the diffusion region of the MOS transistor.Type: ApplicationFiled: December 17, 2013Publication date: January 1, 2015Applicant: Cypress Semiconductor CorporationInventors: Shan SUN, Krishnaswamy RAMKUMAR, Thomas DAVENPORT, Kedar PATEL
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Publication number: 20140374813Abstract: A semiconductor device and method of manufacturing the same are provided. In one embodiment, semiconductor device includes a first oxide layer overlying a channel connecting a source and a drain formed in a substrate, a first nitride layer overlying the first oxide layer, a second oxide layer overlying the first nitride layer and a second nitride layer overlying the second oxide layer. A dielectric layer overlies the second nitride layer and a gate layer overlies the dielectric layer. The second nitride layer is oxygen-rich relative to the second nitride layer and includes a majority of the charge traps. Other embodiments are also described.Type: ApplicationFiled: April 29, 2014Publication date: December 25, 2014Applicant: CYPRESS SEMICONDUCTOR CORPORATIONInventors: Fredrick B. Jenne, Krishnaswamy Ramkumar
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Patent number: 8916432Abstract: Methods of forming memory cells including non-volatile memory (NVM) and MOS transistors are described. In one embodiment the method includes: depositing and patterning a gate layer over a dielectric stack on a substrate to form a gate of a NVM transistor, the dielectric stack including a tunneling layer overlying a surface of the substrate, a charge-trapping layer overlying the tunneling layer and a blocking layer overlying the charge-trapping layer; forming a mask exposing source and drain (S/D) regions of the NVM transistor; etching the dielectric stack through the mask to thin the dielectric stack by removing the blocking layer and at least a first portion of the charge-trapping layer in S/D regions of the NVM transistor; and implanting dopants into S/D regions of the NVM transistor through the thinned dielectric stack to form a lightly-doped drain adjacent to the gate of the NVM transistor.Type: GrantFiled: June 16, 2014Date of Patent: December 23, 2014Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Venkatraman Prabhakar
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Patent number: 8883624Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a gate stack of a NVM transistor in a NVM region of a substrate including the NVM region and a plurality of MOS regions; and depositing a high-k dielectric material over the gate stack of the NVM transistor and the plurality of MOS regions to concurrently form a blocking dielectric comprising the high-k dielectric material in the gate stack of the NVM transistor and high-k gate dielectrics in the plurality of MOS regions. In one embodiment, a first metal layer is deposited over the high-k dielectric material and patterned to concurrently form a metal gate over the gate stack of the NVM transistor, and a metal gate of a field effect transistor in one of the MOS regions.Type: GrantFiled: March 28, 2014Date of Patent: November 11, 2014Assignee: Cypress Semiconductor CorporationInventor: Krishnaswamy Ramkumar
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Patent number: 8871595Abstract: An embodiment of a method of integrating a non-volatile memory device into a logic MOS flow is described. Generally, the method includes: forming in a first region of a substrate a channel of a memory device from a semiconducting material overlying a surface of the substrate, the channel connecting a source and a drain of the memory device; forming a charge trapping dielectric stack over the channel adjacent to a plurality of surfaces of the channel, wherein the charge trapping dielectric stack includes a blocking layer on a charge trapping layer over a tunneling layer; and forming a MOS device over a second region of the substrate.Type: GrantFiled: March 31, 2012Date of Patent: October 28, 2014Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Fredrick Jenne, Sagy Levy
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Patent number: 8859374Abstract: Semiconductor devices including non-volatile memory transistors and methods of fabricating the same to improve performance thereof are provided. In one embodiment, the method comprises: (i) forming an oxide-nitride-oxide (ONO) dielectric stack on a surface of a semiconductor substrate in at least a first region in which a non-volatile memory transistor is to be formed, the ONO dielectric stack including a multi-layer charge storage layer; (ii) forming an oxide layer on the surface of the substrate in a second region in which a metal oxide semiconductor (MOS) logic transistor is to be formed; and (iii) forming a high work function gate electrode on a surface of the ONO dielectric stack. Other embodiments are also disclosed.Type: GrantFiled: November 3, 2011Date of Patent: October 14, 2014Assignee: Cypress Semiconductor CorporationInventors: Igor Polishchuk, Sagy Levy, Krishnaswamy Ramkumar
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Publication number: 20140284696Abstract: A method of fabricating a memory device is described. Generally, the method includes: forming a tunneling layer on a substrate; forming on the tunneling layer a multi-layer charge storing layer including at least a first charge storing layer comprising an oxygen-rich oxynitride overlying the tunneling layer, and a second charge storing layer overlying the first charge storing layer comprising a silicon-rich and nitrogen-rich oxynitride layer that is oxygen-lean relative to the first charge storing layer and comprises a majority of charge traps distributed in the multi-layer charge storing layer; and forming a blocking layer on the second oxynitride layer; and forming a gate layer on the blocking layer. Other embodiments are also described.Type: ApplicationFiled: February 4, 2014Publication date: September 25, 2014Applicant: Cypress Semiconductor CorporationInventors: Sagy Charel Levy, Krishnaswamy Ramkumar, Frederick B. Jenne, Sam G. Geha
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Publication number: 20140264550Abstract: A nonvolatile charge trap memory device is described. The device includes a substrate having a channel region. A gate stack is disposed above the substrate over the channel region. The gate stack includes a multi-layer charge-trapping region having a first deuterated layer. The multi-layer charge-trapping region may further include a deuterium-free charge-trapping layer.Type: ApplicationFiled: March 25, 2014Publication date: September 18, 2014Applicant: Cypress Semiconductor CorporationInventors: Sagy Charel Levy, Frederick B. Jenne, Krishnaswamy Ramkumar
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Publication number: 20140264551Abstract: A memory device is described. Generally, the device includes a memory transistor and a metal oxide semiconductor (MOS) logic transistor. The memory transistor includes: a channel region electrically connecting a source region and a drain region, the channel region comprising polysilicon; an oxide-nitride-nitride-oxide (ONNO) stack disposed above the channel region, the ONNO stack comprising a multi-layer charge-trapping region including an oxygen-rich first nitride layer and an oxygen-lean second nitride layer disposed above the first nitride layer; and a gate electrode comprising doped polysilicon formed over a surface of the ONNO stack. The MOS logic transistor includes a gate oxide and a gate electrode comprising doped polysilicon. Other embodiments are also described.Type: ApplicationFiled: January 20, 2014Publication date: September 18, 2014Applicant: CYPRESS SEMICONDUCTOR CORPORATIONInventors: Igor Polishchuk, Sagy Charel Levy, Krishnaswamy Ramkumar
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Patent number: 8822349Abstract: A method of making a semiconductor structure is provided. The method includes forming a dielectric layer using a high density plasma oxidation process. The dielectric layer is on a storage layer and the thickness of the storage layer is reduced during the high density plasma oxidation process.Type: GrantFiled: February 21, 2012Date of Patent: September 2, 2014Assignee: Cypress Semiconductor CorporationInventors: Jeong Soo Byun, Krishnaswamy Ramkumar
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Publication number: 20140239374Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a dielectric stack on a substrate, the dielectric stack including a tunneling dielectric on the substrate and a charge-trapping layer on the tunneling dielectric; patterning the dielectric stack to form a gate stack of a NVM transistor of a memory device in a first region of the substrate while concurrently removing the dielectric stack from a second region of the substrate; and performing a gate oxidation process of a baseline CMOS process flow to thermally grow a gate oxide of a MOS transistor overlying the substrate in the second region while concurrently growing a blocking oxide overlying the charge-trapping layer. In one embodiment, Indium is implanted to form a channel of the NVM transistor.Type: ApplicationFiled: September 4, 2013Publication date: August 28, 2014Applicant: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Igor G. Kouznetsov, Venkatraman Prabhakar
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Publication number: 20140235046Abstract: A method of fabricating a memory device is described. Generally, the method includes: forming on a surface of a substrate a dielectric stack including a tunneling dielectric and a charge-trapping layer overlying the tunneling dielectric; forming a cap layer overlying the dielectric stack, wherein the cap layer comprises a multi-layer cap layer including at least a first cap layer overlying the charge-trapping layer, and a second cap layer overlying the first cap layer; patterning the cap layer and the dielectric stack to form a gate stack of a memory device; removing the second cap layer; and performing an oxidation process to oxidize the first cap layer to form a blocking oxide overlying the charge-trapping layer, wherein the oxidation process consumes the first cap layer. Other embodiments are also described.Type: ApplicationFiled: March 7, 2014Publication date: August 21, 2014Applicant: CYPRESS SEMICONDUCTOR CORPORATIONInventor: Krishnaswamy Ramkumar
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Publication number: 20140225116Abstract: Nonvolatile charge trap memory devices with deuterium passivation of charge traps and methods of forming the same are described. In one embodiment, the device includes a channel formed from a semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device. A gate stack overlies the channel, the gate stack comprising a tunneling layer, a trapping layer, a blocking layer, a gate layer; and a deuterated gate cap layer. The gate cap layer has a higher deuterium concentration at an interface with the gate layer than at surface of the gate cap layer distal from the gate layer. In certain embodiments, the channel comprises polysilicon or recrystallized polysilicon. Other embodiments are also described.Type: ApplicationFiled: March 28, 2014Publication date: August 14, 2014Applicant: CYPRESS SEMICONDUCTOR CORPORATIONInventors: Krishnaswamy Ramkumar, Fredrick Jenne, William Koutny
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Patent number: 8796098Abstract: Memory cells including embedded SONOS based non-volatile memory (NVM) and MOS transistors and methods of forming the same are described. Generally, the method includes: forming a dielectric stack on a substrate, the dielectric stack including a tunneling dielectric on the substrate and a charge-trapping layer on the tunneling dielectric; patterning the dielectric stack to form a gate stack of a NVM transistor of a memory device in a first region of the substrate while concurrently removing the dielectric stack from a second region of the substrate; and performing a gate oxidation process of a baseline CMOS process flow to thermally grow a gate oxide of a MOS transistor overlying the substrate in the second region while concurrently growing a blocking oxide overlying the charge-trapping layer. In one embodiment, Indium is implanted to form a channel of the NVM transistor.Type: GrantFiled: September 4, 2013Date of Patent: August 5, 2014Assignee: Cypress Semiconductor CorporationInventors: Krishnaswamy Ramkumar, Igor G. Kouznetsov, Venkatraman Prabhakar
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Patent number: 8772059Abstract: Embodiments of structures and methods for determining operating characteristics of a non-volatile memory transistor comprising a charge-storage-layer and a tunneling-layer are described.Type: GrantFiled: March 26, 2012Date of Patent: July 8, 2014Assignee: Cypress Semiconductor CorporationInventors: Yu Yang, Krishnaswamy Ramkumar
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Patent number: 8710578Abstract: Embodiments of a non-planar memory device including a split charge-trapping region and methods of forming the same are described. Generally, the device comprises: a channel formed from a thin film of semiconducting material overlying a surface on a substrate connecting a source and a drain of the memory device; a tunnel oxide overlying the channel; a split charge-trapping region overlying the tunnel oxide, the split charge-trapping region including a bottom charge-trapping layer comprising a nitride closer to the tunnel oxide, and a top charge-trapping layer, wherein the bottom charge-trapping layer is separated from the top charge-trapping layer by a thin anti-tunneling layer comprising an oxide. Other embodiments are also disclosed.Type: GrantFiled: March 27, 2012Date of Patent: April 29, 2014Assignee: Cypress Semiconductor CorporationInventors: Fredrick Jenne, Krishnaswamy Ramkumar
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Patent number: 8710579Abstract: A semiconductor device and method of manufacturing the same are provided. In one embodiment, semiconductor device comprises a split charge-trapping region comprising two nitride layers with charge traps distributed therein, the two nitride layers separated by one or more oxide layers. The two nitride layers include a first nitride layer closer to a substrate over which the split charge-trapping region is formed, and a second nitride layer on the other side of the one or more oxide layers. The second nitride layer comprises a majority of the charge traps. Other embodiments are also described.Type: GrantFiled: July 17, 2012Date of Patent: April 29, 2014Assignee: Cypress Semiconductor CorporationInventors: Fredrick Jenne, Krishnaswamy Ramkumar
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Patent number: 8691648Abstract: Non-volatile semiconductor memories and methods of fabricating the same to improve performance thereof are provided. In one embodiment, the method includes: (i) forming a gate for a non-volatile memory transistor on a surface of a substrate overlaying a channel region formed therein, the gate including a charge trapping layer; and (ii) forming a strain inducing structure over the gate of the non-volatile memory transistor to increase charge retention of the charge trapping layer. Preferably, the memory transistor is a silicon-oxide-nitride-oxide-silicon (SONOS) transistor comprising a SONOS gate stack. More preferably, the memory also includes a logic transistor on the substrate, and the step of forming a strain inducing structure comprises the step of forming the strain inducing structure over the logic transistor. Other embodiments are also disclosed.Type: GrantFiled: June 24, 2011Date of Patent: April 8, 2014Assignee: Cypress Semiconductor CorporationInventors: Igor Polishchuk, Sagy Levy, Krishnaswamy Ramkumar, Jeong Soo Byun
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Patent number: 8685813Abstract: Embodiments of a method of integration of a non-volatile memory device into a MOS flow are described. Generally, the method includes: forming a dielectric stack on a surface of a substrate, the dielectric stack including a tunneling dielectric overlying the surface of the substrate and a charge-trapping layer overlying the tunneling dielectric; forming a cap layer overlying the dielectric stack; patterning the cap layer and the dielectric stack to form a gate stack of a memory device in a first region of the substrate and to remove the cap layer and the charge-trapping layer from a second region of the substrate; and performing an oxidation process to form a gate oxide of a MOS device overlying the surface of the substrate in the second region while simultaneously oxidizing the cap layer to form a blocking oxide overlying the charge-trapping layer. Other embodiments are also disclosed.Type: GrantFiled: March 23, 2012Date of Patent: April 1, 2014Assignee: Cypress Semiconductor CorporationInventor: Krishnaswamy Ramkumar