Patents by Inventor Rajesh A. Rao
Rajesh A. Rao 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: 7563662Abstract: A process for forming an electronic device can be performed, such that as little as one gate electric layer may be formed within each region of the electronic device. In one embodiment, the electronic device can include an NVM array and other regions that have different gate dielectric layers. By protecting the field isolation regions within the NVM array and other regions while gate dielectric layer are formed, the field isolation regions may be exposed to as little as one oxide etch between the time any of the gate dielectric layers are formed the time such gate dielectric layers are covered by gate electrode layers. The process helps to reduce field isolation erosion and reduce problems associated therewith.Type: GrantFiled: March 18, 2005Date of Patent: July 21, 2009Assignee: Freescale Semiconductor, Inc.Inventors: Rajesh A. Rao, Ramachandran Muralidhar
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Publication number: 20090166712Abstract: A method of forming a semiconductor device includes forming a first dielectric layer over a semiconductor substrate, forming a plurality of discrete storage elements over the first dielectric layer, thermally oxidizing the plurality of discrete storage elements to form a second dielectrics over the plurality of discrete storage elements, and forming a gate electrode over the second dielectric layer, wherein a significant portion of the gate electrode is between pairs of the plurality of discrete storage elements. In one embodiment, portions of the gate electrode is in the spaces between the discrete storage elements and extends to more than half of the depth of the spaces.Type: ApplicationFiled: March 4, 2009Publication date: July 2, 2009Applicant: Freescale Semiconductor, Inc.Inventors: Ramachandran Muralidhar, Rajesh A. Rao, Michael A. Sadd, Bruce E. White
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Patent number: 7528047Abstract: A method of forming a split gate memory device using a semiconductor layer includes patterning an insulating layer to leave a pillar thereof. A gate dielectric is formed over the semiconductor layer. A charge storage layer is formed over the gate dielectric and along first and second sides of the pillar. A gate material layer is formed over the gate dielectric and pillar. An etch is performed to leave a first portion of the gate material laterally adjacent to a first side of the pillar and over a first portion of the charge storage layer that is over the gate dielectric to function as a control gate of the memory device and a second portion of the gate material laterally adjacent to a second side of the pillar and over a second portion of the charge storage layer that is over the gate dielectric to function as a select gate.Type: GrantFiled: June 7, 2007Date of Patent: May 5, 2009Assignee: Freescale Semiconductor, Inc.Inventors: Rajesh A. Rao, Tushar P. Merchant, Ramachandran Muralidhar, Lakshmanna Vishnubhotla
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Patent number: 7517747Abstract: A method of forming a semiconductor device includes forming a first dielectric layer over a semiconductor substrate, forming a plurality of discrete storage elements over the first dielectric layer, thermally oxidizing the plurality of discrete storage elements to form a second dielectrics over the plurality of discrete storage elements, and forming a gate electrode over the second dielectric layer, wherein a significant portion of the gate electrode is between pairs of the plurality of discrete storage elements. In one embodiment, portions of the gate electrode is in the spaces between the discrete storage elements and extends to more than half of the depth of the spaces.Type: GrantFiled: September 8, 2006Date of Patent: April 14, 2009Assignee: Freescale Semiconductor, Inc.Inventors: Ramachandran Muralidhar, Rajesh A. Rao, Michael A. Sadd, Bruce E. White
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Publication number: 20090085024Abstract: A phase change memory cell has a first electrode, a plurality of pillars, and a second electrode. The plurality of pillars are electrically coupled with the first electrode. Each of the pillars comprises a phase change material portion and a heater material portion. The second electrode is electrically coupled to each of the pillars. In some examples, the pillars have a width less than 20 nanometers.Type: ApplicationFiled: September 28, 2007Publication date: April 2, 2009Inventors: Ramachandran Muralidhar, Tushar P. Merchant, Rajesh A. Rao
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Publication number: 20090085023Abstract: A phase change memory cell has a first electrode, a heater, a phase change material, and a second electrode. The heater is over the first electrode, and the heater comprises a pillar. The phase change material is around the heater. The second electrode is electrically coupled to the phase change material. In some embodiments, a method includes forming a electrode layer over a substrate, depositing a first layer, providing nanoclusters over the first layer, and etching the first layer. The first layer comprises one of a group consisting of a heater material and a phase change material. The first layer may be etched using the nanocluster defined pattern to form pillars from the first layer.Type: ApplicationFiled: September 28, 2007Publication date: April 2, 2009Inventors: Ramachandran Muralidhar, Tushar P. Merchant, Rajesh A. Rao
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Publication number: 20090061608Abstract: A method of depositing a silicon dioxide layer for a semiconductor device. The method includes depositing the silicon dioxide layer to have a silicon concentration of greater than 30 atomic percent and a nitrogen concentration of less than 5 atomic percent. The depositing includes flowing nitric oxide gas with a silicon precursor over a substrate. In one example, the silicon precursor and nitric oxide are flowed over a substrate with the substrate being at a temperature in a range of approximately 600 to approximately 900 degrees Celsius. In one example, the silicon dioxide layer is formed on a layer including charge storage memory material.Type: ApplicationFiled: August 29, 2007Publication date: March 5, 2009Inventors: Tushar P. Merchant, Lakshmanna Vishnubhotla, Ramachandran Muralidhar, Rajesh A. Rao, Sriram Kalpat
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Publication number: 20080303067Abstract: A self-aligned split gate bitcell includes first and second regions of charge storage material separated by a gap devoid of charge storage material. Spacers are formed along sidewalls of sacrificial layer extending above and on opposite sides of the bitcell stack, wherein the spacers are separated from one another by at least a gap length. Etching the bitcell stack, selective to the spacers, forms a gap that splits the bitcell stack into first and second gates which together form the split gate bitcell stack. A storage portion of bitcell stack is also etched, wherein etching extends the gap and separates the corresponding layer into first and second separate regions, the extended gap being devoid of charge storage material. Dielectric material is deposited over the gap and etched back to expose a top surface of the sacrificial layer, which is thereafter removed to expose sidewalls of the split gate bitcell stack.Type: ApplicationFiled: June 7, 2007Publication date: December 11, 2008Inventors: Rajesh A. Rao, Tushar P. Merchant, Ramachandran Muralidhar, Lakshmanna Vishnubhotla
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Publication number: 20080303094Abstract: A method of forming a split gate memory device using a semiconductor layer includes patterning an insulating layer to leave a pillar thereof. A gate dielectric is formed over the semiconductor layer. A charge storage layer is formed over the gate dielectric and along first and second sides of the pillar. A gate material layer is formed over the gate dielectric and pillar. An etch is performed to leave a first portion of the gate material laterally adjacent to a first side of the pillar and over a first portion of the charge storage layer that is over the gate dielectric to function as a control gate of the memory device and a second portion of the gate material laterally adjacent to a second side of the pillar and over a second portion of the charge storage layer that is over the gate dielectric to function as a select gate.Type: ApplicationFiled: June 7, 2007Publication date: December 11, 2008Inventors: Rajesh A. Rao, Tushar P. Merchant, Ramachandran Muralidhar, Lakshmanna Vishnubhotla
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Patent number: 7445984Abstract: A method of making a semiconductor device includes a substrate having a semiconductor layer having a first portion for non-volatile memory and a second portion exclusive of the first portion. A first dielectric layer is formed on the semiconductor layer. A plasma nitridation is performed on the first dielectric layer. A first plurality of nanoclusters is formed over the first portion and a second plurality of nanoclusters over the second portion. The second plurality of nanoclusters is removed. A second dielectric layer is formed over the semiconductor layer. A conductive layer is formed over the second dielectric layer.Type: GrantFiled: July 25, 2006Date of Patent: November 4, 2008Assignee: Freescale Semiconductor, Inc.Inventors: Rajesh A. Rao, Tien Ying Luo, Ramachandran Muralidhar, Robert F. Steimle, Sherry G. Straub
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Patent number: 7432158Abstract: A method of making a semiconductor device includes a substrate having a semiconductor layer having a first portion for non-volatile memory and a second portion exclusive of the first portion. A first dielectric layer is formed over the semiconductor layer. A first plurality of nanoclusters is formed over the first portion and a second plurality of nanoclusters is formed over the second portion. A layer of nitrided oxide is formed around each nanocluster of the first plurality and the second plurality of nanoclusters. Remote plasma nitridation is performed on the layers of nitrided oxide of the first plurality of nanoclusters. The nanoclusters are removed from the second portion. A second dielectric layer is formed over the semiconductor layer. A conductive layer is formed over the second dielectric layer.Type: GrantFiled: July 25, 2006Date of Patent: October 7, 2008Assignee: Freescale Semiconductor, Inc.Inventors: Rajesh A. Rao, Tien Ying Luo, Ramachandran Muralidhar, Robert F. Steimle, Sherry G. Straub
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Publication number: 20080242022Abstract: An electronic device can include a nonvolatile memory cell having DSEs within a dielectric layer. In one aspect, a process of forming the electronic device can include implanting and nucleating a first charge-storage material to form DSEs. The process can also include implanting a second charge-storage material and growing the DSEs such that the DSEs include the first and second charge-storage material. In another aspect, a process of forming the electronic device can include forming a semiconductor layer over a dielectric layer, implanting a charge-storage material, and annealing the dielectric layer. After annealing, substantially none of the charge-storage material remains within a denuded zone within the dielectric layer. In a third aspect, within a dielectric layer, a first set of DSEs can be spaced apart from a second set of DSEs, wherein substantially no DSEs lie between the first set of DSEs and the second set of DSEs.Type: ApplicationFiled: March 30, 2007Publication date: October 2, 2008Applicant: FREESCALE SEMICONDUCTOR, INC.Inventors: Rajesh A. Rao, Tushar P. Merchant, Ramachandran Muralidhar, Gowrishankar Chindalore, David Sing, Jane Yater
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Publication number: 20080227254Abstract: An electronic device including a nonvolatile memory cell can include a substrate including a first portion and a second portion, wherein a first major surface within the first portion lies at an elevation lower than a second major surface within the second portion. The electronic device can also include a charge storage stack overlying the first portion, wherein the charge storage stack includes discontinuous storage elements. The electronic device can further include a control gate electrode overlying the first portion, and a select gate electrode overlying the second portion, wherein the select gate electrode includes a sidewall spacer. In a particular embodiment, a process can be used to form the charge storage stack and control gate electrode. A semiconductor layer can be formed after the charge storage stack and control gate electrode are formed to achieve the substrate with different major surfaces at different elevations. The select gate electrode can be formed over the semiconductor layer.Type: ApplicationFiled: March 13, 2007Publication date: September 18, 2008Applicant: Freescale Semiconductor, Inc.Inventors: Rajesh A. Rao, Ramachandran Muralidhar
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Patent number: 7416945Abstract: A method forms a split gate memory device. A layer of select gate material over a substrate is patterned to form a first sidewall. A sacrificial spacer is formed adjacent to the first sidewall. Nanoclusters are formed over the substrate including on the sacrificial spacer. The sacrificial spacer is removed after the forming the layer of nanoclusters, wherein nanoclusters formed on the sacrificial spacer are removed and other nanoclusters remain. A layer of control gate material is formed over the substrate after the sacrificial spacer is removed. A control gate of a split gate memory device is formed from the layer of control gate material, wherein the control gate is located over remaining nanoclusters.Type: GrantFiled: February 19, 2007Date of Patent: August 26, 2008Assignee: Freescale Semiconductor, Inc.Inventors: Ramachandran Muralidhar, Rajesh A. Rao, Matthew T. Herrick, Narayanan C. Ramani, Robert F. Steimle
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Publication number: 20080199996Abstract: A method forms a split gate memory device. A layer of select gate material over a substrate is patterned to form a first sidewall. A sacrificial spacer is formed adjacent to the first sidewall. Nanoclusters are formed over the substrate including on the sacrificial spacer. The sacrificial spacer is removed after the forming the layer of nanoclusters, wherein nanoclusters formed on the sacrificial spacer are removed and other nanoclusters remain. A layer of control gate material is formed over the substrate after the sacrificial spacer is removed. A control gate of a split gate memory device is formed from the layer of control gate material, wherein the control gate is located over remaining nanoclusters.Type: ApplicationFiled: February 19, 2007Publication date: August 21, 2008Inventors: Ramachandran Muralidhar, Rajesh A. Rao, Matthew T. Herrick, Narayanan C. Ramani, Robert F. Steimle
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Publication number: 20080188052Abstract: A semiconductor process and apparatus are disclosed for forming a split-gate thin film storage NVM device (10) by forming a select gate structure (3) on a first dielectric layer (2) over a substrate (1); forming a control gate structure (6) on a second dielectric layer (5) having embedded nanocrystals (15, 16) so that the control gate (6) is adjacent to the select gate structure (3) but separated therefrom by a gap (8); forming a floating doped region (4) in the substrate (1) below the gap (8) formed between the select gate structure and control gate structure; and forming source/drain regions (11, 12) in the substrate to define a channel region that includes the floating doped region (4).Type: ApplicationFiled: February 6, 2007Publication date: August 7, 2008Inventors: Brian A. Winstead, Taras A. Kirichenko, Konstantin V. Loiko, Ramachandran Muralidhar, Rajesh A. Rao, Sung-Taeg Kang, Ko-Min Chang, Jane Yater
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Publication number: 20080179658Abstract: A semiconductor device is made on a semiconductor substrate. A first insulating layer is formed on the semiconductor substrate for use as a gate dielectric for a high voltage transistor in a first region of the semiconductor substrate. After the first insulating layer is formed, a second insulating layer is formed on the semiconductor substrate for use as a gate dielectric for a non-volatile memory transistor in a second region of the substrate. After the second insulating layer is formed, a third insulating layer is formed on the semiconductor substrate for use as a gate dielectric for a logic transistor in a third region of the substrate.Type: ApplicationFiled: January 26, 2007Publication date: July 31, 2008Inventors: Rajesh A. Rao, Ramachandran Muralidhar
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Publication number: 20080182428Abstract: An electronic device can include a layer of discontinuous storage elements. A dielectric layer overlying the discontinuous storage elements can be substantially hydrogen-free. A process of forming the electronic device can include forming a layer including silicon over the discontinuous storage elements. In one embodiment, the process includes oxidizing at least substantially all of the layer. In another embodiment, the process includes forming the layer using a substantially hydrogen-free silicon precursor material and oxidizing at least substantially all of the layer.Type: ApplicationFiled: January 26, 2007Publication date: July 31, 2008Applicant: Freescale Semiconductor, Inc.Inventors: Tushar P. Merchant, Chun-Li Liu, Ramachandran Muralidhar, Marius K. Orlowski, Rajesh A. Rao, Matthew Stoker
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Publication number: 20080182377Abstract: In making a multi-bit memory cell, a first insulating layer is formed over a semiconductor substrate. A second insulating layer is formed over the first insulating layer. A layer of gate material is formed over the second insulating layer and patterned to leave a gate portion. The second insulating layer is etched to undercut the gate portion and leave a portion of the second insulating layer between the first insulating layer and the gate portion. Nanocrystals are formed on the first insulating layer. A first portion of the nanocrystals is under the gate portion on a first side of the portion of the second insulating layer and a second portion of the nanocrystals is under the gate portion on a second side of the portion of the second insulating layer. The first and second portions of the nanocrystals are for storing logic states of first and second bits, respectively.Type: ApplicationFiled: January 29, 2007Publication date: July 31, 2008Inventors: Rajesh A. Rao, Ramachandran Muralidhar
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Publication number: 20080164512Abstract: A semiconductor device has a semiconductor substrate that in turn has a top semiconductor layer portion and a major supporting portion under the top semiconductor layer portion. An interconnect layer is over the semiconductor layer. A memory array is in a portion of the top semiconductor layer portion and a portion of the interconnect layer. The memory is erased by removing at least a portion of the major supporting portion and, after the step of removing, applying light to the memory array from a side opposite the interconnect layer. The result is that the memory array receives light from the backside and is erased.Type: ApplicationFiled: January 5, 2007Publication date: July 10, 2008Inventors: Rajesh A. Rao, Leo Mathew, Ramachandran Muralidhar, Bruce E. White