Patents by Inventor Mohan Dunga
Mohan Dunga 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: 8988937Abstract: In a programming operation of a 3D stacked non-volatile memory device, the channel of an inhibited NAND string is pre-charged by gate-induced drain leakage (GIDL) to achieve a high level of boosting which prevents program disturb in inhibited storage elements. In a program-verify iteration, prior to applying a program pulse, the drain-side select gate transistor is reverse biased to generate GIDL, causing the channel to be boosted to a pre-charge level such as 1.5V. Subsequently, when the program pulse is applied to a selected word line and pass voltages are applied to unselected word lines, the channel is boosted higher from the pre-charge level due to capacitive coupling. The pre-charge is effective even for a NAND string that is partially programmed because it does not rely on directly driving the channel from the bit line end.Type: GrantFiled: October 24, 2012Date of Patent: March 24, 2015Assignee: SanDisk Technologies Inc.Inventors: Mohan Dunga, Yingda Dong, Wendy Ou
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Patent number: 8982629Abstract: Techniques are provided for programming and erasing of select gate transistors in connection with the programming or erasing of a set of memory cells. In response to a program command to program memory cells, the select gate transistors are read to determine whether their Vth is below an acceptable range, in which case the select gate transistors are programmed before the memory cells. Or, a decision can be made to program the select gate transistors based on a count of program-erase cycles, whether a specified time period has elapsed and/or a temperature history of the non-volatile storage device. When an erase command is made to erase memory cells, the select gate transistors are read to determine whether their Vth is above an acceptable range. If their Vth is above the acceptable range, the select gate transistors can be erased concurrently with the erasing of the memory cells.Type: GrantFiled: May 23, 2014Date of Patent: March 17, 2015Assignee: SanDisk Technologies Inc.Inventors: Deepanshu Dutta, Yan Li, Masaaki Higashitani, Mohan Dunga
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Publication number: 20140369129Abstract: Techniques are provided for programming select gate transistors in connection with the programming of a set of memory cells. In response to a program command to program memory cells, the select gate transistors are read to determine whether their Vth is below an acceptable range, in which case the select gate transistors are programmed before the memory cells. Or, a decision can be made to program the select gate transistors based on a count of program-erase cycles, whether a specified time period has elapsed and/or a temperature history of the non-volatile storage device.Type: ApplicationFiled: September 4, 2014Publication date: December 18, 2014Inventors: Deepanshu Dutta, Yan Li, Masaaki Higashitani, Mohan Dunga
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Patent number: 8877627Abstract: Non-volatile storage elements having a PN floating gate are disclosed herein. The floating gate may have a P? region near the tunnel oxide, and may have an N+ region near the control gate. In some embodiments, a P? region near the tunnel oxide helps provide good data retention. In some embodiments, an N+ region near the control gate helps to achieve a good coupling ratio between the control gate and floating gate. Therefore, programming of non-volatile storage elements is efficient. Also erasing the non-volatile storage elements may be efficient. In some embodiments, having a P? region near the tunnel oxide (as opposed to a strongly doped p-type semiconductor) may improve erase efficiency relative to P+.Type: GrantFiled: December 13, 2013Date of Patent: November 4, 2014Assignee: SanDisk Technologies Inc.Inventors: Mohan Dunga, Sanghyun Lee, Masaaki Higashitani, Tuan Pham
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Patent number: 8861282Abstract: Techniques are provided for programming and erasing of select gate transistors in connection with the programming or erasing of a set of memory cells. In response to a program command to program memory cells, the select gate transistors are read to determine whether their Vth is below an acceptable range, in which case the select gate transistors are programmed before the memory cells. Or, a decision can be made to program the select gate transistors based on a count of program-erase cycles, whether a specified time period has elapsed and/or a temperature history of the non-volatile storage device. When an erase command is made to erase memory cells, the select gate transistors are read to determine whether their Vth is above an acceptable range. If their Vth is above the acceptable range, the select gate transistors can be erased concurrently with the erasing of the memory cells.Type: GrantFiled: January 11, 2013Date of Patent: October 14, 2014Assignee: SanDisk Technologies Inc.Inventors: Deepanshu Dutta, Yan Li, Masaaki Higashitani, Mohan Dunga
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Publication number: 20140269070Abstract: Techniques for sensing the threshold voltage of a memory cell during reading and verify operations by compensating for changes, including temperature-based changes, in the resistance of a bit line or other control line. A memory cell being sensed is in a block in a memory array and the block is in a group of blocks. A portion of the bit line extends between the group of blocks and a sense component and has a resistance which is based on the length/distance and the temperature. Various parameters can be varied with temperature and the group of blocks to provide the compensation, including bit line voltage, selected word line voltage, source line voltage, sense time and/or sense current or voltage.Type: ApplicationFiled: March 14, 2013Publication date: September 18, 2014Applicant: SANDISK TECHNOLOGIES INC.Inventors: Chia-Lin Hsiung, Mohan Dunga, Man L Mui, Masaaki Higashitani
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Publication number: 20140254277Abstract: Techniques are provided for programming and erasing of select gate transistors in connection with the programming or erasing of a set of memory cells. In response to a program command to program memory cells, the select gate transistors are read to determine whether their Vth is below an acceptable range, in which case the select gate transistors are programmed before the memory cells. Or, a decision can be made to program the select gate transistors based on a count of program-erase cycles, whether a specified time period has elapsed and/or a temperature history of the non-volatile storage device. When an erase command is made to erase memory cells, the select gate transistors are read to determine whether their Vth is above an acceptable range. If their Vth is above the acceptable range, the select gate transistors can be erased concurrently with the erasing of the memory cells.Type: ApplicationFiled: May 23, 2014Publication date: September 11, 2014Applicant: SanDisk Technologies Inc.Inventors: Deepanshu Dutta, Yan Li, Masaaki Higashitani, Mohan Dunga
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Publication number: 20140247670Abstract: In a programming operation of a 3D stacked non-volatile memory device, the channel of an inhibited NAND string is pre-charged by gate-induced drain leakage (GIDL) to achieve a high level of boosting which prevents program disturb in inhibited storage elements. In a program-verify iteration, prior to applying a program pulse, the drain-side select gate transistor is reverse biased to generate GIDL, causing the channel to be boosted to a pre-charge level such as 1.5V. Subsequently, when the program pulse is applied to a selected word line and pass voltages are applied to unselected word lines, the channel is boosted higher from the pre-charge level due to capacitive coupling. The pre-charge is effective even for a NAND string that is partially programmed because it does not rely on directly driving the channel from the bit line end.Type: ApplicationFiled: May 15, 2014Publication date: September 4, 2014Applicant: SanDisk Technologies Inc.Inventors: Mohan Dunga, Yingda Dong, Wendy Ou
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Publication number: 20140198575Abstract: Techniques are provided for programming and erasing of select gate transistors in connection with the programming or erasing of a set of memory cells. In response to a program command to program memory cells, the select gate transistors are read to determine whether their Vth is below an acceptable range, in which case the select gate transistors are programmed before the memory cells. Or, a decision can be made to program the select gate transistors based on a count of program-erase cycles, whether a specified time period has elapsed and/or a temperature history of the non-volatile storage device. When an erase command is made to erase memory cells, the select gate transistors are read to determine whether their Vth is above an acceptable range. If their Vth is above the acceptable range, the select gate transistors can be erased concurrently with the erasing of the memory cells.Type: ApplicationFiled: January 11, 2013Publication date: July 17, 2014Applicant: SANDISK TECHNOLOGIES INC.Inventors: Deepanshu Dutta, Yan Li, Masaaki Higashitani, Mohan Dunga
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Publication number: 20140126286Abstract: Techniques are disclosed for SLC blocks having different characteristics than MLC blocks such that SLC blocks will have high endurance and MLC blocks will have high reliability. A thinner tunnel oxide may be used for memory cells in SLC blocks than for memory cells in MLC blocks. A thinner tunnel oxide in SLC blocks may allow a lower program voltage to be used, which may improve endurance. A thicker tunnel oxide in MLC blocks may improve data retention. A thinner IPD may be used for memory cells in SLC blocks than for memory cells in MLC blocks. A thinner IPD may provide a higher coupling ratio, which may allow a lower program voltage. A lower program voltage in SLC blocks can improve endurance. A thicker IPD in MLC blocks can prevent or reduce read disturb. SLC blocks may have a different number of data word lines than MLC blocks.Type: ApplicationFiled: November 2, 2012Publication date: May 8, 2014Applicant: SANDISK TECHNOLOGIES INC.Inventors: Masaaki Higashitani, Mohan Dunga, Jiahui Yuan
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Publication number: 20140112075Abstract: In a programming operation of a 3D stacked non-volatile memory device, the channel of an inhibited NAND string is pre-charged by gate-induced drain leakage (GIDL) to achieve a high level of boosting which prevents program disturb in inhibited storage elements. In a program-verify iteration, prior to applying a program pulse, the drain-side select gate transistor is reverse biased to generate GIDL, causing the channel to be boosted to a pre-charge level such as 1.5V. Subsequently, when the program pulse is applied to a selected word line and pass voltages are applied to unselected word lines, the channel is boosted higher from the pre-charge level due to capacitive coupling. The pre-charge is effective even for a NAND string that is partially programmed because it does not rely on directly driving the channel from the bit line end.Type: ApplicationFiled: October 24, 2012Publication date: April 24, 2014Applicant: SANDISK TECHNOLOGIES INC.Inventors: Mohan Dunga, Yingda Dong, Wendy Ou
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Publication number: 20140106525Abstract: Non-volatile storage elements having a PN floating gate are disclosed herein. The floating gate may have a P? region near the tunnel oxide, and may have an N+ region near the control gate. In some embodiments, a P? region near the tunnel oxide helps provide good data retention. In some embodiments, an N+ region near the control gate helps to achieve a good coupling ratio between the control gate and floating gate. Therefore, programming of non-volatile storage elements is efficient. Also erasing the non-volatile storage elements may be efficient. In some embodiments, having a P? region near the tunnel oxide (as opposed to a strongly doped p-type semiconductor) may improve erase efficiency relative to P+.Type: ApplicationFiled: December 13, 2013Publication date: April 17, 2014Applicant: SanDisk Technologies Inc.Inventors: Mohan Dunga, Sanghyun Lee, Masaaki Higashitani, Tuan Pham
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Publication number: 20130314995Abstract: A technique for erasing non-volatile memory such as a NAND string which includes non-user data or dummy storage elements. The voltages of the non-user data storage elements are capacitively coupled higher by controlled increases in an erase voltage which is applied to a substrate. The voltages are floated by rendering a pass gate transistor in a non-conductive state, where the pass gate transistor is between a voltage driver and a non-user data storage element. Voltages of select gate transistors can also be capacitively coupled higher. The substrate voltage can be increased in steps and/or as a continuous ramp. In one approach, outer dummy storage elements are floated while inner dummy storage elements are driven. In another approach, both outer and inner dummy storage elements are floated. Write-erase endurance of the storage elements is increased due to reduced charge trapping in the substrate.Type: ApplicationFiled: May 24, 2012Publication date: November 28, 2013Inventors: Deepanshu Dutta, Mohan Dunga, Masaaki Higashitani
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Patent number: 8503229Abstract: Non-volatile storage elements having a P?/metal floating gate are disclosed herein. The floating gate may have a P? region near the tunnel oxide, and may have a metal region near the control gate. A P? region near the tunnel oxide helps provide good data retention. A metal region near the control gate helps to achieve a good coupling ratio between the control gate and floating gate. Therefore, programming of non-volatile storage elements is efficient. Also, erasing the non-volatile storage elements may be efficient. In some embodiments, having a P? region near the tunnel oxide (as opposed to a strongly doped p-type semiconductor) may improve erase efficiency relative to P+.Type: GrantFiled: June 6, 2011Date of Patent: August 6, 2013Assignee: SanDisk Technologies Inc.Inventors: Sanghyun Lee, Mohan Dunga, Masaaki Higashitani, Tuan Pham, Franz Kreupl
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Publication number: 20120243337Abstract: Non-volatile storage elements having a P?/metal floating gate are disclosed herein. The floating gate may have a P? region near the tunnel oxide, and may have a metal region near the control gate. A P? region near the tunnel oxide helps provide good data retention. A metal region near the control gate helps to achieve a good coupling ratio between the control gate and floating gate. Therefore, programming of non-volatile storage elements is efficient. Also, erasing the non-volatile storage elements may be efficient. In some embodiments, having a P? region near the tunnel oxide (as opposed to a strongly doped p-type semiconductor) may improve erase efficiency relative to P+.Type: ApplicationFiled: June 6, 2011Publication date: September 27, 2012Inventors: Sanghyun Lee, Mohan Dunga, Masaaki Higashitani, Tuan Pham, Franz Kreupl
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Publication number: 20120228691Abstract: Non-volatile storage elements having a PN floating gate are disclosed herein. The floating gate may have a P? region near the tunnel oxide, and may have an N+ region near the control gate. In some embodiments, a P? region near the tunnel oxide helps provide good data retention. In some embodiments, an N+ region near the control gate helps to achieve a good coupling ratio between the control gate and floating gate. Therefore, programming of non-volatile storage elements is efficient. Also erasing the non-volatile storage elements may be efficient. In some embodiments, having a P? region near the tunnel oxide (as opposed to a strongly doped p-type semiconductor) may improve erase efficiency relative to P+.Type: ApplicationFiled: March 25, 2011Publication date: September 13, 2012Inventors: Mohan Dunga, Sanghyun Lee, Masaaki Higashitani, Tuan Pham