Sandisk Technologies Inc.

Western Digital Technologies, Inc.

Sandisk Corporation

University of California

Dengtao Zhao

Deepanshu Dutta

Nima Mokhlesi

Henry Chin

Yongke Sun

Xiang Yang

Kroum Stanimirov Stoev

Haibo Li

Huai-Yuan Tseng

Jui-Yao Yang

Peng Zhang

Guirong Liang

Zhiping Zhang

Jiahui Yuan

Ravi J Kumar

Tapan Samaddar

Mei-Man L Syu

Abhijith Prakash

Muhammad Masuduzzaman

Yi Song

Nan Lu

Masaaki Higashitani

Gerrit Jan Hemink

Ken Oowada

Anubhav Khandelwal

Sarath Chandran Puthenthermadam

Jiacen Guo

Chin-Yi Chen

Deepak Chandra Sekar

Yanli Zhang

Peter Rabkin

Zhenming Zhou

Man Lung Mui

Jayavel Pachamuthu

Yu-Chung Lien

Seungpil Lee

Wei Zhao

Hao Nguyen

Zhongguang Xu

Guangming Lu

Jin Liu

Shinji Sato

Xue Bai Pitner

Matthias Baenninger

Ruigang Li

Sanghyun Lee

Bei Li

Wei Cao

Jianlin Liu

Kun-Huan Shih

Yan Zhu

Ryohei Shoji

Weiyi Li

A memory device is provided and includes a memory block that has a plurality of memory cells that are arranged in a plurality of word lines. The memory device also includes a plurality of word line switch transistors that are electrically coupled with the plurality of word lines, where the plurality of word lines are grouped into a plurality of zones based on a size of a word line switch transistor associated with each word line of the plurality of word lines. The memory device also includes a bitline biasing circuit for providing a negative biasing voltage to a bitline corresponding to a memory cell of the selected word line during programming of the selected word line and the bitline biasing circuit is configured to set a magnitude of the negative biasing voltage based on which zone of the plurality of zones the selected word line is in.

Enabling significant scaling of wordline switch with wordline dependent negative bitline voltage

A non-volatile memory system comprises a plurality of non-volatile memory cells divided into three or more tiers. The memory cells can be programmed, erased and read. In order to achieve uniform erase speed for the three or more tiers, the erase process comprises applying a larger voltage bias to control gates of non-volatile memory cells in the outer tiers than the voltage bias applied to control gates of non-volatile memory cells in one or more inner tiers.

Erase method for non-volatile memory with multiple tiers

Non-volatile memory cells are programmed by pre-charging channels of unselected non-volatile memory cells connected to a selected data word line, boosting the channels of unselected non-volatile memory cells connected to the selected data word line after the pre-charging and applying a program voltage pulse to selected non-volatile memory cells connected to the selected data word line while boosting. The pre-charging includes applying pre-charge voltages to one set of data word lines and dummy word line(s) as well as applying overdrive voltages to another set of data word lines connected to already programmed memory cells. At the end of the pre-charging, the dummy word lines are ramped down to a resting voltage prior to lowering the data word lines to one or more resting voltages.

Non-volatile memory with early dummy word line ramp down after precharge

A system has been described that performs differential temperature compensation based on a differential between the temperature at time of programming and temperature at time of reading for a set of data. Differential temperature compensation is useful for bulk programming/reading (e.g., many pages of data) and/or programming/reading super pages of data (multiple pages residing on different memory die).

Non-volatile memory with differential temperature compensation for super page programming

Memory cells are arranged as NAND strings to form a block divided into sub-blocks, and each NAND string includes a dummy memory cell connected to a dummy word line. Memory cells are programmed by applying programming pulses to a selected word line in a selected sub-block with program-verify performed between pulses. Unselected NAND strings are inhibited from programming by boosting channels of the unselected NAND strings in the selected sub-block from a positive pre-charge voltage to a boosted voltage. The pre-charging of the channels of unselected NAND strings is performed while lowering voltages at the end of program-verify by applying overdrive voltages to data word lines in a sub-block closer to the source line than the selected sub-block and lowering to a resting voltage a dummy word line between the sub-blocks prior to lowering to a resting voltage the data word lines in the sub-block closer to the source line.

Non-volatile memory with tier-wise ramp down after program-verify

A plurality of memory programming the memory cells to at least one programmed data state in a plurality of program-verify iterations. In each iteration, after a programming pulse, a sensing operation is conducted to compare the threshold voltages of the memory cells to a low verify voltage associated with a first programmed data state and to a high very voltage associated with the first programmed data state. The sensing operation includes discharging a sense node through a bit line coupled to one of the memory cells and monitoring a discharge time of the sense node. At least one aspect of the sensing operation is temperature dependent so that a voltage gap between the high and low verify voltages is generally constant across a range of temperatures.

Memory device that is optimized for operation at different temperatures

Non-volatile memory with differential temperature compensation for bulk programming

A memory system reads data from non-volatile memory cells using a set of read compare voltages to determine which data state the memory cells are in, where each data state is associated with predetermined data values. The read compare voltages are determined dynamically based on a difference between memory cell current at time of programming and memory cell current at time of reading.

Non-volatile memory with updating of read compare voltages based on measured current

To help reduce program disturbs in non-selected NAND strings of a non-volatile memory, a sub-block based boosting scheme in introduced. For a three dimensional NAND memory structure, in which the memory cells above a joint region form an upper sub-block and memory cells below the joint region form a lower sub-block, dummy word lines in the joint region act as select gates to allow boosting at the sub-block level when the lower block is being programmed in a reverse order.

Non-volatile memory with sub-block based self-boosting scheme

Technology is provided for extending the useful life of a block of memory cells by changing an operating parameter in a physical region of the block that is more susceptible to wear than other regions. Changing the operating parameter in the physical region extends the life of that region, which extends the life of the block. The operating parameter may be, for example, a program voltage step size or a storage capacity of the memory cells. For example, using a smaller program voltage step size in a sub-block that is more susceptible to wear extends the life of that sub-block, which extends the life of the block. For example, programming memory cells to fewer bits per cell in the region of the block (e.g., sub-block, word line) that is more susceptible to wear extends the useful life of that region, which extends the life of the block.

Reliability compensation for uneven NAND block degradation

A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to one of a plurality of word lines and arranged in strings and configured to retain a threshold voltage corresponding to one of a plurality of memory states. A control circuit is coupled to the plurality of word lines and strings and is configured to erase the memory cells using a stripe erase operation in response to determining a cycle count is less than a predetermined cycle count maximum threshold. The control circuit is also configured to perform a dummy cycle operation in response to determining the cycle count is not less than the predetermined cycle count maximum threshold.

Memory apparatus and method of operation using periodic normal erase dummy cycle to improve stripe erase endurance and data retention

A memory apparatus and method of operation is provided. The apparatus includes a block of memory cells. Each of the memory cells is connected to one of a plurality of word lines and are also arranged in strings and configured to retain a threshold voltage within a common range of threshold voltages. A control circuit coupled to the plurality of word lines and the strings is configured to determine an erase upper tail voltage of a distribution of the threshold voltage of the memory cells following an erase operation. The erase upper tail voltage corresponds to a cycling condition of the memory cells. The control circuit is also configured to calculate a program voltage to apply to each of selected ones of the plurality of word lines associated with the memory cells to program the memory cells during a program operation based on the erase upper tail voltage.

Memory apparatus and method of operation using zero pulse smart verify

A memory apparatus and method of operation is provided. The apparatus includes memory cells connected to word lines and bit lines and arranged in strings and configured to retain a threshold voltage. Each of the memory cells is configured to be erased in an erase operation occurring during an erase time period. A control circuit is configured to adjust at least a portion of the erase time period in response to determining the erase operation is a segmented erase operation and is resumed after being suspended. The control circuit applies an erase signal having a plurality of voltage segments temporally separated from one another during the erase time period to each of the strings while simultaneously applying a word line erase voltage to selected ones of the word lines to encourage erasing of the memory cells coupled to the selected ones of the word lines in the segmented erase operation.

Memory apparatus and method of operation using adaptive erase time compensation for segmented erase

A non-volatile memory system adjusts the speed of a memory operation for a subset of non-volatile memory cells. For example, during a GIDL based erase process, the GIDL generation can be dampened for a subset of memory cells (e.g., for a set of NAND strings, or one or more sub-blocks).

Non-volatile memory with speed control

A nonvolatile memory control method includes a step of writing, repeatedly to a nonvolatile memory cells. The method continues with detecting when writing reaches a writing threshold value. Upon reaching the writing threshold, the method continues with driving a charge to at least one parasitic area intermediate at least two charge storage areas of the nonvolatile memory cells to improve data retention in at least one of the at least two charge storage areas of the nonvolatile memory cells.

Periodic write to improve data retention

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Santa Clara, CA, United States of America

Dengtao Zhao