Sandisk Technologies Inc.

Western Digital Technologies, Inc.

Parth Amin

Anubhav Khandelwal

Sai Gautham Thoppa

Xiang Yang

Jiahui Yuan

Abhijith Prakash

Long C Pham

Kazuki Isozumi

Deepanshu Dutta

Dana Lee

Henry Chin

Sarath Chandran Puthenthermadam

Abu Naser Zainuddin

Xiaochen Zhu

Sayako Nagamine

Sateesh Desireddi

Sujjatul Islam

Jia Li

Nidhi Agrawal

Longju Liu

Vishwanath Basavaegowda Shanthakumar

Xiangying Deng

Ashwin D T

Harshul Gupta

A memory apparatus includes memory cells each connected to one of a plurality of word lines and configured to store a threshold voltage corresponding to one of a plurality of data states. The memory apparatus also includes a control means configured to identify ones of the plurality of word lines as slow word lines. The control means is also configured to ramp at least one program pulse applied to the slow word lines to a program kick voltage higher in magnitude than a program voltage for a program kick period of time during at least one program loop of a program operation.

Real time ramp rate adjustment for better performance and current consumption tradeoff

A non-volatile memory comprises a non-volatile memory structure that includes non-volatile memory cells. The non-volatile memory adjusts a ramp rate of a voltage signal applied to the non-volatile memory structure as part of a memory operation for the non-volatile memory cells. The adjusting the ramp rate is performed during the ramping up of the voltage signal and is based on voltage magnitude of the voltage signal at a particular time during the ramping up of the voltage signal.

Non-volatile memory with adjustable ramp rate

A memory apparatus and method of operation are provided. The apparatus includes memory cells configured to retain a threshold voltage and disposed in memory holes coupled to bit lines and grouped into blocks. A control means is configured to determine an amount of the memory cells of one of the blocks that are programmed based on an electrical current consumed by the memory apparatus during a fourth period of time of a read operation in which selected ones of the bit lines are ramped up to a bit line voltage. The control means adjusts at least one read parameter accordingly. The control means is also configured to utilize the adjusted at least one read parameter while reading the memory cells to determine if the memory cells have the threshold voltage above one or more read levels associated with each of the data states in the read operation.

Open block detection using current consumption peak during fourth time period of read operation and method of lowering current consumption for non-volatile memory apparatus

A duration of a program pulse used to program non-volatile memory cells such as NAND may be increased responsive to a programming failure using a shorter duration program pulse. The duration of at least one program pulse may be increased for at least one group of memory cells in response to a failure to program a group using a default program pulse duration. The group that experiences the increased duration program pulse may be the same group for which the program operation failed using the shorter program pulse or may be a different group than the group for which the program operation failed using the shorter program pulse.

Program pulse duration increase for NAND program failure

Non-volatile memory cells are programmed by raising a voltage applied to a selected word line to a program voltage during a first time period of a programming process for selected non-volatile memory cells connected to the selected word line; programming the selected non-volatile memory cells using the program voltage during a second time period after the first time period; testing, during the first time period, whether the voltage applied to the selected word line is greater than one or more intermediate voltages; and elongating the first time period during the first time period if the voltage applied to the selected word line is not greater than one or more of the intermediate voltages.

Non-volatile memory with slow voltage ramp compensation

Technology is disclosed herein for detecting evolved bad blocks in three-dimensional NAND. The test may include a drain side erase that includes applying an erase voltage from the bit lines and a source side erase that includes applying an erase voltage from the source line(s). If the source side erase performed worse than the drain side erase this may indicate a defect near the source side of the block. For example, the source side erase may fail but the drain side erase may pass. As another example the source side erase may take at least a pre-determined number of additional erase pulses to pass than the drain side erase. If the block is found as having a defect the entire block could be marked bad or the defective region could be identified such that the defective region is no longer used.

Evolving bad block detection in non-volatile memory

As part of the erase operation for a memory block, one or more post-erase tests can be incorporated into the erase operation to see whether the block has grown any defects. After erasing a block and verifying the erase, the post-erase tests can be performed on the block. As these test involve biasing the block and performing a sensing operation, these post erase tests come with a time penalty. To reduce the associated time penalty and improve memory performance while incorporating the defect tests into the erase process, when biasing the memory array for the post-erase defect tests different ramp rates can be used. In particular, faster ramp rates for bias levels, such those applied to the word lines of the block, are used for the post-erase tests than are used for the same bias level when performing the standard read, program verify, or read verify operations.

Non-volatile memory with faster post-erase defect testing

Embodiments described herein aim to optimize the Erratic Program Detection (EPD) process by eliminating unnecessary operations and adjusting operations that are not optimized for the EPD process. For example, one optimization includes the EPD read operations being performed based on a read mode optimized for faster data retrieval. Further, another optimization includes a first read voltage ramping up at a rate that is faster than a ramp rate used to ramp up a read voltage during performance of a normal read operation. Another optimization also includes a read voltage kick operation between the EPD read operations being eliminated. Finally, another optimization includes parallelizing the scan operation with other ongoing operations.

Optimized erratic program detection process

An apparatus is provided that includes a control circuit coupled to a plurality of non-volatile memory cells disposed in a plurality of planes. The control circuit is configured to concurrently erase a block of memory cells in each of the plurality of planes, determine that the concurrent erase failed, disconnect a first one of the planes from the plurality of planes to form first remaining planes, and concurrently erase a block of memory cells in each of the first remaining planes.

Apparatus and method for detecting neighbor plane erase failures

Technology is disclosed herein for quickly determining which erase block is bad if there is a failure in parallel erasing a set of erase blocks. The erase blocks may be tested individually in response to a fail of the parallel multi-block erase. A voltage generator ramps up the erase voltage from a steady state magnitude towards a target magnitude. The magnitude of the erase voltage is measured at a pre-determined time. If there is a defect then the erase voltage may fail to be above a threshold voltage after the ramp-up period. If the erase voltage is below the threshold voltage after the ramp-up period then the erase block may be marked as defective. If the erase voltage is above the threshold voltage after the ramp-up period then the erase block may be marked as good.

Vera detection method to catch erase fail

Technology is disclosed herein for detecting grown bad blocks in a non-volatile storage system. A stress test may accelerate stressful conditions on the memory cells and thereby provide for early detection of grown bad blocks. The stress test may include applying a program voltage to a selected word line and a stress voltage that is less than a nominal boosting voltage to a word line adjacent one side of the selected word line. The combination of the program voltage and the stress voltage may generate an e-field that is stronger than an e-field that would be generated in a normal program operation, thereby accelerating the stress on the memory cells. The stress test mat further include programming all of the memory cells to a relatively high threshold voltage, which may create additional stress on the memory cells.

Stress test for grown bad blocks

The following disclosure is directed to mitigating issues related to semi-circle drain side select gate (SC-SGD) memory holes in memory structures. When a memory hole is cut, the channel and the charge trap layer of the memory hole cut. Further, the outer dielectric layer (used to shield the channel and the charge trap layer) is cut and partially removed. When the selected SC-SGD is selected for an operation (e.g., programming), the channel and the charge trap layer are exposed to neighboring electrical field from bias voltage applied to an unselected SC-SGD. To prevent or mitigate the effects of this electrical field, a negative bias voltage is applied to the unselected SC-SGD. Additionally, this disclosure is directed to self-compensating techniques for SC-SGD. For example, the memory structure can utilize the neighboring electric field during verify, program, and read operations, whether the neighboring electric field is relatively strong or weak.

Systems and methods for adjusting threshold voltage distribution due to semi-circle SGD

Apparatus and methods are described to reduce program disturb for a memory string with a partial select gate drain, which is partially cut by a shallow trench. The memory string with a partial select gate drain is linked with a neighboring full select gate drain that during its programming can cause a program disturb in the memory string with a partial select gate drain. The bias voltage applied to the selected full select gate drain can be controlled from a high state for low memory program states to a lower state for the high memory program states. The high data states may cause program disturb. The reduction in the bias voltage can match a reduction in the bias voltage applied to the bit lines to reduce the program disturb while providing adequate signal to program the high states on the memory string of the full select gate drain.

System and methods for programming nonvolatile memory having partial select gate drains

The programming techniques include the step of providing a memory device that includes a plurality of memory cells that are divided into at least two groups including a first group and a second group. The first group includes memory cells that are coupled to full select gate drains (SGDs), and the second group includes memory cells that are coupled to partial SGDs. The method continues with the step of applying a programming voltage to a selected word line that includes at least one memory cell of the first group and at least one memory cell of the second group. Simultaneous to the application of the programming voltage, the method continues with applying voltages to bit lines coupled to memory cells. The voltages being determined based on if the memory cells are of the first group or are of the second group.

Programming techniques for memory devices having partial drain-side select gates

A method for detecting a 'slow to erase' condition of a non-volatile memory structure, wherein the method comprises initiating an erase/verify memory operation with respect to the memory structure, wherein the erase/verify memory operation comprises applying an erase verify voltage according to an alternating word line scheme; following the erase/verify memory operation, determining if a first bit scan mode criteria is satisfied; and, if the first bit scan mode criteria is satisfied, initiating a read/verify memory operation wherein, the read/verify memory operation comprises applying a read-pass voltage according to an all word line scheme, and a magnitude of the read-pass voltage is greater than a magnitude of the erase verify voltage. Following the read/verify memory operation, the method also comprises determining if a second bit scan mode criteria is satisfied and, if the criteria is not satisfied, designating the memory structure with a fail status.

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Fremont, CA, United States of America

Parth Amin