Sandisk Technologies Inc.

Akashic Memories Corp.

Wei Cao

Xiang Yang

Jiacen Guo

Deepanshu Dutta

Jiahui Yuan

Dengtao Zhao

Abhijith Prakash

Xingbo Yang

Mike Tregoning

James Ward

Weiyi Li

Hyo Jung Son

The memory device includes circuitry which is configured to sense threshold voltages of the memory cells of a selected word line of the plurality of word lines in a sensing operation. During the sensing operation, the circuitry, in a first sensing process, senses the memory cells of the selected word line using both a fast read technique and a positive sensing technique. The circuitry also determines a fail bit count and compares the fail bit count to a threshold. In response to the fail bit count being less than or equal to the threshold, the circuitry completes the sensing operation. In response to the fail bit count exceeding the threshold, then the circuitry performs a second sensing process to sense threshold voltages of the memory cells of the selected word line using a relatively slower read technique.

Energy efficient fast read in a memory device

The memory device includes a memory block that includes an array of memory cells that are arranged in a plurality of word lines. The memory device also includes circuitry for programming the memory cells of the memory block. The circuitry is configured to program the memory cells of the memory block to a single bit per memory cell storage format that includes a first data state and a second data state that is at a higher threshold voltage range than the first data state. In response to the memory cells experiencing data retention stress that causes the memory cells in the second data state to fall, the circuitry is configured to perform an in-place programming operation on a selected word line of the plurality of word lines. The in-place programming operation includes the circuitry programming the memory cells in the second data state to higher threshold voltages.

In-place refresh techniques for non-volatile memory devices

To improve programming performance in NAND memory, while maintaining programming accuracy and reducing program disturb, the channel pre-charge phase before a programming pulse can be eliminated. Instead, a read recovery phase after the program verify directly discharges a selected word line from the verify voltage to a negative word line voltage, with non-selected word lines being directly discharged from the read bypass voltage to the negative word line voltage. From the negative word line voltage, the word lines are then ramped up to ground and then on the bias levels of the following programming pulse. These conditions can drive electrons from the charge storage region of the selected memory cell, resulting in a high degree of channel boosting and much less program disturb. Variations of the technique can be applied to NAND memory operable in a sub-block mode where it can be difficult to use the typical channel pre-charge.

Negative word line enabled pre-boosting strategy to improve NAND program performance

A block of non-volatile memory cells is divided into a first sub-block and a second sub-block. Programming non-volatile memory cells of the second sub-block after programming non-volatile memory cells of the first sub-block comprises boosting unselected channels in the second sub-block to a boosted condition; prior to boosting unselected channels in the second sub-block to the boosted condition, boosting unselected channels in the first sub-block to the boosted condition to pre-charge the channels of the second sub-block; and applying a program voltage to a selected word line of the second sub-block while channels in the first sub-block are in the boosted condition and channels in the first sub-block are in the boosted condition.

Non-volatile memory with efficient precharge in sub-block mode

A storage device is disclosed herein. The storage device comprises a non-volatile memory, where the non-volatile memory includes a block of 3N wordlines partitioned into a plurality of sub-blocks. The plurality of sub-blocks include an upper sub-block of a first subset of the block of 3N wordlines, a lower sub-block of a second subset of the block of 3N wordlines, and a middle sub-block of a third subset of the block of 3N wordlines. Further, the storage device comprises control circuitry coupled to the block of 3N wordlines and configured to: perform a program operation in a normal order programming sequence on the upper sub-block; perform a program operation in a reverse order programming sequence on the lower sub-block; and perform a program operation in the reverse order programming sequence on the middle sub-block.

Multi-tier sub-block mode operation

A non-volatile memory includes a plurality of non-volatile memory cells arranged in blocks. Each block includes multiple sub-blocks that can be independently erased and programmed. A control circuit is connected to the non-volatile memory cells. The control circuit is configured to independently erase and program sub-blocks of a same block. The control circuit is configured to only allow one sub-block per block to be open at a time.

Non-volatile memory with sub-blocks

While programming a first set of memory cells, a non-volatile memory apparatus determines an initial magnitude of a programming signal for a second set of memory cells based on testing during the programming of the first set of memory cells. The testing comprises sensing at a first test voltage level and sensing at a second test voltage level without apply a voltage spike between the two sensing operation. Removing the voltage spike results in a performance increase (i.e. faster programming speed) and as well as a decrease in power usage.

Non-volatile memory with efficient setting of initial program voltage

The memory device includes a memory block with memory cells that are arranged in word lines, some of which are reconfigurable word lines that are dummy word lines when the memory block is operating in a one bit per cell mode and are data word lines when the memory block is operating in a multiple bits per cell mode. Circuitry is configured to program the memory cells of a selected word line. The circuitry determines if the selected word line is a reconfigurable word line. If the selected word line is not a reconfigurable word line, the circuitry programs the memory cells of the selected word line with a first programming scheme. If the selected word line is a reconfigurable word line, the circuitry programs the memory cells of the selected word line with a second programming scheme that is different than the first programming scheme.

Reconfigurable lines in different sub-block modes in a NAND memory device

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

The memory device includes at least one memory block with a plurality of memory cells arranged in a plurality of word lines. The memory device includes control circuitry that is configured to program the memory cells of the at least one memory block in a plurality of program loops. The control circuitry is further configured to receive a command to write user data to the memory device. On at least a portion of a selected word line of the plurality of word lines, the control circuitry is configured to perform a smart verify operation to acquire a smart verify programming voltage. After the smart verify programming voltage is acquired, in a plurality of program loops, the control circuitry is configured to program the memory cells of the selected word line to include the user data and data that corresponds to the smart verify programming voltage.

High performance verify techniques in a memory device

In NAND memory, data sanitization allows a relatively small unit of data (e.g., less than a block) to be effectively destroyed by increasing threshold voltages of memory cells from their programmed threshold voltage to the highest threshold state. To reduce the amount of disturb on memory cells not selected for data sanitization, prior to applying a program voltage to a target word line, a hole based pre-charge operation is performed. More specifically, for NAND strings having a memory cell selected for data sanitation, prior to applying a programming pulse to the corresponding word line, a soft erase operation is performed. After biasing the memory cells and select gates of the NAND strings to a low voltage, a soft erase voltage pulse is applied to the source lines and bit line to pre-charge the NAND string channels with holes.

Hole channel pre-charge to enable large-volume in-place data sanitization of non-volatile memory

In a multi-tiered non-volatile memory structure that can perform operations on sub-blocks, performance of the different tiers/sub-blocks is made consistent by using different word line to word line pitches in the different tiers/sub-blocks.

Non-volatile memory with different word line to word line pitches

The memory device has a plurality of memory blocks including a plurality of memory cells arranged in a plurality of word lines. The memory device also includes control circuitry that is in communication with the plurality of memory blocks. The control circuitry is configured to receive a data write instruction. The control circuitry is further configured to program the memory cells of the memory blocks to an SLC format. In response to the data programmed to the memory cells of the memory blocks in the SLC format reaching an SLC limit prior to completion of the data write instruction, without erasing the memory cells programmed to the SLC format, the control circuitry is configured to program the memory cells of at least some of the plurality of memory blocks from the SLC format to a TLC format.

In-place write techniques without erase in a memory device

The present invention provides magnetic recording media comprising a rigid substrate and an underlayer disposed over the substrate, in which the underlayer comprises CrTiCu or CrTiV. A magnetic layer is disposed over this underlayer, and is also disposed over a texturized surface. Generally, the substrate comprises aluminum, and an NiP layer is disposed over the substrate and below the underlayer. The texture will typically be imposed on this NiP layer. Advantageously, the CrTiCu or CrTiV underlayer has been found to compensate for texture-induced anisotropy, limiting a ratio of circumferential coercivity to radial coercivity within the range between about 0.8 and 1.25.

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Fremont, CA, United States of America

Wei Cao