Sandisk Technologies Inc.

Sandisk Corporation

Ken Oowada

Gerrit Jan Hemink

Yingda Dong

Masaaki Higashitani

Deepanshu Dutta

Shih-Chung Lee

Xiang Yang

Toru Miwa

Man Lung Mui

Kiyohiko Sakakibara

Jun Wan

Cynthia Hsu

Jeffrey W Lutze

Seungpil Lee

Masatoshi Nishikawa

Rajdeep Gautam

Yupin K Fong

Huai-Yuan Tseng

Zhixin Cui

Hardwell Chibvongodze

Chun-Hung Lai

Ippei Yasuda

Genki Sano

Jian Feng Chen

Hiroyuki Ogawa

Dana Lee

Dengtao Zhao

Teruhiko Kamei

Aaron Lee

Hao Nguyen

Geoffrey Steven Gongwer

Mitsuteru Mushiga

Hiroki Yabe

Fumitoshi Ito

Fanglin Zhang

Yosuke Kato

Jong Park

Yan Li

Peter Rabkin

Henry Chin

Yu-Chung Lien

Koichi Nishimura

Michiaki Sano

Guirong Liang

Takashi Murai

Xue Bai Pitner

Zhiping Zhang

Toru Ishigaki

Shota Murai

Xiaochang Miao

Cheng-Kuan Yin

Natsu Honda

A memory apparatus and method of operation are provided. The memory apparatus includes memory cells connected to one of a plurality of word lines including an edge word line and a plurality of other data word lines. The memory cells are disposed in memory holes organized in rows grouped in a plurality of strings. The rows include full circle rows and semi-circle rows. A control means is configured to program the memory cells connected to the edge word line and in the semi-circle rows of a first one and a second one of the plurality of strings to a predetermined one of a plurality of data states in a first program operation. The control means then selects both the first one and the second one of the plurality of strings together and programs the memory cells of the full circle rows together in a second program operation.

Edge word line concurrent programming with verify for memory apparatus with on-pitch semi-circle drain side select gate technology

Technology for applying a positive temperature coefficient (Tco) voltage to a control terminal of a dummy select transistor. The dummy select transistor resides on a NAND string having non-volatile memory cells and a regular select transistor. The dummy select transistor is typically ON (or conductive) during memory operations such as selected string program, read, and verify. In an aspect, the positive Tco voltage is applied to the control terminal of a dummy select transistor during a program operation. Applying the positive Tco voltage during program operations reduces or eliminates program disturb to the dummy select transistor. In some aspects, the dummy select transistor is used to generate a gate induced drain leakage (GIDL) current during an erase operation. In some aspects, the dummy select transistor is a depletion mode transistor.

Positive TCO voltage to dummy select transistors in 3D memory

A method for programming a target memory cell of a memory array of a non-volatile memory system, the method comprises determining a total number of erase/programming (EP) cycles that were applied previously to the memory cell and, (1) if the determined total number of cycles does not exceed a threshold value, applying an asymmetric programming scheme, and, (2) if the determined total number of cycles exceeds the threshold value, applying a symmetric programming scheme. Further, a magnitude of a boosting voltage bias (VPASS) that is to be applied to an unselected word line may be determined according to the determined total number of erase/programming (EP) cycles.

EP cycling dependent asymmetric/symmetric VPASS conversion in non-volatile memory structures

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

Apparatuses and techniques are described for programming data in memory cells while concurrently storing backup data. One or more initial pages of data are programmed into both a primary block and a first backup block in a first program pass. A power loss then occurs which can corrupt the data or otherwise prevent reading of the one or more initial pages of data from the primary block. The one or more initial pages of data are read from the first backup block and used to perform a second program pass in which one or more additional pages of data are programmed into the primary block. Single bit per cell data can be stored in a second backup block to decode the one or more initial pages of data as read from the first backup block.

Programming memory cells with concurrent redundant storage of data for power loss protection

Apparatuses and techniques are described for programming data in memory cells while concurrently storing backup data. Initial pages of multiple bit per cell data are encoded to obtain at least first and second pages of single bit per cell data. The initial pages of multiple bit per cell data are programmed into a primary set of memory cells, while concurrently the first and second pages of single bit per cell data are programmed into first and second backup sets of memory cells, respectively. In the event of a power loss, the first and second pages of single bit per cell data are read from the first and second backup sets of memory cells, and decoded to recover the initial pages of multiple bit per cell data.

Programming memory cells with concurrent storage of multi-level data as single-level data for power loss protection

Technology is disclosed herein for concurrently programming the same data pattern in multiple sets of non-volatile memory cells. Voltage are applied to bit lines in accordance with a data pattern. A select voltage is applied to drain select gates of multiple sets of NAND strings. The system concurrently applies a program pulse to control gates of a different set of selected memory cells in each respective set of the multiple sets of the NAND strings while the select voltage is applied to the drain select gates of the multiple sets of the NAND strings and the voltages are applied to the plurality of bit lines to concurrently program the data pattern into each set of the selected memory cells.

Concurrent programming of multiple cells for non-volatile memory devices

A semiconductor structure includes a peripheral circuit, a first three-dimensional memory array overlying the peripheral circuit and including a first alternating stack of first insulating layers and first electrically conductive layers containing first word lines and first select lines, and first memory stack structures vertically extending through the first alternating stack, and a second three-dimensional memory array overlying the first three-dimensional memory array and including a second alternating stack of second insulating layers and second electrically conductive layers containing second word lines and second select lines, and second memory stack structures vertically extending through the second alternating stack. The peripheral circuit includes a first word line driver circuit having first word line driver output nodes electrically connected to at least some of the first word lines and at least some of the second word lines, and each first word line is electrically connected to a respective second word line.

Three-dimensional memory device containing a shared word line driver across different tiers and methods for making the same

For a non-volatile memory die formed of multiple blocks of memory cells, the memory die has a multi-bit bad block flag for each block stored on the memory die, such as in a fuse ROM. For each block, the multi-bit flag indicates if the block has few defects and is of the highest reliability category, is too defective to be used, or is in of one of multiple recoverability categories. The multi-bit bad blocks values can be determined as part a test process on fresh devices, where the test of a block can be fail stop for critical category errors, but, for recoverable categories, the test continues and tracks the test results to determine a recoverability category for the block and write this onto the die as a bad block flag for each block. These recoverability categories can be incorporated into wear leveling operations.

Block quality classification at testing for non-volatile memory, and multiple bad block flags for product diversity

Methods for reducing read disturb using NAND strings with poly-silicon channels and p-type doped source lines are described. During a boosted read operation for a selected memory cell transistor in a NAND string, a back-gate bias or bit line voltage may be applied to a bit line connected to the NAND string and a source line voltage greater than the bit line voltage may be applied to a source line connected to the NAND string; with these bias conditions, electrons may be injected from the bit line and annihilated in the source line during the read operation. To avoid leakage currents through NAND strings in non-selected memory blocks, the threshold voltages of source-side select gate transistors of the NAND strings may be set to a negative threshold voltage that has an absolute voltage value greater than the source line voltage applied during the read operation.

Threshold voltage setting with boosting read scheme

Methods for reducing manufacturing cost and improving the reliability of non-volatile memories using NAND strings with polysilicon channels and p-type doped source lines are described. A NAND string may include a polysilicon channel that is orthogonal to a substrate and connects to a boron doped source line at a source-side end of the NAND string. To reduce the likelihood of the polysilicon channel being cut-off or pinched near the source-side end of the NAND string, a thicker polysilicon channel may be formed near the source-side end of the NAND string while a thinner polysilicon channel may be formed for the remainder of the NAND string by diffusing boron into a first portion of the polysilicon channel corresponding with the thicker polysilicon channel and then etching the polysilicon channel with etchants that exhibit a reduction in their etch rate at a boron concentration above a threshold concentration.

Buried source line structure for boosting read scheme

Apparatuses, systems, and methods are disclosed for concurrently programming non-volatile storage cells, such as those of an SLC NAND array. The non-volatile storage cells may be arranged into a first block comprising a first string of storage cells that intersects with a first word line at a first storage cell, a second block comprising a second string of storage cells that intersects with a second word line at a second storage cell, a bit line electrically connectable to the first string and the second string, and controller configured to apply a programming pulse, at an elevated voltage, to the first word line and second word line to concurrently program the first and second storage cells.

To improve the erase process, multiple methods of erasing are utilized. A first method of erasing is relied on at the beginning of life of the memory system. A second method is increasingly relied on as the memory system is used and undergoes many program/erase cycles. In one example, the first method of erase includes applying an erase enable voltage separately to different subsets of the word lines while word lines not receiving the erase enable voltage receive an erase inhibit voltage. In one example, the second method of erase includes applying an erase enable voltage concurrently to all subsets of the word lines.

Non-volatile memory with switchable erase methods

Growing community of inventors

Fujisawa, Japan

Ken Oowada