Sandisk Technologies Inc.

Pao-Ling Koh

Deepak Raghu

Gautam Ashok Dusija

Chris Avila

Yingda Dong

Man Lung Mui

Alexander Kwok-Tung Mak

Philip David Reusswig

Yan Li

Harish Reddy Singidi

Xiying Costa

Tien-Chien Kuo

Jian Feng Chen

Dana Lee

Jiahui Yuan

Henry Chin

Jun Wan

Seungpil Lee

Liang Pang

Mrinal Kochar

Chris Nga Yee Avila

Eugene Jinglun Tam

Pitamber Shukla

Yuheng Zhang

Charles S Kwong

Chris Nga Yee Yip

Khanh T Nguyen

Zelei Guo

Rohan Patel

A non-volatile memory system comprises a memory structure and a control circuit connected to the memory structure. The control circuit is configured to control the non-volatile memory structure to perform memory operations by generating and applying a set of control signals to the non-volatile memory structure The control circuit includes a programmable and reprogrammable microcontroller. For example, the microcontroller includes one or more processors that are programmed using software (e.g., firmware). The use of a programmable processor and software allows for updates and changes to be made easily. Additionally, to reduce the time taken to make some calculations, the microcontroller also includes one or more combinational logic circuits that are in communication with the one or more processors.

Microcontroller for non-volatile memory with combinational logic

A storage device with a memory may modify throttling to reduce cross temperature effects. The decision to throttle may be based on a memory device temperature (i.e. temperature throttling) or may be based on the memory device's health, usage, or performance (e.g. hot count or bit error rate). Temperature throttling may be implemented that considers the memory device's health, usage, or performance (e.g. hot count or bit error rate). Likewise, throttling based on the memory device's health, usage, or performance may utilize the memory device's temperature to optimize throttling time. For example, a test mode matrix (TMM) may be modified to depend on temperature.

Adaptive temperature and memory parameter throttling

Techniques are provided for improving the accuracy of read operations of memory cells, where the threshold voltage (Vth) of a memory cell can shift depending on when the read operation occurs. In one aspect, a dummy voltage is applied to the word lines to cause a coupling up of the word lines and weak programming. This can occur when a specified amount of time has elapsed since a last program or read operation, or when a power on event is detected for the memory device. A number of read errors can also be considered. The dummy voltage is similar to a pass voltage of a program or read operation but no sensing is performed. The word line voltages are therefore provided at a consistently up-coupled level so that read operations are consistent. The coupling up occurs due to capacitive coupling between the word line and the channel.

Dummy voltage to reduce first read effect in memory

Methods and systems are provided where non-volatile solid state memory may include selected memory cells coupled to a selected word line and proxy memory cells coupled to a proxy word line. The selected memory cells may be non-adjacent to the proxy memory cells and be selected for a read operation. A read proxy voltage may be applied to the proxy word line when data is read from the selected memory cells. A read disturb may be determined based on a difference between a predetermined value stored in the proxy memory cells and a value read from the proxy memory cells.

Proxy wordline stress for read disturb detection

A storage system includes a controller that is configured to make host data inaccessible. To do so, the controller may control power control circuitry to supply pulses to storage locations storing host data. The pulses may include flash write pulses but no erase pulses, or a combination of flash write pulses and erase pulses. If erase pulses are supplied, the number of the erase pulses may be less than the number supplied for performance of a default erase operation.

Accelerated physical secure erase

In a three-dimensional NAND memory in which a block contains multiple separately-selectable sets of strings connected to the same set of bit lines, sets of strings are zoned, and different operating parameters applied to different zones. Operating parameters for a zone are obtained from characterizing a reference set of strings in the zone.

String dependent parameter setup

Layers in a multi-layer memory array are categorized according to likely error rates as predicted from their memory hole diameters. Data to be stored along a word line in a high risk layer is subject to a redundancy operation (e.g. XOR) with data to be stored along a word line in a low risk layer so that the risk of both being bad is low.

Selection of data for redundancy calculation by likely error rate

Techniques are disclosed herein for determining whether there is a defect that occurred as a result of programming non-volatile storage elements. Example defects include: broken word lines, control gate to substrate shorts, word line to word line shorts, double writes, etc. The memory cells may be programmed such that there will be a substantially even distribution of the memory cells in different data states. After programming, the memory cells are sensed at one or more reference levels. Two sub-groups of memory cells are strategically formed based on the sensing to enable detection of defects in a simple and efficient manner. The sub-groups may have a certain degree of separation of the data states to avoid missing a defect. The number of memory cells in one sub-group is compared with the other. If there is a significant imbalance between the two sub-groups, then a defect is detected.

Asymmetric state detection for non-volatile storage

Data that is stored in a higher error rate format in a nonvolatile memory is backed up in a lower error rate format. Data to be stored may be transferred once to on-chip data latches where it is maintained while it is programmed in both the high error rate format and the low error rate format without being resent to the nonvolatile memory. High error rate format may be MLC format and programming in the high error rate format may program both lower page and upper page data together in a full sequence programming scheme that is suitable for handling high data volume.

Write operations with full sequence programming for defect management in nonvolatile memory

Multiple bits of data are programmed together to each cell of a segment of a word line while other segments of the same word line are unprogrammed. Subsequently, additional segments are similarly programmed. Data is read from a partially programmed word line (with a mix of programmed and unprogrammed segments) using a single reading scheme.

Systems and methods for partial page programming of multi level cells

Erasing memory cells in certain 3-D NAND charge-storage memory arrays is achieved by rapidly charging vertical conductors using Gate Induced Drain Leakage (GIDL) current generated in select transistors. When bit line voltage drops below its nominal value, select line voltage is controlled to maintain a constant voltage difference between bit line voltage and select line voltage thus maintaining a gate-drain voltage difference in select transistors that provides sufficient GIDL current for erase.

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Fremont, CA, United States of America

Pao-Ling Koh