Dual polarity read operation

Patent metadata

Field	Value
Publication number	US-2016111150-A1
Application number	US-201414518105-A
Country	US
Kind code	A1
Filing date	Oct 20, 2014
Priority date	Oct 20, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

A data storage device includes a memory die and a controller coupled to the memory die. The memory die includes a resistive memory and read/write circuitry configured to determine a first hard bit value and a second hard bit value of a storage element of the resistive memory. The first hard bit value and the second hard bit value are determined using opposite polarity read voltages. The controller is configured to perform error correction with respect to data read from the resistive memory.

First claim

What is claimed is:

1 . A method comprising:
at a data storage device that includes a resistive memory:
performing a first read operation with respect to a storage element of the resistive memory to determine a first read bit value of the storage element, wherein performing the first read operation comprises applying a first read voltage having a first polarity;
performing a second read operation with respect to the storage element to determine a second read bit value of the storage element, wherein performing the second read operation comprises applying a second read voltage having a second polarity opposite the first polarity; and
determining read confidence information associated with the storage element based on at least one of the first read operation or the second read operation.

2 . The method of claim 1 , wherein the second read operation is performed in response to determining that a number of read errors associated with the resistive memory exceeds a threshold.

3 . The method of claim 1 , wherein the second read operation is performed in response to determining that a number of program/erase cycles associated with the resistive memory exceeds a threshold.

4 . The method of claim 1 , wherein the read confidence information is determined at a memory die that includes the memory and is provided to a controller of the data storage device.

5 . The method of claim 1 , wherein the first read bit value and the second read bit value are provided from a memory die that includes the memory to a controller of the data storage device, and wherein the read confidence information is determined at the controller.

6 . The method of claim 1 , wherein the first read bit value comprises a first hard bit value, wherein the second read bit value comprises a second hard bit value, and wherein the read confidence information comprises at least one soft bit value.

7 . The method of claim 6 , wherein the at least one soft bit value indicates whether the first hard bit value matches the second hard bit value.

8 . The method of claim 6 , further comprising:
detecting a property of the storage element, wherein the property corresponds to a current through the storage element or corresponds to a resistance of the storage element, wherein the first hard bit value indicates whether the property exceeds a first threshold, wherein a first soft bit value indicates whether the property exceeds a second threshold that is less than the first threshold, and wherein a second soft bit value indicates whether the property exceeds a third threshold that is greater than the first threshold.

9 . The method of claim 8 , wherein the first threshold corresponds to a midpoint between an ERASE state curve of the data storage device and an A state curve of the data storage device, wherein the second threshold is within the ERASE state curve and wherein the third threshold is within the A state curve.

10 . The method of claim 1 , wherein the resistive memory comprises a resistive random access memory (ReRAM).

11 . The method of claim 1 , wherein the resistive memory has a three-dimensional (3D) memory configuration.

12 . The method of claim 11 , wherein the 3D memory configuration is monolithically formed in one or more physical levels of arrays of memory cells having an active area above a silicon substrate, and wherein the data storage device further includes circuitry associated with operation of the memory cells.

13 . A data storage device comprising:
a memory die including a resistive memory and read/write circuitry, wherein the resistive memory includes a plurality of storage elements that stores a representation of an error correction code (ECC) codeword, wherein the read/write circuitry is configured to determine first hard bit values and second hard bit values of the plurality of storage elements, and wherein the first hard bit values and the second hard bit values are determined using opposite polarity read voltages; and a controller coupled to the memory die, wherein the controller is configured to correct at least one bit error in the representation of the ECC codeword.

14 . The data storage device of claim 13 , wherein the controller is configured to determine log likelihood ratio (LLR) values corresponding to the plurality of storage elements based on soft bit values corresponding to the plurality of storage elements, wherein the LLR values are used to correct the at least one bit error.

15 . The data storage device of claim 13 , wherein the resistive memory has a three-dimensional (3D) memory configuration.

16 . The data storage device of claim 15 , wherein the 3D memory configuration is monolithically formed in one or more physical levels of arrays of memory cells having an active area above a silicon substrate, and wherein the memory die further includes circuitry associated with operation of the memory cells.

17 . A data storage device comprising:
a memory die including a resistive memory and read/write circuitry, wherein the read/write circuitry is configured to determine a first hard bit value and a second hard bit value of a storage element of the resistive memory, and wherein the first hard bit value and the second hard bit value are determined using opposite polarity read voltages; and a controller coupled to the memory die, wherein the controller is configured to perform error correction with respect to data read from the resistive memory.

18 . The data storage device of claim 17 , wherein the memory die includes circuitry configured to generate one or more soft bit values and to provide the one or more soft bit values to the controller.

19 . The data storage device of claim 17 , wherein the controller is further configured to generate one or more soft bit values corresponding to the storage element.

20 . The data storage device of claim 17 , wherein the resistive memory has a three-dimensional (3D) memory configuration, wherein the 3D memory configuration is monolithically formed in one or more physical levels of arrays of memory cells having an active area above a silicon substrate, and wherein the memory die further includes circuitry associated with operation of the memory cells.

Assignees

• Sandisk Technologies Inc

Inventors

• Bazarsky Alexander
• Achtenberg Stella
• Sharon Eran
• Navon Ariel
• Alrod Idan
• Liu Tz-Yi
• Yan Tianhong

Classifications

• G11C13/004 Primary

  Reading or sensing circuits or methods · CPC title

• G11C29/52

  Protection of memory contents; Detection of errors in memory contents · CPC title

• G06F11/1068

  in sector programmable memories, e.g. flash disk (G06F11/1072 takes precedence) · CPC title

• G06F11/1012

  using codes or arrangements adapted for a specific type of error (G06F11/1048 takes precedence) · CPC title

• G11C13/0002

  using resistive RAM [RRAM] elements · CPC title