Storage device including nonvolatile memory device and controller with varied read weights

Patent metadata

Field	Value
Publication number	US-10049755-B2
Application number	US-201715423629-A
Country	US
Kind code	B2
Filing date	Feb 3, 2017
Priority date	Jun 30, 2016
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A storage device includes a nonvolatile memory device and a controller. The nonvolatile memory device includes multiple memory blocks, each of which includes memory cells. The controller reads data from selected memory cells of a memory block selected from the memory blocks during a read operation. The selected memory cells correspond to both a word line and a string selection line selected as a read target. The controller increases a read count by a read weight corresponding to the selected word line and string selection line of the selected memory block, and performs a refresh operation on the selected memory cells if the read count reaches a threshold value. In the selected memory block, two or more read weights are assigned according to locations of the string selection lines and the word lines.

First claim

What is claimed is:

1. A storage device, comprising:
a nonvolatile memory device comprising a plurality of memory blocks, each of which comprises string selection transistors connected to a plurality of string selection lines, ground selection transistors connected to a plurality of ground selection lines, and memory cells connected to a plurality of word lines; and
a controller configured to read data from selected memory cells, which correspond to both a word line and a string selection line selected as a read target, of a memory block, selected as a selected memory block from the memory blocks, during a read operation,
wherein the controller increases a read count for the selected memory block by a read weight corresponding to the selected word line and string selection line of the selected memory block and performs a refresh operation on the selected memory block if the read count reaches a threshold value,
wherein, in the selected memory block, two or more read weights are assigned according to locations of the string selection lines and the word lines,
wherein each of the selected memory cells is configured to store a plurality of page data, and
wherein the controller is configured to further adjust the read weight based on whether any page data among the plurality of page data is a read target.

2. The storage device of claim 1 ,
wherein the memory cells of each memory block are stacked in a direction perpendicular to a substrate.

3. The storage device of claim 2 ,
wherein the read weight decreases as a distance between the selected memory cells and the substrate increases.

4. The storage device of claim 2 ,
wherein, in each memory block, the string selection lines are connected to rows of cell strings, each of which comprises a ground selection transistor, memory cells, and a string selection transistor.

5. The storage device of claim 4 ,
wherein the string selection lines comprise a first string selection line, a second string selection line, and intermediate string selection lines arranged between the first and second string selection lines, and
wherein the read weight decreases as a distance between the selected string selection line and the first string selection line decreases.

6. The storage device of claim 1 ,
wherein the controller increases the read weight as a number of reads performed to determine the page data of the read target increases.

7. The storage device of claim 6 ,
wherein the nonvolatile memory device is configured to send information about the number of reads performed to determine each of the page data, to the controller.

8. The storage device of claim 1 ,
wherein the controller is configured to adjust the read weight based on a period that the read operation is performed.

9. The storage device of claim 8 ,
wherein the controller increases the read weight if a previous read operation of the selected memory block was performed within a first time period from a time point when the read operation is performed.

10. The storage device of claim 9 ,
wherein the controller further increases the read weight if the previous read operation of the selected word line was performed within a second time period from a time point when the read operation is performed.

11. The storage device of claim 1 ,
wherein the controller is configured to adjust the read weight based on a temperature when the read operation is performed.

12. The storage device of claim 11 ,
wherein the controller increases the read weight when the read operation is performed when a temperature is lower than a predetermined temperature.

13. The storage device of claim 11 ,
wherein the controller increases the read weight when a temperature difference between a temperature when the read operation is performed and a temperature when data is written in the selected memory cells is greater than a predetermined temperature difference.

14. The storage device of claim 1 ,
wherein the refresh operation comprises an operation in which the controller reads valid data among data written in memory cells of the selected memory block and writes the read data in another memory block.

15. The storage device of claim 1 ,
wherein the controller is configured to receive a read command and a logical address, to convert the logical address into a physical address of the nonvolatile memory device, and to perform the read operation on the selected memory cells corresponding to the selected word line and string selection line as indicated by the physical address, in response to the read command.

16. A storage device, comprising:
a nonvolatile memory device comprising a plurality of memory blocks, each of which comprises string selection transistors connected to a plurality of string selection lines, ground selection transistors connected to a plurality of ground selection lines, and memory cells connected to a plurality of word lines;
a controller configured to read data from selected memory cells, which correspond to both a word line and a string selection line selected as a read target, of a memory block, selected as a selected memory block from the memory blocks, during a read operation,
wherein the controller is configured to increase a read count for the selected memory block by a read weight corresponding to the selected word line and string selection line of the selected memory block and to perform a refresh operation on the selected memory block if the read count reaches a threshold value,
wherein, in the selected memory block, a read weight changes according to which of the plurality of string selection lines is selected with respect to the selected word line,
wherein the controller is configured to read page data selected from a plurality of page data written in the selected memory cells and to select a value corresponding to all of the selected string selection line, the selected word line, and the selected page data as the read weight, and
wherein, in the selected memory block, the controller decreases the read weight as a distance between the selected memory cells and a substrate increases, and as a number of read operations performed to determine the selected page data decreases.

17. A storage device, comprising:
a nonvolatile memory device comprising a plurality of memory blocks each comprising a plurality of memory cells stacked in a direction perpendicular to a substrate and connected with a plurality of word lines; and
a controller configured to read data from selected memory cells, which correspond to a word line selected as a read target, of a memory block, selected as a selected memory block from the memory blocks, during a read operation,
wherein the controller is configured to increase a read count for the selected memory block by a read weight corresponding to the selected word line of the selected memory block and to perform a refresh operation on the selected memory block if the read count reaches a threshold value,
wherein, in the selected memory block, the controller decreases the read weight as a distance between the selected memory cells and the substrate increases, and
wherein the controller is configured to adjust the read weight based on a temperature.

18. The storage device of claim 17 ,
wherein the controller is configured to adjust the read weight based on a number of times that the read operation is performed.

Assignees

• Lee Heewon
• Go Sari
• Ro Seungkyung
• Kwon Seongnam
• Samsung Electronics Co Ltd

Inventors

• Lee Heewon
• Go Sari
• Ro Seungkyung
• Kwon Seongnam

Classifications

• G11C16/349

  Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles · CPC title

• G11C16/26

  Sensing or reading circuits; Data output circuits · CPC title

• G11C16/3427

  Circuits or methods to prevent or reduce disturbance of the state of a memory cell when neighbouring cells are read or written · CPC title

• G11C16/3495

  Circuits or methods to detect or delay wearout of nonvolatile EPROM or EEPROM memory devices, e.g. by counting numbers of erase or reprogram cycles, by using multiple memory areas serially or cyclically · CPC title

• G11C16/3418 Primary

  Disturbance prevention or evaluation; Refreshing of disturbed memory data · CPC title