Data storage device and data writing method thereof

• US 10,096,357 B2
• Filed: 07/25/2017
• Issued: 10/09/2018
• Est. Priority Date: 10/25/2016
• Status: Active Grant

• Current Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Original Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Inventors: Lin, Wen-Sheng
• Primary Examiner(s): LE, THONG QUOC
• Application Number:
  US15/659,216
• Publication Number:
  US 20180114570A1
• Time in Patent Office: 441 Days
• Field of Search: 36518503, 36518502, 36518509, 36518511, 36518512
• CPC Class Codes: G11C 11/5621 using charge storage in a floating gate
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: G11C 16/10 Programming or data input circuits
• CPC Class Codes: G11C 16/22 Safety or protection circuits preventing unauthorised or accidental access to memory cells
• CPC Class Codes: G11C 16/225 Preventing erasure, programming or reading when power supply voltages are outside the required ranges
• CPC Class Codes: G11C 16/28 using differential sensing or reference cells, e.g. dummy cells
• CPC Class Codes: G11C 16/3459 Circuits or methods to verify correct programming of nonvolatile memory cells
• CPC Class Codes: G11C 2211/5621 Multilevel programming verification
• CPC Class Codes: G11C 2211/5641 Multilevel memory having cells with different number of storage levels
• CPC Class Codes: G11C 2211/5642 Multilevel memory with buffers, latches, registers at input or output
• CPC Class Codes: G11C 2211/5648 Multilevel memory programming, reading or erasing operations wherein the order or sequence of the operations is relevant
• CPC Class Codes: G11C 2216/14 Circuits or methods to write a page or sector of information simultaneously into a nonvolatile memory, typically a complete row or word line in flash memory

Abstract

The present invention provides a data storage device including a flash memory and a controller. The controller checks whether a first number of a first page in the flash memory is greater than a predetermined threshold when the data storage device resumes operation after a power-off event, and stops writing data into a first TLC block when the first number of the first page is greater than the predetermined threshold, wherein the first TLC block was undergoing a first write operation which was unfinished when the power-off event occurred, and the first page was the last one being written in the first TLC block.

Claims

1. A data storage device, comprising:

a flash memory, having a plurality of TLC blocks, wherein each of the TLC blocks has a plurality of pages numbered in sequence starting from X; and

a controller, checking whether a first number of a first page is greater than a predetermined threshold when the data storage device resumes operation after a power-off event, and stopping the writing of data into a first TLC block when the first number of the first page is greater than the predetermined threshold, wherein the first TLC block was undergoing a first write operation which was unfinished when the power-off event occurred, and the first page was the last one being written in the first TLC block.

2. The data storage device as claimed in claim 1, wherein the flash memory has a plurality of SLC blocks, and each of the SLC blocks has a plurality of pages, wherein the first write operation of the first TLC block is arranged to program the data stored in a first predetermined number of SLC blocks into one of the TLC blocks.

3. The data storage device as claimed in claim 1, wherein each of the TLC blocks has a second predetermined number of pages, and the predetermined threshold is between one-half and one-third of the second predetermined number.

4. The data storage device as claimed in claim 1, wherein the controller further writes dummy data into the pages of the first TLC block other than at least one specific page to close the first TLC block.

5. The data storage device as claimed in claim 1, wherein the numbers of the specific pages are X˜

Y, and Y is equal to the first number of the first page minus a first predetermined value.

6. The data storage device as claimed in claim 4, wherein after the first TLC block is closed, the controller checks whether number of error-bits in each of the pages in the first TLC block is higher than a second predetermined value.

7. The data storage device as claimed in claim 6, wherein when the number of error-bits in any of the pages of the first TLC block is higher than the second predetermined value, the controller selects a second TLC block from the TLC blocks and performs a second write operation to write the data of the first TLC block into the second TLC block.

8. The data storage device as claimed in claim 6, wherein when no power-off event has occurred during the second write operation of the second TLC block, the controller continues to execute other tasks and bypasses the step of checking whether the number of error-bits of the second TLC block is higher than the second predetermined value after the second write operation of the second TLC block.

9. The data storage device as claimed in claim 1, wherein when the first number of the first page is lower than the predetermined threshold, the controller selects a second TLC block from the TLC blocks and writes the data which was arranged to be written into the first TLC block into the second TLC block.

10. The data storage device as claimed in claim 1, wherein before checking whether the first number of the first page is higher than the predetermined threshold, the controller further checks whether the first page can be successfully read, and performs the step of checking whether the first number of the first page is higher than the predetermined threshold when the first page can be successfully read.

11. A data writing method, applied to a data storage device, wherein the data storage device comprises a flash memory having a plurality of TLC blocks, each of the TLC blocks has a plurality of pages numbered in sequence starting from X, and the data writing method further comprises:

when the data storage device resumes operation after a power-off event, checking whether any of the TLC blocks was undergoing a write operation which was unfinished at the time that the power-off event occurred;

when a first TLC block was undergoing a first write operation which was unfinished at the time that the power-off event occurred, checking whether a first number of a first page is greater than a predetermined threshold; and

when the first number of the first page is greater than the predetermined threshold, stopping the writing of data into a first TLC block when the first number of the first page is greater than the predetermined threshold, wherein the first TLC block was undergoing the first write operation which was unfinished at the time that the power-off event occurred, and the first page was the last one being written in the first TLC block.

12. The data writing method as claimed in claim 11, wherein the flash memory has a plurality of SLC blocks, and the first write operation of the first TLC block is arranged to program the data stored in a first predetermined number of SLC blocks into one of the TLC blocks.

13. The data writing method as claimed in claim 11, wherein each of the TLC blocks has a second predetermined number of pages, and the predetermined threshold is between one-half and one-third of the second predetermined number.

14. The data writing method as claimed in claim 11, further comprising when the first number of the first page is greater than the predetermined threshold, writing dummy data into the pages of the first TLC block other than at least one specific page to close the first TLC block.

15. The data writing method as claimed in claim 11, wherein the numbers of the specific pages are X˜

Y, and Y is equal to the first number of the first page minus a first predetermined value.

16. The data writing method as claimed in claim 14, further comprising checking whether the number of error-bits in each of the pages in the first TLC block is higher than a second predetermined value after the first TLC block is closed.

17. The data writing method as claimed in claim 16, further comprising:

when the number of error-bits in any of the pages of the first TLC block is higher than the second predetermined value, selecting a second TLC block from the TLC blocks; and

performing a second write operation to write the data of the first TLC block into the second TLC block.

18. The data writing method as claimed in claim 16, further comprising:

when no power-off event has occurred during the second write operation of the second TLC block, continually executing other tasks and bypassing the step of checking whether the numbers of error-bits of the second TLC block are higher than the second predetermined value after the second write operation of the second TLC block is finished.

19. The data writing method as claimed in claim 11, further comprising:

when the first number of the first page is lower than the predetermined threshold, selecting a second TLC block from the TLC blocks and writing the data which was arranged to be written into the first TLC block into the second TLC block.

20. The data writing method as claimed in claim 11, further comprising:

before checking whether the first number of the first page is higher than the predetermined threshold, checking whether the first page can be successfully read; and

when the first page can be successfully read, performing the step of checking whether the first number of the first page is higher than the predetermined threshold.