Method for operating storage device determining wordlines for writing user data depending on reuse period

• US 10,127,984 B2
• Filed: 08/23/2016
• Issued: 11/13/2018
• Est. Priority Date: 08/24/2015
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Moon, Sangkwon, Lee, Heewon, Ahn, Seongjun
• Primary Examiner(s): Ojha, Ajay
• Application Number:
  US15/245,164
• Publication Number:
  US 20170060447A1
• Time in Patent Office: 812 Days
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/04 using variable threshold transistors, e.g. FAMOS

Abstract

Embodiments include a method of operating a storage device including a flash memory, comprising: calculating a reuse period of a selected memory block in the flash memory; determining a set of wordlines of the selected memory block for writing data based on the reuse period of the selected memory block; and writing the data into the set of wordlines.

Claims

1. A method of operating a storage device including a flash memory, comprising:

calculating a reuse period of a selected memory block in the flash memory;

determining a set of wordlines of the selected memory block for writing data based on the reuse period of the selected memory block;

writing the data into the set of wordlines; and

writing dummy data into a wordline of the selected memory block not in the set of wordlines,

wherein writing the data comprises;

writing dummy data to a dummy wordline having a lower reliability of the selected memory block; and

writing the data to wordlines of the selected memory block sequentially from the dummy wordline.

2. The method as set forth in claim 1, wherein:

the reuse period is referred to as a current reuse period; and

the method further comprises comparing the current reuse period with a previous reuse period; and

the determining of the set of wordlines is based on the comparison of the current reuse period and the previous reuse period.

3. The method as set forth in claim 2, wherein the determining of the set of wordlines is based on the previous reuse period when the current reuse period is longer than the previous reuse period.

4. The method as set forth in claim 1, wherein the calculating of the reuse period of the selected memory block comprises calculating a time interval between current erase time and previous erase time.

5. The method as set forth in claim 1, wherein the calculating of the reuse period of the selected memory block comprises calculating a time interval between current program time and previous program time.

6. The method as set forth in claim 1, wherein the determining of the set of wordlines comprises determining all of the wordlines of the selected memory block as the set of wordlines when the reuse period of the selected memory block is longer than a first threshold.

7. The method as set forth in claim 6, wherein the determining of the set of wordlines comprises determining all of the wordlines except a first wordline of the selected memory block as the set of wordlines when the reuse period of the selected memory block is shorter than the first threshold.

8. The method as set forth in claim 6, wherein the determining of the set of wordlines comprises determining all of the wordlines except a first wordline and a last wordline of the selected memory block as the set of wordlines when the reuse period of the selected memory block is shorter than a second threshold that is less than the first threshold.

9. A method of operating a storage device including a flash memory, comprising:

calculating a reuse period of a selected memory block in the flash memory;

determining types of programming to use to program wordlines of the selected memory block based on the reuse period; and

programming the wordlines using the types of programming,

wherein the types of programming comprise a slow program operation and a normal program operation when the reuse period is less than a first threshold.

10. The method as set forth in claim 9, wherein the slow program operation uses a lower program voltage than the normal program operation.

11. The method as set forth in claim 9, wherein the types of programming comprise only the normal program operation when the reuse period is greater than the first threshold.

12. The method as set forth in claim 9, wherein when the reuse period is less than the first threshold, the programming of the wordlines comprises:

programming a first wordline of the wordlines using the slow program operation; and

programming at least one of a remainder of the wordlines using the normal program operation.

13. The method as set forth in claim 12, wherein when the reuse period is less than a second threshold that is less than the first threshold, the programming of the wordlines further comprises programming a last wordline of the wordlines using the slow program operation.

14. A method of operating a storage device including a flash memory, comprising:

calculating a reuse period of a selected memory block in the flash memory;

determining a programming technique to use to program the selected memory block based on the reuse period; and

programming the selected memory block using the programming technique,

wherein determining the programming technique comprises;

determining programming all wordlines of the selected memory block as the programming technique when the reuse period is in a first state; and

determining programming less than all of the wordlines of the selected memory block as the programming technique when the reuse period is in a second state different from the first state.

15. The method of claim 14, wherein determining the programming technique comprises:

determining programming all wordlines of the selected memory block with a normal program operation as the programming technique when the reuse period is in a first state; and

determining programming some of the wordlines of the selected memory block with a slow program operation as the programming technique when the reuse period is in a second state different from the first state.

16. The method of claim 14, further comprising:

recalculating the reuse period of the selected memory block; and

changing the programming technique based on the recalculated reuse period.