Systems and methods for managing non-volatile memory based on temperature

Patent metadata

Field	Value
Publication number	US-9891859-B1
Application number	US-201615232253-A
Country	US
Kind code	B1
Filing date	Aug 9, 2016
Priority date	Aug 9, 2016
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

Systems and methods for managing data in non-volatile memory devices across a large range of operating temperatures are provided. Embodiments discussed herein selectively reprogram previously programmed data at a temperature that better enables the data to be read regardless of where within the range of operating temperatures the data is being read. Circuitry and methods discussed herein can keep track of a program temperature associated with each portion of non-volatile memory and use this information along with other criteria to selectively perform temperature based moves of data. This enables a mechanism for data to programmed in out-of-bounds temperature ranges to be reprogrammed within an in-bounds temperatures range so that a temperature delta between the reprogrammed temperature and the read operation temperature is below a threshold that ensure efficient and error free read operations to be performed.

First claim

What is claimed is:

1. A system, comprising non-volatile memory, a temperature sensor; and control circuitry configured to:
receive an instruction to program data into a band of the non-volatile memory, wherein in response to the received instruction, the control circuitry is configured to:
open the band;
receive a temperature value from the temperature sensor, wherein the temperature value is classified as one of an in-bounds temperature and an out-of-bounds temperature;
program the data and the temperature value into the band; and
close the band; and

perform temperature-based moves of previously programmed bands when the temperature sensor indicates the temperature value is within the in-bounds temperature, wherein the temperature-based moves include:
determine which previously programmed bands were programmed at the out-of-bounds temperature; and
reprogram the previously programmed bands determined to be programmed at the out-of-bounds temperature into new bands while the temperature value is within the in-bounds temperature.

2. The system of claim 1 , wherein the non-volatile memory comprises three dimensional (3-D) Nand.

3. The system of claim 1 , wherein the control circuitry is configured to:
receive a read instruction to read data out of the non-volatile memory, wherein in response to the received read instruction, the control circuitry is further configured to:
receive a current temperature value:
select a band to read;
determine the temperature value of the selected band;
commence a read operation of the selected band if the determined temperature value is within a fixed range of the current temperature; and
prevent the read operation of the selected band if the determined temperature value is not within the fixed range of the current temperature.

4. The system of claim 1 , wherein the system is subjected to temperature swings that cause the temperature values to cycle between the in-bounds and out-of-bounds temperatures.

5. The system of claim 4 , wherein the temperature swing is at least 50 degrees centigrade.

6. The system of claim 1 , wherein the out-of-bounds temperature represents first and second ranges of temperatures, wherein the first range represents temperature values below the in-bounds temperature, and wherein the second range represents temperature values above the in-bounds temperature.

7. The system of claim 1 , wherein the temperature sensor is a first of a plurality of temperature sensors, wherein the first temperature sensor is associated with one of the non-volatile memory and the control circuitry.

8. The system of claim 1 , wherein the control circuitry is configured to balance a total number of program operations with the temperature-based moves.

9. The system of claim 1 , wherein the control circuitry is operative to:
program data in a single level cell mode when the data is initially programmed into a band; and
program data in a multi-level cell mode when performing a temperature based move.

10. A method for managing temperature-based moves of data stored in non-volatile memory, comprising:
receiving a current temperature value from at least one temperature sensor;
programming data into a first band of the non-volatile memory;
programming the current temperature value as a program temperature into metadata associated with the first band; and
selectively reprogramming the data stored in the first band to a second band of the non-volatile memory if performance based criteria are satisfied, wherein the data stored in the second band is programmed at a temperature that provides enhanced temperature swing tolerance than the data stored in the first band.

11. The method of claim 10 , wherein the performance based criteria comprises the program temperature and the current temperature.

12. The method of claim 11 , wherein the program temperature is classified as one of an in-bounds temperature and an out-of-bounds temperature.

13. The method of claim 12 , wherein the in-bounds temperature represents a range of temperatures in which data is programmed into the non-volatile memory and still be accurately read even if the read operation is performed at an out-of-bounds temperature.

14. The method of claim 12 , wherein the out-of-bounds temperature represents a range of temperatures in which data is programmed into the non-volatile memory and potentially experience read errors if a read operation is performed when a temperature delta between the out-of-bounds temperature and the read temperature exceeds a threshold.

15. The method claim 12 , wherein the selectively reprogramming comprises:
determining that the first band was programmed at the out-of-bounds temperature; and
reprogramming the data stored in the first band to the second band when the current temperature is within a range associated with the in-bounds temperature.

16. The method claim 12 , wherein the selectively reprogramming comprises:
determining that the first band was programmed at the in-bounds temperature; and
allowing the data stored in the first band to remain stored in the first band.

17. A method for managing temperature based moves of data stored in three-dimensional non-volatile memory (NVM), the method implemented in a device that is subjected to temperature swings that can affect read performance, the method comprising:
monitoring a current temperature;
programming a plurality NVM portions with data, wherein each NVM portion includes metadata specifying a program temperature into a first band of the non-volatile memory, wherein the program temperature is classified as one of an in-bounds temperature and an out-of-bounds temperature;
determining which of the plurality of NVM portions were programmed at the out-of-bounds temperature; and
reprogramming the NVM portions determined to have been previously programmed at the out-of-bounds temperature into new bands while the current temperature is within the in-bounds temperature.

18. The method of claim 17 , further comprising determining that the current temperature has been maintained in a steady state before reprogramming the NVM portions determined to have been previously programmed at the out-of-bounds temperature into new bands while the current temperature is within the in-bounds temperature.

19. The method of claim 17 , wherein the NVM portions programmed within the in-bounds temperature are readable regardless of the temperature swings, and wherein the NVM portions programmed within the out-of-bounds temperatures are not always readable due to the temperature swings.

Assignees

• Apple Inc

Inventors

• Vogan Andrew W
• Srinivasan Charan
• Byom Matthew J

Classifications

• G11C7/04 Primary

  with means for avoiding disturbances due to temperature effects · CPC title

• G06F3/0619

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/0653

  Monitoring storage devices or systems · CPC title

• G06F3/0679

  Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP] · CPC title

• G11C16/10

  Programming or data input circuits · CPC title