Accelerated physical secure erase

Patent metadata

Field	Value
Publication number	US-9633738-B1
Application number	US-201615195583-A
Country	US
Kind code	B1
Filing date	Jun 28, 2016
Priority date	Jun 28, 2016
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A storage system includes a controller that is configured to make host data inaccessible. To do so, the controller may control power control circuitry to supply pulses to storage locations storing host data. The pulses may include flash write pulses but no erase pulses, or a combination of flash write pulses and erase pulses. If erase pulses are supplied, the number of the erase pulses may be less than the number supplied for performance of a default erase operation.

First claim

We claim:

1. A storage system comprising:
a memory; and
power control circuitry that, in order to execute a host command requesting host data to be inaccessible, is configured to:
supply one or more flash write pulses to storage locations of the memory storing the host data without supply of one or more erase pulses to the storage locations; or
supply a combination of one or more erase pulses and one or more flash write pulses to the storage locations, wherein a number of the one or more erase pulses is less than a number of erase pulses supplied for performance of a default erase operation in the storage system.

2. The storage system of claim 1 , wherein when the power control circuitry is configured to supply the one or more flash write pulses without supply of the one or more erase pulses, a sole flash write pulse or an initial flash write pulse of the one or more flash write pulses is supplied at a higher magnitude than a magnitude of an initial write pulse that the power control circuitry is configured to supply for a regular program operation.

3. The storage system of claim 2 , wherein when the power control circuitry is configured to supply the one or more flash write pulses without supply of the one or more erase pulses, the one or more flash write pulses comprises the sole flash write pulse.

4. The storage system of claim 1 , wherein, when the power control circuitry is configured to supply the combination of the one or more erase pulses and the one or more flash write pulses, at least one of:
the one or more flash write pulses comprises a sole flash write pulse, or
the one or more erase pulses comprises a sole erase pulse.

5. The storage system of claim 4 , wherein both the one or more flash write pulses comprises the sole flash write pulse and the one or more erase pulses comprises the sole erase pulse.

6. The storage system of claim 1 , wherein, when the power control circuitry is configured to supply the combination of the one or more erase pulses and the one or more flash write pulses, a sole erase pulse or an initial erase pulse of the one or more erase pulses is supplied at a higher magnitude than a magnitude of an initial erase pulse that the power control circuitry is configured to supply for a default erase operation.

7. The storage system of claim 1 , wherein the power control circuitry is configured to supply the one or more flash write pulses without supply of the one or more erase pulses on a block-by-block basis, or supply the combination of the one or more erase pulses and the one or more flash write pulses on a block-by-block basis.

8. The storage system of claim 1 , wherein the power control circuitry is configured to supply the one or more flash write pulses without supply of the one or more erase pulses on a write all basis, or supply the combination of the one or more erase pulses and the one or more flash write pulses on an erase all basis and a write all basis, respectively.

9. A storage system comprising:
a memory; and
power control circuitry configured to perform a default erase operation and a secure erase operation on a single unit of erase of the memory,
wherein, for performance of the default erase operation, the power control circuitry is configured to supply a default number of a plurality of erase pulses, and
wherein for performance of the secure erase operation, the power control circuitry is configured to supply one or more secure erase pulses that comprises a fewer number of erase pulses than the default number of the plurality of erase pulses.

10. The storage system of claim 9 , wherein the one or more secure erase pulses comprises a flash write pulse and no erase pulses.

11. The storage system of claim 10 , wherein the flash write pulse has a higher magnitude than a magnitude of an initial write pulse that the power control circuitry is configured to supply for a regular program operation.

12. The storage system of claim 11 , wherein the flash write pulse comprises a sole flash write pulse or an initial one of a plurality of flash write pulses.

13. The storage system of claim 9 , wherein the one or more secure erase pulses comprises a combination of an erase pulse and a flash write pulse.

14. The storage system of claim 13 , wherein the power control circuitry is configured to supply the erase pulse at a higher magnitude than a magnitude of an initial erase pulse of the plurality of erase pulses supplied for performance of the default erase operation, and wherein the erase pulse is a sole erase pulse or an initial one of a plurality of erase pulses that the power control circuitry is configured to supply for performance of the secure erase operation.

15. The storage system of claim 9 , wherein the power control circuitry is configured to perform the secure erase operation on a block-by-block basis.

16. The storage system of claim 9 , wherein the power control circuitry is configured to perform the secure erase operation on an erase all basis and a write all basis.

17. A method of corrupting data in a storage system, the method comprising:
determining, with a controller, to corrupt host data stored in a memory; and
in response to the determination, issuing, with the controller, one or more commands to the memory to cause the memory to:
perform a flash write operation on storage locations of the memory storing host data without performing an erase operation on the storage locations; or
perform a combination of a flash write operation and a fast erase operation on the storage locations of the memory, wherein the fast erase operation comprises a supply of a fewer number of erase pulses than a number of erase pulses supplied for a default erase operation.

18. The method of claim 17 , further comprising:
receiving, with the controller, a host secure erase command from a host system; and
selecting, with the controller, which of a plurality of different types of physical secure erase operations to perform based on information included in the host secure erase command.

19. The method of claim 17 , further comprising:
in response to the one or more commands:
supplying, with power control circuitry, a single flash write pulse to each of a plurality of blocks on a die storing host data without supply any erase pulses to the plurality of blocks; or
supplying, with the power control circuitry, a combination of a single flash write pulse and a single erase pulse to each of the plurality of blocks on the die storing host data.

20. The method of claim 17 , further comprising:
sending, with the controller, configuration data to the memory for storage in the memory after issuing the one or more commands to the memory.

21. A storage system comprising:
a memory; and
means for performing a default erase operation and a secure erase operation on a single unit of erase of the memory, wherein the means supplies a default number of a plurality of erase pulses for performance of the default erase operation and supplies a fewer number of erase pulses than the default number of the plurality of erase pulses for performance of the secure erase operation.

Assignees

• Sandisk Technologies Llc

Inventors

• Guo Zelei
• Koh Pao-Ling
• Chin Henry
• Shukla Pitamber
• Raghu Deepak
• Lee Dana

Classifications

• G11C16/10

  Programming or data input circuits · CPC title

• G11C16/16 Primary

  for erasing blocks, e.g. arrays, words, groups · CPC title

• G11C16/30

  Power supply circuits · CPC title

• G11C16/14

  Circuits for erasing electrically, e.g. erase voltage switching circuits · CPC title

• G11C16/22

  Safety or protection circuits preventing unauthorised or accidental access to memory cells · CPC title