Physical secure erase of solid state drives
Embodiments of the present disclosure relate to physical secure erase (PSE) of solid state drives (SSDs). One embodiment of a method of PSE of a SSD includes receiving a PSE command, erasing the memory cells of the blocks, programming the memory cells, and programming the select gates to a portion of the blocks. One embodiment of a SSD includes a controller and a plurality of blocks having a plurality of NAND strings. Each NAND string includes connected in series a select gate drain, memory cells, and a select gate source. The SSD includes a memory erasing instruction that cause the controller to erase the memory cells of the block, program the memory cells, and increase the threshold voltage to the select gate drain and/or the select gate source of some of the NAND strings from the blocks.
1. A solid state drive, comprising:
a controller;
means for storing data in a plurality of blocks; and
memory erasing instructions that, when executed by the controller, cause the controller to:
erase a first portion of the plurality of blocks;
program the first portion of the plurality of blocks; and
render a second portion of the plurality of blocks unreadable, wherein rendering the second portion unreadable comprises increasing a threshold voltage of select gate drain transistors (SGDs) to a level above a read level.
2. The solid state drive of claim 1 , wherein the second portion of the plurality of blocks is permanently rendered inaccessible.
3. The solid state drive of claim 1 , wherein the first portion of the plurality of blocks is refreshed for further use as long term data storage.
4. A solid state drive, comprising:
means for storing data in a plurality of blocks;
means to receive a physical secure erase command from a host;
means for performing a block erase operation on blocks of the means for storing data;
means for performing a memory programming operation on blocks erased by the means for performing a block erase operation;
means for identifying blocks that failed to erase;
means to perform a select gate programming operation, wherein the select gate programming operation comprises increasing a threshold voltage of select gate drain transistors (SGDs) to a level above a read level; and
means to securely refresh the means for storing data.
5. The solid state drive of claim 4 , wherein the means for performing a block erase operation are capable of excluding erasing of a system area of non-volatile memory.
6. The solid state drive of claim 4 , wherein the means for performing a block erase operation are capable of erasing certain portions of a system area of non-volatile memory.
7. The solid state drive of claim 4 , wherein the means for performing a memory programming operation are capable of conducting a flash write.
8. The solid state drive of claim 7 , wherein the flash write is conducted by programming all pages of a block to be erased.
9. The solid state drive of claim 8 , wherein all pages are programmed at the same time.
10. The solid state drive of claim 9 , wherein the flash write is performed by one or more programming pulses to all memory cells of the block.
11. The solid state drive of claim 4 , further comprising means to identify which portion of the block failed the block erase operation.
12. The solid state drive of claim 4 , wherein the means for identifying blocks that failed to erase also identifies blocks that failed to program.
13. A solid state drive, comprising:
means for storing data in a plurality of blocks;
means to receive a physical secure erase command from a host;
means to determine which portion of blocks of the means for storing data is functioning;
one or more of:
means to program select gate drain transistors; or
means to program select gate source transistors; or
both means to program select gate drain transistors and means to program select gate source transistors;
means to perform a select gate programming operation, wherein the select gate programming operation comprises increasing a threshold voltage of select gate drain transistors (SGDs) to a level above a read level; and
means to securely refresh the means for storing data.
14. The solid state drive of claim 13 , further comprising means for determining which portions of the blocks of the means for storing data are not functioning.
15. The solid state drive of claim 13 , further comprising means to program a threshold voltage of select gate drain transistors greater than a read level.
16. The solid state drive of claim 13 , further comprising means to program a threshold voltage of select gate source transistors greater than a read level.
17. The solid state drive of claim 13 , further comprising means to program a threshold voltage of select gate source transistors and select gate drain transistors greater than a read level.
18. The solid state drive of claim 13 , further comprising means to identify one or more failed erased memory cells.
19. The solid state drive of claim 13 , further comprising means to identify one or more failed programmed memory cells.
20. The solid state drive of claim 13 , further comprising means to make word lines of the means for storing data inaccessible.