Non-volatile memory with faster post-erase defect testing

Abstract

As part of the erase operation for a memory block, one or more post-erase tests can be incorporated into the erase operation to see whether the block has grown any defects. After erasing a block and verifying the erase, the post-erase tests can be performed on the block. As these test involve biasing the block and performing a sensing operation, these post erase tests come with a time penalty. To reduce the associated time penalty and improve memory performance while incorporating the defect tests into the erase process, when biasing the memory array for the post-erase defect tests different ramp rates can be used. In particular, faster ramp rates for bias levels, such those applied to the word lines of the block, are used for the post-erase tests than are used for the same bias level when performing the standard read, program verify, or read verify operations.