Patent ID: 6650571
Filing Date: 2003-11-18
Classification: G11C

Abstract:
A method of operating a non-volatile memory comprising:pre-charging each memory cell in a block of flash memory cells before an initial erase pulse is applied; applying at least one erase pulse to the block of flash memory cells, wherein the block of memory cells is arranged in rows; verifying if each row is erased in the block after each erase pulse is applied; programming memory cells in a register that is associated with the block to track rows that have been verified as being erased; counting die number of erase pulses used to verify a predetermined number of rows have been erased in the block wherein the rows not verified as being erased are labeled as not erased for subsequent memory operations to the block; and applying a predetermined number of erase pulses to the block to try to erase the rows that have not been verified as being erased, wherein the predetermined number of erase pulses is a fraction of the number of erase pulses used to verify the predetermined number of rows.