Write abort detection for multi-state memories

Abstract

Techniques are presented to determine whether a multi-state memory device suffers has a write operation aborted prior to its completion. In an example where all the word lines of a memory block is first programmed to an intermediate level (such as 2 bits per cells) before then being fully written (such as 4 bits per cell), after determining that intermediate programming pass completed, the block is searched using the read level for the highest multi-state to find the last fully programmed word line, after which the next word line is checked with the lowest state's read level to determine whether the full programming had begun on this word line. In an example where each word line is fully written before beginning the next word line of the block, after determining the first erased word line, the preceding word line is checked as the highest state to see if programming completed and, if not, checked at the lowest read level to see if programming began.