Patent ID: 11894079
Assignee: SAMSUNG ELECTRONICS CO., LTD.
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. A method of operating a memory system including memory cells, the method comprising:
preprogramming and erasing the memory cells to set a first threshold voltage distribution for the memory cells;
detecting fast cells among the memory cells set in the first threshold voltage distribution, wherein normal cells among the memory cells each have a threshold voltage equal to or greater than a first threshold voltage, and the fast cells each have a threshold voltage less than or equal to a second threshold voltage which is less than the first threshold voltage; and
programming the memory cells set in the first threshold voltage distribution to a second threshold voltage distribution greater than the first threshold voltage distribution, said programming comprising,
normal programming the normal cells to the second threshold voltage distribution by applying a sequence of incremental step pulse program (ISPP) voltage pulses to the normal cells, and
over-programming the fast cells to the second threshold voltage distribution by applying the sequence of ISPP voltage pulses to the fast cells,

wherein a voltage of an ISPP voltage pulse applied during over-programming is greater than a voltage of a corresponding ISPP voltage pulse applied during normal programming, and
wherein a level of a verification voltage applied during the over-programming is greater than a level of a corresponding verification voltage applied during the normal programming.