Memory devices and methods of operating the memory devices by programming normal cells after programming a first dummy cell

摘要

A method of operating a memory device including a first memory block having a plurality cell strings is provided. Each of the plurality of cell strings includes a string selection transistor connected in series to a first dummy cell, a plurality of normal cells, a second dummy cell and a ground selection transistor. The method includes programming the first dummy cell, and programming the normal cells in at least one of the cell strings after the programming the first dummy cell. The normal cells are selected based on a first program command inputted to the memory device. The programming the first dummy cell is performed at least twice before the normal cells are programmed. A number of times of programming the first dummy cell is different according to a level of a voltage applied to the first dummy cell and a level of a voltage applied to the normal cells.