Semiconductor memory device for controlling having different refresh operation periods for different sets of memory cells

Abstract

Provided is a semiconductor memory device for controlling a refresh operation of redundancy memory cells. The semiconductor memory device may include normal memory cells and redundancy memory cells that are used to repair normal memory cell(s) to which a defective cell is connected, and an error-correction code (ECC) memory cell row that stores parity bits for controlling the defective cell. Memory cells on the normal memory cell rows are refreshed during a first refresh cycle. Other memory cells on, such as redundancy memory cell rows, an edge memory cell row that is adjacent to the redundancy memory cell row(s) from among the normal memory cell rows, and/or the ECC memory cell row may be refreshed during a second refresh cycle that is different from the first refresh cycle.