Memory device and program speed control method thereof

Abstract

A memory device includes: a memory cell array including a first memory cell group including memory cells located within a first physical distance from a reference node and a second memory cell group including memory cells located beyond the first physical distance from the reference node; a peripheral circuit configured to perform a program operation of applying program voltages increasing gradually to memory cells included in the memory cell array through word lines; and control logic configured to determine a time at which a first program permission voltage is applied to the first memory cell group and determine a magnitude of the first program permission voltage on the basis of a magnitude of the program voltages in response to a gradual increase in the program voltages, the control logic is further configured to control the peripheral circuit to apply the first program permission voltage to the first memory cell group through bit lines.