Nonvolatile memory devices having multi-filament variable resistivity memory cells therein

Abstract

There is provided a resistive memory device, the device including: a plurality of word lines and a plurality of bit lines arranged such that the word lines intersect the bit lines; a plurality of resistive memory cells each having a variable resistive material coupled between the corresponding word line and the corresponding bit line and an access element; selecting circuits selecting one of the plurality of resistive memory cells; and a filament-forming circuit supplying a filament-forming voltage to the selected resistive memory cell through the bit line coupled to the selected resistive memory cell while increasing the filament-forming voltage from a predetermined voltage level until filaments having a predetermined thickness are formed in the variable resistive material of the selected resistive memory cell.