Patent ID: 7955981

Claim:
A method of making non-volatile memory device, comprising: forming a stack of device layers; and patterning the stack to form a plurality of pillars; wherein: at least one of top corner or bottom corner of each of the plurality of pillars is rounded; each of the plurality of pillars comprises a non-volatile memory cell comprising a steering element and a storage element; the step of forming a stack of device layers comprises: forming a first conductivity type semiconductor layer; forming a second conductivity type semiconductor layer over the first conductivity semiconductor layer; and forming a storage material layer over the second conductivity type semiconductor layer; and the step of patterning the stack of device layers comprises: forming a hard mask layer over the storage material layer; patterning the hard mask layer to form mask features; undercutting an upper portion of the storage material layer underneath the mask features; and etching the stack of device layers using the mask features as a mask to form the plurality of pillars.