Patent ID: 7538043

Claim:
A method for forming a phase change memory device, comprising: providing a substrate, comprising a transistor with a source or a drain formed therein; forming a bottom dielectric layer with vias therein overlying the substrate, the vias electrically connecting the source or the drain of the transistor; forming a first dielectric layer with a strip-shaped lower electrode therein overlying the bottom dielectric layer and vias, comprising the steps of: forming a metal layer on the bottom dielectric layer and the vias; patterning the metal layer to form the strip-shaped lower electrode; depositing a first dielectric layer on the strip-shaped lower electrode and the bottom dielectric layer; and polishing a first dielectric layer, exposing the strip-shaped lower electrode; forming a second dielectric layer with a phase change layer therein overlying the first dielectric layer and the strip-shaped lower electrode, the phase change layer crossing and contacting the strip-shaped lower electrode at a cross region and the phase change layer is a strip-shaped; and forming a top electrode, electrically connecting the phase change layer, wherein the step of patterning the metal layer to form the strip-shaped lower electrode comprises: forming a patterned photoresist layer on the metal layer, wherein the patterned photoresist layer is strip-shaped; trimming the patterned photoresist layer to reduce width of the patterned photoresist layer; and etching the metal layer using the trimmed patterned photoresist layer as a mask to form the strip-shaped lower electrode.