Method for avoiding short-circuit of conductive wires

A method for avoiding short-circuit of conductive wires, comprising:

• providing a substrate having a contact area;
• forming a first opening in the substrate to expose the contact area;
• filling the first opening with a first conductive material to form a first conductive layer;
• removing a portion of the first conductive layer to form a second opening for exposing a sidewall of the substrate;
• forming a spacer on the sidewall;
• depositing a poly-silicon layer over the substrate to fill the second opening to form a second conductive layer;
• and
• etching back the poly-silicon layer to expose a portion of the spacer;
• forming a patterned dielectric layer over the substrate, the patterned dielectric layer defining a plurality of wire openings to expose the second conductive layer and a portion of the substrate;
• and
• filling the plurality of wire openings with a third conductive material to form a plurality of wires, at least one of the plurality of wires electrically contacting the second conductive layer, and at least one of the plurality of wires electrically insulating the second conductive layer.