1. A method for forming a semiconductor device including a resistive memory cell, the method comprising: providing a substrate having an upper surface; forming a first conductive layer over the upper surface of the substrate; forming an amorphous silicon layer over the first conductive layer; cleaning a surface of the amorphous silicon layer to remove native oxide formed on the surface of the amorphous silicon layer; depositing a silver layer over the amorphous silicon layer after removing the native oxide by performing the cleaning step; and etching the amorphous silicon layer and the silver layer to form a pillar comprising amorphous silicon and silver above the first conductive layer, wherein the resistive memory cell includes the first conductive layer, the amorphous silicon layer, and the silver layer, and wherein the surface of the amorphous silicon layer is cleaned to prevent silver agglomeration on the native oxide.