Metal etching process and rework method thereof

A rework method in a metal etching process, comprising the steps of:

• providing a substrate, wherein the substrate has a dielectric layer formed thereon;
• forming an aluminum-copper alloy layer on the dielectric layer;
• forming a hard mask layer on the aluminum-copper alloy layer;
• forming a first patterned photoresist layer on the hard mask layer;
• inspecting the first patterned photoresist layer to determine whether or not a rework process is required;
• if the rework process is required, performing the rework process which including the steps of:
• removing the first patterned photoresist layer;
• and
• forming a second patterned photoresist layer over the hard mask layer;
• patterning the hard mask layer;
• removing the patterned photoresist layer above the hard mask layer;
• performing a thermal treatment at a temperature greater than 300° C. for a period of at least 3 minutes;
• and
• etching the aluminum-copper alloy layer using the patterned hard mask layer as an etching mask.