Method for forming aluminum bumps by CVD and wet etch

摘要

A method for forming aluminum bumps that has significantly reduced processing steps than the conventional method is disclosed. The method utilizes a chemical vapor deposition technique for the selective deposition of aluminum into an opening for forming the bump and then a wet etch process for removing a polyimide layer that functioned both as a photoresist layer for providing an opening in a passivation layer and as a support for a via hole during the selective aluminum deposition process. The thickness of the passivation layer and the polyimide layer formed on top of the metal I/O pad is important since it determines the height of the aluminum bump formed.