Low temperature dry etching of copper using a new chemical approach

The increasing demand for faster microelectronic circuits with improved performance will force fundamental changes in future semiconductor manufacturing. The realization of deep submicron feature sizes in ultra-large-scale integration (ULSI) devices together with higher clock frequencies will depend on the use of new microelectronic materials. Due to its lower resistivity and better resistance to electromigration copper is the most likely material to replace aluminum or aluminum alloys as interconnect metal. Several problems connected to the physical and chemical properties of this metal have to be solved to achieve this. One of these problems concerns the formation of patterned copper films. In addition to selective CVD of Cu and chemical mechanical polishing (CMP) of blanket films deposited in trenches, the dry etching of Cu using standard photoresist masks would be the ´common´ way to perform this. In this work we report a new chemical approach to the dry etching of copper by the formation of volatile metal-organic copper(I)compounds.