Bevel RIE Application to Reduce Defectivity in Copper BEOL Processing

Bevel etch used during wafer fabrication for semiconductor devices is discussed. In this paper, the bevel etch process was utilized in middle of the line processing to reduce back end of line (BEOL) defectivity. Tungsten and titanium nitride films, from the formation of contacts to the transistors, extend into the bevel region of the wafer and have been shown to initiate arcing. This can spread foreign material defects on the front side of the wafer in various BEOL postprocessing steps, including subsequent reactive ion etching, SEM metrology, and film depositions. The bevel etch tool confines a plasma etch to the outer edge of the front side of the wafer (which can be individually adjusted), and can remove dielectric, organic, and Ti/TiN/W films using a fluorine based chemistry.