Defect reduction of copper BEOL for advanced ULSI interconnect

In this paper, a full discussion of the defect reduction in copper BEOL technology of a 1P/3M logic product is presented for the first time. Defectivity is inspected from AEI to CMP on various metal levels. Defectivity is classified into non CMP-related type and CMP-related type. Most of the non-CMP type defects are foreign matter coming from the environment or from the processing residues. They can be effectively removed in a CMP step, as long as they were not trapped in the metal trench. On the other hand, the CMP-related type defects impact the consecutive process and yield significantly. Examples of the killer defects are slurry residues, corrosion, and scratching. Prevention and reduction of defects is discussed. Product yield is greatly improved after the reduction of defectivity.