A Method to Recover Defective Aluminum Interconnect Films in Mass Production

In mass manufacturing, the quality of aluminum interconnect films could be compromised due to various reasons. Such a compromise could result in electrical shorts and hence failure to yield at the end of the line or, worse, could result in reliability failure such as electromigration if the film morphology or linewidth is affected. As a result of such potential failures, wafers with these types of problems are usually scrapped at the point of detection inline. Scrapping wafers in the line or, worse, at the end of the line, results in financial loss as well as potential delivery problems to customers if there are no backup wafers in the vicinity of the affected step to replace the scrapped wafers. Missing timely delivery to a customer may impact not only the immediate customer but also the customer's customers who may be dependent upon uninterrupted and timely supply in their lean supply chain management system. This paper describes a study done that demonstrated the successful recovery of such problematic wafers along with verification by inline and end of line testing, including device functionality and reliability verification. This feasibility opens the door to avoid potentially huge losses and undesirable delivery impact to multiple stakeholders in the supply chain where time to market is important.