Aluminum Cleaning on Single Wafer Tool: A Case Study with Diluted HF

Abstract

For integrated circuit fabrication on 300 mm wafers, copper interconnections cleaning is generally done with single wafer tools. In this study, we focused on the cleaning of aluminum interconnections, on single wafer tool, with a cheap and easy to use chemistry. Aluminum compatibility with diluted HF solutions was first evaluated, then short and efficient cleaning processes were developped for two kind of applications : cleaning after aluminum line etching and cleaning after final dielectric etching over the aluminum pad. It was demonstrated that cleaning efficiency was poor for the shorter process time (20 s), but improved with process time increase, highlighting a lift-off mechanism for polymers removal. Best process was achieved with 40 s of HF 0.2%, that offers a good compromise between polymer removal and lateral recess of the aluminum.