Development And Optimization Of Wet Clean Process For Metal Hard Mask In 55nm CMOS Copper Damascene Technology

The paper researches wet clean process of 55 nm CMOS Metal Hard Mask(MHM) copper interconnect flow. In 55 nm technology platform, three kinds of chemical is evaluated, the first is amine based solvent, the second is semi-aqueous based chemical, the third is diluted HF. Base on ER, defect, WAT and Q-time performance comparison, the first Amine based solvent is best. By chemical exchange setting optimization, below 60 nm particle performance becomes best, and process development completed.During production, some issue happened, such as copper loss, ball defect and organic residue. Root cause is found by detail study. Copper loss is induced by electrochemical erosion during process, key factor is light. The issue can be prevented by keeping chamber dark. Ball defect is caused by dirty chamber and chemical. And issue is covered by optimizing nozzle spray start point in recipe, which base on central special defect map. Organic residue can be reduced by adding DIW rinse time, which will not induce more copper loss. After the issue solved, WET clean process become stronger, defect reduced, and yield improved.And the paper also do some analysis on MHM copper interconnect WET clean technology development trend?New requirement on equipment and chemical is mentioned.