Corrosion Control in Copper Damascene Process

摘要

Corrosion control is the key for realizing copper damascene interconnection, since the most of the processes are treated in wet chemical atmosphere. In addition to ordinary corrosion due to chemical and galvanic reaction with slurries, a newly found type of corrosion, i.e., pattern specific corrosion was investigated. The corrosion is a kind of anodic corrosion observed only when the damascene process was applied to fabricating copper interconnection for actual ULSI devices. The corrosion occurs after the metal polishing completed, and the electrodes are electrically separated each other. Positive potential is generated to copper electrodes connected with p~+ diffused region against that connected with n+ diffused region of a p junction. The positively biased electrodes corrode quickly especially in diluted slurries rather than in the undiluted slurries, resulting in the pattern specific corrosion. The slurries which have less corrosive characteristics especially in diluted state are required.