Evaluation of non-contact post-CMP cleaning process utilizing split-lot polishing and cleaning comparisons

A non-contact, post-chemical mechanical planarization (CMP) cleaning method is presented as an alternative to the commonly used physical scrubbing method. This cleaning method uses one tank for aqueous ammonia cleaning and rinsing with megasonic energy, and a second tank for HF processing. Since the planarization and cleaning processes are interdependent, truly useful evaluation of different cleaning methods dictates the use of wafers from the same polish lot. The production environment split-lot testing reviewed in this paper shows the non-contact cleaner (40 +/-24 defects greater than or equal to 0.20 mu m) to be a viable alternative to the contact cleaner (88 +/-112 defects greater than or equal to 0.20 mu m). It should be considered that both types of cleaners have independently shown better net results, but the data presented in this paper represents split lot testing using the same polished wafer for both cleaners.