A Study on Water- Mark Defects in Copper/ Low-k Chemical MechanicalPolishing

摘要

The prevention of watermark defect after copper/low-k CMP is a critical barrier for the successfulintegration of sub-100 nm devices. The water-mark can act as a leakage source and cause electricalshorts. The mechanism of water-mark formation during Cu/low-k CMP is suggested and itsprevention methods are proposed in this study. A suitable surfactant treatment can improve thewettability of low-k films and reduce the watermark defects very effectively. The relatively stablelow-k film surface is activated during polishing and prone to adsorb surfactant molecules duringcleaning, which results in the reduction of water-marks after CMP. Another solution to eliminatewater-mark is the application of IPA dryer in post CMP cleaning.