Papers by Author: Ja Hyung Han

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

Abstract: Corrosion on specific Cu patterns was evaluated during Cu CMP. The corrosion was observed at isolated patterns and outer edge area of pad surrounded by oxide field after polishing and showed dependency on process. Two different commercial slurries were chosen and used for polishing after characterizing electrochemical and frictional properties. Stress simulations were conducted on these patterns. Higher stress was calculated on these patterns. The process temperature and friction behavior of Cu affected the magnitude of corrosion on Cu on these patterns.

Abstract: The adhesion force and removal of alumina particles on Cu, Ta, TEOS, SILKTM, Aurora and FSG wafer surfaces were experimentally and theoretically investigated in slurry solutions of different pHs. These wafer surfaces showed negative zeta potentials in the investigated pH ranges with exception of FSG and Ta. However, the zeta potentials of FSG surface drastically decreased with increasing pH. The lowest adhesion force and smallest number of alumina particles were measured between alumina particle and FSG surface in a slurry solution of pH 11. Alkaline slurry was much more desirable in controlling the level of particle contamination during Cu CMP. The pH of the slurry and zeta potentials of the surfaces played important roles in controlling the interaction force.