Real-Time Observation of Cu Electroless Deposition: Synergetic Suppression Effect of 2,2′-Dipyridyl and 3-N,N-Dimethylaminodithiocarbamoyl-1-propanesulfonic Acid

• Published in: Journal of the Electrochemical Society 2014-01, Vol.161 (4), p.D135-D140
• Main Authors: Lim, Taeho, Park, Kyung Ju, Kim, Myung Jun, Koo, Hyo-Chol, Kim, Kwang Hwan, Choe, Seunghoe, Kim, Jae Jeong
• Format: Article
• Language: English
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/2.028404jes

The effect of 2,2′-dipyridyl and 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid (DPS) during Cu electroless deposition was observed in real time by measuring open-circuit potential and mass change of an electrode with a electrochemical quartz crystal microbalance. During Cu electroless deposition, the addition of 2,2′-dipyridyl reduced the deposition rate. DPS switched its role sensitively according to its concentration: deposition was accelerated at low concentrations and strongly suppressed at high concentrations. However, synergetic suppression effect was observed even at low DPS concentrations when 2,2′-dipyridyl was added together. In this system, the rate of suppression depended on DPS concentration: the higher DPS concentration decreased the deposition rate faster, while the minimum deposition rate was independent of the DPS concentration. Using the synergetic suppression effect, electroless Cu filling of 55-nm trenches was also successfully achieved.