Copper Repassivation Characteristics in Carbonate-Based Solutions

The present work reports on carbonate-based solutions, which can provide copper passivity in a wide potential range. This report focuses mainly on the identification of copper repassivation features obtained subsequent to mechanical damage of copper passive films in carbonate-based solutions. The repassivation rate of copper in carbonate-based solutions was measured with the use of a slurryjet system. The measured repassivation rate of copper in a slurryjet system utilizing a carbonate-based solution was found to be in the range of 1-2 ms. An increase in the concentration of carbonate ions leads to a decrease of the copper repassivation time at potentials ranging from 200 to 600 mVAg/AgCl. The impingement angle between the copper surface and the single abrasive particle has an insignificant impact on the repassivation time and characteristics. It is therefore recommended that the use of carbonate anions as a passivating component in a future chemical mechanical planarization slurry design should be considered.