Mechanism analysis of the affect the copper line surface roughness after FA/O alkaline barrier CMP

Abstract

The surface roughness seriously affects the performance of devices after barrier CMP. Due to the high surface roughness of copper line, the local resistance of a device will be high when working, then the copper line will overheat prompting the generation of electro-migration and the circuit will lose efficacy. Reducing the surface roughness of the copper line in barrier CMP is still an important research topic. The main factors influencing the surface roughness of copper line in alkaline barrier slurry are analyzed in the paper. Aimed at influencing the law on the surface roughness of copper line, using a new type of alkaline barrier slurry with a different pH of the chelating agent and changing the content of non-ionic surfactant, we then analyze the influencing law both on the surface roughness of copper line, and the influence mechanism. The experimental results show that with a chelating agent with a low pH value in the barrier slurry, the surface roughness of the copper line is 1.03 nm and it is the lowest in all of the barrier slurries, and with the increase of non-ionic surfactant concentration, the surface roughness of copper line is reduced to 0.43 nm, meeting the demand of further development of integrated circuits.