Effect of Chelating Agent and Ammonium Dodecyl Sulfate on the Interfacial Behavior of Copper CMP for GLSI

Abstract

Multi-layered copper wiring chemical mechanical planarization (CMP) of Giant Large Scale Integrated circuit (GLSI) is one of the key processes for the improvement of microelectronic technique. During copper interconnection CMP, high removal rate (RR) and lower surface roughness for copper film are required. Slurry is one of the key factors to achieve highly effective planarization for copper film, and is also one of the research hotspots. In this work CMP and electrochemical behavior of copper with the synergistic effect of chelating agent and Ammonium Dodecyl Sulfate (ADS) using a new type alkalescent slurry was investigated. The slurry was composed of colloidal silica, FAOII chelating agent, surfactant (ADS) and hydrogen peroxide. The Potentiodynamic polarization plots revealed that FAOII chelating agent had strong chelating ability to improve copper removal rate, which was verified by polishing experiments. When FAOII concentration increasing from 0 to 5wt%, copper RR dramatically increased from 377Å/min to 5523Å/min. [CuR(NH2)2]2 + as one of the key generated products relating to RR improvement was verified by XPS. Meanwhile, with the addition of ADS, the static etch rate decreased from 1080Å/min to 442Å/min, and the surface roughness decreased from 4.81nm to 2.69nm, which indicated that ADS acted as a surfactant and an inhibitor simultaneously. From the result it can be seen that high and controllable removal rate and low surface roughness can be achieved by adjusting the concentration of FAOII chelating agent and anionic surfactant ADS. Slurry is stabilized till 48 hours. Such simple and component adjustable alkalescent slurry has certain guiding significance to practical production.