(Invited) Cobalt Damascene Chemistry for Advanced Interconnect

Abstract

In recent years, cobalt has caught more and more attention as an alternative material to Cu as the material for interconnect in advanced semiconductor technology. For electronic devices, the desire of reduction in size, but increase in performance, has driven the development of the process of interconnect toward a direction that the feature size of interconnects becomes smaller, so more components can be integrated in a more limited area on electronics. As feature size shrinking, cobalt brings benefits over copper as the material of interconnects1: 1) cobalt can have less resistance as there can be less electron scattering than is seen with copper, 2) and cobalt is less mobile than copper thus reducing electromigration. Electrodeposition is well known for its low cost of ownership as a metallization process. To achieve void-free and seam-free fill by electrodeposition for a feature less than 10nm, a bottom-up fill is required, and it is one of most challenging process among modern semiconductor technology. Filling a feature, usually a trench or via, via bottom-up fill means that the metallization grows predominately from bottom. MacDermid Enthone has developed a Co chemistry which can provide void-free and seam-free fill to feature < 10nm. Also, it can achieve leveled overburden with good uniformity. In Fig 1., it is a FIB/TEM image of a feature, post-seed opening ~8nm and A/R of ~10, filled by MacDermid Enthone Co chemistry. In this report, a proposed electrochemical bottom-up fill mechanism will be discussed to reveal the challenge of cobalt damascene for advanced interconnect, and how they are overcome by the latest MacDermid Enthone Co chemistry Figure 1: FIB/STEM of a feature filled by MacDermid Enthone Co chemistry References J. Jezewski, J. S. Clarke, T. K. Indukuri, F. Gstrein and D. J. Zierath, US 2014/0183738A1 (2012) Figure 1