Investigation On Chemical Mechanical Polishing Of Novel Copper Diffusion Barrier Of Ru

Ta/TaN bilayer serves as the diffusion barrier as well as the adhesion promoter between Cu and the dielectric in 32 nm technology devices. With the continuous improvement of IC technology, integrated circuit develops toward high speed and high performance. In sub-16 nm node, novel barrier materials besides current Ta/TaN bilayers need to be investigated. Due to the lower resistivity, good adhesion with Cu and directly plating property of Cu onto the barrier surface without using Cu seed layers, Hence, ruthenium(Ru), is being considered for replacing Ta/TaN as barrier materials for Cu interconnects in future technology devices. But there are few reports focused on the chemical mechanical polishing(CMP) of Ru. The study of CMP performance and process of these novel materials has important scientific value.The thesis first investigates the effect of process parameters on Ru CMP. Experimental results indicated that get best surface roughness(1.96 ?, the scanned area was 10 μm×10 μm) and higher polishing rate(25.6 nm/min), the optimal parameters were: pressure, 2 psi; slurry flow rate, 150 ml/min; polishing head speed, 60 rpm; platen speed, 65 rpm. In order to enhance the material removal is by modifying its chemical and mechanical properties using Hydrogen peroxide(H2O2) and FA/OⅠcomplexing agents. This paper investigated the effect of FA/OⅠand H2O2 on Ru material removal rate(MRR) and static etching rate(SER). It was revealed that Ru RR and SER ?rst linearly increased then slowly decreaseed with the increasing H2O2 probably due to the formation of uniform Ru oxides on the surface during polishing. And their corrosion behaviors and states of surface oxidation were analyzed. In addition, FA/O Ⅰ could chelate Ru oxides(such as(RuO4)2- and RuO4-changed into soluble amine salts [R(NH3)4](RuO4)2) and enhance Ru MRR. In addition, by adjusting the concentration of FA/OⅠand H2O2, Ru and Cu polishing rate can be adjusted to 1:1. The fact that FA/OⅠcan inhibit Ru and Cu galvanic corrosion. In this paper, the non-ionic surfactant were used to improve the Ru CMP performance. Especially the addition of non-ionic surfactant can lead to significantly improvement of the surface roughness.