Chemical Mechanical Polishing of Inlaid Copper Structures with Ru/Ta/TaN as Barrier/Liner Layer

Abstract

Ru as a novel barrier/liner material for Cu interconnects, has gained application in the sub-10 nm technology node. In this paper, methods to polish patterned wafer with Ru/Ta/TaN tri-layers as liner/barrier have been proposed. Effects of pattern geometry and CMP variables (such as polishing down pressure and oxidant content) on polishing uniformity were fully investigated. Apart from this, interfacial defects after barrier polishing were comprehensive characterized by atomic force microscopy and transmission electron microscopy methods. Results show that hydrogen peroxide (H 2 O 2 ) is effective in the mutual material removal of Cu/Ru/Ta/TaN/BD1 heterogeneous materials. Good surface quality could be obtained by using proper CMP process, with Cu dishing of 604.1 Å for the 100/100 μm array.

Role of Diethylene Triaminepentaacetic Acid Pentapotassium Salt on Ruthenium CMP in H2O2-Based Slurries

“…[3][4][5] Recently, most researchers have been reminded that ruthenium (Ru) was considered to be a candidate for replacing the conventional Ta/TaN diffusion bilayer in Cu interconnects due to its resistivity, which is lower than that of the Ta/TaN bilayer, excellent step coverage, and good Cu wettability. [6][7][8][9][10] Chemical mechanical polishing (CMP) is described as a process of smoothing and planarizing a surface via a combination of chemical and mechanical forces. [11][12][13][14] It is an important technology for achieving global and local planarization during manufacture of ICs.…”

Synergetic Effect of 5-Methyl-1H-Benzotriazole and Sodium Dodecyl Benzene Sulfonate on CMP Performance of Ruthenium Barrier Layer in KIO4-Based Slurry

“…[2][3][4][5] Hence, many researchers choose ruthenium as barrier material for 14 nm and below technology node, as it can drastically decrease the barrier layer thickness and allow direct electrodeposition of copper. [6][7][8][9][10][11][12][13][14] However, according to the most of studies, the polishing performance of the ruthenium barrier layer of the copper wiring faces the most critical challenge: ruthenium is inert to many chemicals and its hardness is 6.5 Mohs, so it is cruelly difficult to attain higher removal rate (RR). 7,[9][10][11][12][13] In order to overcome the above problem, the significance of research focuses on selecting appropriate and valid oxidizers in an attempt to attain high ruthenium RR.…”