Nano-Ridge Bending during Conformal Ruthenium Metallization: Implications for Interconnect Fabrication

Abstract

Conformal deposition of ruthenium in a damascene-like approach has shown promising results to form Ru nanowires with superior resistive and reliability characteristics for application as interconnects in very large-scale integrated circuits. Nevertheless, the mechanical integrity of nanostructures during process development for novel materials' integration is paramount. In this paper, a mechanism of dielectric pattern distortion is identified, which occurs during conformal deposition of ruthenium and cannot be explained by metal film stress alone. Using experimental characterization and thermodynamic analysis, we show that metal-coated dielectric nanoridges bend under the influence of zipping stresses and establish contact to minimize their free energy.

Inertness and Other Properties of Thin Ruthenium Electrodes in ReRAM Applications

“…This chapter looks at the material properties of thin Ru films from the perspective of their suitability for use as an inert electrode in ReRAM cells, such as Cu/TaO x /Ru [1], that lends itself to be readily integrated in the CMOS back-end-of-line (BEOL) [2]. Advanced interconnects at 10 nm half-pitch, in order to overcome the scaling issues with Cu interconnects, increasingly pin hopes on ruthenium metallization, not only as a liner and diffusion barrier for Cu, but also as a stand-alone material for contact plug, via, and even interconnect lines [3][4][5]. Such integration of ReRAM memory into BEOL has the potential of reducing the latency in connectivity-constrained computational devices and of bringing logic and memory closer together [6][7][8].…”