Ultrathin Ru–Ta–C Barriers for Cu Metallization

Abstract

The use of an ultrathin Ru-Ta-C film as a barrier for copper metallization in sub-32-nm ultra-large-scale integration ͑ULSI͒ has been evaluated. The films, fixed at 5 nm, were deposited by magnetron sputtering using Ru and TaC targets, and the film composition and structure were adjusted by tuning the respective deposition power. The structure of the Ru-Ta-C films gradually changed from Ru 4 Ta͑C͒ to nanocrystalline or nearly amorphous when optimizing TaC. For a sandwiched scheme of Cu/Ru 82 Ta 12 C 5 /Si or Cu/Ru 77 Ta 15 C 7 /Si, the failure temperature was at least 750°C. We also electroplated Cu directly onto a Ru-Ta-C film without Cu seeding. Because of their low resistivity ͑ Ͻ 100 ⍀ cm͒ and high thermal stability, Ru-Ta-C films are promising as a Cu barrier.

Low-Resistivity Ru-Ta-C Barriers for Cu Interconnects

“…The electrical resistivity of the Ru-Ta-C films was strongly correlated with their Ru content and, in particular, the associated structural changes in the films. 10 Characterization of the Annealed Cu/Ru-Ta-C/ Si Stacked Films Ten-nanometer Ru-Ta-C films were stacked between 100 nm-Cu and Si substrates and then annealed at temperature between 300°C and 700°C for 30 min to assess the applicability of the Ru-Ta-C barrier for Cu interconnects. The room-temperature sheet resistance of the stacked films gradually decreased when the films were annealed at gradually increasing temperatures up to 500°C, as shown in Fig.…”

“…The structure of Ru 77 Ta 15 C 7 makes it comparatively difficult for copper atoms to diffuse along the grain boundaries, thus the film shows superior barrier properties. 10 Bilayer-structured Ru/Ta-C extends the diffusion path along the grain boundary. Therefore, Cu diffusion along the grain boundary appears to be more difficult, and barrier failure can be delayed to a higher temperature.…”

“…10 According to the equilibrium phase diagram, carbon atoms tend to incorporate into the Ru lattice, since Ru has solid solubility of up to 3 at.% carbon at high temperatures.…”

Bulk and surface sensitivity of a resonant waveguide grating imager

“…6 These biosensors, although divergent in throughput and operational schemes, have found widespread applications for both biomolecular interaction analysis 7,8 and cell phenotypic profiling. [9][10][11] To overcome throughput limitation posed by SPR and OWLS, RWG employs nano-grating waveguide biosensors embedded in the Society for Biomolecular Screening compatible microplates, e.g., 96-well, 384-well, and 1536-well microplates. 9,10 The RWG readers, in particular the recently developed imager, 5,12 permit high-throughput and highly sensitive drug profiling and screening, and in-depth analysis of receptor signaling pathways in living cells.…”

“…[9][10][11] To overcome throughput limitation posed by SPR and OWLS, RWG employs nano-grating waveguide biosensors embedded in the Society for Biomolecular Screening compatible microplates, e.g., 96-well, 384-well, and 1536-well microplates. 9,10 The RWG readers, in particular the recently developed imager, 5,12 permit high-throughput and highly sensitive drug profiling and screening, and in-depth analysis of receptor signaling pathways in living cells. 10 The RWG imager uses a tunable light source to interrogate simultaneously all biosensors in the microplate with a temporal resolution of 3 s and a spatial resolution of $80 lm.…”