The Effect of Ultrasonic Agitation on the Seedless Growth of Cu on Ru-W Thin Films.

Ru attracted considerable attention as a candidate to replace TaN as a diffusion barrier layer for Cu interconnect metallisation. The addition of W improves the diffusion barrier properties of Ru but appears to weaken the adhesion strength between the barrier and Cu and the direct (seedless) electroplatability behaviour. Although Cu can be directly electroplated on near equimolar Ru-W thin films, no complete substrate coverage is obtained.

Co-W Barrier Layers for Metallization of Copper Interconnects: Thermal Performance Analysis.

The back-end-of-line (BEOL) copper interconnect structure has been subjected to downscaling for the last two decades, while the materials used for conforming and assuring its physical integrity during processing have faced significant obstacles as the single-digit nanometer process node is implemented. In particular, the diffusion barrier layer system comprised of Ta/TaN has faced major constraints when it comes to the electrical performance of the smaller Cu lines, and thus alternative formulations have been investigated in recent years, such as Ru-Ta or Co-W alloys. In this work, we assess how PVD (physical vapor deposition) deposited equimolar Co-W films perform when exposed to different vacuum annealing temperatures and how these films compare with the Ta adhesion layer used for Cu seeding in terms of dewetting resistance.

Seedless Cu Electroplating on Ru-W Thin Films for Metallisation of Advanced Interconnects.

For decades, Ta/TaN has been the industry standard for a diffusion barrier against Cu in interconnect metallisation. The continuous miniaturisation of transistors and interconnects into the nanoscale are pushing conventional materials to their physical limits and creating the need to replace them. Binary metallic systems, such as Ru-W, have attracted considerable attention as possible replacements due to a combination of electrical and diffusion barrier properties and the capability of direct Cu electroplating.

Seedless Cu Electroplating on Co-W Thin Films in Low pH Electrolyte: Early Stages of Formation.

The use of Ta/TaN barrier bilayer systems in electronic applications has been ubiquitous over the last decade. Alternative materials such as Co-W or Ru-W alloys have gathered interest as possible replacements due to their conjugation of favourable electrical properties and barrier layer efficiency at reduced thicknesses while enabling seedless Cu electroplating. The microstructure, morphology, and electrical properties of Cu films directly electrodeposited onto Co-W or Ru-W are important to assess, concomitant with their ability to withstand the electroplating baths/conditions.