Electrochemical deposition of copper for gigascale interconnect technologies
Abstract
With the evolution of computer chip technologies from aluminum-based metallization schemes to their copper-based counterparts, electrochemical deposition (ECD) has been applied as a viable deposition technique for copper (Cu) interconnects. However, the continuous scaling-down of device and interconnect dimensions, as outlined in the International Technology Roadmap for Semiconductors (ITRS), creates fundamental limits, such as the conformality and continuity of the ultra-thin Cu seed needed to ensure successful ECD Cu in aggressive device structures, that threaten the extendibility of ECD Cu. Accordingly, a detailed investigation is presented herein of the extendibility limits of ECD Cu. Nucleation and growth studies on ultra-thin Cu seed layers led to the identification of key parameters that control ECD Cu nucleation, growth, and subsequent feature fill. Furthermore, results from feasibility studies of ECD Cu directly on "seedless" liners and modified dielectric surfaces are presented, including findings from potential nucleation barriers and possible integration protocols to enhance the nucleation characteristics and fill efficiency of ECD Cu.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 2002
- Bibcode:
- 2002PhDT.......131G