LEUVEN (Belgium), June 30, 2022— This week, at the 2022 IEEE
International Interconnect Technology Conference (IITC 2022), imec, a
world-leading research and innovation hub in nanoelectronics and digital
technologies, presents options to reduce the metal line resistance at
tight metal pitches, mitigating the resistance/capacitance (RC) increase
of future interconnects using direct metal patterning. For the first
time, high aspect ratio (AR=6) processing of ruthenium (Ru) in a
semi-damascene fashion is experimentally shown to result in about 40%
resistance reduction without sacrificing area. Additional simulations
confirm the benefits at circuit level in combination with airgaps as
dielectrics. A complementary experimental study shows that the
reliability of semi-damascene with airgaps is competitive when compared
to dual-damascene with low-k dielectrics.
After providing the first experimental demonstration of a functional
two-metal-level semi-damascene module at 18nm metal pitch, AR=3, with
fully self-aligned vias at VLSI 2022, imec proposes to extend this
integration scheme to further reduce the line resistance of the Ru
interconnects, while keeping the same footprint. This can be achieved by
high-AR processing of the Ru lines using an advanced subtractive metal
etch process. Zsolt Tokei: “We measured a significant line resistance
reduction of about 40% on Ru lines with AR=6 compared to lines with
conventional AR=3. In addition, we showed the benefits at circuit level
of implementing high-AR semi-damascene lines with airgaps.” In a
benchmark study, imec also demonstrated that the semi-damascene flow
with airgaps is reliable with more than 10 years lifetime.
“With no less than 10 oral presentations at this year’s IITC, addressing
the main challenges in interconnect scaling, imec has a proven path to
push the interconnect roadmap for the coming ten years,” concludes Zsolt
Tokei. “The papers cover advances in semi-damascene integration as a
promising interconnect scheme for future logic nodes, memory
technologies and highlight progress in middle-of-line (MOL)
metallization schemes, dielectrics, alternative metals exploration, and
reliability.”
