Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low...

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Nanotechnology

Background:

• Interconnect scaling to sub-5 nm nodes requires thinner barrier/liner materials.
• Conventional tantalum nitride/tantalum (TaN/Ta) bilayers (>4 nm) limit interconnect conductance due to high resistance and volume.
• Existing 2D material diffusion barriers often require high processing temperatures incompatible with back-end-of-line (BEOL) fabrication.

Purpose of the Study:

• To develop a novel, ultrathin 2D material as a replacement for TaN/Ta bilayer diffusion barriers.
• To evaluate the barrier and liner properties of the proposed 2D material.
• To enable continued scaling of semiconductor interconnects beyond the 5 nm technology node.

Main Methods:

• Development of a 2D layered tantalum sulfide (TaSx) with a thickness of approximately 1.5 nm.
• Assessment of TaSx film properties for compatibility with industry back-end-of-line (BEOL) processes.
• Comparative analysis of TaSx barrier/liner properties against conventional TaN/Ta bilayers.

Main Results:

• A 1.5 nm thick 2D TaSx film was successfully developed as a single-stack barrier/liner.
• The TaSx film demonstrated industry-friendly and BEOL-compatible characteristics, enabling direct deposition on dielectrics.
• TaSx exhibited superior diffusion barrier and liner properties compared to the conventional TaN/Ta bilayer.

Conclusions:

• The developed 2D TaSx material effectively replaces the thicker TaN/Ta bilayer in ultrascaled interconnects.
• This single-stack TaSx solution offers improved conductance and enables continued interconnect scaling.
• TaSx is a promising material for future semiconductor technology nodes beyond 5 nm.