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

Abstract

The interconnect half‐pitch size will reach ≈20 nm in the coming sub‐5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross‐section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back‐end‐of‐line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaSx ) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaSx ultrathin film is industry‐friendly, BEOL‐compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaSx compared to the TaN/Ta bilayer. This single‐stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

Incorporating Niobium in MoS2 at BEOL‐Compatible Temperatures and its Impact on Copper Diffusion Barrier Performance

“…compared to Mo-SiO 2 . Thus, NbO x in our case, could not only enhance barrier performance, but also assist MoS 2 lateral growth [72] .…”

Scalable Substitutional Re‐Doping and its Impact on the Optical and Electronic Properties of Tungsten Diselenide

“…[ 7–12 ] Moreover, integration of 2D TMDCs with Si complementary metal–oxide–semiconductor at the back‐end‐of‐line (BEOL) is being actively explored for diffusion barriers, liners, and thin‐film‐transistors to improve the overall integrated circuit performance. [ 13–16 ] However, BEOL production lines are usually limited to temperatures <500 °C whereas current state‐of‐the‐art synthesis (and doping) of TMDCs is carried out at front‐end‐of‐line (FEOL) temperatures (>700 °C). [ 17,18 ] In addition, realization of scalable intrinsic and extrinsic 2D TMDCs can find its application beyond digital electronics such as chemical sensors, [ 19,20 ] electrodes in Li ion batteries, [ 21 ] and room temperature 2D magnets, [ 22 ] to name a few.…”

Control of Cu morphology on Ru-passivated and Ru-doped TaN Surfaces – promoting growth of 2D conducting copper for CMOS interconnects

“…In this area, studies of potential liner materials are carried out in conjunction with a barrier material, whether known or novel, or in testing of a potential combined barrier and liner material. [7,17,18,[27][28][29][30][31][32][33][34] In experimental work, the primary characteristics of a potential liner for Cu deposition include adhesion of Cu to the liner, [17,27,30,33] wettability of Cu, [7,17,31,33] resistivity [28][29][30][31][32][33] and electromigration reliability. [32,34] Adhesion is studied through a simple tape exfoliation test: if the metal and liner remain adhered, then the adhesion is deemed strong enough for typical manufacturing conditions.…”