Sputtered Amorphous Boron Nitride‐Silicon Oxide Composite Toward Thickness‐Scalable Low‐k Interlayer Dielectric Applications

With the aggressive scaling of integrated circuits, ultralow dielectric constant ( k ) materials like amorphous boron nitride (aBN) are being explored as potential interlayer dielectrics (ILDs) in back‐end‐of‐line processes. However, achieving low‐ k and robust dielectric integrity across various thicknesses remains challenging for aBN. In this study, a semiconductor‐compatible magnetron sputtering technique is used to deposit aBN films with an ultrathin thickness of 2.5 nm. It is observed that significant increases in k ‐value and current density, alongside a sharp decrease in electric breakdown field ( E BD ), as film thickness increased. This degradation stems from the crystallization of turbostratic boron nitride (tBN) in thicker films. To address this thickness scalability issue, an aBN‐SiO x composite has been developed, inserting thin SiO x layers between BN layers to suppress tBN crystallization. This composite achieved a 26% reduction in k ‐value, a 20‐fold improvement in leakage current density, and a 2.2‐fold increase in E BD compared to 7.1 nm BN films without SiO x . Notably, the aBN‐SiO x composite maintained a low k ‐value of 3 at a thickness of 13.6 nm. These results demonstrate the feasibility of scalable aBN films and highlight the potential of aBN‐SiO x composites as low‐k ILD materials for next‐generation microelectronics.