Amorphous boron nitride as a low-k dielectric for next-generation BEOL interconnects

As back-end-of-line (BEOL) scaling pushes porous low-k dielectrics toward their reliability limits, nonporous dielectrics that combine a low dielectric constant (k) with mechanical, thermal, and interfacial robustness are increasingly needed. Among nonporous low-k candidates, amorphous boron nitride (aBN) has attracted attention for advanced BEOL interconnects owing to its low-k value (k ≈ 2) and high mechanical robustness, as reflected by a Young's modulus of ~50 GPa. In this review, we discuss aBN from a BEOL process-integration perspective, focusing on the origin of its low-k behavior, process-dependent structure-property relationships, and its potential roles in BEOL interconnects and hybrid-bonding interfaces. Finally, we discuss remaining issues and future directions for validating aBN as a nonporous low-k dielectric/interface material under BEOL and hybrid-bonding integration.