Experimental and first-principles insights into Ti-mediated Cu–Si3N4 interfaces for high-reliability electronic substrates

This study elucidates the atomistic mechanisms governing the robust bonding between β-Si 3 N 4 and Cu via a Ti-induced TiN interlayer employing an integrated experimental and computational approach. Density functional theory (DFT) calculations of the potential energy surfaces (PESs) of β-Si 3 N 4 revealed a stronger chemical affinity of Ti compared with other metals. Following Ti deposition, the formation of TiN on β-Si 3 N 4 was confirmed, and transmission electron microscopy (TEM) identified five distinct crystallographic orientation relationships (ORs) at the β-Si 3 N 4 /TiN interface. Lattice misfit analysis showed that all ORs exhibited minor mismatches, indicating a structurally adaptable interface. DFT-based adhesion energy calculations for representative ORs confirmed that these low-misfit configurations correspond to energetically stable interfaces exhibiting substantial work of adhesion. Electronic structure analyses revealed strong Ti–N bonds with both covalent and ionic character. These findings suggest that the system’s robustness stems from its inherent ability to form multiple, structurally coherent, and strongly bonded interfaces. Notably, thermal cycling tests confirmed the excellent interfacial reliability of the TiN-mediated Cu/β-Si 3 N 4 /Cu substrates, with a negligible delamination increase of less than 1% after 4500 cycles between –55 and 150 °C. This study provides direct atomistic insights into the Ti-mediated bonding mechanism and demonstrates the potential of the Cu–β-Si 3 N 4 interface for high-reliability power electronics. Our integrated experimental–computational approach offers a framework for designing advanced metal–ceramic interfaces with optimized crystallographic alignment and adhesion properties.