Enhanced Adhesion Between Cu and Si₃N₄ Ceramic by Inserting a Zr-Ru Gradient Layer

Silicon nitride ceramic is proposed as the most potential substrate to meet the heat dissipation requirements of high-power electronic devices. However, metallization of silicon nitride with high interfacial strength and reliability is still challenging. Here we report a novel approach for enhancing the reliability of silicon nitride substrate by designing a nano-scale Zr-Ru gradient layer using magnetron sputtering. Cu/Zr-Ru films were deposited on Si3N4 substrate to investigate the microstructure, composition distribution and adhesion properties. The results show that the Zr-Ru films were characterized by gradient structure, low resistance and uniform thickness, which further improve the bonding properties of Cu, moreover, the thinner gradient layer demonstrate better bonding properties, thus has abnormal size effect.