Theoretical screening and experimental fabrication of metallized layer for enhanced Cu wetting and adhesion on Si3N4 substrate

A computational screening and experimental fabrication of metallized layer was developed to improve the interfacial binding strength of Cu/Si₃N₄ system in this work. The suitable metallized layer was computational screened based on the melting point, coefficient of thermal expansion, the solid solubility with Cu metal and the work of adhesion of metal/Si₃N₄ interface sequentially. Then, the Si₃N₄ copper-clad laminate (Si₃N₄ CCL) with Cu/metallized layer/Si₃N₄ structure was fabricated and the corresponding mechanical and electrical performances were further tested and discussed. The results show that Ni was the most suitable metallized layer considering the highest work of adhesion with Si₃N₄ ceramic compared with other promising metals. The sintered Ni layer with suitable screen-printing passes shows a uniform porous morphology, characterized by evenly distributed pore sizes that contribute to its overall structural integrity. And Ni layer exhibits a defect-free interface with the Si₃N₄ substrate, ensuring strong interfacial adhesion. The molten Cu presents planar spreading and vertical infiltration state on/in the sintered Ni layer in the subsequent Cu coating process, forming a dense metallized layer coupled with the typical equiaxed grain under the condition of suitable Cu-sheet mass. However, the over accumulation of Cu-rich phase at the interface derived from the excessive Cu-sheet mass can deteriorate the interfacial binding strength between the metal and Si₃N₄. Moreover, the fabricated Si₃N₄ CCL with a defect-free metal layer and interface structure presents excellent interfacial binding and surface conductivity, which can facilitate the vertical heat conduction across the interface and planar electron transport in the actual application. This study provides a new strategy for designing and fabricating the Si₃N₄ CCL.