Copper bonding silicon nitride substrate using atmosphere plasma spray

Abstract

Silicon nitride (Si3N4) is an excellent engineering ceramic with high strength, fracture toughness, wear resistance, and good chemical and thermal stability. Recently, the enhanced thermal conductivity enables Si3N4 to have potential application prospects in the electronic and orthopedic fields. Metal bonding with Si3N4 is often the key to these applications. Here we report a facile approach for the titanium-activated Cu bonding on Si3N4 substrates using an atmosphere plasma spray (APS) process. With X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) observation, it was shown that the interaction between the pre-bonded Ti (by APS) on Si3N4 promoted the adhesion and high bonding strength of APS Cu on Si3N4. The interfacial structure and phases were characterized, and tensile strength, electrical resistivity, thermal conductivity, and residual stress of Cu bonded Si3N4 were measured accordingly. The APS deposited Cu layer is dense, has a high purity, and is joined firmly with Ti pre-bonded Si3N4 substrate. The maximum tensile strength between Cu and Si3N4 is as high as 89.4 MPa. The Si3N4 substrate bonded with highly dense Cu demonstrates a low surface resistivity of 8.72 × 10−4 Ω∙mm, and high thermal conductivity of 98.12 W/m·K, which shows potential applications in electronic devices.