Research On Microstructure And Properties Of Solid Phase Interface Bonding Between High Purity Metallic Tantalum And Cu Alloy

Welding can bond together for different metals,alloys or non-metals with different properties,to achieve compound performances by taking the advantages of different materials on the basis of whole materials after bonding.Compared with the same metal,dissimilar metal welding,especially the large area contact welding,is tremendously difficult,cause the melting point,density,crystal structure and physical and chemical properties of bonded metals exhibit huge difference,solid-phase bonding is an important method to implement the welding between dissimilar metals.Tantalum(Ta)is an ideal sputtering material in PVD(Physical Vapor Deposition)process,considered as the source of the barrier layer material between the conductive materials and the semiconductive materials for the integrated circuit(IC)manufacturing.Cu alloy is an ideal backing plate material to support Tantalum sputtering material.In this paper,solid-phase bonding is adopted to realize large area(?148000mm~2),high strength welding.The solid-phase bonding technology between Ta and Cu alloy was explored in many aspects,cold pressure welding and hot pressure welding were used for experiments,and the treatment method of Ta metal surface was involved.It was found that cold pressure welding can notform an effective solid bonding between Ta and CuZn alloy in case of no treatment on Ta metal surface.The hot pressure welding under vacuum condition is not ideal either,and the area ratio with poor bonding reaches 85%.However,it was found that the local area of the edge was effectively bonded,and the mutual diffusion occurred between Ta atoms and CuZn atoms.In addition,under the condition of Ta metal surface treatment,cold pressure welding can notform an effective solid bonding between Ta and CuZn alloy.However,it was found that the solid phase bonding under vacuum hot-pressing welding condition showed effective bonding between Ta and CuZn alloy,and the bonding area ratio was more than 98.5%.The results show that under cold pressure welding,the solid bonding between Ta and CuZn alloy is not desirable,no matter with or without surface treatment.While under hot pressure welding,even if Ta metal does not perform surface treatment,it can obtain effective solid bonding in some local area.it can obtain more than 95%effective solid bonding after surface treatment on Ta metal.Based on the principle of preferential surface treatment for high-melting metal,the effect of different metal surface treatment methods on the solid boning performance of Ta metal samples was studied.It was found that the surface treatment with 0.45×0.2mm sawtooth pattern can obtain best bonding strength for solid bonding under hot pressure welding.With hot-pressure welding conditions of 105 MPa,5 h,550°C,the solid bonding between Ta and CuZn can achieve bonding strength of 140MPa and bonding rate of 100%,while the solid bonding between Ta and CuCr can achieve bonding strength of 110 MPa and bonding rate of 100%.In order to understand the influence of the hot-pressing temperature on joint microstructure and mechanical properties,solid-phase bonding tests were conducted with 5 kinds of temperature ranging from 450°n to 850°C,after Ta metal surface were treated with 0.45×0.2 mm saw-tooth pattern.It was found that under the condition of450°C~650°C,joint fracture occurred in the region of the joint.Under the condition of750°C~850°C,the bonding strength can reach highest point(up to 330 MPa),joint fracture did not appear in the Ta and CuZn bonding interface,but the Ta ductile fracture appeared.The bonding strength of Ta-CuCr is 235 MPa,the fracture is still located in the joint area,but local ductile fracturealso occurs on CuCr backing plate.It is indicated that with the increase of temperature for hot pressure,the bonding strength becomes stronger and stronger,and even the bonding strength exceeds the matrix strength.In conclusion,the optimum solid bonding process parameters for Ta/CuZn,Ta/CuCr are 0.45×0.2 mm surface roughen processing and 750°C hot pressure for 5h preservation time and fixed pressure of 110MPa.