Cu-w, Cu-mo Non-of Immiscible Alloy Homogeneous Film Structure And Performance Studies

Cu-W and Cu-Mo are typical binary immiscible alloys. It is difficult to get a practical Cu-W or Cu-Mo alloy by conventional preparation method as theirs high mixed heat(Cu-W system:ΔHmix>35.5KJ/mol, Cu-Mo system:ΔHmix>28KJ/mol). Tungsten and molybdenum possessed high melting point, density, intensity and lower coefficient of thermal expansion, whereas copper have the advantage of eximious electrical conductivity and thermal conductivity. The complementary of properties make Cu-W and Cu-Mo alloys attracted increasing attention. With further research, Cu-W and Cu-Mo alloys will be used in microelectronic material, aviation and heat interchange etc.In this paper, we prepared a series of Cu-W and Cu-Mo thin films by magnetron sputtering technology. The content of those thin films is distributing from 2.12at.% to 53.14at.% of Cu-W thin films and 2.19at.% to 74.91at.% of Cu-Mo thin films. In order to investigate the percentage composition, structure, surface topography and properties, all of those thin films were characterized by energy dispersive X-ray detector(EDX), X-ray diffraction(XRD), transmission electron microscope(TEM), scanning electron microscope(SEM), atomic force microscope(AFM), micro-hardness testing device and resistivity testing device. The results indicated that the addition of W and Mo changes in the structure of films, thereby affecting the mechanical and electrical properties. The XRD patterns of Cu-W thin films with W content less than 6at.% and Cu-Mo thin films with Mo content less than 10at.% showed Cu(111) preferred orientation, and the thin films are crystalline structure. When the W content of Cu-W thin films exceeds 6at.%, the XRD patterns show a superimposed peak make up of Cu(111) and W(110). The peak width was enlarged as the increasing of W content, and those films were composited of ultra-fine copper microcrystalline, tungsten microcrystalline and a certain amount amorphous structure. With the Mo content than 10at.%, a superimposed peak comprise of Cu(111) and W(110) appeared in the XRD patterns. The peak width was enlarged as the increasing of Mo content, and those films were composited of ultra-fine copper microcrystalline, Molybdenum microcrystalline and a certain amount amorphous structure. As the W and Mo content to further improve, the XRD patterns of thin films main Show W(110) peak or Mo(110)peak.TEM analysis revealed that Cu-2.12at.%W thin films and Cu-4.27at.%Mo thin films are polycrystalline structure, but Cu-14.20at.%W thin films and Cu-9.89at.%Mo film contains a certain amount of amorphous. SEM and AFM analysis showed that the films surface roughness and flatness improve with the increasing of W or Mo content in the films. The knoop ultra-microhardness of deposited pure copper film is lGPa, and the electrical resistivity is 5.24μΩ·cm. The addtions of W and Mo can make the microhardness increased to 7.0 GPa and 8.76GPa respectively, the electrical resistivity were increased to 27.72μΩ·cm and 32.32μΩ·cm.After 200,400 and 650℃annealed for 1h, the XRD patterns of Cu-W thin films and Cu-Mo thin films appeared Cu(111), W(110), Mo(110) and Cu(200) peak et al. This means that the structure has been changed durning the annealing process. SEM analysis revealed that there are some copper-rich sub-micron particles emerge in those films after heat treatment, which reduced the surface roughness and flatness of those films. Both of the microhardness and electrical resistivity were drcreased after 200,400 and 650℃annealing for 1h, the higher the temperature, the greater the decline. This is due to the microstructure of thin films has undergone significant changes with the increasing of annealing temperature.