| In recent years, with the rapid development of microelectronic devices, micro mechanical systems (MEMS) and interconnection material, nano-multilayer and composite films of Cu/Mo are concerned wide. Copper has good conductive and thermal conductivity, And Characteristics of molybdenum is high melting point, the larger density, high strength and low thermal expansion coefficient and so on, Copper and molybdenum has a strong complementary in performance, which belong to the rational interconnection materials. Service reliability is the important guarantee of the material properties, it is very meaningful to study the ductility and mechanical properties. With the research go through, Cu/Mo nano-multilayers will show a broad application prospect in microelectronics, micro mechanical field and ULSI etc.In this article, modulation period for60nm,80nm,100nm and modulation ration for0.25,0.5,1,2,2.5,3, respectively, Cu/Mo nano-multilayered films were prepared by magnetron sputtering method. The structure and morphology of films were characterized by XRD, AFM, HRTEM etc. Nanoindetaion, uniaxial tensile system and four-point probe resistance meter were used to research the mechanical and electrical properties of the films. XRD results show that Cu/Mo nano-multilayer films have obvious Cu (111) and Mo (110) preferred orientation, under the condition of same modulation ratio, with the increase of modulation period, appear the peak of Cu(200) and (220), Cu preferred orientation degree reduces, intensity of Cu(111) peak increases, the grain size of Cu layers increasing, with the decrease of modulation period, the peak of Mo(110) exists migration to the high Angle direction. Under the condition of same modulation period, with the increase of modulation ratio, Cu layer thickness reduces, grain size becomes small, the intensity of Cu(111) peak weakens, Peak width is obvious, Mo layer thickness increases, preferred orientation of Mo(110) becomes strong. For Cu/Mo nano-multilayer films, AFM results show that smoothness of Cu layer surface improves with the increase of modulation period, and with the increase of modulation ration, Cu layer thickness reduces, grain size becomes small, so smoothness of multilayer film improves. HRTEM results show that Co/Mo nano-multilayer films are good layer periodic structure, there is a mixing layer between Cu layer and Mo layer, the growth way between Cu layer and Mo layer is incoherency.Experimental results show that the value of hardness, elastic modulus, yield strength and resistivity increases with the decrease of modulation period for the same modulation ration Cu/Mo nano-multilayer films. The maximum hardness of multilayer reaches9.926Gpa, the maximum elastic modulus reaches191.709Gpa. In multilayer films, With the decrease of modulation period, the thickness of soft phase Cu layer reduces, grain size decreases, the density of grain boundary increases, plastic deformation ability decreases, that is the reason why the strength of multilayer films enhances. Since the total thickness of films is the same, interface number increases with the decrease of modulation period, it is also play a certain degree of enhanced role on the strength of multilayer films. The weakening of the plastic deformation ability leads to the multilayer critical crack initiation strain value reduces with the decreasing of modulation period. For [Cu(80nm)/Mo(20nm)]8film, the value of critical crack initiation strain reaches1.71%.For the same modulation period,with the increasing of modulation ration, Research results show that the thickness of soft phase Cu layer reduces, grain size of Cu decreases, the density of grain boundary increases, plastic deformation ability decreases, scattering effects of electronic boundary enhances, which leads to the value of microhardness, elastic modulus, yield strength and resistivity increases with the increasing of modulation period in general, and also ductility reduces with the increasing of modulation ration. |
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