Research On The Strucure And Performance Of The W-Based W-Cu Thin Films

W-Cu thin film is a typical binary immiscible alloy thin film, it has broad application prospects in the field of electronic packaging and diffusion barrier layers because of the excellent thermal electrical conductivity, high strength and low thermal expansion coefficient. Therefore, it has important academic value and engineering significance to study the structure characteristics and explore the evolution rules, and discuss the impact on properties.The microstructures of W-Cu film which W contents is 75at.%, were characterized by methods such as XRD, SEM, and TEM. The influence of substrate temperature and deposition time on the micro structure of W-Cu thin film was studied in the dual target magnetron sputtering deposition technology. The mechanical properties etc were obtained by nanoindentation et al. The main research results are as follows:At the initial stage of deposition process, the thin film is metastable, and with the increment of deposition time increased from 10 s to 30 s, it has a tendency to crystallization. And before the temperature reaches 150 ?, the Cu solubility in W increased, while decreased under 400 ?. When the deposition time is equal, the thin film gradually crystallized with the temperature increased. With the substrate temperature increased, the Cu solid solubility gradually enhanced while declined at 400?.The atomic energy by magnetron sputtering is high enough to atomic mixing before it reaches substrate, so the component is evenly distributed. Because of the Gibbs free energy of amorphous is lower than crystalline, so amorphous was formed at first. With the extension of the substrate temperature and deposition time, atomic energy was increased by crash and the raising temperature, while it is sufficient to overcome the energy of solution, so the film crystallized, and the metastable solid solution was formed. Accord to Arrhenius equation and Diffusion process formula, when the temperature is below 150 ?, W atomic diffusion distance less than 10-7 nm, W atom is "frozen", while the diffusion distance of Cu increased with the enhanced of substrate temperature and deposition time, more than 10-1 nm, so the Cu solubility improved. When the temperature is too high, W atom is "active", so reduced the shackles of Cu, so that Cu atoms in W tendency to agglomerate, resulting in solubility decreased.With the increase of deposition time and temperature, film density and roughness gradually improved, the unevenness of resistance is reduced; Meanwhile, the structure of the film transformed from amorphous to crystalline, so the ordered of the film increased, and the resistivity decreased. At the same deposition time, the flatness and density of the thin film is enhanced along with the temperature raised up, so adhesive properties and the hardness and elastic modulus improved, so the hardness and elastic modulus increased. When the temperature is too high, the grain growth unevenly, defects reduced, so the hardness and elastic modulus decreased; Mechanical properties of the film did not change significantly with the temperature increased, film has good thermal stability. At the same time, because of the high temperature, the difference in thermal expansion coefficient leads to film stress between the substrate and thin film is large, so that the adhesive properties declined.