Research On Effect Of Laser Shock Processing On Electrical Properties Of Cu Films And Simulation Of Impact Effects

IC industry is the basis of the microelectronics industry and plays an important role in economic development. However, with the incresement of the degree of integration and width reduction in the designing and manufacturing of large integrated circuits, it has become a hot topic of research to improve strength and reduce resistivity of circuit connecting material. Laser shock processing is a new type of surface treatment technology, which has the unique advantages of enabling the deformed material, phase transition and organizational changes dislocations to improve the performance. In the present thesis, electrical properties change of Cu films after laser shock processing with a small energy laser was studied and simulations of the impact effects after the treatment was also performed. Some achievements were made as following:(1) Preparation of nano-copper films was investigated:Films have been coated on silicon(Si)and polyimide(PI)substrates by changing the substrate temperature and surface morphology, microstructure and electrical properties were analized. The results show that: the film surface is smooth, grain size become homogenous, and has less faults than those prepared in other different temperatures with preparation parameters of working pressure 0.5Mpa, the sputtering power 100 w, the substrate temperature 150?; the resistivity of Cu/Si and Cu/PI film prepared with parameters mentioned above are 1.4×10-8?.m and 2.3 ×10-8?.m, respectively.(2) Experimental studies were carried out on nano-copper film after microimpact laser. Based on stress wave theory, the fundamental process of internal material stress wave propagation under the impact was analyzed. Through analysis of films after laser shock with SEM, XRD, TEM and other methods, it is found that: the surface roughness of films is reduced,grain gets to grow, and twin structure is generated in the interior after laser shock. Electrical tests show that: the resistivity of Cu/Si film andCu/PI film reduced to 87.2% and 89.4% of its original residtivity, respectively.(3)Simulation of the effect of laser shock on nano-copper film was performed.The stress wave propagation characteristics between the film and substrate interface after laser shock have been simulated and analyzed by using the stress wave theory; and the surface strain degree after impact was also discussed. Studies show that: When the peak pressure of shock wave is smaller than the elastic limit of the film, the wave works as elastic shock wave; when the peak pressure of shock wave exceeds the elastic limit of the film, it works as elastic-plastic shock wave. In addition, the surface strain degree increases with the increasement of laser energy density and the maximum value appeares in the laser spot center position; the table also shows that at the same parameters, the surface strain degree gets deeper with the increasement of number of impact, but the strain amplitude decreases when the number of impact is increasing.