SURFACE ROUGHENING OF ULTRA-THIN COPPER FILM
DOI:
https://doi.org/10.20535/2305-9001.2012.65.33953Keywords:
ultrathin copper film, stress-strain state, scanning tunnelling microscope, diamond tipAbstract
Metal ultra-thin films are widely used in microelectronic devices. Stress-induced morphological instability is the one of the more important defect creation processes in these films. This process related to the tends that roughen film surface by mass diffusion during growth or heat treatment. This article gives an overview of theoretical and experimental studies on cupper film surface roughening. It is shown that diffusional atomic flux along the film surface related to the strain caused by lattice mismatch drives in such a way that an initially flat film evolves into an undulating profile with surface valleys with singular stress concentration near the valley tip. The stress concentration at cycloid-like surface valleys caused by roughening is found to create dislocations of various characters that participate in the overall strain relaxation. The experimental data were compared with the analytical data obtained on the basis of the developed physical-mathematical model of the surface formation topography. The discrepancy between experimental data and the model is ≈ 0,5% in the lateral direction and ≈ 3% in the direction of axis z
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