Abnormal grain growth of sputtered CuNi(Mn) thin films

The evolution in both stress and microstructure was investigated on sputtered Cu0.57Ni0.42Mn0.01 thin films of 400 nm thickness during the first temperature cycle up to 550 degrees C. Samples from stress-temperature measurements up to various maximum temperatures were analyzed by x-ray diffraction, scanning and transmission electron microscopy, and Auger electron spectroscopy. The columnar grains with lateral diameters of about 20 nm in the as-deposited state coarsen to about 400 nm above 300 degrees C, Probably due to the impurity (Mn) drag effect, the coarsening occurs by abnormal grain growth rather than by normal grain growth, starting near the film-substrate interface. The stress development results from a combination of densification due to grain growth and plastic stress relaxation.