Tuesday, 3 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
Copper is one of highly elastically anisotropic materials, it is possible to acquire the films with (111) preferred orientation by sputtering and electroplating processes on Si substrate. The Cu films on Si substrate has very flat surface, and we investigated etching rates for various oriented surfaces by coupled techniques of AFM and FIB. The faceting surface appeared after etching in 10 vol% nitric acid and the etched surfaces with three kind orientations of (111), (110) and (100) had triangular flake, ridge and rectangular pyramidal shapes, respectively. The etching rates were measured quantitatively, it was found that etching rates for nanosized as-plated initial region, (111), (110) and (100) oriented regions were 383, 270, 276, and 317 ㎚/min, respectively. These faceting surfaces seemed to be built up based on the thermodynamic equilibrium state of etching reaction because most of them had (111) front surface. The difference of etching rates was owing to the planar density of kink or ledge for each recrystallized orientation grains. In other words, the etching happened by step flow mechanism maintaining the thermodynamic equilibrium state. By using this technique, we expect to robustly perform fundamental studies of etching solutions with various organic and inorganic additives, effects of stress and impurity in the Cu thin films.