Surface Morphology and Sputtering Mechanism of Etched Areas of a Metallic Target by Magnetron Sputtering

Abstract

As an important functional thin-film material in the field of electronic information, high-purity titanium (Ti) is widely used in different industries, such as integrated circuits, flat-panel displays and solar energy, indicating the importance of further research on Ti targets. Herein, a titanium target is placed in a UDP-650 closed-field nonequilibrium magnetron sputtering ion coating machine for deep etching to form racetrack grooves, and different positions of etching grooves are analyzed to understand the target etched behavior. The sputtering-induced etching of the Ti target, from shallow to deep regions, changes from the preferential sputtering of scratches and other defects in the edge area to the surface sputtering pits, with discontinuous distribution and uneven size, to grain boundary sputtering and, finally, to closely packed grain surface sputtering. The etching behavior of different regions exhibits different characteristics, mainly showing selective sputtering. The surface roughness of the sputtered area initially increases with the increase of sputtering depth and plasma density, followed by a slight decrease. Moreover, different degrees of incomplete recrystallization occur in different sputtering areas due to the uneven distribution of plasma on the target surface. The grain size increased from the transition area between sputtering and non-sputtering (112 μm) to the deepest sputtering area (139 μm). Moreover, the relationship between the cross-sectional grain size and sputter surface roughness renders a correlation coefficient of 0.802, indicating a strong influence of grain size on surface roughness. Therefore, it is of utmost importance to refine grains and increase the sputtering yield of the target as well as reduce the surface roughness of the target after etching to obtain a high-quality thin film.