Effects of power on ion behaviors in radio-frequency magnetron sputtering of indium tin oxide (ITO)

This study delves into ion behavior at the substrate position within RF magnetron discharges utilizing an indium tin oxide (ITO) target. The positive ion energies exhibit an upward trajectory with increasing RF power, attributed to heightened plasma potential and initial emergent energy. Simultaneously, the positive ion flux escalates owing to amplified sputtering rates and electron density. Conversely, negative ions exhibit broad ion energy distribution functions (IEDFs) characterized by multiple peaks. These patterns are clarified by a combination of radiofrequency oscillation of cathode voltage and plasma potential, alongside ion transport time. This elucidation finds validation in a one-dimensional model encompassing the initial ion energy. At higher RF power, negative ions surpassing 100 eV escalate in both flux and energy, posing a potential risk of sputtering damages to ITO layers.