OPTIMIZATION OF RF-SPUTTERED ITO THIN FILMS FOR AUTOMOTIVE DISPLAY AND HEAD-UP DISPLAY APPLICATIONS

Abstract

Indium tin oxide (ITO) thin films are widely used as transparent electrodes in display technologies; however, automotive display and head-up display (HUD) applications impose additional requirements on optical stability, electrical reliability, and mechanical robustness. In this study, ITO thin films were deposited on glass substrates by radio-frequency (RF) magnetron sputtering, and the effect of sputtering power on their optical, electrical, and mechanical properties was systematically investigated. The RF sputtering power was varied from 40 W to 70 W while other deposition parameters were kept constant. Optical transmittance measurements show that all films exhibit high transparency exceeding 80% in the visible region, whereas changes in absorption edge position and optical constants indicate power-dependent microstructural evolution. Electrical characterization reveals a significant reduction in resistivity and sheet resistance with increasing sputtering power up to an optimal condition, beyond which electrical performance degrades due to defect formation. Residual stress analysis demonstrates that compressive stress strongly depends on sputtering power, with a pronounced minimum observed at an intermediate power level. Among the investigated conditions, an RF sputtering power of 60 W yields the most balanced performance, combining high optical transparency, low electrical resistivity, smooth surface morphology, and minimal residual stress. These results provide practical guidelines for optimizing RF-sputtered ITO thin films for automotive display and head-up display applications, where optical quality and long-term reliability are critical.