Uniform Al0.87Sc0.13N Thin Film Deposition at Wafer Scale through Magnetron Sputtering

With the rapid advancement in the information age, the performance of advanced memory devices faces increasingly stringent demands and challenges. Sc-doped AlN film (Al(Sc)N) ferroelectric materials have garnered significant attention and applications owing to their unique polarization properties and diverse preparation processes. While several studies have focused on aspects such as ferroelectricity, crystal structure, and film thickness, the preparation of uniform, high-quality films has often been overlooked. This study systematically investigated the effects of sputtering time (30–45 min) and substrate temperature (250–450 °C) on the characteristics of Al_0.87Sc_0.13N thin films fabricated on Si substrates via radio frequency magnetron sputtering (RF-MS). Specifically, as sputtering time increased, film thickness nonuniformity initially increased and then decreased to a minimum of 1.65% at 45 min; the sputtering rate showed minor fluctuations; the films maintained a prominent (002) orientation; fwhm decreased to a minimum of 0.32°; crystallite size exhibited an inverse trend to fwhm; and both microstrain and dislocation density decreased, reaching minima of 4.3 × 10^–3 and 1.5 × 10^–3 nm^–2 at 45 min, respectively. Regarding substrate temperature, increasing temperature led to increased thickness nonuniformity, a decreased sputtering rate, and orientation transitions (coexistence of orientations at 250 °C, dominant (002) at 350 °C, and dominant (100) at 450 °C); fwhm decreased; the smallest crystallite size (24.5 nm) occurred at 250 °C, while the largest (84.3 nm) was observed at 450 °C, accompanied by the lowest microstrain (1.45 × 10^–3) and dislocation density (0.14 × 10–3 nm^–2) at 450 °C. Optimal film uniformity (1.69%) was achieved at 250 °C for 45 min. The findings provide valuable insights into the fabrication of highly uniform Al(Sc)N ferroelectric films, potentially enhancing their industrial yield.