High-quality remote plasma enhanced atomic layer deposition of aluminum oxide thin films for nanoelectronics applications.

Here, we report comprehensive investigations of aluminum oxide (Al 2 O 3) high-κ gate oxides deposited via remote plasma enhanced atomic layer deposition (Re-PEALD) with mesh configuration in a commercial 100 mm ALD reactor. Trimethylaluminum (Al(CH 3) 3), dioxygen (O 2) plasma, and Argon (Ar) are used as the metal precursor, oxidant, and carrier/purge, respectively. The growth rate per cycle and non-uniformity of Al 2 O 3 thin films is analyzed with the variation in duration of (Al(CH 3) 3) pulse, O 2 plasma, post-precursor purge, post-oxidant purge, RF power, and substrate temperature. High-quality monolayer type Al 2 O 3 thin films with a growth rate of ~ 1.1 Å/cycle are achieved for a wide temperature range from ~ 100 °C to ~ 300 °C suitable for various nanoelectronics applications ranging from flexible substrates to low thermal budget and high mobility alternate semiconductor substrates. Further, the Al/Re-PEALD-Al 2 O 3 /p-Si, metal-oxide-semiconductor (MOS) structures are investigated for capacitance-voltage, capacitance-frequency, and leakage current-voltage characteristics to demonstrate the quality of Re-PEALD-Al 2 O 3 thin films. The Al/Re-PEALD-Al 2 O 3 /p-Si, MOS structures revealed excellent electrical characteristics with ultralow minimum interface trap density (D it) ~ 9.9 × 109 eV−1cm−2, negative effective oxide charges (N eff) ~ 5.52 × 1012 cm−2, low leakage current density of ~ 4.1 nA/cm2 at −1 V, hysteresis-free, insignificant V th shift, and trivial frequency dispersion. Moreover, the chemical analysis using XPS depth profiling disclosed that Re-PEALD deposited Al 2 O 3 thin films results in a high-quality gradient Al 2 O 3 /SiO x /Si interface rather than an abrupt Al 2 O 3 /Si interface, and the oxygen rich thin films due to the oxygen (O2−) interstitials close to the interface are the sources of negative fixed oxide charges in Re-PEALD-Al 2 O 3 /Si, system. These results intend to boost the investigations of Re-PEALD Al 2 O 3 ultrathin films for low thermal budget high mobility alternate semiconductor substrates for nanoelectronics applications. [ABSTRACT FROM AUTHOR]