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

Here, we report comprehensive investigations of aluminum oxide (Al2O3) high-kappa gate oxides deposited via remote plasma enhanced atomic layer deposition (Re-PEALD) with mesh configuration in a commercial 100 mm ALD reactor. Trimethylaluminum (Al(CH3)3), dioxygen (O2) plasma, and Argon (Ar) are used as the metal precursor, oxidant, and carrier/purge, respectively. The growth rate per cycle and non-uniformity of Al2O3 thin films is analyzed with the variation in duration of (Al(CH3)3) pulse, O2 plasma, post-precursor purge, postoxidant purge, RF power, and substrate temperature. High-quality monolayer type Al2O3 thin films with a growth rate of - 1.1 angstrom/cycle are achieved for a wide temperature range from - 100 degrees C to - 300 degrees 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-Al2O3/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-Al2O3 thin films. The Al/Re-PEALD-Al2O3/p-Si, MOS structures revealed excellent electrical characteristics with ultralow minimum interface trap density (Dit) - 9.9 x 109 eV- 1cm- 2, negative effective oxide charges (Neff) - 5.52 x 1012 cm- 2, low leakage current density of - 4.1 nA/ cm2 at -1 V, hysteresis-free, insignificant Vth shift, and trivial frequency dispersion. Moreover, the chemical analysis using XPS depth profiling disclosed that Re-PEALD deposited Al2O3 thin films results in a high-quality gradient Al2O3/SiOx/Si interface rather than an abrupt Al2O3/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-PEALDAl2O3/Si, system. These results intend to boost the investigations of Re-PEALD Al2O3 ultrathin films for low thermal budget high mobility alternate semiconductor substrates for nanoelectronics applications.

Automated summary

In this study, comprehensive investigations were conducted on aluminum oxide high-k gate oxides deposited via remote plasma enhanced atomic layer deposition (Re-PEALD) in a commercial reactor, revealing the optimal growth conditions and characteristics of high-quality aluminum oxide thin films for various nanoelectronics applications.