Effects of Ar Addition to O₂ Plasma on Plasma-Enhanced Atomic Layer Deposition of Oxide Thin Films

Abstract

A method for significantly increasing the growth rates (GRs) of high- k oxide thin films grown via plasma-enhanced atomic layer deposition (PE-ALD) by enhancing the plasma density through the addition of Ar gas to the O₂ plasma oxidant was developed. This approach led to improvements of ∼60% in the saturation GRs of PE-ALD ZrO₂, HfO₂, and SiO₂. Furthermore, despite the significantly higher GR enabled by PE-ALD, the mechanical and dielectric properties of the PE-ALD oxide films were similar or even superior to those of films grown via the conventional O₂ plasma process. Optical emission spectroscopy analyses in conjunction with theoretical calculation of the electron energy distribution function revealed that adding Ar gas to the O₂ plasma increased the density of high-energy electrons, thereby generating more O₂ plasma species, such as ions and radicals, which played a key role in improving the GRs and the properties of the films. This promising approach is expected to facilitate the high-volume manufacturing of films via PE-ALD, especially for use as gate insulators in thin-film transistor-based devices in the display industry.