Preparation of Hf-Si-O films by simultaneous deposition and reaction process using pulsed ion-beam evaporation

Abstract

SUMMARYA pulsed ion-beam evaporation method (IBE) has been applied to prepare hafnium silicate (Hf-Si-O) thin film which is one of the promising gate dielectrics for metal-oxide-semiconductor (MOS) transistor instead of SiO 2 . Here, IBE has the potential to make films containing fewer impurities due to the ablation of pure hafnium oxide (HfO 2 ) targets in vacuum, while the chemical vapor deposition (CVD) precursor leaves its constituents in the films. From microstructural observation, the thin film consists of an upper layer and a lower layer. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses reveal that the upper layer is polycrystalline HfO 2 and that the lower layer is amorphous hafnium silicate. It may be understood that the hot Hf-O plasma impinging on the Si substrate resulted in the reaction of Si and Hf-O to prepare the Hf-Si-O thin film. The energy from the intense pulsed ion beam makes it possible to induce such a surface reaction. The film has been found to have a uniform distribution of Hf and O in the depth. Impurity content such as carbon incorporated from the environment into the film is lower than the detection limit of XPS.

Single- and Dual-Layer Nanocrystalline Indium Tin Oxide Embedded ZrHfO High-k Films for Nonvolatile Memories – Material and Electrical Properties

“…It contains Hf, Si, and O, probably contributed by the Hf-silicate (HfSiO x ) structure. 16 Since HfSiO x has relatively low conduction and valance band offsets with respect to Si compared with those of SiO 2 , 17 charges can be easily injected to the high-k stack, which favors the data programming efficiency.…”