Low-Temperature Dopant-Assisted Crystallization of HfO₂ Thin Films

Abstract

We have studied the thermal atomic layer deposition (ALD) of HfO2 on native and chemical oxide GaAs(100) surfaces using the amide precursors tetrakis ethymethyl amino hafnium and tetrakis dimethylamino hafnium. Bright-field and HRTEM data for as-prepared HfO2 films deposited on both GaAs(100) oxide surfaces show that the films are polycrystalline and contain several large grains of the order of the film thickness and numerous smaller ones. X-ray diffraction confirms the presence of small crystallites that can be classified in forms other than monoclinic while control films deposited on native oxide Si(100) surfaces are amorphous.Thermally treated films deposited on both Si and GaAs contain mainly monoclinic grains.Gallium and arsenic oxides are known to bubble through the growing HfO2 film so that at any point during the ALD process, there is mixing of the various III-V oxides in the film. These oxides seem to stabilize the various HfO2 polymorphs during low-temperature thermal ALD allowing control of the film microstructure via the deposition process.

Improved Ferroelectricity and Endurance of Hf0.5Zr0.5O2 Thin Films in Low Thermal Budget with Novel Bottom Electrode Doping Technology

“…The reason behind this is that when HfO 2 is deposited by atomic layer on a substrate containing As ions, the oxide of As ions on the surface of the substrate will undergo a reduction reaction to provide oxygen for the precursor of Hf, which can also reduce the crystallization temperature of HfO 2 . [27,28] Therefore, it is necessary to explore the impacts of the implantation of As ion on the structure and electrical properties of HfO 2 -based ferroelectric thin films at different doses and annealing conditions. The impacts of implantation and annealing conditions on the structural and electrical properties of ferroelectric film were investigated in detail.…”