Microstructure of hard and optically transparent HfO2 films prepared by high-power impulse magnetron sputtering with a pulsed oxygen flow control

Abstract

Reactive high-power impulse magnetron sputtering was used to deposit HfO 2 films on Si substrates using a voltage pulse duration, t 1 , from 100 to 200 µs and an deposition-averaged target power density, <S d >, from 7.2 to 54 Wcm-2. The effects of these processing parameters on the microstructure and properties of the films were studied by atomic force microscopy, nanoindentation, X-ray diffraction, electron diffraction and high-resolution transmission electron microscopy. Four HfO 2 films were prepared with (1) t 1 = 100 µs, <S d > = 7.2 Wcm-2 (T100S7), (2) t 1 = 200 µs, <S d > = 7.3 Wcm-2 (T200S7), (3) t 1 = 200 µs, <S d > = 18 Wcm-2 (T200S18) and (4) t 1 = 200 µs, <S d > = 54 Wcm-2 (T200S54). All films were found to be composed of an interlayer next to the Si interface followed by a nano-columnar structure layer. The interlayer structure of the films was found to contain a population of lower density nanoscale regions. A reduction in <S d > in films T200S54, T200S18, T200S7 and T100S7 caused an increase in the interlayer thickness and a decrease in the width of the nano-columnar structures from ~46 nm to ~21 nm. This microstructural change was accompanied by a concomitant change of the grain boundary

Effect of Annealing on Optical, Mechanical, Electrical Properties and Structure of Scandium Oxide Films

“…The brief overview of the mechanical and elastic properties of Sc 2 O 3 was done previously . The obtained in the present research hardness of Sc 2 O 3 films are higher when compared with pure hafnium oxide films (monoclinic phase, H = 18 GPa), and comparable with hafnium oxide of high‐temperature phases stabilized by nitrogen (tetragonal/cubic, H = 20 GPa) . In the case of pure and partly oxidized Sc films, the hardness values of the order of H = 3 GPa with E* = 105 GPa have been obtained.…”

Characterization of HfO2 Optical Coatings Deposited by MF Magnetron Sputtering

“…In the last decade, hafnium dioxide (HfO 2 ) has been widely studied because of its attractive properties and potential technological applications [1][2][3][4][5][6][7][8][9]. A high transmittance over a wide wavelength range, a hydrophobic nature, and hardness represent an important combination required in optical coatings [1][2][3]10,11]. HfO 2 is a material with a high refractive index (1.85-2.1) [3,12] and a low absorption from ultraviolet to the mid-infrared [1,4,5].…”

“…A high transmittance over a wide wavelength range, a hydrophobic nature, and hardness represent an important combination required in optical coatings [1][2][3]10,11]. HfO 2 is a material with a high refractive index (1.85-2.1) [3,12] and a low absorption from ultraviolet to the mid-infrared [1,4,5]. Various optical applications of HfO 2 thin films have been pursued such as, for example, chirped mirrors and band pass filters, UV mirrors with a high damage threshold, and heat mirrors for energy efficient windows.…”

“…5.7 eV, whereas the dielectric constant is 25 [4,[10][11][12]15]. HfO 2 is also considered to be one of the most promising candidates to replace SiO 2 in Si-based gate electronic devices, because of their high dielectric constant and thermodynamic stability [1,16]. Moreover, there has been increased interest in the use of HfO 2 as the insulator layer in the metal-insulator-metal (MIM) stack for RRAM (resistive random-access memory) applications [7,8].…”

“…Although many studies have been conducted on the microstructure, optical, and dielectric properties of HfO 2 prepared under different growth conditions and thermal treatments, there are only a few reports regarding its mechanical behavior [12,13,[21][22][23][24][25]. Vlček et al [5] and Pi et al [1] showed that the HfO 2 thin films prepared by high-power impulse magnetron sputtering (HiPIMS) with a pulsed oxygen flow control had a relatively high refractive index of 2.07-2.12 at 550 nm. In the previous work [26] of Mazur et al, it was shown that the values of the refractive index at the same wavelength increased with the increase of the deposition power.…”