Thin Ta/Ta oxide core-shell nanoparticle film size-dependent energy structure

Structure, phase evolution and properties of Ta films deposited using hybrid high-power pulsed and DC magnetron co-sputtering

“…All the substrates were ultrasonically cleaned with acetone and alcohol for 10 min, dried with compressed air, and mounted on a substrate holder which was supplied a rotation speed of 10 r/min and a negative DC bias of 60 V for dominating the direction and energy of the deposit to the substrate and improving film uniformity. [2,21,22] The crystal structures of Ta films were investigated by xray diffraction (XRD) by using Rigaku SmartLab 9 kW with Cu Kα radiation in grazing incidence (GIXRD, 0.5 • ). The surface and cross-section of Ta films were detected by a field emission scanning electron microscope (FE-SEM) by using ZEISS sigma 500 (Zeiss, Germany) with BRUKER XFlash 6130.…”

“…3(d). [2,14,23] Combined with the above XRD analysis, the structure of tantalum film was changed from β to α, and the surface morphology was also changed from block to needle by the addition of HiPIMS. The reason for this transition was that the flux and energy of tantalum ions in the plasma were increased by the addition of HiPIMS, and the grown tantalum film would be bombarded by tantalum ions strongly and energetically, which leads to β towards α phase and change the morphology.…”

“…Tantalum (Ta) films are of interest for technological applications in microelectronics industry due to excellent physical and chemical properties. [1,2] Since non-equilibrium thermodynamic growth is inherent to film deposition, magnetron sputtered Ta films can exhibit the stable BCC α-phase and metastable tetragonal β -phase, or a mixture of two phases. The α-Ta film with high hardness (8 GPa-12 GPa), high melting point (T m ≈ 3000 • C), low resistivity (15 µΩ • cm-80 µΩ•cm), and high temperature wear resistance, is the candidate material in many applications such as tool coating, barrel protective coating and Cu/Si diffusion barrier.…”

“…However, only leading to β -Ta film with inhomogeneous deposition, low density and porous columnar structures, DCMS has a drawback that includes the low degree of ionization (1%-3%). [2] High-power impulse magnetron sputtering (HiPIMS), an IPVD technique combining magnetron sputtering and pulsed plasma discharges, is characterized by high peak power density, plasma density and target ionization (up to 90%) at a low duty cycle (below 10%) and a low frequency (less than 2 kHz), which makes a high degree of ionization and formation of dense, smooth and hard films, even deposition on complex geometries. [2,6,8,9] Unfortunately, in HiPIMS, the deposition rate is only 20%-40% of DCMS and the internal stress and defects in the films can be caused by the unstable arc discharge phenomenon (ARC) under low pressure.…”

“…[2] High-power impulse magnetron sputtering (HiPIMS), an IPVD technique combining magnetron sputtering and pulsed plasma discharges, is characterized by high peak power density, plasma density and target ionization (up to 90%) at a low duty cycle (below 10%) and a low frequency (less than 2 kHz), which makes a high degree of ionization and formation of dense, smooth and hard films, even deposition on complex geometries. [2,6,8,9] Unfortunately, in HiPIMS, the deposition rate is only 20%-40% of DCMS and the internal stress and defects in the films can be caused by the unstable arc discharge phenomenon (ARC) under low pressure. [10][11][12] More recently, the hybrid HiPIMS/DCMS co-sputtering have begun to be used to surmount the defect of the pure HiPIMS technique.…”