In Situ Synchrotron X‐Ray Diffraction Analysis of Phase Transformation in Epitaxial Metastable hcp Nickel Thin Films, Prepared via Plasma‐Enhanced Atomic Layer Deposition

Abstract

thickness and the crystal structure are necessary requirements. [15,16] Epitaxial growth of magnetic thin films enables the precise control of strain and crystal orientation, both of which have critical effects on the magnetization of thin films. [17,18] Another important benefit of epitaxial growth is limiting the grain boundary diffusion, which is shown to play a critical role in interlayer diffusion of the multilayer ultrathin films. [19,20] In order to fully realize the benefits of the ultrathin magnetic films, they need to be grown in an epitaxial fashion with a fine-tuned crystal structure and orientation. This subject is explored in the present paper.Plasma-enhanced atomic layer deposition (PEALD) is a method for the deposition of Ni films that offers several advantages over more mainstream deposition methods, such as sputtering and chemical vapor deposition (CVD). These advantages include precise thickness control, relatively low growth temperature, and conformality, i.e., the ability to deposit a film with a uniform thickness over a non-flat substrate. [21][22][23] All of these benefits make this method suitable for growing ultrathin films, where thickness and structure are critical parameters. [24] The authors have previously reported the plasma-enhanced ALD growth and characterization of nickel thin films with quasi-epitaxial crystal structure. [25] As reported, increasing the deposition temperature resulted in improving the crystallinity of the films. At deposition temperature of 360 °C, chemically pure nickel films were deposited. Crystal structure analysis showed the films had a polycrystalline textured structure with a strong out-of-plane orientation relationship with the sapphire substrate. However, full epitaxial growth was not achieved. This issue has been addressed in this paper.Apart from the above-mentioned publication, there have been other recent reports on nickel deposition. Park et al. [26] recently reported on PEALD of nickel thin films using [Ni(dpdab) 2 ] and NH 3 plasma, with the films reportedly having a fcc polycrystalline structure. In a separate study, Suturin et al. [27] demonstrated the deposition of epitaxial nickel islands on CaF 2 at 600 °C, using an electron beam source. The isolated islands had fcc crystal structure and crystallographic orientations dictated by that of the substrate. On a related subject, Tarachand et al. [28] investigated phase structure and magnetism in nickel nanoparticles grown by thermal decomposition, and reported that the Ultrathin metal films have a wide variety of applications, especially in microelectronics. A key method to deposit these films is plasma-enhanced atomic layer deposition (PEALD), which is known for its ability to deposit thin films conformally and at relatively low temperatures. Building on the recent work, an improved recipe is reported on for the development of nickel PEALD technology, through which fully epitaxial nickel thin films are deposited. The effect of continuous heating on the phase structure and agglomeration in the met...

The lower energy diffraction and scattering side-bounce beamline for materials science at the Canadian Light Source

“…Low-level motor control is accomplished with EPICS. The endstation was operational and producing scientific results (Dey et al, 2017;Motamedi et al, 2018) at the IDEAS beamline at the CLS before moving to the LE beamline in August 2020. It now occupies the outboard side of the hutch at a 2 = 29 , resulting in fixed energies of 7.9 keV using Si(111) or 15.1 keV using Si(311).…”

Resolving the Evolution of Atomic Layer-Deposited Thin-Film Growth by Continuous In Situ X-Ray Absorption Spectroscopy

“…On the other hand, to monitor the evolution of local structural motifs through different phases of growth, measurements must be executed throughout the growth. To date, there has been important progress using in situ XANES to study ALD thin-film growth, focusing on quasi-steady-state conditions between precursor pulses during early growth cycles, often with intermittent pauses in the ALD-growth process. ,− We also note that other synchrotron-based techniques have been previously applied to monitor several material-growth techniques in situ , including organometallic vapor-phase epitaxy, molecular beam epitaxy, − and ALD. ,− …”