Texture and Stress Evolution in HfN Films Sputter-Deposited at Oblique Angles

Abstract

In this study, polycrystalline hafnium nitride (HfN) thin films were grown by oblique angle deposition (OAD) technique to investigate the relationship between column tilt angle, texture development and residual stress evolution with varying inclination angle α of the substrate. The films (~1 μm thickness) were grown at various angles (α = 5°, 25°, 35°, 65°, 75°, and 85°) with respect to the substrate normal by reactive magnetron sputtering at 0.3 Pa and 300 °C. The film morphology, crystal structure and residual stress state were characterized by scanning electron microscopy and X-ray diffraction (XRD), including pole figure and sin2ψ measurements. All HfN films had a cubic, NaCl-type crystal structure with an [111] out-of-plane orientation and exhibited a biaxial texture for α ≥ 35°. XRD pole figures reveal that the crystal habit of the grains consists of {100} facets constituting triangular-base pyramids, with a side and a corner facing the projection of the incoming particle flux (indicative of a double in-plane alignment). A columnar microstructure was formed for α ≥ 35°, with typical column widths of 100 nm. It is observed that the column tilt angle β increases monotonously for α ≥ 35°, reaching β = 34° at α = 85°. This variation at microscopic scale is correlated with the tilt angle of the (111) crystallographic planes, changing from −24.8 to 11.3° with respect to the substrate surface. The residual stress changes from strongly compressive (~−5 GPa at α = 5°) to negligible or slightly tensile for α ≥ 35°. The observed trends are compared to previous works of the literature and discussed based on existing crystal growth and stress models, as well as in light of energy and angular distribution of the incident particle flux calculated by Monte Carlo. Importantly, a decrease of the average kinetic energy of Hf particles from 22.4 to 17.7 eV is found with increasing α due to an increase number of collisions.

Atomistic Simulation of Stresses in Growing Silicon Dioxide Films

“…Since the electron beam evaporation is a low-energetic process, the experimental stress values in [27] were lower than those obtained in our simulation. A change in the sign of stress with an increase in the deposition angle was also found for GLAD diamond-like carbon films [7] and hafnium nitride films [28]. Thus, the simulation results we obtained are in good qualitative agreement with previously reported experimental results.…”

Study of columnar growth, texture development and wettability of reactively sputter-deposited TiN, ZrN and HfN thin films at glancing angle incidence

“…In particular, TiN films were found to exhibit a biaxial texture [30], in which the growing crystallites possess both a specific out-of-plane and in-plane preferred orientations. While for TiN films a single in-plane orientation was observed by Mahieu et al [30], a double in-plane orientation was recently reported by Abadias et al for the case of HfN films [31].…”

“…They are located at 18 cm from the substrate holder in a confocal configuration, and make an angle of 25° with respect to the vertical axis of the chamber. A custom-made plate was fixed to the substrate holder to get the desired inclination angle [27,31]. The targets were operated at constant power (300 W) using a direct current power supply (Advanced Energy AE MDX 1.5K) in an Ar+N2 plasma discharge, the gases being introduced into the chamber through separate mass flow controllers.…”

“…Our previous works have revealed that the microstructural features of TiN and HfN GLAD films produced by magnetron sputtering are primarily dictated by the angular distribution of the particle flux [27,31]. This was achieved by varying the working pressure and substrate inclination angle .…”

Manufacture and optimization of nanostructured Cr-Al-N coatings produced by reactive magnetron sputtering

“…Along with the materials and techniques chosen for the manufacture of coatings, the deposition geometry is also an important factor. The description of production of films by means of Glancing Angle Depostion (GLAD) is extense in literature (ROBBIE; BRETT, 1997;ROBBIE, 1998;SIT et al, 1999;GONZALEZ-ELIPE, AGUSTIN R.;ABADIAS et al, 2019;RYDOSZ et al, 2020). In this type of deposition, the substrate is placed at an oblique angle in relation to the sputtering target, so that the flux of arriving species is off-normal with relation to the substrate surface (BARRANCO; BORRAS; GONZALEZ-ELIPE, AGUSTIN R.;.…”