Stoney Formula: Investigation of Curvature Measurements by Optical Profilometer

Applied Surface Science

Ardigò

Imhoff

et al. 2019

The Stoney formula, based on the measurement of the substrate curvature, is often used for the determination of the thin films' residual stress. In this study, titanium nitride coatings were deposited by DC reactive magnetron sputtering on silicon substrates. An optical profiler was used to determine the curvature of the surface before and after coating. Two radii were then obtained, along the principal perpendicular directions of the surface curvature. A simple and efficient method to determine the experimental error on the stress calculation was developed taking into account the film thickness dispersion and the radii dispersion. Using constant deposition parameters, some samples' characteristics were tested: film and substrate thickness, size, shape and crystallographic orientations of the substrates. With the help of the developed error method, we analyzed what can be conclude about the influence of these characteristics on the calculated stress values, obtained from the experimental measurements.

Section: Influence Of the Sample's Shape And Sizesupporting

confidence: 90%

Curvature radius measurement by optical profiler and determination of the residual stress in thin films

Applied Surface Science

Ardigò

Imhoff

et al. 2019

“…The residual stress in all coatings was evaluated by the modified Stoney equation [15,16]: With E s the Young's modulus of the substrate (130 GPa), s the Poisson's ratio (0.28) and h s the thickness of the substrate, h f the thickness of the film, R the mean radius of the strain curvature. The orthogonal radius of curvature R 1 and R 2 were measured by "Gwyddion" on the image of the substrate strain (subtraction of the images before and after coating obtained by optical profilometer [16]). The residual stresses of the four coating are presented in Fig.…”

Section: Residual Stressmentioning

confidence: 99%

Residual stress, mechanical and microstructure properties of multilayer Mo 2 N/CrN coating produced by R.F Magnetron discharge

Bouaouina

Applied Surface Science

Abaidia

et al. 2017

We have investigated the effect of the period thickness of the multilayer Mo 2 N/CrN deposited on Si substrate produced by reactive magnetron sputtering. Mo 2 N presents a face centered cubic structure and CrN an orthorhombic one. The residual stress of the coatings was determined by the measurement of the substrate curvature. The microstructure of the multilayer was investigated from the X-ray diffraction and scanning electron microscopy (cross section images). The residual stresses resulting from the deposition of the different bi-layer thickness were measured and correlated to the structural properties of the coating as well as the nanoindentation analysis of the coating. The stresses are compressive and tensile for the individual Mo 2 N and CrN layer respectively. The result shows that an increase of the multilayer coatings Mo 2 N/CrN thicknesses induce an increase of the hardness and the elastic modulus, in the other hand the tensile stress increases. The shift of the XRD diffraction peak (1 1 1) of Mo 2 N at high angle which means the reduction of the residual stress is in good agreement with the residual stresses measurements.

“…The substrate curvatures, i.e. the topographic images of the whole substrate [30], before and after deposition were measured by optical profilometry (VEECO, Wyko NT-1100). The subtraction of the initial curvature image to the coated one allows obtaining the topographic image of the substrate deformation from where the radii are then extracted.…”

Section: Methodsmentioning

confidence: 99%

Critical angles in DC magnetron glad thin films

Siad

Nouveau

et al. 2016

Vacuum

Self Cite

a b s t r a c tThe objective of this study is to examine the sudden drop in properties of aluminum, titanium and chromium thin films prepared by the glancing angle deposition method. The thin films were deposited by DC magnetron sputtering under identical deposition conditions. A substrate-holder with seven different orientations with respect to the target normal was used. The thickness and the column tilt angles (b) of the thin films were determined by scanning electron microscopy. The residual stress of the thin films was evaluated using the wafer curvature technique and calculated by the Stoney's formula. The thickness variation and column tilt angle versus the orientation of the substrate indicated that the critical point is around 60 for all metallic materials and a critical angle of 60 is also found for the residual stress. Simulations of the particles transport are compared to the experimental data and moderate the critical angles analyses.