A 4-view imaging to reveal microstructural differences in obliquely sputter-deposited tungsten films

Abstract

We report on the morphological disparity of the columnar growth in W thin films sputter-deposited by oblique angle deposition. Oriented tungsten thin films (400 ± 50 nm thick) are prepared using a tilt angle α of 80° and a sputtering pressure of 0.25 Pa. Inclined columns (β = 38 ± 2°) are produced and the microstructure is observed by scanning electron microscopy. A 4-view imaging is performed in order to show inhomogeneous growing evolutions in the columns. Morphological features vs. viewing direction are also investigated from a growth simulation of these tilted W columns. Experimental and theoretical approaches are successfully compared and allow understanding how the direction of the W particle flux leads to dense or fibrous morphologies, as the column apexes are in front of the flux or in the shadowing zone.