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arXiv · 1909.07197

Reactive magnetron sputtering of tungsten target in krypton/trimethylboron atmosphere

Martin Magnuson·Lina Tengdelius·Fredrik Eriksson·Mattias Samuelsson·Esteban Broitman·Grzegorz Greczynski·Lars Hultman·Hans Högberg
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Abstract

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by X-ray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 oC or with 10 sccm TMB and 300-600 oC thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 oC result in the formation of WSi2 due to a reaction with the substrate. At 900 oC, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 oC. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 oC and Si-rich surface at 900 oC.

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Martin Magnuson, Lina Tengdelius, Fredrik Eriksson, Mattias Samuelsson, Esteban Broitman, Grzegorz Greczynski, Lars Hultman, Hans Högberg. 2019-09-16. Reactive magnetron sputtering of tungsten target in krypton/trimethylboron atmosphere. https://doi.org/10.1016/j.tsf.2019.06.034

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