High resolution residual stress gradient characterization in W/TiN-stack on Si(100): Correlating in-plane stress and grain size distributions in W sublayer

Publication date: 15 October 2017
Source:Materials & Design, Volume 132
Author(s): René Hammer, Juraj Todt, Jozef Keckes, Bernhard Sartory, Georg Parteder, Jochen Kraft, Stefan Defregger
Residual stress gradient characterization by the ion beam layer removal method (ILR), using a milling step of 10nm, was applied to W/TiN stacks processed on thermal SiO2-insulated standard silicon wafers. The stress profiles indicate a pronounced stress gradient with high tensile, as well as compressive stress concentrations in polycrystalline W and amorphous TiN sublayers ranging between 3.5 and −4GPa. Electron backscatter diffraction shows that the W sublayer exhibits zone T microstructure with nano-sized crystallites in the nucleation region at the interface to TiN and above that columnar or V-shaped grain morphology typical for competitive grain growth. In the W sublayer, the stress distributions correlate well with this in-plane crystallite size distribution on the base of a Hall-Petch mechanism, reaching a tensile maximum in the transition region between the nucleation layer and the region with columnar microstructure.

Graphical abstract

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