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

• Published in: Materials & design 2017-10, Vol.132, p.72-78
• Main Authors: Hammer, René, Todt, Juraj, Keckes, Jozef, Sartory, Bernhard, Parteder, Georg, Kraft, Jochen, Defregger, Stefan
• Format: Article
• Language: English
• Subjects: Grain size distribution; Hall-Petch; Ion beam layer removal; Nanocrystalline; Residual stress profile; Tungsten thin film
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2017.06.052

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. [Display omitted] •Residual stress gradient characterization using the ion beam layer removal method, with a depth resolution of up to 10nm•Transition zone between nanocrystalline nucleation region and columnar microstructure in W showing maximum stress of 3.5GPa•Stress profiles can be related to the grain size distribution by a Hall-Petch mechanism