160 nm Ti-W-N layers were sputtered on Si/SiO2/Al-Si-Cu substrates with the thickness of the Al-Si-Cu layer varying between 0 and 1000 nm. As a result the apparent grain size of the Ti-W-N increased from 40 to 130 nm and the compressive deposition stress of the Ti-W-N decreased from 1.77 to 0.34 GPa. The relation between stress and the inverse grain size was found to be linear for grain sizes smaller than 130 nm. Assuming a simple model, the excess volume per unit area of grain boundary can be estimated from the slope of the fit and was found to be 0.17 nm.
Light scattering measurements can be used as a quick and non-destructive method for evaluating the microstructure of these layers.