Residual stress analysis of electrodeposited thick CoMnP monolayers and CoMnP/Cu multilayers

Residual stress in electroplated hard magnetic layers is crucial to the stability and durability in end applications. We electrodeposited highly HCP (002) textured CoMnP hard magnetic layers on copper substrate. We characterized and compared the residual stresses of mono-and multi-layered configurations using sin(2)psi X-ray diffraction (XRD) for the apparent crystallite stress (sigma(XRD)), and curvature measurement methods for the macro stress (sigma(f)). Intermediate Cu layer having a fixed thickness of 1.4 mu m was introduced as a stress reliever for the multilayered CoMnP/Cu through sequential electrodeposition. In multilayers, thickness of all single magnetic layers was added to around similar to 20 mu m similar to that of a monolayer. The surface morphology, layer composition and microstructure remain the same regardless of individual CoMnP single layer thickness. XRD results of phi-scan and psi-scan depict the transversely isotropic CoMnP layers are under an equi-biaxial stress status, making a simplified analytical solution of sin(2)psi method. The residual stresses measured by XRD sin(2)psi method have been correlated with those acquired by curvature method. Increasing the number of layers from 2, 3 to 6 in the CoMnP/Cu multilayers reduces the sigma XRD by 8.3%, 25%, 33%, respectively; while the sigma f by 7.7%, 15% and 23%, respectively, as compared to those of the CoMnP mono-layer. These reductions are attributed to the released strain energy due to soft interlayer confinement and stacking fault formation. Elaborated includes unambiguous understandings of residual stress and microstructures for the electrodeposited CoMnP layers.

Automated summary

Residual stress is crucial in electroplated hard magnetic layers. In this study, highly HCP (002) textured CoMnP hard magnetic layers were electrodeposited on a copper substrate. The residual stresses of mono- and multi-layered configurations were characterized and compared using X-ray diffraction and curvature measurement methods. An intermediate Cu layer was introduced to relieve stress in the multilayered CoMnP/Cu. The results showed that the number of layers in the multilayers affected the residual stresses, with more layers leading to a reduction in residual stress.