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

• Published in: Surface & coatings technology Vol. 434; p. 128169
• Main Authors: Chen, Yu-Shan, Lin, Chiao-Chi, Chin, Tsung-Shune, Chang, Jen-Yuan (James), Sung, Cheng-Kuo
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25-03-2022; Elsevier BV
• Subjects: Axial stress; Cobalt manganese phosphide; Copper; Crystallites; Curvature; Electrodeposition; Exact solutions; Hard magnet; Interlayers; Measurement methods; Microelectromechanical systems (MEMS); Microstructure; Monolayers; Multilayer; Multilayers; Residual stress; Stacking faults; Stress analysis; Substrates; Thickness; X-ray diffraction; XRD sin2ψ method; Electrodeposition; Microelectromechanical systems (MEMS); Hard magnet; Multilayer; XRD sin2ψ method; Residual stress
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2022.128169

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 sin2ψ X-ray diffraction (XRD) for the apparent crystallite stress (σXRD), and curvature measurement methods for the macro-stress (σf). Intermediate Cu layer having a fixed thickness of 1.4 μm 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 ~20 μm 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 ϕ-scan and ψ-scan depict the transversely isotropic CoMnP layers are under an equi-biaxial stress status, making a simplified analytical solution of sin2ψ method. The residual stresses measured by XRD sin2ψ 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 σXRD by 8.3%, 25%, 33%, respectively; while the σf 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.
•CoMnP/Cu hard magnetic multilayers have been electrodeposited on copper substrate.•Insertion of the Cu interlayer reduces the curvature for the CoMnP layers.•The residual stresses measured by XRD sin2ψ and curvature methods are correlated.•The relief of residual stress is attributed to the released strain energy.•The electrodeposited CoMnP/Cu multilayers can be tuned for material properties.