Improved electro-mechanical reliability of flexible systems with alloyed Mo-Ta adhesion layers

Sputter deposited Mo/Al/Mo multilayers are widely used material systems for electrodes in display technologies. In this study, the electro-mechanical behavior of simplified bilayer versions was improved for flexible applications through substitution of the Mo by Mo-Ta alloy layers. Sputter deposited Al/Mo-Ta bilayers were tested under uniaxial tensile and cyclic bending loads. Compared to similar Al/Mo bilayers from previous studies, the Mo-Ta interlayer with 50 at.% Ta improved the crack onset strain under tensile load by more than 1% strain. Furthermore, after 50 000 cycles under 1.3% bending strain, the Al/Mo-Ta bilayers were nearly undamaged and experienced a relatively small electrical resistance increase of 25%, compared to Al/Mo bilayers, which were 40 to 100 times higher. This work shows that the substitution of the brittle Mo interlayer with a more ductile Mo-Ta interlayer can improve the performance and lifetime of the electrodes and is more suitable for flexible displays than the currently used materials.