EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Modern technological devices rely on a multitude of constituents with local variations on the micrometre to nanometre scale. Specifically, in the microelectronics industry, where very confined regions are precisely processed for individual functionalities, e.g. semiconducting properties, diffusion barriers, heat sinks, etc., this is observed quite frequently. Therefore, a need for materials testing methods able to resolve mechanical parameters of theses individual materials or structures arises. In the present work, we show experimental micromechanical approaches to address the fracture behaviour of individual interfaces and constituents of a plane multi-layered Si-WTi-Cu system, as a representative substitute for classical microelectronic devices. The basic method for such small scale fracture mechanical investigations is the microcantilever deflection technique, followed by linear elastic fracture mechanical considerations for evaluation. However, with the inherent structural heterogeneity of the system and the significant amount of plastic deformation that Cu can sustain, it is necessary to apply more intricate elastic-plastic evaluation methods, e.g. J-integral evaluation. Therefore, we utilize a sinusoidal signal on top of the standard loading procedure to investigate the change in system compliance, which gives a measurable quantity that can be translated to physical crack extension. This allows the derivation of J-Δa characteristics for individual crack paths along interfaces or inside of individual constituents. Furthermore, we show the influence of interface chemistry on cohesion between WTi and Cu based on an intentionally air-exposed sample in comparison to vacuum processed specimens.