Full-Field Identification of Interfaces in Microelectronic Devices

To improve the integrity of densely stacked multilayers in microelectronic systems, e.g., Light Emitting Diodes (LED), and thereby overcome the currently experienced problems related to interface failure during manufacturing of such devices, accurate identification of interface properties is essential. The behavior of the interface is only measurable through kinematic information from adjacent materials. The goal of this research is to identify interface parameters by Integrated Digital Image Correlation (IDIC), in which experimental images of a deformation process are correlated by utilizing the mechanical response from finite element (FE) simulations. An interface is herein modeled by cohesive zone (CZ) elements exhibiting constitutive traction-separation laws. The versatility of FE simulations and the kinematic richness of the full-field measurements are thereby exploited. Comprising an elastic hinge system, a small-scale mechanical test-setup is designed from two 3-axes (XYZ) piezo stages, with which micrometer displacements and realistic interface loading conditions (shear, normal, and mixed-mode loading) can be applied to an LED specimen. This allows to, in a well-controlled manner, mechanically mimic interface delamination that is typically induced during fabrication steps by thermal expansion. This setup and the IDIC method are integrated to identify the CZ parameters of the critical interface of an LED specimen.