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The embedded interposer carrier (EIC) technology for 3D-integrated circuits (3D-ICs) play an important role as a promising candidate to deal with the assembly/bonding processes of thin stacked chip and substrate. However, peeling stress of the interface between stacked via holes and copper-filled through silicon via silicon-based interposer may cause a thermomechanical reliability issue among multi-stacked film EIC architectures. For dealing with this situation, we propose a process-oriented finite element analysis method considering material nonlinear behaviors as well as process flows including process temperature and steps. This method is able to analyze systematically the effect of cycling temperature loads induced during the bonding process. From the result of simulations, it indicates that the curing process of laminated material is the critical step among the entire bonding process. In addition, the material about a compliant interposer is recommend to be a suitable solution for EIC architecture enhancing operational reliability. Furthermore, the thermal stress of each thin film stacked inside EIC structure can be relieved by means of the flexible of the carrier laminate design. [ABSTRACT FROM AUTHOR]

The suitability of stacked thin films for next-generation display technology was analyzed based on their properties and geometrical designs to evaluate the mechanical reliability of transparent conducting thin films utilized in flexural displays. In general, the high bending stress induced by various operation conditions is a major concern regarding the mechanical reliability of indium-tin-oxide (ITO) films deposited on polyethylene terephthalate (PET) substrates; mechanical reliability is commonly used to estimate the flexibility of displays. However, the pattern effect is rarely investigated to estimate the mechanical reliability of ITO/PET films. Thus, this study examined the flexible content of patterned ITO/PET films with two different line widths by conducting bending tests and sheet resistance measurements. Moreover, a stress-strain simulation enabled by finite element analysis was performed on the patterned ITO/PET to explore the stress impact of stacked film structures under various levels of flexural load. Results show that the design of the ITO/PET film can be applied in developing mechanically reliable flexible electronics. [ABSTRACT FROM AUTHOR]

This study employed the four-point bending test (4-PBT) to measure the interfacial strength of pressure-sensitive adhesive (PSA)/SiN passivation stacked thin films. Finite element analysis (FEA) is combined with the J integral approach and the modified virtual crack closure technique to validate the results of 4-PBT. The FEA simulation results verify the measurement results. The stress status and energy release rate of the delaminated tip are also determined at different elevations of stacked thin films of 4-PBT specimens adjacent to the PSA/SiN interface. The crack in the PSA parallel to the foregoing interface with a slight span occurs on the fractured interface. This behavior is confirmed by observing the scanning electron micrographs of the specimens after 4-PBT. [ABSTRACT FROM AUTHOR]

Abstract: Developing a robust predicting methodology on the interfacial fracture energy of dissimilar materials is urgently needed to meet the mechanical strength requirements for investigating novel materials and subsequent device structures with the bonded types of multi thin films. Thus, this paper provides an overview of useful approaches according to linear-elastic interfacial fracture mechanics, such as J-integral method, modified virtual crack closure technique (MVCCT), and analytical solutions derived from the relationship between the stress field of delaminated tip and crack tip opening displacements to compare their estimated capability of cracking energy. A popular technique for determining the interface adhesion of thin coatings is the four-point bending test (4-PBT). The testing vehicles of 4-PBT allow a more thorough validation of the foregoing predicted approaches based on finite element analysis compared with the simulated results with related experimental data. The critical energies of 18J/m2, 78.53J/m2, 52.01J/m2, and 71.02J/m2 for the bonded interfaces of SiO2/SiLK, Ta/SiLK, TaN/SiLK, and Si3N4/SiLK stacked nano-scaled thin films are precisely judged, respectively. The predicted results of the J-integral method match well with the MVCCT estimation. The results reveal that the opening fractured mode is dominant at the beginning of the crack advances along the bonded interface of Ta/SiLK, TaN/SiLK, and Si3N4/SiLK stacked films as the interfacial crack length increases. Moreover, the essential trends of dependences for the modulus ratio and thickness ratio of stacked thin films on interfacial energy release rate are logically identified and investigated. Therefore, this paper could be regarded as a design guideline of interfacial fracture behavior for stacked films utilized in the development of advanced device technologies. [Copyright &y& Elsevier]

Abstract: The interfacial adhesion of thin films between Al metal and TiN barrier is one of the major concerns dominating the mechanical reliability of semiconductor devices. The measured accuracy of cracking energy for stacked films with a nanoscale order is arduous to preserve because of the uncertainty in specimen preparations and instrumental operations. Consequently, the present research proposes a robust estimation of interfacial cracks using simulation-based methodologies to meet the requirement for mechanical designs in multi-level interconnected systems of electronic devices. According to the framework of the four-point bending test (4-PBT), the interfacial fracture energy of Al/TiN films is predicted via finite element analysis (FEA), combined with the J-integral method and modified virtual crack closure technique (VCCT). The foregoing simulated approaches are also verified by related analytical solutions and experimental data. Moreover, the effects of several patterned types of metal lines underneath the Al/TiN interface with various embedded cracks are analyzed. The primary results highlight a significant increase in the energy release rate (G) induced by the passing of a crack along the interface of Al/TiN films through the region below a metal line with a high degree of hardness. Dielectrics with a lower modulus would have the capacity to restrain progressive crack growth. Thus, a high G is expected to drop, as simultaneously demonstrated by the present simulated methodologies. [Copyright &y& Elsevier]

In order to resolve the issues of RC time delay and high power consumption, IC chips with Cu/low-k interconnects are developed to meet the foregoing requirements. However, there is a high potential that in doing so it may contribute to interfacial cracks occurring or propagating between the copper metal and the low-k dielectric material as a result of poor adhesion and lower fracture toughness, which results from the inherent mechanical imperfection of low-k materials. This fracturing problem is one of the most urgent issues for the thermomechanical reliability of Cu/low-k interconnects, and it needs to be resolved urgently. For this reason, we propose a prediction methodology of finite-element analysis (FEA) based on J-integral value estimation to investigate the interfacial fracture opportunity of low-k packages. However, the J-integral calculation is path dependent and so crucial in FEA for a crack on an interface between dissimilar materials. Therefore, various paths with an integral contour surrounding the crack tip are considered to avoid a misunderstanding of the cracking energy. All the analytic results indicate that a rectangular contour with a proper ratio of length/width, and multilayers of element close to the delaminating surfaces, is suggested for obtaining a stable J-integral value. On the other hand, the proposed methodology has been validated by a four-point bending test and compared with the relative experimental data of multi-low-k dielectric films. Moreover, under a reliable integral contour path that crack driving force predicted using the type of interfacial crack constructed by means of the element death technique, it shows good agreement with the simulated results of embedding actual crack. [ABSTRACT FROM AUTHOR]

This work analyses the overall stress/strain characteristic of flexible encapsulations with organic light-emitting diode (OLED) devices. A robust methodology composed of a mechanical model of multi-thin film under bending loads and related stress simulations based on nonlinear finite element analysis (FEA) is proposed, and validated to be more reliable compared with related experimental data. With various geometrical combinations of cover plate, stacked thin films and plastic substrate, the position of the neutral axis (NA) plate, which is regarded as a key design parameter to minimize stress impact for the concerned OLED devices, is acquired using the present methodology. The results point out that both the thickness and mechanical properties of the cover plate help in determining the NA location. In addition, several concave and convex radii are applied to examine the reliable mechanical tolerance and to provide an insight into the estimated reliability of foldable OLED encapsulations. [ABSTRACT FROM AUTHOR]