Mixed mode interfacial crack energy estimation of glass interposer and SiNx coatings by using fracture mechanics based computer methods and experimental validations

Abstract

Glass-based interposer is a promising candidate for novel 3D-IC integrations because of its characteristics, such as low cost, low coefficient of thermal expansion, smooth surface quality, and large size fabrication. However, an inherent behavior of brittle material such as glass is its low fracture toughness, which easily induces both interfacial delamination and fracture failure modes, particularly for bonds with neighboring passivation coating of silicon nitride (SiNx). Accordingly, this research proposes a simulated methodology based on the index of interfacial strain energy released rate (G-value) to estimate the glass/SiNx interface using a J-integral approach and modified virtual crack closure technique. Adhesion measurement of glass/SiNx was also implemented by means of four-point bending architecture to validate the predicted accuracy. The results show that a 17.95 J/m2 of G-value for aforementioned interface is obtained. A higher modulus of SiNx coating as determined by different deposited conditions utilized at the concerned glass/SiNx interface also had an effect on the critical fracture energy of the crack after it begins to advance.