The trend towards decreasing dielectric constant of Interlayer Dielectric (ILD) materials has required significant trade-off between electrical performance and mechanical integrity of the die stack. Fracture caused by thermal stresses due to large coefficient of thermal expansion (CTE) mismatch between these materials arising during fabrication or testing are often the main driving force for failure. In this paper, we use CAD-inspired hierarchical field compositions [1] to carry out Isogeometric (meshfree) fracture simulations. We model cracks as arbitrary curves/surfaces and the crack propagation criterion is based on the evolving energy release rate (ERR) of the system. We simulate the solder reflow process to assess the impact of chip-package interaction on the reliability of ILD stacks. We use multi-level modeling to extract displacement boundary conditions for the local model of the ILD stack. Eight layers of metallization are considered in the ILD stack. We study the relative risks of replacing stronger dielectric (SiO2) with weaker dielectrics (SiCOH, ULK) on the criticality of preexisting flaws in the structure. Further, we study the impact of varying interfacial toughness values on the crack growth patterns in ILD stacks. Crack patterns reflect the propensity towards predominantly bulk failure with increasing interfacial toughness.

The risk of fracture in Interlayer Dielectric (ILD) stack is evaluated for various configurations of flip-chip packages in this paper. A novel analysis on the mechanical behavior of package with a focus on die surface provides the insights into the critical deformation state as well as its location. In Controlled Collapse Chip Connection (C4) process, the reflow phase involves a cooling of the entire package from the reflow temperature to room temperature, and is critical for package induced die cracking (Chip-Package Interaction or CPI). We use commercial finite element software ABAQUS to construct local sub-models of ILD region from global models of a representative 3-D package with component materials modeled as being temperature dependent elastic or elasto-plastic as appropriate. The risk of ILD fracture is systematically investigated using the described approach.