Thermomechanical asymmetries in ULK dielectric glasses

Abstract

We show that ULK dielectric materials can have a marked asymmetric elastic modulus and coefficient of thermal expansion (CTE) that is inherently related to the interaction of terminal chemical groups and is controlled by the material's density and network connectivity. The existence of asymmetric elastic and thermal expansion behavior has fundamental implications for computational approaches to molecular materials modeling and practical implications on the thermomechanical strains and associated elastic stresses. We develop a design space to control the degree of elastic asymmetry in ULK materials and explore the differences in predicted crack driving forces due to the asymmetric modulus, a vital step towards their integration into the semiconductor industry.