Role of dielectric material and geometry on the thermo-mechanical reliability of microvias

A comprehensive experimental and theoretical program is underway at the Georgia Institute of Technology to develop microvia substrate technology. The experimental aspect of this program involves fabrication in a class 1000 clean room facility to understand the effect of process parameters on yield and reliability of the microvia and high density wiring (HDW) structures. The theoretical program aims to understand the mechanics of deformation and thus predict and enhance the reliability of the HDW structures. The focus of this paper is to understand the effect of processing parameters on yield, to characterize the effect of microvia geometry parameters on the evolution of strain, and to determine the effect of dielectric material properties on the thermo-mechanical reliability of the microvias. Finite element simulations were carried out with different microvia diameters to understand the failure mechanisms of these structures. The reliability predictions are compared with thermal cycling test data of the test vehicles.