Analysis of microstructural evolution in SLID-bonding used for hermetic encapsulation of MEMS devices

The need for reliable hermetic sealing of electronic components has arisen along the increasing popularity of silicon based Micro Electro Mechanical Systems (MEMS). In this paper we have analyzed the formation and evolution interconnections made with Solid Liquid Interdiffusion (SLID) bonding by utilizing thermodynamic-kinetic method. The analysis of the phase transformations and consequent formation of stresses in Au-Sn system during bonding as well as the remelting temperatures of the Au-In-Sn interconnections can be carried out with the help of thermodynamic equilibrium diagrams. In addition, by combining qualitative thermodynamic calculations with qualitative kinetic considerations the evolution of interfacial microstructures between Ni contact metallization and the Au-Sn bonding alloy was predicted.