Bond Strength Optimization of Plasma Activated Low Temperature Oxide-Oxide Fusion Bonding Through Thermocycling

Abstract

In this work, the influence of annealing time and number of annealing steps on the shear strength of plasma activated low temperature oxide-oxide fusion bonding wafer stacks is investigated. Shear strength measurements of previously manufactured shear strength measurement test structures are introduced to analyze the shear strength and related bond strength, respectively. An improved two-step annealing/cooling thermocycle is demonstrated which leads to a tremendous increase of the shear strength compared to a conventional single annealing step. Based on an optimized annealing through thermocycling, plasma activated low temperature oxide-oxide fusion bonding with reduced process time, lower temperature and higher bond strength becomes feasible.