Quantification of Wafer Bond Strength of Silicon Nitride under Controlled Atmosphere

Wafer bonding is a key technology for packaging and integration of a wide range of applications. Bond strength is the most important factor for the evaluation of mechanical reliability of the bonding interface, although the measured value depends on the surrounding atmosphere, especially presence of water. In order to quantify the effect of the measurement atmosphere on the bond quality, we developed a new methodology of the bond strength measurement under controlled atmosphere. The bond strengths of bonded silicon nitride wafers are measured using double cantilever beam method in ambient air, dry N
2
gas, and under high vacuum. The bonding strength is, in descending order, in vacuum, in N
2
, and in air. The experimental results suggest that the measurement of bond strength in a controlled atmosphere evaluates the effect of residual water at the bond interface, as well as stress corrosion caused by water in the atmosphere.