Non-destructive mechanical characterization of metal to metal bond interface for 3D-ICs

Mechanical testing on bonded processed wafers to assess their bond quality can be very costly, particularly on production wafers which have multilayer devices fabricated in the chips. A new non-destructive characterization method based on measured resonance frequency of the bond interface is proposed. Capacitive and resistive characteristics of the contact interface are amplified and utilized together with a designed external circuit that consists of an inductor and a resistor. This technique shows an improvement in measurement sensitivity to correlated mechanical adhesion strength, as compared to contact resistance measurement. It also eliminates stray resistances from line resistance and probing contact resistance.