Opto-acoustic metrology of signal attenuating structures

Methods and systems for manufacturing and analyzing interconnect structures in integrated circuit (IC) devices. The methods include forming an interconnect structure, such as a pillar, in an IC device. The pillar is analyzed using an opto-acoustic sensor to quantify physical characteristics used to determine whether the pillar satisfies predetermined quality criterion. The analysis includes capturing an opto-acoustic signal from the pillar and estimating optical parameters for a number of local maxima of the signal. A mode may then be fitted for each of the identified local maxima based on the optical characteristics. The modes and estimated optical parameters may then be iteratively corrected in an order from strongest to weakest local maximum. The corrected values may then be compared to a predicted physical model to identify the physical characteristics of the pillar. If the physical characteristics fall outside of the quality criterion, manufacturing processes may be altered.