A measurement structure for in-situ electrical monitoring of cyclic delamination

Abstract

Cyclic delamination is the root cause for many different failure modes in semiconductor devices that are related to a loss of mechanical, electrical, or thermal contact. Some of them, such as failure due to local melting, can be considered as catastrophic. An accurate root cause analysis or precise localization of the failure is very challenging or even not possible at all. For this reason, the development of experimental methods capable of assessing early-stage delamination is desired. This work introduces a novel delamination-sensing structure integrated onto an actively heated microelectronic test chip. Actuation of the chip causes thermo-mechanical stress that initiates and drives cyclic delamination of a metallization from a functional base layer. The delamination-sensing structure allows continuous monitoring of the delamination progress by in-situ electrical resistance measurements. Its distinct geometric layout features have the effect that, when passed by a gradually advancing delamination crack front, result in characteristic responses in the monitored signal. This allows a straightforward interpretation of the measurement data without having to rely on modeling or separate calibration. The proper function of the delamination sensor is validated by a comparison of independently determined delamination distances from electrical measurements and cross-sectional inspections, respectively. Its distinguishing property of allowing a simple and time-efficient quantification of delamination is demonstrated by a study comprising 80 delamination experiments. This study investigates the effect of different heating amplitudes ΔT on the delamination rate.