Non-destructive fault localization in advanced IC packages using electro optical terahertz pulse reflectometry

Traditional, all electronic, microwave time domain reflectometry (TDR) is a well established fault isolation technique within the semiconductor industry and can typically localize an open or short fault to within 500μm of the defect. This level of fault localization is not sufficient in advanced IC packages due to the increased complexity and the reduction in physical package size, hence, the ability to isolate the exact fault location is essential to shorten the failure analysis cycle time. Electro optical terahertz pulse reflectometry (EOTPR) is a novel and innovative technique which offers the ability to quickly and non-destructively isolate faults in advanced IC packages to an accuracy of 20μm or better. The EOTPR system uses photoconductive terahertz pulse generation and detection technology, resulting in a system with: (i) high measurement bandwidth, (ii) extremely low time base jitter, and (iii) high time base resolution and range with greater sensitivity. Here, an EOTPR system is used to non-destructively isolate faults in a series of state-of-the-art IC packages. We present results which demonstrate the superior accuracy and sensitivity of EOTPR compared to traditional TDR.