The Application of Thermal Sensor to Locate IC Defects in Failure Analysis

Precise defect positioning by EFA has become critically important for yield improvement due to the reduction in CMOS size and the increase in complexity. Some kind of leakage current caused by metal defects could not be detected by conventional Photo emission microscope (like InGaAs EMMI), because the InGaAs detector responds to near-infrared light (NIR); therefore, the Lock-in thermography (LIT) equipped with the InSb camera is used for the detection of mid-infrared wavelength (MIR), and has better sensitivity in the heat dissipation. The LIT system has been proven to be very useful in 3D packaging or PCBs failure analysis. In this article, we utilize the sensitivity of LIT system and compare the emission differences between EMMI and LIT in three different cases. By understanding the characteristics of the LIT system in IC detection, we realized the emission differences it represents and have succeeded in positioning the defect location and finding the real reason for failure.