The separation of superimposed ultrasonics pulse echo signals for semiconductor failure analysis using scanning acoustic tomography (S.A.T.)

Ultrasonics is used as an important nondestructive test tool in semiconductor reliability evaluation and failure analysis. Inspection of the die bottom to die attach adhesive interface for thin die has proven difficult as the reflected signals from the die top and bottom are superimposed. It is important that inspection of delamination of the bottom of the die can take place as it can greatly affect the thermal conductivity of thin semiconductor devices. In this study a transfer function technique is used to separate the reflected signal from the die bottom from the superimposed signal