FEA-Integrated 3PB And BOR Testing For Fracture Strength Characterization Of Ultra-thin Dies: Effects Of Thickness, Surface Conditions, And Anisotropy

초록

As semiconductors become increasingly miniaturized, thermomechanical failures such as cracking and fracture have emerged as critical reliability issues. In particular, an accurate method for measuring ultra-thin die strength that accounts for large deformation and anisotropic material properties is required. In this study, a finite element analysis (FEA)-integrated strength measurement method using three-point bending (3PB) and ball-on-ring (BOR) tests was developed. Fracture strength was determined by extracting the maximum principal stress from FEA simulations at crack origins identified through scanning electron microscopy (SEM) fractography. The fracture strength of silicon dies and device dies with front-end-of-line (FEOL) and back-end-of-line (BEOL) layers was evaluated. A comparison of fracture strength predictions between FEA and conventional closed-form solutions revealed significant thickness-dependent deviations, reaching up to 29.2% for the thinnest specimens. Surface characterization showed that 3PB tests were more sensitive to edge chipping while BOR tests were more sensitive to surface roughness. This validated framework enables accurate strength assessment and provides guidance for process optimization to improve packaging yield and reliability.

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