Evaluation of Metal/Polymer Adhesion and Highly Reliable Four-Point Bending Test Using Stealth Dicing Method in 3-D Integration

The adhesion between metal and polymer layer was studied using four-point bending tests. It was shown that as the annealing temperature increased, oxidation binding increased, which decreased adhesion and reduced the $G_{c}$ value. A new four-point bending test sample prepared using the stealth dicing method with a 100% success rate was proposed for the first time. With samples prepared with stealth dicing, the region where crack extension occurred was smaller after the stress test. Less crack extension generated less loading on the samples. Owing to the coefficient of thermal expansion (CTE) mismatch after increasing the temperature in a highly accelerated stress test (HAST), a void formed in stealth dicing was made close to the interface between the silicon layer and the polymer layer after the stress test, and less crack extension occurred compared with samples kept at room temperature. The smaller loading force guarantees much more stable measurement with a higher success rate after the stress tests. The stealth dicing method can be applied to other structures, such as redistribution layers (RDLs).