Die cracking evaluation and improvement in ULSI plastic package

A new test chip is particularly designed to evaluate the large die (12 min x 12 mm, for example) plastic assembly reliability, and is able to sensitively detect the die cracking due to the thermo-mechanical stresses when undergoing packaging and reliability testing. Die cracking failures are found in the chips with six-level Al-0.5Cu metal, and depend strongly upon the encapsulated molding compound material properties during temperature cycling (TC) and thermal shock (TS) testing. While using damascene copper (Cu) technology for top two-level metal in the same packaging, the chips show no cracking failures during the same reliability testing.