Die cracking evaluation and improvement in ULSI plastic package

A new test chip is specially designed to evaluate large die (12 mm/spl times/12 mm, for example) plastic assembly reliability, and is able to sensitively detect die cracking due to thermo-mechanical stresses when undergoing packaging and reliability testing. Die cracking failures are found in 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 the top two metal levels in the same packaging, the chips show no cracking failures during the same reliability testing.