Research on the Interfacial Reaction and Mechanism of Cu/Sn/Ni Copper Pillar Bump

Copper pillar bump interconnect technology, with its good electrical properties and electromigration resistance, is becoming the next key technology for fine pitch interconnection of chips. The study of the effect of copper pillar bump size on the interfacial diffusion reaction has directive significance to the application of copper pillar bump. This paper focuses on the effect of size on the reliability of copper pillar bump. We use the multi-layer electroplating method to prepare Cu/Sn/Ni copper pillar bump sandwich structure with different diameters of Φ20μm and Φ100μm. We find that the reduction of bump size will promote the growth of interfacial intermetallic compound (IMC). A void growth model in the copper pillar bump is explored by investigating Kirkendall voids and the growth of IMC in Φ20μm Cu/20μmSn/Ni copper pillar bumps.