Abstract :
In this paper, surface activated bonding (SAB), as a new high density bonding method and its application on the interconnection between metal micro-bump and metal film for the chip-on-chip and chip-on-flex/chip-on-film system, was introduced. Bonding feasibility of Au bump and Al film in the vacuum at room temperature, Au bump and Cu film, Au bump and Au film, and Cu bump and Cu film in air or nitrogen ambience with atmospheric pressure at low temperature were well demonstrated. Bonding shear strength of more than 15MPa and electrical resistance below 7mOmega proved a good performance of SAB process on the interconnection for electronic system. Thermal electrical and mechanical performance appearance of SAB interconnection illustrated an acceptable anti-heat ability of SAB bond even without the protection of under-fill layer. The obviously different bonding feasibility, reliability, and interface structure of Au-Al bond by SAB and wire bonding (WB) selected the advantages of SAB over the traditional bonding technique. SAB process could establish a dense surface contact between the surfaces of two bonding materials, which inhibited the potentially inhomogeneous formation and growth of intermetallic compound layer, thus help establish a stable mechanical and electrical performance for interconnection in the electronic system even after a long time application (Zhonghua Xu et al., 2005). SAB was a new process for the interconnection in the microelectronic system. Compared with thermal compress, soldering flip chip process, etc., as of low/room temperature process characteristics, SAB was especially suitable for high density interconnection. Micro-bump/film for COC and COF system based on SAB technique were discussed. New generation SAB bonders were developed successfully. Bonding accuracy of about 1mum at room temperature in vacuum or low temperature in air or nitrogen ambience could be easily succeeded for the interconnection in packaging system. Optoelectronics, medi- - cal system or other high precise microelectronic system were well developed based on the system of SAB technology
Keywords :
copper alloys; flip-chip devices; gold alloys; integrated circuit interconnections; lead bonding; nitrogen; shear strength; silver alloys; Al; Al film; Au; Au bump; Au-Al bond; COC system; COF system; Cu; N; bonding shear strength; chip-on-chip system; chip-on-film system; chip-on-flex system; flip chip process; high density bonding method; interface structure; intermetallic compound layer; low temperature interconnection technique; mechanical performance; metal film; microbump film; microelectronic system; room temperature interconnection technique; surface activated bonding method; thermal compress; thermal electrical performance; wire bonding; Bonding; Contacts; Electric resistance; Gold; Intermetallic; Microelectronics; Nitrogen; Protection; Temperature; Wire;
