Backside Metallization of Ag–Sn–Ag Multilayer Thin Films and Die Attach for Semiconductor Applications

• Published in: Journal of electronic materials Vol. 49; no. 7; pp. 4265 - 4271
• Main Authors: Choi, Jinseok, An, Sung Jin
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2020; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Contact resistance; Electric contacts; Electrical conduction; Electronics and Microelectronics; Gold; High temperature; Instrumentation; Intermetallic compounds; Materials Science; Metallizing; Multilayers; Optical and Electronic Materials; Requirements specifications; Sandwich structures; Semiconductor devices; Shear strength; Silver; Solid State Physics; Thin films; Tin; Sn–Ag binary system; die attach; multilayer thin film; Backside metallization
• DOI: 10.1007/s11664-020-08148-0
• ISSN: 0361-5235

Backside metallization, which offers the advantages of a thin die-attach layer, excellent ohmic contacts, good thermal dissipation, and electrical conduction, is a reliable die-attach method for high-temperature semiconductor devices. Optimized Ag–Sn–Ag thin film structures have been deposited as a backside metal layer and their mechanical and electrical characteristics evaluated as a replacement for conventional Au-based backside metal. The results confirmed that the Ag/Sn/Ag sandwich structure provided more reliable properties than the Sn/Ag and Ag/Sn structures. After the die-bonding process using the Ag/Sn/Ag backside metal, Cu 6 Sn 5 , Cu 3 Sn, and Ag 3 Sn intermetallic compounds were observed at the interface between the Si chip and Cu-plated Alloy 42 lead frame. The shear strength of the Ag/Sn/Ag backside metal was superior to that of conventional Au-12Ge backside metal, and its electrical characteristics met the requirement specifications of a commercial discrete semiconductor package.