Interfacial Reactions in the Cu/Ga/Co and Cu/Ga/Ni Samples

• Published in: Journal of electronic materials Vol. 48; no. 6; pp. 3643 - 3654
• Main Authors: Chen, Sinn-wen, Lin, Ji-min, Yang, Tsu-ching, Du, Yi-huei
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2019; Springer Nature B.V
• Subjects: Barrier layers; Characterization and Evaluation of Materials; Chemistry and Materials Science; Consumption; Copper; Electronics and Microelectronics; Instrumentation; Interdiffusion; Interface reactions; Materials Science; Nickel; Optical and Electronic Materials; Phases; Rate constants; Reaction time; Solid State Physics; Solid–liquid interdiffusion (SLID); Cu; Ga; Ni; interfacial reaction; Co
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-019-07121-w

To fundamentally understand the solid–liquid interdiffusion joining processes between a Cu electrode and Co and Ni barrier layers using a Ga solder, the interfacial reactions in the Cu/Ga, Co/Ga, Ni/Ga, Cu/Ga/Co and Cu/Ga/Ni samples have been systematically examined. The reaction phases at the Cu/Ga interface in the Cu/Ga, Cu/Ga/Co and Cu/Ga/Ni samples reacted at 200°C, 350°C and 500°C are all the same, and are γ 3 -Cu 9 Ga 4 and CuGa 2 , γ 2 -Cu 9 Ga 4 and γ 1 -Cu 9 Ga 4 respectively. No Co/Ga interfacial reaction phase was found in either the Co/Ga or Cu/Ga/Co samples reacted at 200°C, and the reaction phase is CoGa 3 when reacted at 350°C and 500°C. The reaction phase in the Ni/Ga couples reacted at 200°C and 350°C is the Ni 3 Ga 7 phase while it is Ni 2 Ga 3 at 500°C. In the Cu/Ga/Ni samples, no Ni/Ga interfacial reaction phase is observed at 200°C, and the Ni 3 Ga 7 and Ni 2 Ga 3 phases formed at 350°C and 500°C have 8.5 at.%Cu and 14.0 at.%Cu solubilities. The growth rates of the reaction phases have been determined, and the Ga consumption rates in the Cu/Ga/Co and Cu/Ga/Ni samples at 200°C, 350°C and 500°C were calculated. It is observed that the consumption rates increase with the square root of the reaction time, and the consumption rate constants are 39.2 μ m/h 0.5 and 77.3 μ m/h 0.5 , respectively.