New approach to apply 1,2,3-benzotriazole as a capping layer on UBMs for 3D TCB stacking and investigation of oxidation protection and solder wetting

In this paper, the oxidation protection and solder wettability is investigated after coating an organic compound 1,2,3-benzotriazole (BTAH, C
₆
H
₅
N
₃
) or BZT on copper UBMs. Since BZT serves as a very strong corrosion inhibitor for copper and its alloys, therefore the investigation is specifically focused on oxidation prevention during shelf life and also during bonding of copper UBMS. Different characterization and experimental analysis are performed involving water contact angle CA, XPS, FT-IR to identify the best coating recipe for the organic film in terms of film stability. Afterwards, stacking is performed using 3D (three dimensional) test vehicle, containing Cu based UBMs which faces the TCB (thermal compression bonding) process for fine pitch interconnection. Then wettability and performance of stacked coupons are analyzed by SEM cross-section and electrical resistance measurements.