Bonding temperature optimization and property evolution of SU-8 material in metal/adhesive hybrid wafer bonding.

Bonding temperature optimization of SU-8 material for metal/adhesive hybrid bonding was investigated. The good bond quality of SU-8 adhesive can be achieved with the bonding temperature between 150 degrees C and 250 degrees C, while bond failures of SU-8 wafers are observed starting from 275 degrees C. IR transmittance spectra measurements indicate the crosslinks inside SU-8 break and further bond failure is observed due to the large decomposition of epoxy rings and phenyl in plane bending above 275 degrees C. This research provides guidelines of material selection and bonding parameters for heterogeneous integration, 3DIC and MEMS applications using metal/adhesive hybrid bonding.