Low-temperature gold-gold bonding using argon and hydrogen gas mixture atmospheric-pressure plasma treatment for optical microsystems

Room temperature bonding of semiconductor chips with Au thin film to coined Au stud bumps with smooth surfaces (Ra: 1.3 nm) using Ar+H₂ atmospheric-pressure plasma activation was demonstrated in ambient air. Die shear strength was high enough to exceed the strength requirement of MIL-STD-883F, method 2019 (×2). The measured results of light-currentvoltage characteristics of laser diode chips and dark current of photodiode chips indicated no degradation after bonding. By applying this technique, miniaturized polarization sensors were fabricated.