Flip-chip packaging using micromachined conductive polymer bumps and alignment pedestals for MOEMS

• Published in: IEEE journal of selected topics in quantum electronics 1999-01, Vol.5 (1), p.119-126
• Main Authors: Oh, K.W., Ahn, C.H., Roenker, K.P.
• Format: Article
• Language: English
• Subjects: Bonding; Couplers; Gallium arsenide; Optical design; Optical design techniques; Optical polymers; Packaging; Photodetectors; Prototypes; Resists
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/2944.748115

Using flip-chip bonding techniques with micromachined conductive polymer bumps and passive alignment techniques with electroplated side alignment pedestal bumps, a prototype microoptoelectromechanical systems (MOEMS) structure for optical input/output (I/O) couplers has been designed, fabricated and characterized. A top MOEMS substrate has through holes, contact metal pads, and side alignment pedestals with electroplated NiFe to align GaAs metal-semiconductor-metals (MSMs). Conductive polymer bumps have been formed on contact metal pads of GaAs MSMs using thick photoresist bump-holes as molding patterns. A diced GaAs photodetectors die with micromachined conductive polymer bumps was aligned to the side alignment pedestals and flip-chip bonded onto the substrate. This conductive polymer flip-chip bonding technique allowed a very low contact resistance (/spl sim/10 m/spl Omega/), a lower bonding temperature (/spl sim/170/spl deg/C), and simple processing steps. The GaAs MSM photodetectors flip-chip mounted on the top of OE-MCM substrate showed a low dark current of about 10 nA and a high responsivity of 0.33 A/W.