Integrated packaging of over 100 GHz bandwidth uni-traveling-carrier photodiodes

Hybrid packaging techniques, in which the device substrate is different from the package substrate, and wire bonding or solder interconnections are used, are inadequate for ultrahigh-speed (>100 GHz) wideband applications. By employing wafer-bonding techniques, an integrated packaging (IP) technology was developed, in which devices are fabricated directly on the package substrate, and the interconnections are made as a part of the device fabrication process. This IP process was used to fabricate uni-traveling-carrier photodiodes (UTC-PD´s) integrated with millimeter-wave coplanar waveguides (CPW) on package compatible sapphire with high yield. The performance of wafer-bonded UTC-PD´s with 3-dB bandwidth of 102 GHz was similar to that of conventional devices, and the CPW´s exhibited low dispersion.