Flip-chip planar GaInAs/InP p-i-n photodiodes-fabrication and characteristics

New flip-chip planar GaInAs/InP p-i-n photodiodes have been fabricated as an array. We describe the structure of the photodiode, the design of a microlens, the fabrication processes, characteristics, and the optical fiber-coupled modules. This photodiode satisfied the requirements for a small junction capacitance and low dark current, good optical fiber coupling, and easy fabrication. We obtained a low dark current with good reproducibility by using two layer polyimide and SiN passivation films. A microlens with a 50 /spl mu/m /spl phi/ to 120 /spl mu/m /spl phi/ aperture could easily be fabricated with an InP-substrate. By electroplating, flip-chip metal bumps were directly formed on the active region of the photodiode for the first time.