PHOTODIODE PASSIVATION TECHNIQUE

摘要

A method for passivating a photodiode so as to reduce dark current, Isdark, due to the exposed semiconductor material on the sidewall of the device. The method includes etching away sidewall surface damage using a succinic acid-hydrogen peroxide based sidewall etch. This is followed by a subsequent hydrochloric acid (HCl)-based surface treatment which completes the surface treatment and reduces the dark current Isdark. Finally, a polymer coating of benzocyclobutene (BCB) is applied after the surface treatment to stabilize the surface and prevent oxidation and contamination which would otherwise raise the dark current were the diodes left with no coating. The BCB is then etched away from the contact pad areas to allow wirebonding and other forms of electrical contact to the diodes. Such method effectively stabilizes the etched surfaces of photodiodes resulting in significantly reduced and stable dark current.