Tomokazu Yamashita

A temperature resistant wide dynamic range CMOS image sensor

A temperature resistant wide dynamic range (WDR) CMOS image sensor has been developed using the very low dark current front-end of line (VLDC FEOL) and the metal hermetic seal ceramic leadless chip carrier (CLCC) package suppressing the degradation of the spectra response of the on-chip micro lens and color filter (OCML/OCCF). A 1/4 inch VGA 5.6 &mgr;m pixel pitch WDR CMOS image sensor has been fabricated through 0.18 &mgr;m 2P3M process with the VLDC FEOL which contains the pinned photodiode with less electrical fields, the less plasma etching damages, the transfer gate with the suppressed current at Si-SiO2 interface and the furnace temperature process for the re-crystallization. The sensor chips with the conventional OCML/OCCF assembled into the metal hermetic seal package by the low residual oxygen vacuum welding machine has finally received the thermal stress test (150 deg.C/500 hours). The dark current is 350 pA/cm2 at 85 deg.C (50 pA/cm2 at 60 deg.C). No degradation of the spectra response in any of R/G/B pixels is observed after the thermal stress test. It is found that the thermal decomposition of the OCML/OCCF (phenol resin) is not caused easily in nitrogen with the low residual oxygen concentration. The sample images captured by the WDR CMOS image sensor assembled camera keep good quality up to 85 deg.C.