A Fabrication of an Image Sensor Using SiGe-BiCMOS Technology
Jun OHTA, Naoyuki TOKIDA, Keiichiro KAGAWA Takashi TOKUDA and Masahiro NUNOSHITA
Abstract:We have demonstrated an image sensor using SiGe BiCMOS fabrication process for detecting object illuminated by light in "eye-safe" band. The fabrication process is general 0.8 ƒÊm 2-poly 2-metal SiGe BiCMOS process for RF application. SiGe-Si photodiodes and Si-SiGe-Si hetero-phototransistors as well as Si homojunction photodiodes and phototransistors have been fabricated and measured. The gain of the hetero-phototransistor was around 100. There was little difference between the sensitivity characteristics of SiGe and Si photodetectors. An image sensor with 32x32 pixels has been fabricated using a phototransistor as a detector, which of the base is made of SiGe layer. The dynamic range was 23 dB and the minimum detectable light intensity was 10 lux. We have successfully acquired images by using this image sensor. The future issues to use SiGe BiCMOS process for image sensors are discussed. Key Words:Image sensor, SiGe BiCMOS, Hetero bipolar transistor, Eye-safe band, Phototransistor, Active pixel sensor