CMOS IMAGE SENSOR WITH BACKSIDE BIASED SUBSTRATE

摘要

A CMOS image sensor 101 comprises an active layer 11 of a first conductivity type arranged to be reversed biased and a pixel 20 comprising a photosensitive element comprising a well 22 of a second conductivity type and a well 21 of the first conductivity type containing active CMOS elements for reading and resetting the photosensitive element. The CMOS image sensor further comprises a doped buried layer 111 of the second conductivity type in the active layer beneath the well of the first conductivity type. The buried layer is arranged to extend a depletion region below the well of the second conductivity type also below the well of the first conductivity type.

主权项

1. A CMOS image sensor comprising:
an active layer of a first conductivity type arranged to be reversed biased and a pixel comprising: a photosensitive element comprising a well of a second conductivity type; and a well of the first conductivity type containing active CMOS elements for reading and resetting the photosensitive element; anda doped buried layer of the second conductivity type in the active layer beneath the well of the first conductivity type arranged to extend a depletion region below the well of the second conductivity type also below the well of the first conductivity type to form an extended depletion region in the active layer;wherein the extended depletion area in the active layer is arranged to pinch off a parasitic current path between the well of the first conductivity type containing active CMOS elements and a substrate or backside contact.