SHARED TYPE IMAGE SENSOR WITH CONTROLLABLE FLOATING DIFFUSION CAPACITANCE

摘要

A shared type image sensor capable of controlling the capacitance of a floating diffusion region is provided to effectively increase a fill factor by maximizing the area of a photoelectric conversion device and by selecting a layout in which almost all of the increased area of the photoelectric conversion device can be used as a light receiving region. Four photoelectric conversion devices(PD1,PD2,PD3,PD4) are formed on a semiconductor substrate, adjacent to each other in one direction. The charges accumulated in two adjacent photoelectric conversion devices are transferred to a first floating diffusion region(FD1) by two transfer devices. The charges accumulated in the rest of the four photoelectric conversion devices are transferred to a second floating diffusion region(FD2) electrically coupled to the first floating diffusion region by two transfer devices. A MOS capacitor is electrically coupled to the first or second floating diffusion region. The charges in the first and second floating diffusion regions are reset to be a predetermined value by a reset device. The charges of the first or second floating diffusion region are outputted by a drive device and a select device. A part of the charges transferred from the four photoelectric conversion devices to the first and second floating diffusion regions is stored in the MOS capacitor.