IMAGE SENSOR AND FABRICATING METHOD THEREOF

摘要

An image sensor and a manufacturing method thereof are provided to stably operate a source follower transistor in a saturation region, thereby improving linearity characteristics of the source follower transistor. An image sensor comprises a photoelectric conversion element, a source follower transistor(17) and a selecting transistor(19). The photoelectric conversion element produces electric charges in response to incident light, and changes voltage of a detection node. The source follower transistor comprises a gate(130) which is coupled with the detection node and consists of material having first work function. The selecting transistor comprises a gate(120) which is coupled between the source follower transistor and the voltage node and consists of material having a second work function lower than the first work function. The material having the first work function is semiconductor material doped with dopant of a first conductive type. The material having the second work function is semiconductor material doped with dopant of a second conductive type different from the first conductive type.