IMAGE SENSOR ACHIEVING ELECTRON MULTIPLICATION VIA VERTICAL GATES

摘要

The invention relates to image sensors, and more particularly to sensors that are intended to detect images at low light levels. An active-pixel image sensor is provided, each pixel comprising, on the surface of an active semiconductor layer (12), a photodiode region (PHD) adjacent to a transfer gate (TR) itself adjacent to a charge storage region (18), the transfer gate permitting, when it receives a transfer pulse, the transfer of charge from the photodiode region to the storage region. The photodiode is adjacent to two multiplication gates (GA, GB) that extend vertically depthwise in the active layer between two adjacent pixels. The multiplication gates are isolated from the photodiode by a planar vertical insulating layer (22). They receive, during an integration phase preceding the transfer pulse, a series of high and low potential alternations in phase opposition, inducing opposed electric fields alternately, in one direction and then the other, between the gates and the photodiode.