Patent ID: 6489658
Filing Date: 2002-12-03
Classification: H01L

Abstract:
A MOS transistor for an image sensor comprising:a semiconductor substrate; an oxide layer formed on the semiconductor substrate, the oxide layer having a passive surface region and an active surface region, wherein the oxide layer is configured as a thin oxide film in the active surface region and a thick oxide film in the passive surface region, the thick oxide film framing the active surface region and being insulated by means of a trench extending below the substrate surface filled with an oxide; a gate electrode separating a photosensitive source region and a drain electrode and being formed on the thin oxide film in the active surface region of the oxide layer, the gate electrode comprising a section of closed annular shape with a section extending from the thin oxide film in the active surface region to the think oxide film in the passive surface region where the gate electrode is electrically contacted; the drain electrode being arranged within the section of closed annular shape and the photosensitive source region being arranged outside the section of closed annular shape; and the gate electrode and the drain electrode are connected to the same electrical potential.