Hardened photodiode image sensor

A method for manufacturing an image sensor comprising a pixel array, the method comprising the steps, for each pixel in a substrate of a doped semiconductor material of a first conductivity type, of:

• forming a first doped region of a second conductivity type at the surface of the substrate;
• forming a trench of an insulating material surrounding the first region;
• forming a second doped region of the first conductivity type, more heavily doped than the substrate, at the surface of the substrate and surrounding the trench;
• forming a third doped region of the second conductivity type, forming with the substrate a photodiode junction, extending in depth into the substrate under the first and second regions and being in contact with the first region or connected to the first region by one or several regions of the second conductivity type;
• and
• forming a fourth doped region of the first or second conductivity type, more lightly doped than the second and third regions, interposed between the second and third regions and in contact with the second region and/or with the third region.