Image sensing device including source follower transistor

An image sensing device comprising:

• a semiconductor substrate configured to include a first surface upon which light is incident from a scene and a second surface facing or opposite to the first surface;
• first and second photoelectric conversion elements that are supported by the semiconductor substrate and are spaced apart from each other, each photoelectric conversion element configured to receive incident light and generate photocharges by sensing the received incident light;
• a first pixel isolation structure recessed from the second surface and configured to surround the first and second photoelectric conversion elements;
• second and third pixel isolation structures disposed between the first photoelectric conversion element and the second photoelectric conversion element and spaced apart from each other;
• and
• a source follower transistor supported by the semiconductor substrate and configured to include a gate disposed on the second surface in at least a portion of a gap region between the second pixel isolation structure and the third pixel isolation structure.