Solid-state image pickup device and method of manufacturing the same

A method of manufacturing a solid-state image pickup device, comprising:

• forming a first P-type semiconductor layer by performing heat treatment on a semiconductor substrate which comprises (i) a substrate body containing P-type impurities, and (ii) a first N-type semiconductor layer containing N-type impurities and provided on the substrate body, to diffuse the P-type impurities into a portion of the first N-type semiconductor layer, which is located on the substrate body;
• forming a plurality of optical/electrical conversion portions by injecting N-type impurities into a plurality of portions of a surface portion of the first N-type semiconductor layer to form a plurality of second N-type semiconductor layers, respectively;
• and
• forming a plurality of second P-type semiconductor layers by continuously injecting P-type impurities thereinto until the second P-type semiconductor layer are formed to surround the optical/electrical conversion portions and along element isolation regions provided in respective positions of the surface portion of the first N-type semiconductor layer, and extend from the surface portion of the first N-type semiconductor layer to a surface portion of the first P-type semiconductor layer.