Semiconductor device with solid state image pickup element

A semiconductor device, comprising:

• a first impurity diffusion region provided in a semiconductor substrate and including at least one impurity diffusion region having an impurity of a first conductivity type;
• an element isolation insulating film provided in said first impurity diffusion region and isolating one element forming region from another element forming region;
• a second impurity diffusion region provided in said first impurity diffusion region and including at least one impurity diffusion region having an impurity of a second conductivity type, the second conductivity type being opposite to the first conductivity type;
• and
• an interface level present portion in which a level is produced in an interface where said element isolation insulating film and said semiconductor substrate are in contact;
• wherein:
• a position of an interface between said first impurity diffusion region and said second impurity diffusion region is set such that a depletion layer formed to contain the interface between said first impurity diffusion region and said second impurity diffusion region does not reach said interface level present portion;
• said first impurity diffusion region includes
• a third impurity diffusion region having an impurity of the first conductivity type and
• a fourth impurity diffusion region formed between said second impurity diffusion region and said element isolation insulating film and having an impurity of the first conductivity type, of a density higher than that of said third impurity diffusion region;
• and
• a position of an interface between said second impurity diffusion region and said fourth impurity diffusion region is set such that a depletion layer formed to contain the interface between said second impurity diffusion region and said fourth impurity diffusion region does not reach said interface level present portion.