Patent ID: 6894268

Claim:
A semiconductor photo detector comprising: a device isolation insulating region formed in a surface layer of a semiconductor substrate, the device isolation insulating region defining an active region; a first layer of a first conductivity type formed in a partial surface layer of the active region; a buried layer of a second conductivity type opposite to the first conductivity type for defining a depletion layer between the first layer and the buried layer, as viewed along a line parallel to a normal of a surface of the semiconductor substrate the buried layer being disposed so as to be partially superposed upon the first layer, and being disposed deeper than the first layer, with an upper surface of the buried layer being set to a position deeper than a bottom of the device isolation insulating region; a MISFET formed in a region of the active region where the first layer is not formed, the MISFET comprising first and second impurity diffusion regions of the second conductivity type disposed in the surface layer of the semiconductor substrate and sandwiching a channel region and a gate electrode formed on a gate insulating film on the channel region, bottoms of the first and second impurity diffusion regions being disposed at a position shallower than the upper surface of the buried layer; and a buried layer connection region of the second conductivity type for electrically connecting the first impurity diffusion region and the buried layer.