Patent ID: 7619293

Claim:
A semiconductor device comprising: a light receiving semiconductor region that is disposed on a main surface of a semiconductor substrate, receives signal light and has a low impurity concentration; and an anode region and a cathode region that are formed on a surface of the light receiving semiconductor region apart from each other with the light receiving semiconductor region disposed therebetween the anode region and cathode region extending only to a partial depth of the light receiving semiconductor region, wherein the anode region is a first conductivity type semiconductor region to which a first voltage is applied and that has an impurity concentration higher than the light receiving semiconductor region; the cathode region is a second conductivity type semiconductor region to which a second voltage is applied and that has an impurity concentration higher than the light receiving semiconductor region; the anode region and the cathode region are formed on a surface of a groove portion formed on the main surface of the semiconductor substrate; the groove portion is embedded with an insulting film and made flat; at least a portion of an uppermost surface of one of the anode region and the cathode region extends in substantially the same plane as an uppermost surface of the light receiving semiconductor region between the anode region and the cathode region; the anode region, the light receiving semiconductor region and the cathode region comprise a lateral PIN photodiode; and, the anode region and the cathode region are put into a reverse bias state owing to the first voltage and the second voltage to form a depletion layer in the light receiving semiconductor region.