Patent ID: 6950134

Claim:
A method of storing charges generated by an optical signal in a solid state imaging device comprising the steps of: (i) preparing the solid state imaging device comprising a unit pixel including (a) a photo diode provided with (1) a semiconductor layer of a first conductivity type, and (2) an impurity region of a second conductivity type formed on a surface layer of the semiconductor layer so that the photo diode has a buried structure, and (b) a field effect transistor for optical signal detection formed in the semiconductor layer adjacently to the photo diode, provided with (1) a source region of the second conductivity type formed on the semiconductor layer, (2) a drain region of the second conductivity type formed on the semiconductor layer and connected to the impurity region, (3) a channel region formed on the surface layer of the semiconductor layer between a source region and a drain region, (4) a gate electrode formed covering the entire channel region by interpolating a gate insulating film, and (5) a carrier pocket of a high-density buried layer of the first conductivity type provided in the semiconductor layer under the channel region; (ii) generating optically generated charges in the photo diode by light irradiation; (iii) transferring the optically generated charges to the carrier pocket while accumulating movable charges of the same conductivity type as that of the source region over the entire channel region by means of a potential of the gate electrode; and (iv) storing the optically generated charges in the carrier pocket while accumulating movable charges of the same conductivity type as that of the source region over the entire channel region by means of a potential of the gate electrode.