Patent ID: 6914228

Claim:
A solid-state imaging device, comprising: a pixel array including a plurality of unit pixels, each of the unit pixels including a photo diode and an insulated gate field effect transistor that detects photocharges; and a control circuit that controls an operation of the pixel array, wherein: the photo diode and the insulated gate field effect transistor share a well region of a first conductivity type that is formed in a semiconductor layer of a second conductivity type, the semiconductor layer of the second conductivity type being formed on a semiconductor substrate of the first conductivity type; the insulated gate field effect transistor comprises: a source diffused region of the second conductivity type formed on a surface of the well region; a drain diffused region of the second conductivity type formed on a surface of the semiconductor layer other than the surface of the well region; a gate electrode formed above the well region between the drain diffused region and the source diffused region with a gate insulating film therebetween; a channel region formed in the surface of the well region below the gate electrode and having an impurity layer of the second conductivity type; and a heavily doped buried layer of the first conductivity type formed below the channel region in the well region and adjacent to the source diffused region, having an impurity concentration higher than that of the well region, and being an accumulation region that accumulates charges of a given conductivity type generated in response to light incident on the photo diode; the control circuit comprises a drain control circuit providing any of constant voltage, a constant current, and constant charges to the drain diffused region; and the control circuit previously forward biases a junction region between the semiconductor substrate and the semiconductor layer by the any of the constant voltage, the constant current, and the constant charges, that is provided from the drain control circuit to the drain diffused region, so as to accumulate a predetermined amount of the charges of the given conductivity type in the accumulation region, and the charges of a given conductivity type accumulated in the accumulation region being discharged thereafter.