Patent ID: 9564466
Date: 2017-02-07
CPC Classifications: H01L

Claim:
1. A semiconductor device, comprising a photodiode, and a transfer transistor, the photodiode and the transfer transistor being coupled in series, the transfer transistor comprising: a gate electrode formed over a main surface of a semiconductor substrate via a gate insulating film; a source region of a first conductivity type arranged on one end side of the gate electrode; and a drain region of the first conductivity type arranged on the other end side of the gate electrode, and the photodiode comprising: a charge storage layer of the first conductivity type formed in the semiconductor substrate, and also serving as the source region; and a surface layer of a second conductivity type arranged over the charge storage layer, the second conductivity type being opposite to the first conductivity type, wherein the surface layer comprises a first sub-region having a low impurity concentration, and a second sub-region having a higher impurity concentration than that of the first sub-region, the first sub-region being positioned closer to the drain region than the second sub-region, and wherein at least a portion of a lower surface of the first sub-region being in direct contact with the charge storage layer.