Patent ID: 8399914

Claim:
A method for making a solid-state imaging device including a semiconductor substrate having a signal-readout surface in which a photoelectric conversion unit and a transfer transistor are formed, the photoelectric conversion unit including a first region and a second region that form a pn junction therebetween, the transfer transistor being configured to transfer signal charges from the photoelectric conversion unit to a readout drain via a channel region, the method comprising the steps of: forming the first region in the semiconductor substrate by implanting ions of an impurity of a first conductivity type into a portion of the signal-readout surface where the photoelectric conversion unit, the channel region, and the readout drain are to be formed; forming the second region in the semiconductor substrate by implanting an impurity of a second conductivity type into a portion of the signal-readout surface where the photoelectric conversion unit, the channel region, and the readout drain are to be formed, the portion being located at a position deeper than the first region; forming a resist pattern over the signal-readout surface, the resist pattern having an opening that leaves a portion of the signal-readout surface uncovered where the channel region and the readout drain are to be formed; forming a third region in the semiconductor substrate by implanting an impurity of the first conductivity type into a portion of the signal-readout surface where the channel region and the readout drain are to be formed, the portion being located at a position deeper than the first region, while using the resist pattern as a mask; removing a portion of the first region that lies above the third region by etching; forming a gate insulating film of the transfer transistor on a portion of the signal-readout surface of the semiconductor substrate from which the first region has been removed; forming a transfer gate electrode that extends from above the channel region with the gate insulating film therebetween to above the first region; and forming the readout drain by implanting ions of an impurity of the second conductivity type into a portion of the signal-readout surface of the semiconductor substrate from which the first region has been removed, while using the transfer gate electrode as a mask.