Solid state image sensor and method of manufacturing solid state image sensor
A solid state image sensor according to an embodiment includes a transfer gate, a floating diffusion portion that converts signal charge transferred from a photodiode via the transfer gate into a voltage signal, and an extraction electrode that is formed of a film of conductive material including any of amorphous silicon, monocrystalline silicon, or N+ polysilicon, that has a peripheral edge portion surrounded by a film of insulating material and one end electrically connected to the floating diffusion portion, and that transmits the voltage signal.
1 . A method of manufacturing a solid state image sensor comprising:
forming a transfer gate covered with a first film of insulating material made of a first insulating material on a semiconductor substrate;
forming a mask with a second insulating material that can be selectively etched with respect to the first insulating material, at a predetermined connection position between an extraction electrode and a Si surface;
performing oxidation treatment in a state where the mask is formed, in order not to oxidize the planned connection position; and
selectively etching the second insulating material and removing the second insulating material;
forming a film of conductive material with a conductive material, at a predetermined position where the extraction electrode is formed, and forming the extraction electrode; and
forming a floating diffusion portion by thermal diffusion, via the extraction electrode.
2 . The method of manufacturing a solid state image sensor according to claim 1 , wherein
the solid state image sensor includes an amplification transistor, and
the method comprises forming wiring for a gate terminal of the amplification transistor, with the same film of conductive material as the film of conductive material forming the extraction electrode, in parallel with the forming of the extraction electrode.
3 . The method of manufacturing a solid state image sensor according to claim 1 , wherein
the solid state image sensor includes a reset transistor, and
the method comprises forming wiring with a source terminal of the reset transistor by a floating diffusion portion formed by diffusing an N-type dopant via the extraction electrode, after forming the extraction electrode.