Solid-state image pickup device, image pickup apparatus including the same, and method of manufacturing the same

An image pickup apparatus, comprising:

• a solid-state image pickup device;
• and
• an optical system for imaging an image of a subject on said solid-state image pickup device;
• said solid-state image pickup device including
• a semiconductor substrate, and
• a plurality of pixel circuits formed on said semiconductor substrate;
• each of said plurality of pixel circuits formed on said semiconductor substrate including
• a photoelectric conversion element,
• a first buried gate electrode formed adjacent to said photoelectric conversion element,
• a second buried gate electrode formed away from each of said photoelectric conversion element and said first buried gate electrode,
• a first diffusion layer formed between said first buried gate electrode and said second buried gate electrode, and
• a second diffusion layer formed between said first buried gate electrode and said second buried gate electrode away from said first diffusion layer so as to overlap said first diffusion layer;
• wherein electric charges accumulated in said photodiode conversion element are transferred to said second diffusion layer through said first diffusion layer.

A method of manufacturing a solid-state image pickup device, comprising the steps of:

• forming a hole for a first buried gate electrode of each of a plurality of pixel circuits and a hole for a second buried gate electrode of each of said plurality of pixel circuits on one surface side of a semiconductor substrate in said solid-state image pickup device in which said plurality of pixel circuits are formed on said semiconductor substrate;
• forming a first impurity region and a second impurity region in a circumference of said hole for said first buried gate electrode and in a circumference of said hole for said second buried gate electrode, respectively;
• forming said first buried gate electrode and said second buried gate electrode in said hole for said first buried gate electrode and in said hole for said second buried gate electrode, respectively;
• forming a first channel formation region having a lower impurity concentration than that of said first impurity region in a part of said first impurity region;
• forming a second channel formation region having a lower impurity concentration than that of said second impurity region in a part of said second impurity region;
• forming a photoelectric conversion element on said semiconductor substrate in a position contacting each of said first impurity region and said first channel formation region;
• and
• forming a second diffusion layer on one surface side of said semiconductor substrate between said first impurity region and said second impurity region so as to contact said second channel formation region, and forming a first diffusion layer within said semiconductor substrate away from said second diffusion layer so as to overlap said second diffusion layer and so as to contact each of said first channel formation region and said second channel formation region.