Image pickup device, method of manufacturing image pickup device, and electronic apparatus
An image pickup device includes: a photodiode provided in a silicon substrate, and configured to generate electric charge corresponding to an amount of received light, by performing photoelectric conversion; and a transfer transistor provided at an epitaxial layer on the silicon substrate, and configured to transfer the electric charge generated in the photodiode, wherein the transfer transistor includes a gate electrode and a channel region, the gate electrode being embedded in the epitaxial layer, and the channel region surrounding the gate electrode, and the channel region has, in a thickness direction, a concentration gradient in which a curvature of a potential gradient is free from a mixture of plus and minus signs.
1. A method of manufacturing an image pickup device, the method comprising:
forming an epitaxial layer on a top surface of a silicon substrate by performing In-Situ Dope epitaxial growth, the epitaxial layer having a concentration distribution in which a curvature of a concentration gradient in a thickness direction is free from a mixture of plus and minus signs, and the silicon substrate including a photodiode that is configured to generate electric charge corresponding to an amount of received light, by performing photoelectric conversion; and
forming a channel region in a part of the epitaxial layer by inverting a part of the epitaxial layer, the channel region having, in a thickness direction, a concentration gradient in which a curvature of a potential gradient is free from a mixture of plus and minus signs, and the part being immediately above the photodiode.
2. The method of manufacturing the image pickup device according to claim 1 , wherein the channel region has a concentration distribution in which a curvature of a concentration gradient in the thickness direction is free from a mixture of plus and minus signs.
3. The method of manufacturing the image pickup device according to claim 2 , wherein
the channel region is of one conductivity type in the thickness direction, and
the channel region is a single layer.