Image sensor having 3-dimensional transfer transistor and its method of manufacture

Abstract

In an embodiment, an image sensor includes an isolation layer disposed in a semiconductor substrate to define a first active region and a second active region extending from the first active region. A photodiode is disposed in a portion of the first active region. A floating diffusion region is provided in the second active region at a position spaced apart from the photodiode. A transfer gate electrode is disposed on the second active region between the photodiode and the floating diffusion region. The transfer gate electrode is disposed to cover both sidewalls and an upper portion of the second active region. The transfer gate electrode has a region extending onto the first active region and overlapping the photodiode. The photodiode has a protrusion into the second active region at the portion adjacent to the transfer gate electrode. A deep n-impurity region of the photodiode extends in the protrusion.