Solid-state imaging device having a defect control layer and an inversion layer between a trench and a charge accumulating area
View Patent ↗An inversion layer is formed in a part as a boundary between (a) a defect control layer formed along a trench surface for isolating pixel calls and (b) a photo diode. The defect control layer is a P-type, and the photo diode and the inversion layer are N-type. Here, an impurity concentration in the inversion layer is at least twice as high as an impurity concentration in the photo diode.
1. A solid-state imaging device comprising:
a semiconductor substrate; and
a well of a first conductivity type that is formed in the semiconductor substrate and is divided into a plurality of pixel cells by a trench to isolate the pixel cells from each other, the trench forming a lattice pattern in plan view, and each pixel cell having a photo diode, a shield layer, a defect control layer, and an inversion layer, wherein
the photo diode is of a second conductivity type,
the shield layer is of the first conductivity type, is located between a surface of the pixel cell and the photo diode, and contacts the photo diode,
the defect control layer is of the first conductivity type, is highly concentrated by addition of an impurity of the first conductivity type, and is located along a trench surface, and
the inversion layer is of the second conductivity type, contacts the defect control layer, the shield layer, and the photo diode, and separates the defect control layer from the photo diode, an impurity concentration in the inversion layer being higher than an impurity concentration in the photo diode.
2. The solid-state imaging device of claim 1 , wherein a maximum value of an impurity concentration in the inversion layer is at least twice as high as a maximum value of an impurity concentration in the photo diode.