Patent ID: 9224875
Filing Date: 2015-12-29
Classification: H01L

Abstract:
1. A nonvolatile semiconductor storage device, comprising: a semiconductor substrate; a control gate formed on the semiconductor substrate and having a cylindrical through hole extending from a top surface to a bottom surface thereof; a block insulating film formed on a side surface of the control gate inside the through hole; a charge storage film formed on the side surface of the block insulating film inside the through hole; a tunnel insulating film formed on the side surface of the charge storage film inside the through hole; and a semiconductor layer formed on the side surface of the tunnel insulating film inside the through hole, wherein the tunnel insulating film includes a first insulating film having SiO the tunnel insulating film includes a first point, a second point, and a third point in this order from the semiconductor layer toward the charge storage film, and a first density of the element at the first point is lower than a second density of the element at the second point and the second density of the element is lower than a third density of the element at the third point.