Patent ID: 7560767
Filing Date: 2009-07-14
Classification: H01L

Abstract:
1. A nonvolatile semiconductor device comprising: a source/drain diffusion layer provided in a semiconductor substrate; a first insulation film provided on a channel between the source/drain diffusion layers; a floating gate electrode provided on the first insulation film and composed of stacked first electrically conductive layers; a second insulation film provided on the floating gate electrode; and a control gate electrode provided on the second insulation film, wherein a bottom layer of the first electrically conductive layers is defined as a reference layer having a work function of 4.0 eV or more, and wherein a work function of each of the first electrically conductive layers increases gradually from the bottom layer toward a top layer of the first electrically conductive layers, wherein the reference layer is composed of an electrically conductive semiconductor material including impurities, and at least one first electrically conductive layer above the reference layer is composed of a metal.