Semiconductor memory which is protected from erasure by light shields

Abstract

A nonvolatile semiconductor memory device having memory cells in which a control gate is stacked on a floating gate through an insulating film. The memory device has redundant memory cells so as to compensate defective memory cells and a transistor to select the redundant memory cells and the redundant memory cells and the transistor to select the redundant memory cells are formed by a nonvolatile memory transistor. The transistor to select the redundant memory cells has a structure in which the upper surface and side walls of the floating gate are covered by a control gate or a structure in which the floating gate and control gate are covered by a light shielding film and an antireflection film formed under the light shielding film. In a nonvolatile semiconductor memory device having memory cells of a structure in which a control gate is stacked on a floating gate through an insulating film, a phosphosilicate glass film is formed on side walls of the floating gate and the control gate and a silicon nitride film and an arseno-silicate glass film or boro-phospho-silicide glass film are sequentially formed so as to cover the control gate.