Patent ID: 6165847
Filing Date: 2000-12-26
Classification: H01L,Y10S

Abstract:
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of:(a) preparing a semiconductor substrate of a first conductive type;(b) effecting an ion implantation impurity of a first conductive type unto said semiconductor substrate to provide a first impurity diffusion layer region of a first conductive type in said semiconductor substrate;(c) forming a gate dielectric film an said semiconductor substrate and forming a floating gate on said gate dielectric film;(d) ion-implanting impurity of a second conductive type into said semiconductor substrate un an oblique direction relative to a surface of said semiconductor substrate, to thereby form at least a pair of impurity diffusion layers of a second conductive type defining source and drain, with one end overlapping with said floating gate and with the other end being spaced therefrom, and forming a split gate defined by a channel uncovered with said floating gate;(e) ion-implanting impurity of a second conductive type into said semiconductor substrate generally perpendicularly with respect to the surface of said semiconductor substrate, to such an extent as not to invert conductive type of the semiconductor substrate at said split gate, to thereby regulate threshold voltage of the split gate;(f) forming an interlayer dielectric so as to cover said floating gate and forming a control gate on said interlayer dielectric.