Patent ID: 7772654

Claim:
A method of fabricating a nonvolatile memory device, the method comprising: forming device isolation films on a semiconductor substrate having a cell field region, a high-voltage field region, and a low-voltage field region; forming a high-voltage gate-insulation film and a high-voltage gate-conductive film on the high-voltage field region; forming a low-voltage gate-insulation film and a low-voltage gate-conductive film both in the cell field region and low-voltage field region of the substrate; forming a first mask on the substrate, wherein the first mask exposes an entire top surface of the low-voltage gate-conductive film in the cell field region, and exposes a top surface of the high-voltage gate-conductive film to reveal the device isolation films in the high-voltage field region, and covers an entire top surface of the low-voltage gate conductive film in the low-voltage field region; implanting impurities into substrate according to the mask; removing all the low-voltage gate-insulation film and all the low-voltage gate-conductive film in the cell field region, the high-voltage gate-insulation film, the high-voltage gate-conductive film and a portion of the device isolation films in the high-voltage field region according to the first mask; and after the implanting, forming a cell gate-insulation film and a cell gate-conductive film in the cell field region, wherein the cell gate-insulation film, the low-voltage gate-insulation film and the high-voltage gate-insulation film are different materials or have different thicknesses.