METHOD FOR MANUFACTURING NONVOLATILE MEMORY DEVICES

摘要

PURPOSE: A fabrication method of nonvolatile memory is provided to improve a reliability of gate oxide by reducing a recess generated at the surface of active region adjacent to an isolation layer. CONSTITUTION: The method comprises the steps of: forming an isolating oxide layer(61) defining an active region and a device isolation region on a semiconductor substrate(51) divided by memory cell array, high voltage device and low voltage device regions; sequentially depositing a first gate oxide(63) and a first conductive layer(65); forming an interlayer dielectric(67) and selectively etching the interlayer dielectric, the first conductive layer and the first gate oxide formed in the high voltage device region; forming a second gate oxide(71) and selectively etching the interlayer dielectric, the first conductive layer and the first gate oxide formed in the memory cell array and the low voltage device regions; depositing a third gate oxide(75) and a second conductive layer on the resultant structure; and forming a control gate(77) in the cell array region and forming gates(77',77") of the high voltage and low voltage devices in the high voltage and low voltage device regions, respectively.