MANUFACTURE AND STRUCTURE FOR NONVOLATILE SEMICONDUCTOR MEMORY DEVICE PROVIDED WITH STORAGE CELL ARRAY AND WITH PERIPHERAL CIRCUIT

摘要

PURPOSE: To readily adjust the thickness of a gate oxide film in an upper surface of a peripheral circuit region regardless of the thickness of an O-N-O insulation layer by forming an 0-N-0 insulation layer in a floating gate upper surface of a storage cell region and thereafter forming an oxide film in the upper surface and an upper surface of an exposed substrate in a peripheral circuit region. CONSTITUTION: An upper surface and a side surface of a floating gate 46 of a storage cell region 120 is covered with an O-N-O insulation layer 85. Then, a second insulation film 92 is formed in an upper surface of a substrate 70. Although the second insulation film 92 grows little in an upper surface of an oxide film of an upper part of the O-N-O insulation film 85, its growth is good in an upper surface of an exposed substrate of a peripheral circuit region 125. Therefore, the thickness of the second insulation film 92 which becomes a gate oxide film of the peripheral circuit region 125 can be adjusted readily to be optimum for circuit operation.