METHOD FOR MANUFACTURING NONVOLATILE SEMICONDUCTOR MEMORY DEVICE

PROBLEM TO BE SOLVED: To suppress variations in cell characteristics due to widening of a diffusion layer as a bit line in a thermal process at the time of gate oxidation. SOLUTION: After a tunnel oxide film which needs a high temperature process is formed, a film for forming a floating gate and a first insulating film are patterned in a rectangular shape, and after impurity ions for forming a bit line are implanted, the floating gate is surrounded with a spacer by forming the side wall spacer at a side wall part of the film for forming the floating gate and the first insulating film, and then a first silicon oxide film is formed on the bit line and a second thick silicon oxide film is further formed thereupon by using a liquid phase deposition method.