Method of manufacturing a flash memory cell

A method of manufacturing a flash memory cell, comprising the steps of:

• sequentially forming a tunnel oxide film, a first polysilicon layer and a pad nitride film on a semiconductor substrate;
• forming a trench at the semiconductor substrate;
• forming a trench insulating film by which the trench is buried and then performing a chemical mechanical polishing (CMP) process to isolate the trench insulating film;
• removing the pad nitride film and then performing an etch process by which given portions of the trench insulating film are protruded;
• depositing a second polysilicon layer on the entire structure and then patterning the second polysilicon layer to form a floating gate;
• and
• forming a dielectric film and a control gate on the floating gate.