Non-volatile memory having three states and method for manufacturing the same

A method for manufacturing a non-volatile memory comprising the steps of:

• providing a silicon substrate having a device separation film;
• forming a first diffusion barrier film, a ferroelectric substance, and a second diffusion barrier film successively on the entire substrate;
• patterning the second diffusion barrier film, the ferroelectric substance, and the first diffusion barrier film into a size smaller than that of a desired floating gate;
• forming a third diffusion barrier film on the entire substrate including the patterned laminated films;
• etching the third diffusion barrier film to remove a part formed on the substrate;
• oxidizing the resulting substrate to selectively grow a silicon oxide film only on the substrate surface;
• forming a first polysilicon film for a floating gate on the silicon oxide film;
• patterning the first polysilicon film and the silicon oxide film into the shape of lines extending along a direction;
• forming an oxide film for a control gate, a second polysilicon film for a control gate, a tungsten silicide film, and a hard mask film successively on the entire substrate including the patterned first polysilicon film;
• etching the hard mask film, the tungsten silicide film, the second polysilicon film, and the oxide film to form a control gate in the shape of a line extending perpendicularly to the direction and a gate oxide film positioned below the control gate;
• etching the first polysilicon film and the silicon oxide film to form a floating gate made of the first polysilicon film and a tunnel oxide film positioned below both ends of the floating gate;
• forming spacers on both lateral walls of the laminated floating gate and control gate, respectively;
• and
• forming source/drain regions within the substrate surfaces on both sides of the control gate including the spacers, respectively.