Semiconductor device having thin electrode laye adjacent gate insulator and method of manufacture

A method of manufacturing a semiconductor device having non-volatile memory cells, each of the non-volatile memory cells including a floating gate electrode formed over a surface of an active region of a semiconductor substrate through a first gate insulating film and a control gate electrode formed over a surface of the floating gate electrode through a second gate insulating film, comprising the steps of:

• (a) forming over a part of a surface of the first gate insulating film a first gate material, in which an amorphous silicon film, a polycrystalline silicon film or a film of a combination of amorphous and polycrystalline silicon materials, with an average thickness of less than 10 nm, is formed as a first layer over the first gate insulating film, in which a surface of an uppermost layer of the first gate material is covered with an oxidation resistant mask, and in which a width in a direction of gate length is defined;
• (b) performing a heat treatment to form a thermally oxidized insulating film over the surface of the active region of the semiconductor substrate;
• (c) removing the oxidation resistant mask;
• (d) forming over surfaces of the thermally oxidized insulating film and the first gate material a second gate material made of a silicon film whose width in the direction of gate length is defined;
• (e) forming a second gate insulating film over a surface of the second gate material;
• and
• (f) forming a third gate material over a surface of the second gate insulating film,
• wherein said first layer of the first gate material has a second, conductive layer formed thereover, said second, conductive layer constituting Dart of the first gate material, and wherein an insulating film is formed on the first layer, between the first layer and second, conductive layer.

A method of manufacturing a semiconductor device, comprising the steps of:

• forming an amorphous silicon film, the amorphous silicon film having a thickness;
• and
• forming an insulating film over a surface of the amorphous silicon film at a temperature such that the amorphous silicon film does not crystallize, said temperature being less than a crystallization temperature based upon the thickness of the amorphous silicon film;
• wherein subsequent processes, after forming the insulating film, are performed at temperatures such that the amorphous silicon film does not crystallize, said temperatures being less than the crystallization temperature based upon the thickness of the amorphous silicon film.

A method of manufacturing a semiconductor device, comprising the steps of:

• forming a first film, of an electrode, over a gate insulating film on a semiconductor substrate, the first film being made of a material selected from the group consisting of amorphous silicon, polycrystalline silicon and a mixture thereof, the first film having a thickness of less than 10 nm;
• forming an insulating film on the first film;
• forming a conductive second film, of said electrode, on the insulating film, the conductive second film being thicker than the first film;
• and
• performing a heat treatment, wherein during said heat treatment the insulating film is eliminated.

A method of manufacturing a semiconductor device, comprising the steps of:

• forming a first film, of an electrode, over a gate insulating film on a semiconductor substrate, the first film being made of amorphous silicon;
• forming an insulating film on the first film;
• forming a conductive second film, of said electrode, on the insulating film, the conductive second film being thicker than the first film and
• performing a heat treatment, wherein during said heat treatment the insulating film is eliminated.