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US 2003/0209753 A1Published application
Nonvolatile semiconductor memory device and method for manufacturing the same
AssigneeKabushiki Kaisha Toshiba
InventorsEiji Kamiya, Kazuhiro Shimizu
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Abstract
In a memory cell, a gate oxide film is formed on a surface of semiconductor substrate and a first floating gate is formed on the gate oxide film. An insulating film is formed on a first floating gate and a second floating gate is formed on the insulating film. The first and second floating gates constitute a floating gate in the memory cell. An insulating film between the first floating gate and the second floating gate acts as an etching stopper when a polysilicon constituting the second floating gate is etched.
Claims19
A nonvolatile semiconductor memory device comprising:
- a memory cell having a floating gate formed over a semiconductor substrate with a gate insulating film formed therebetween and a control gate insulated from the floating gate and source/drain regions formed in the semiconductor substrate at those areas situated on both sides of the floating gate;
- and
- an insulating film provided inside the floating gate.
A nonvolatile semiconductor memory device comprising:
- a first conductive film formed over a semiconductor substrate with a gate insulating film formed therebetween;
- a first insulating film formed on the first conductive film;
- a second conductive film formed on the first insulating film, the second conductive film and first conductive film constituting a floating gate;
- a second insulating film formed on the second conductive film;
- a third conductive film formed on the second insulating film and constituting a control gate;
- and
- source/drain regions formed in the semiconductor substrate at those areas situated on both sides of the floating gate.
4 more elements
A method for manufacturing a nonvolatile semiconductor memory device comprising the steps of:
- forming a first polysilicon film over a semiconductor substrate with a gate insulating film formed therebetween;
- forming a first insulating film on the first polysilicon film;
- forming a second polysilicon film on the first insulating film;
- forming a second insulating film on the second polysilicon film;
- forming a third polysilicon film on the second insulating film;
- forming a mask material on the third polysilicon film;
- a first etching process for etching the third polysilicon film by using mask material as a mask, the first etching process forming a control gate;
- a second etching process for etching the second polysilicon film to the first insulating film by using mask material as a mask, the second etching process forming a first floating gate;
- and
- a third etching process for etching the first polysilicon film to the gate insulating film by using mask material as a mask, the third etching process forming a second floating gate.
7 more elements
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of:
- sequentially forming a gate insulating film, first polysilicon film and first insulating film over a semiconductor substrate;
- forming a trench in the semiconductor substrate through a gate insulating film, first polysilicon film and first insulating film;
- depositing a second insulating film over a whole surface to bury the trench with the second insulating film;
- removing the second insulating film by etching to allow the second insulating film to remain in the trench at a height level lower than the surface of the first insulating film;
- removing the first insulating film;
- forming a third insulating film on the first polysilicon film;
- forming a second polysilicon film on the third insulating film;
- forming a fourth insulating film on the second polysilicon film;
- forming a third polysilicon film on the fourth insulating film;
- forming a mask material on the third polysilicon film;
- a first etching process for etching the third polysilicon film by using mask material as a mask, the first etching process forming a control gate;
- a second etching process for etching the second polysilicon film to the third insulating film by using mask material as a mask, the second etching process forming a first floating gate;
- and
- a third etching process for etching the first polysilicon film to the gate insulating film by using mask material as a mask, the third etching process forming a second floating gate.
11 more elements
A nonvolatile semiconductor memory device comprising:
- a plurality of first conductive films formed over a semiconductor substrate with a gate insulating film formed therebetween;
- a trench formed between those adjacent first insulating films and in the semiconductor substrate;
- a first insulating film for element isolation which is provided on the trench;
- a second insulating film formed on the first conductive film;
- a second conductive film formed on the second insulating film and, together with the first conductive film, constituting a floating gate;
- a third insulating film formed on the second conductive film;
- a third conductive film formed on the third insulating film and constituting a control gate;
- and
- source/drain regions formed in the semiconductor substrate at those areas situated on both sides of the floating gate.
6 more elements
Dependencies are inferred from the claim text.