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US 2012/0235222 A1Published application
Nonvolatile semiconductor memory device and method for manufacturing the same
AssigneeKabushiki Kaisha Toshiba
InventorTakeshi KAMIGAICHI
Life of this patent
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Abstract
A device isolation film has a first height in a first area and a second height higher than the first height in a second area. The first area includes a first end of a dummy memory transistor facing a memory string and a part of a device isolation film adjacent thereof. The second area includes a second end of the dummy memory transistor facing a select transistor and a part of the device isolation film adjacent thereof.
Claims19
A nonvolatile semiconductor memory device comprising:
- a semiconductor layer having a first area and a second area;
- an active area formed in the semiconductor layer and including a memory string including memory transistors connected in series, a dummy memory transistor connected to one end of the memory string and not used for storing data, and a select transistor connected to one end of the memory string via the dummy memory transistor;
- and
- a device isolation film formed on the semiconductor layer, surrounding the active area, and having a first height in the first area and a second height higher than the first height in the second area,
- the first area including a first end of the dummy memory transistor facing the memory string and a part of the device isolation film adjacent thereof, and the second area including a second end of the dummy memory transistor facing the select transistor and a part of the device isolation film adjacent thereof.
2 more elements
A method for manufacturing a nonvolatile semiconductor memory device, comprising:
- forming an electric storage film above a semiconductor layer via a gate insulating film;
- forming a plurality of trenches in the electric storage film, the gate insulating film and the semiconductor layer thereby to form active areas;
- forming a device isolation film to embed the trenches;
- forming a resist so as to expose a first area and to cover a second area of the semiconductor layer;
- etching back the device isolation film using the resist as a mask to lower a position of a top surface of the device isolation film in the first area;
- forming a control gate film above the electric storage film via an insulating film;
- and
- processing the control gate film, the insulating film, and the electric storage film, thereby to form a memory string including memory transistors connected in series, a dummy memory transistor connected to one end of the memory string, not used for storing data in, and formed in a boundary of the first and the second areas, and a select transistor connected to one end of the memory string via the dummy memory transistor.
5 more elements
Dependencies are inferred from the claim text.