Fabrication method for flash memory
AssigneeWinbond Electronics Corp.
InventorWen-Yueh Jang
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Abstract
The present invention describes a method for fabricating flash memory. In accordance with the present invention, the forming of the floating gate does not require an additional photolithography step. As a result, the misalignment problem between the floating gate and the active area may be resolved. On the other hand, because of the specific floating gate structure of the present invention, high coupling capacitance between the floating gate and control gate can be achieved by recessing the shallow trench isolation more. Therefore, the method does not sacrifice the whole cell size.
Claims12
A flash memory structure formed on a semiconductor substrate having a plurality of active area islands isolated by a recessed isolation structure, said structure comprising:
- a plurality spacers respectively located on sides of said plurality of active area islands;
- a plurality of tunnel oxide layers respectively located over top surfaces of said plurality of active area islands;
- a plurality of doped silicon layers respectively located over said tunnel oxide layers and said spacers, wherein said doped silicon layers are formed as floating gates;
- a dielectric layer located over surfaces of said doped silicon layers and said recessed isolation structure;
- and
- a conductive layer located over said dielectric layer, wherein said conductive layer is a control gate.
Dependencies are inferred from the claim text.