| 摘要 |
Substrate isolation regions (570) initially protrude upward above a semiconductor substrate (520) but are later etched down. Before they are etched down, floating gate layer (590) is deposited and etched or polished off the top surfaces of the substrate isolation regions. The floating gate layer thus has upward protrusions overlying sidewalls of the substrate isolation regions. When the substrate isolation regions are etched down, the floating gate layer's upward protrusions' outer sidewalls become exposed. The upward protrusions serve to increase the capacitance between the floating and control gates. The floating gates' bottom surfaces are restricted to the active areas (564) not to overlie the substrate isolation regions. Other features are also provided.
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