Importance

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Abstract

To fabricate a nonvolatile memory, a select gate (140) is formed over a semiconductor substrate. A dielectric (810, 1010, 1030) is formed over the select gate. A floating gate layer (160), e.g. doped polysilicon, is formed over the select gate. The floating gate layer is removed from over at least a portion of the select gate. A dielectric (1510), e.g., ONO, is formed over the floating gate layer, and a control gate layer (170) is formed over this dielectric. The control gate layer has an upward protrusion over the select gate. Then another layer (1710), e.g. silicon nitride, is formed on the control gate layer, but the protrusions of the control gate layer are exposed. The exposed portion of the control gate layer is etched selectively until the control gate layer is removed from over at least a portion of the select gate. Then another layer (1910) is formed on the exposed portion of the control gate layer. This is thermally grown silicon dioxide in some embodiments. Then the silicon nitride is removed. The control gate layer, the ONO, and the floating gate layer are etched selectively to the silicon dioxide to define the control and floating gates. Other embodiments are also provided.

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First Claim