Non-volatile semiconductor memory devices with dual control gate memory
cells and methods of forming are provided. A charge storage layer is
etched into strips extending across a substrate surface in a row
direction with a tunnel dielectric layer therebetween. The resulting
strips may be continuous in the row direction or may comprise individual
charge storage regions if already divided along their length in the row
direction. A second layer of dielectric material is formed along the
sidewalls of the strips and over the tunnel dielectric layer in the
spaces therebetween. The second layer is etched into regions overlaying
the tunnel dielectric layer in the spaces between strips. An intermediate
dielectric layer is formed along exposed portions of the sidewalls of the
strips and over the second dielectric layer in the spaces therebetween. A
layer of control gate material is deposited in the spaces between strips.
The resulting control gates are separated from the strips by the
intermediate dielectric layer and from the substrate surface by the
tunnel dielectric layer, the second layer of dielectric material and the
intermediate dielectric layer.