Layers of epitaxial silicon are used to protect the tunnel dielectric layer of a floating-gate memory cell from excessive oxidation or removal during the formation of shallow trench isolation (STI) regions. Following trench formation, the layers of epitaxial silicon are grown from silicon-containing layers on opposing sides of the tunnel dielectric layer, thereby permitting their thickness to be limited to approximately one-half of the thickness of the tunnel dielectric layer. The epitaxial silicon may be oxidized prior to filling the trench with a dielectric material or a dielectric fill may occur prior to oxidizing at least the epitaxial silicon covering the ends of the tunnel dielectric layer.