Split gate storage device including a horizontal first gate and a vertical second gate in a trench

摘要

A split gate storage device includes a first gate electrode in contact with a first gate dielectric and a second gate electrode in contact with a second gate dielectric. A first diffusion region underlies a portion of a trench defined in a semiconductor substrate and a second diffusion region occupies an upper portion of the substrate. A first gate dielectric lines the trench. One of the first and second gate dielectrics includes a layer of discontinuous storage elements (DSEs) and one of the first and second gate electrodes is located at least partially within the trench. In one case, the first gate electrode is a control gate and the first dielectric contains the layer of DSEs. In another case, the first gate electrode is a select gate and the second dielectric contains the layer of DSEs. The second gate dielectric lies over an upper surface of the substrate.