US Patent 7482649 Multi-bit nonvolatile memory devices

Multi-bit nonvolatile memory devices and related methods of manufacturing the same are described. In some multi-bit nonvolatile memory devices, a semiconductor substrate has a recessed region defined therein. An insulating layer, which can include an ONO layer, is configured to store data within programming regions therein, and covers a sidewall and a lower surface of the recess region. A gate electrode is on the insulating layer in the recessed region. At least one pair of impurity regions are in the semiconductor substrate. The impurity regions adjoin a side surface of the insulating layer in the recess region and form a relative angle that is less than 120° therebetween with respect to a center of the gate electrode.