Abstract: A localized trapping multi-level memory cell operating method includes the following steps. First, a localized trapping memory cell with the initial threshold voltage of ˜2.5V is provided. Next, an erasing operation is performed to obtain a negative threshold level which has the uniform distribution along the channel region. Taking into account the over-erasure issue in the erasing course, a programming operation is performed to precisely adjust the threshold voltage to a predetermined level of ?2V˜?1V. Then, with the negative voltage as a new initial state, corresponding programming operation is performed and electrons are locally injected the storage layer. By controlling the quantity of injected electrons, the MLC storage is achieved.

Abstract: A localized trapping multi-level memory cell operating method includes the following steps. First, a localized trapping memory cell with the initial threshold voltage of approximately 2.5V is provided. Next, an erasing operation is performed to obtain a negative threshold level having uniform charge distribution along the channel region. Taking into account the over-erasure issue in the erasing operation, a programming operation is performed to precisely adjust the threshold voltage to a predetermined level of ?2V to ?1V. Then, with this negative voltage as a new initial state, a corresponding programming operation is performed and electrons are locally injected into the storage layer. By controlling the quantity of injected electrons, the MLC storage is achieved.