| 摘要 |
A method for operating a semiconductor memory device includes the steps of: erasing memory cells of a memory block to set the memory cells in a first erased state, programming a part of the memory cells of the memory block to convert them into a programmed state, raising threshold voltages of selected memory cells of the memory block and converting the selected memory cells from the programmed state to a second erased state, and reading data from the memory cells in the first erased state, the programmed state, and the second erased state, and outputting the data read from the memory cells in the first and second erased states with the same value. |
