Nonvolatile semiconductor memory cell capable of saving overwritten cell and its saving method

• Main Authors: IMAMIYA; KENITI, NAKAMURA; HIROSHI
• Format: Patent
• Language: English
• Published: 29.06.1999
• Edition: 6
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INFORMATION STORAGE; PHYSICS; SEMICONDUCTOR DEVICES; STATIC STORES

If data is read from a selected memory cell at the time of overwrite verifying, a potential of a bit line is changed in accordance with data. If a transistor is turned on, a latch circuit is set in accordance with data of the bit line. In a case where there is a memory cell being in an overwrite state, data of the selected memory cell is latched to the latch circuit, and data corresponding to one page is erased. Thereafter, a normally writing operation is executed by data latch to the latch circuit, thereby the memory cell being in the overwrite state can be used as a normal threshold voltage.