摘要:
A nonvolatile semiconductor memory device comprises a memory cell array in which a plurality of memory cell units are arranged in a matrix, and a first and second common signal lines for exchanging signals with the memory cell array, wherein each of the memory cell units contains a nonvolatile memory section having at least one nonvolatile memory cell, a first select MOS transistor for making the nonvolatile memory section conducting to the first common signal line, and a second select MOS transistor with a threshold voltage different from that of the first select MOS transistor for making the nonvolatile memory section conducting to the second common signal line.
摘要:
A nonvolatile semiconductor memory device comprises a memory cell array in which a plurality of memory cell units are arranged in a matrix, and a first and second common signal lines for exchanging signals with the memory cell array, wherein each of the memory cell units contains a nonvolatile memory section having at least one nonvolatile memory cell, a first select MOS transistor for making the nonvolatile memory section conducting to the first common signal line, and a second select MOS transistor with a threshold voltage different from that of the first select MOS transistor for making the nonvolatile memory section conducting to the second common signal line.
摘要:
A nonvolatile semiconductor memory device comprises a memory cell array in which a plurality of memory cell units are arranged in a matrix, and a first and second common signal lines for exchanging signals with the memory cell array, wherein each of the memory cell units contains a nonvolatile memory section having at least one nonvolatile memory cell, a first select MOS transistor for making the nonvolatile memory section conducting to the first common signal line, and a second select MOS transistor with a threshold voltage different from that of the first select MOS transistor for making the nonvolatile memory section conducting to the second common signal line.
摘要:
A nonvolatile semiconductor memory device has reduced parasitic capacitance at a select transistor obtained by providing a depletion-mode select transistor with a charge accumulation layer, virtually making a gate insulating film thicker, or providing under the gate insulating film a channel layer that is of a same conductivity type as that of a source and drain regions and connects thereto, thereby enabling the potential of the select gate to be almost fixed at a desired value, preventing a faulty operation and making it possible to cause the select transistor to operate at high speed.
摘要:
The time required for the program verify and erase verify operations can be shortened. The change of threshold values of memory cells can be suppressed even if the write and erase operations are executed repetitively. After the program and erase operations, whether the operations were properly executed can be judged simultaneously for all bit lines basing upon a change, after the pre-charge, of the potential at each bit line, without changing the column address. In the data rewrite oepration, the rewrite operation is not effected for a memory cell with the data once properly written, by changing the data in the data register.
摘要:
The time required for the program verify and erase verify operations can be shortened. The change of threshold values of memory cells can be suppressed even if the write and erase operations are executed repetitively. After the program and erase operations, whether the operations were properly executed can be judged simultaneously for all bit lines basing upon a change, after the pre-charge, of the potential at each bit line, without changing the column address. In the data rewrite operation, the rewrite operation is not effected for a memory cell with the data once properly written, by changing the data in the data register.
摘要:
An EEPROM for storing multi-level data includes a memory cell array in which electrically erasable and programmable memory cells are arranged in matrix and each of the memory cells has at least three storage states, a write circuit for writing data to the memory cells, first and second write verify means each constituted of a sense amplifier, a data latch circuit and a detection circuit, for verifying an insufficient-written state of a memory cell and an excess-written state of a memory cell, respectively, an additional write circuit for additionally writing data to the memory cell in the insufficient-written state, and an additional erase circuit for additionally erasing data from the memory cell in the excess-written state.
摘要:
The time required for the program verify and erase verify operations can be shortened. The change of threshold values of memory cells can be suppressed even if the write and erase operations are executed repetitively. After the program and erase operations, whether the operations were properly executed can be judged simultaneously for all bit lines basing upon a change, after the pre-charge, of the potential at each bit line, without changing the column address. In the data rewrite operation, the rewrite operation is not effected for a memory cell with the data once properly written, by changing the data in the data register.