Nonvolatile semiconductor memory device
AssigneeHitachi, Ltd.
InventorKeiichi Yoshida
Life of this patent
Estimating the term…
Abstract
The bit (B6) indicating whether there is the possibility or not to normally complete the write operation by executing again the write operation is provided, together with the bit (B7) indicating whether the access is possible or not from the external side of the chip and the bit (B4) indicating whether the write operation is normally completed or not, to the status register within a non-volatile semiconductor memory device. Accordingly, it can be prevented that the effective memory capacity is reduced with an accidental write error in the electrically programmable and erasable non-volatile semiconductor memory device such as a flash memory.
Claims10
A nonvolatile memory device comprising:
- a plurality of memory cells;
- and
- a status register,
- wherein each of said memory cells has a threshold voltage within one of a plurality of threshold voltage ranges, one of which is for an erase state and others are for program states,
- said nonvolatile memory is capable of performing an erase operation and a program operation, in said erase operation each threshold voltage of selected memory cells of said plurality moves within a threshold voltage range for said erase state, and in said program operation each threshold voltage of said selected memory cells moves within a desired threshold voltage range according to data,
- wherein said status register has a plurality of status bits,
- wherein a first bit in said status bits indicates performance of said erase operation or said program operation,
- wherein a second bit in said status bits indicates whether all threshold voltages of said selected memory cells move within the desired threshold voltage range or at least one threshold voltage of said selected memory cells does not move within the desired threshold voltage range, and
- wherein a third bit in said status bits indicates that at least one threshold voltage of said selected memory cells moves over the desired threshold voltage range.
Dependencies are inferred from the claim text.