Method and device for erasing nor-type flash memory

Abstract

The embodiment of the invention provides an erasing method and a device of a NOR-type flash memory, comprising the steps of over-erasing and verifying a memory unit; Performing at least one programming operation on a memory cell that has not passed the erase verification, and recording the number of times of the programming operation; Performing erasure verification on the memory unit that performs at least one programming operation and passes the over-erasure verification; determining An erase pulse signal according to the number of programming operations, a preset erase time for performing an erase operation is instructed to be increased or decreased according to the erase pulse signal, and the erase operation is performed on a memory cell that has not passed the erase verification. Theembodiment of the invention provides an erasing method and a device of a NOR-type flash memory, which automatically adjusts the erasing time by recording the programming times of a memory cell after the current over-erasing verification fails, thereby reducing the erasing time and greatly improving the running speed of the NOR-type flash memory.

Description

technical field [0001] Embodiments of the present invention relate to the technical field of non-volatile memory, in particular to a method and device for erasing a NOR flash memory. Background technique [0002] In NOR flash memory, the time to erase a fixed-capacity storage unit is often used as one of the parameters to measure product performance. [0003] Traditional erasing methods include operations such as over-erase verification and erasure verification. The main function of the over-erase verification is to avoid the problem that the threshold voltage of the erased memory cell is too low. Because the threshold voltage that is too low will increase the time of the next programming operation. And erasure verification, its purpose is to see whether the memory cell is effectively erased. After the over-erased verification fails, a programming operation is required to increase the threshold voltage of the over-erased memory cell. However, after the erasure verificati...

AI Technical Summary

Problems solved by technology

If the erasing operation time is too long, it means that the erasing is too deep, then the more times of over-erase verification in the process of over-erase verification, the longer the required programming operation time; if over-erase verification The number of times is less, for example, only 1 or 0 times, then the erasing operation time is too short, which means that the erasing is not enough, which will increase the number of erasing operations

Therefore, if the single erasing time set in advance is too long or too short, it will increase the time required for the entire erasing process.

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