Operation method for increasing high-density storage characteristic of non-volatile flash memory

Abstract

An operation method to improve the high-density multi-value storage characteristics of non-volatile flash memory. 1) First adjust the initial state of the local capture type non-volatile flash memory cell to the threshold voltage -2V~-1V: use bilateral band -The erasing method with tunneling hot hole injection (BBHH) is adjusted to the threshold voltage; then a transient FN operation is performed to promote uniform charge distribution in the channel; 2) Step 1) is performed by repeating several times , the bilateral BBHH and FN operation steps adjust the initial state to a threshold voltage of -2V ~ -1V, and finally achieve the same threshold voltage distribution in the channel area; 3) Using the above threshold as the initial state of multi-value storage, for NOR type The local capture memory unit performs the programming operation of the multi-valued unit; 4) After reaching the programming state, a short-time -FN process is performed; the present invention can improve the retention characteristics and tolerance characteristics of the memory device.

Description

technical field [0001] The invention relates to an operation method of a non-volatile flash memory (Flash), in particular to a method for effectively improving storage retention characteristics and enhancing the tolerance of storage devices after high-density multi-valued storage programming of a local capture type memory . Background technique [0002] Nowadays, non-volatile flash memory has been widely used in various portable electronic products, such as digital cameras, personal digital assistants, mobile phones and laptop computers, etc., and high-capacity and low-cost flash memory has become an urgent demand in the market. However, as the cell size of the memory is further reduced and approaches the physical limit, it becomes more and more difficult to increase the storage capacity by reducing the cell size. Therefore, once the concept of multi-value cell storage is proposed, it immediately attracts everyone. look. However, in the existing multi-value storage method,...

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Problems solved by technology

However, if you want to realize 3-bit storage on each side of the NROM cell, it is equivalent to realizing 8 threshold voltage distributions in the 3V operating window. Traditional CHE programming technology is difficult to achieve such a small distribution range (0.3V).

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