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

A non-volatile, method-of-operation technology, applied in the field of non-volatile flash memory, can solve problems such as small distribution intervals, difficult problems, etc., and achieve the effects of improving retention characteristics, large spacing, and reducing the number of defects

Active Publication Date: 2012-06-20
NANJING UNIV
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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).

Method used

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

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Embodiment Construction

[0028] The present invention proposes a new method for improving the storage properties of multi-value units for local capture non-volatile memory, which realizes 3-bit multi-value storage, avoids overlapping between different programming states, and enhances the retention characteristics of multi-value storage at the same time With tolerance characteristics, the problem of poor reliability of multi-value unit storage is solved.

[0029] figure 2It is a flowchart of the multi-value unit storage operation in the present invention. Firstly, the bilateral BBHH erasing process and the short-time FN programming operation are performed on the initial memory cell, so that the initial threshold voltage of the memory cell is set in the range of -2V ~ -1V. The above operation can be repeated several times to ensure that the charge in the storage layer of each memory unit is evenly distributed above the channel region, and to minimize the number of defects in the silicon nitride storag...

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Abstract

The invention relates to an operation method for increasing a high-density multi-valued storage characteristic of a non-volatile flash memory. The operation method comprises the following steps of: (1), adjusting an initial state of a local captured type non-volatile flash storage unit to threshold voltage of minus 2V to minus 1 V at first: adjusting to the threshold voltage by adopting a bilateral belt-belt tunnelling hot hole injection (BBHH) erasing method; and then carrying out a transient FN operation so as to promote charges in a channel to be distributed uniformly; (2), repetitively carrying out the step (1) for many times, wherein the initial state is adjusted to the threshold voltage of minus 2V to minus 1 V through the bilateral BBHH and FN operation steps, and the fact that the threshold voltage in a channel region is same everywhere is finally realized; (3), taking the threshold as the multi-valued storage initial state, and carrying out a multi-valued unitary programming operation on an NOR type local captured storage unit; and (4), carrying out a -FN process for a short time at one time after achieving a programming state. The operation method disclosed by the invention is capable of increasing holding characteristic and tolerance characteristic of a storage 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,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11C16/34G11C16/02
Inventor 闫锋吴春波徐跃纪晓丽
Owner NANJING UNIV
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