Accurate multi-valued memory cell programming method

A programming method and multi-value storage technology, applied in the field of precise programming, local capture type memory to realize multi-value storage, can solve the degradation of memory cell tolerance and retention characteristics, program/erase position mismatch, short channel The memory cell aggravates the second bit effect and other problems, and achieves the effect of reducing the second bit effect, accurate programming, and small spatial distribution range.

Inactive Publication Date: 2014-08-27
NANJING UNIV
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Problems solved by technology

When programming a higher threshold voltage in the traditional ISPP multi-value cell programming method, the initial amplitude of the programming pulse used is very large, and the distribution range of electrons will be too wide for the local capture type flash memory cell. Make the program / erase position mismatch more serious, degrade the tolerance and retention characteristics of the memory cell, and aggravate the second bit effect for short-channel memory cells

Method used

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  • Accurate multi-valued memory cell programming method
  • Accurate multi-valued memory cell programming method
  • Accurate multi-valued memory cell programming method

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Embodiment

[0032] Taking the local trap type SONOS multi-value memory cell as an example, the programming operation of each state of the above-mentioned multi-value cell can adopt the substrate positive bias to suppress the second-generation hot electron injection (CHE) programming method, or use the pulse-excited The programming method of Substrate Hot Electron Injection (PASHEI) realizes the programming of charge localization. Figure 4 It is a schematic diagram of the programming principle of realizing different programming states by using the CHE method of substrate positive bias. The structure of the SONOS memory cell is: on a P-type semiconductor substrate 10 N-type semiconductor regions are provided on both sides above to form the source 11 and drain 12 , directly above the substrate, between the source and drain is the channel region. Tunneling layers are arranged directly above the channel region 16 , charge storage layer 15 and barrier 14 , above the barrier is the gate ...

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Abstract

An accurate multi-valued memory cell programming method, the steps are as follows: first, the cell in the erasing state is programmed to the programming state of the lowest bit of the threshold voltage through the continuous multiple pulse ISPP method with a lower programming pulse voltage; Whether the threshold voltage reaches the first-level programming verification voltage VPV1, and if so, stop programming and record the last programming pulse voltage V1max of the first-level programming; use the last programming pulse voltage V1max of the first-level programming state as the initial voltage to perform ISSP mode Programming; verify whether the threshold voltage after programming reaches the second-level programming verification voltage; if VPV2 reaches, stop programming and record the last programming voltage V2max of the second-level programming; otherwise, continue the second-level programming operation; continue the same operation, Until all bits are stored. A narrow electron distribution can be obtained after programming.

Description

technical field [0001] The invention relates to a programming method of a non-volatile flash memory, in particular to a precise programming method for realizing multi-value storage of a local capture memory. Background technique [0002] Non-volatile flash memory has been widely used in various portable electronic products such as USB flash drives, MP3 players, digital cameras, personal digital assistants, mobile phones and laptop computers. Increasing storage capacity and reducing production cost have become the most important technical issues of non-volatile flash memory. In recent years, more and more attention has been paid to increasing storage density and reducing production cost through multi-value storage technology, which has become a hot spot in the research of non-volatile flash memory. Different from single-value memory cells that can only store one bit, multi-value memory cells use different programming voltages or programming times to change the amount of char...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G11C16/34
Inventor 徐跃闫锋濮林纪小丽
Owner NANJING UNIV
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