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Accurate multi-valued memory cell programming method

A technology of multi-value storage and programming method, which is applied in the field of local capture memory to realize multi-value storage and precise programming, and can solve the problem of memory cell tolerance and retention characteristic degradation, programming/erasing position mismatch, short channel The storage unit aggravates the second bit effect and other problems, and achieves the effects of reducing the second bit effect, accurate programming, and small spatial distribution range

Inactive Publication Date: 2012-03-21
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

The invention discloses an accurate multi-valued memory cell programming method. The accurate multi-valued memory cell programming method comprises the following steps of 1, applying low programming pulse voltage to a unit in an erasing state, and programming through a continuous multi-pulse ISPP method to obtain a lowest-threshold voltage programming state, 2, verifying if after programming, threshold voltage reaches verifying voltage VPV1 of first-stage programming or not, wherein if the threshold voltage reaches the verifying voltage VPV1 of the first-stage programming, the first-stage programming is stopped and last programming pulse voltage V1max of the first-stage programming is recorded, 3, carrying out ISSP-type programming, wherein the last programming pulse voltage V1max of the first-stage programming is utilized as initial voltage, 4, verifying if after programming, threshold voltage reaches verifying voltage VPV2 of second-stage programming or not, wherein if the threshold voltage reaches the verifying voltage VPV2 of the second-stage programming, the second-stage programming is stopped and last programming pulse voltage V2max of the second-stage programming is recorded, and if the threshold voltage does not reach the verifying voltage VPV2 of the second-stage programming, the second-stage programming is carried out sequentially, and 5, carrying out a process same as above until all bits are stored. After programming, narrow electron distribution is realized.

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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IPC IPC(8): G11C16/34
Inventor 徐跃闫锋濮林纪小丽
Owner NANJING UNIV
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