Operation method of silion nitride read-only memory element

Abstract

The user of silicon nitride read-only memory elements is that a heavy doping base is provided for surroundings of source electrode / drain electrode. When programming, a relative plus source bias-voltage or a relatively minus base bias-voltage are used for increasing base effect and reducing the electric current of channel hot electron injection program. Before erasing of array of silicon nitride read-only memory element, a pre-programming is applied for all memory units to prevent over erasion.

Description

technical field [0001] The present invention relates to a method for operating a read-only memory device, and in particular to a method for operating a silicon nitride read-only memory device (NROM device for short). Background technique [0002] The current silicon nitride read-only memory device uses a stacked structure composed of a silicon oxide / silicon nitride / silicon oxide (ONO) composite layer as a charge trapping layer, while silicon oxide / silicon nitride / silicon oxide The (ONO) layer has a gate and a source / drain in the substrate adjacent to the gate. Because the material of the charge trapping layer is mainly silicon nitride, this kind of electrically erasable and programmable read-only memory (electrically erasable programmable ROM) is also called silicon nitride read-only memory (NROM). [0003] Since the silicon nitride layer has the effect of capturing charges, the electrons injected into the silicon nitride layer are not evenly distributed in the entire silic...

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Problems solved by technology

[0004] However, as semiconductor devices continue to be miniaturized, the gate line width will gradually shrink, which will cause problems in the operation of silicon nitride read-only memory devices, such as requiring a large current for programming operations; and especially When erasing (erasing), because it will locally inject holes (holes) in the channel close to the source or drain, especially after multiple erasing, because a large amount of Therefore, there will be serious leakage (leakage) for another electron that uses the same bit line or word line, especially at high temperatures. This is the so-called "over-erase )”

Moreover, the above situation will also be more serious after the initial voltage is reduced or the channel length is shortened.

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