Method for improving performance of device of SONOS (silicon-oxide-nitride-oxide-silicon) structure

Abstract

The invention discloses a method for improving performance of a device of an SONOS (silicon-oxide-nitride-oxide-silicon) structure. The SONOS structure comprises a substrate, a tunneling dielectric layer, a charge storage layer, a barrier dielectric layer and a conducting layer, wherein the substrate comprises a source and a drain inside, and the tunneling dielectric layer, the charge storage layer, the barrier dielectric layer and the conducting layer are arranged on the substrate from bottom to top in sequence, wherein a concave SONOS structure design is adopted and a graded silicon nitride layer is used for forming the charge storage layer. The method has the following beneficial effects: the formation of the concave SONOS structure facilitates the difference of distribution of the electric field strength in different layers, so that the compiling and erasing speeds can be increased, and the impact of the erasing saturation on the erasing speed can be inhibited; due to relatively low difference between the Young's moduli of the graded silicon nitride layer and the tunneling silicon oxide layer, the impact of stress caused by relatively high difference between the Young's moduli of the tunneling silicon oxide layer and the silicon nitride on the device can be reduced; and the trapped electrons can be redistributed by the gradual silicon nitride layer, so that the storage charges can be distributed in the charge storage layer more uniformly.

Description

technical field [0001] The invention relates to the technical field of SONOS structure, in particular to a method for improving the performance of SONOS structure devices. Background technique [0002] Flash memory is a kind of non-volatile memory device. Traditional flash memory uses floating gates to store data. Since polysilicon is a conductor, the charges stored in floating gates are continuously distributed. When there is a leakage channel, the charge stored on the entire floating gate is lost through this leakage channel. Therefore, the biggest obstacle limiting the ability of flash memory to scale down is that its tunnel oxide thickness cannot be continuously reduced. Because in the case of a thin tunnel oxide layer, effects such as direct tunneling and stress-induced leakage current will pose a huge challenge to the leakage control of the memory. With the widespread application of flash memory, the newly developed SONOS structure (Sillicon-Oxide-Nitride-Oxide-Silli...

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Problems solved by technology

When the two tunneling speeds are equal, the loss and injection of electrons in the charge storage silicon nitride layer reac...

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