SONOS (silicon oxide nitride oxide semiconductor) structure and manufacturing method thereof

Abstract

The invention provides an SONOS (silicon oxide nitride oxide semiconductor) structure and a manufacturing method thereof. The manufacturing method of the SONOS structure includes preparing a tunneling oxidation layer on a substrate, preparing a silicon-rich silicon nitride layer on the tunneling oxidation layer, preparing a gradient-silicon-content silicon nitride layer on the silicon-rich silicon nitride layer, and preparing an oxidation stopping layer on the gradient-silicon-content silicon nitride layer, wherein the Si / N ratio of the silicon-rich silicon nitride layer is constant, and the silicon content of the gradient-silicon-content silicon nitride layer is gradually decreased in the direction from the silicon-rich silicon nitride layer to the oxidation stopping layer. By modifying the silicon nitride layer in the SONOS structure, the silicon-rich silicon nitride layer and the gradient-silicon-content silicon nitride layer are formed; since shallower strap energy levels exist in the silicon-rich silicon nitride layer, capturing charges is facilitated, and speed of compiling and erasing is increased. Further, the charges are limited in deeper trap energy levels in the nitrogen-rich silicon nitride layer in the gradient-Si / N silicon nitride layer, so that retention time of the charges can be prolonged and reliability of devices is enhanced.

Description

Technical field [0001] The present invention relates to the field of semiconductor manufacturing. More specifically, the present invention relates to a SONOS structure manufacturing method and a SONOS structure. Background technique [0002] With the miniaturization and miniaturization of semiconductor storage devices, traditional polysilicon floating gate storage has too large stack thickness and requires too high insulation of the tunnel oxide layer to meet the development requirements of future memory. Recently, SONOS (Polysilicon-Oxide-Nitride-Oxide-Silicon, silicon / silicon dioxide / silicon nitride / silicon dioxide / silicon) non-volatile memory devices based on silicon nitride with excellent insulating properties have been compared with Traditional polysilicon floating gate memory has stronger charge storage capacity, easy to realize miniaturization and simple process characteristics, and has received renewed attention. [0003] Kuo-Hong Wu (SONOS device with tapered bandgap nitr...

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But this improvement also did not significantly improve the initial compilation erasure speed

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