Three-dimensional nonvolatile semiconductor memory based on nanocrystalline floating gate and its preparation method

Abstract

The invention belongs to the field of preparation of a three-dimensional flash memory, and more specifically relates to a three-dimensional nonvolatile semiconductor memory based on a nanocrystal floating gate and a preparation method thereof. The three-dimensional semiconductor memory includes a plurality of three-dimensional NAND storage strings in the vertical direction, each three-dimensional NAND storage string includes a semiconductor region, and a four-layer wrapping structure surrounding the semiconductor region, which is sequentially a tunneling dielectric layer, a charge storage layer, and a barrier A dielectric layer and a control gate electrode; wherein, the material of the charge storage layer includes a nanocrystalline material, and the nanocrystalline material is a chalcogenide compound nanocrystal. The present invention adopts chalcogenide compound nanocrystals with high self-hole structure content as the charge storage layer material, which improves the programming / erasing efficiency, programming / erasing speed and charge storage capacity of a single storage unit of a three-dimensional flash memory, and The technological process of the nano crystal floating gate of the present invention is simple, and is compatible with the vertical channel technology.

Description

technical field [0001] The invention belongs to the field of preparation of a three-dimensional flash memory, and more specifically relates to a three-dimensional nonvolatile semiconductor memory based on a nanocrystal floating gate and a preparation method thereof. Background technique [0002] The storage density of the three-dimensional flash memory is no longer limited by the feature size of the process, and the storage density can be continuously improved by stacking in the vertical direction. [0003] However, in the three-dimensional flash memory structure, due to the limitation of the gate structure, there is a serious contradiction between the requirement of fast write / erase operation and the requirement of long-term stable storage. And with the continuous increase of the number of three-dimensional stacked layers and the continuous reduction of the feature size, this contradiction becomes more significant. On the other hand, in the three-dimensional structure, the...

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Problems solved by technology

[0003] However, in the three-dimensional flash memory structure, due to the limitation of the gate structure, there is a serious contradiction between the requirements of fast write / erase operations and the requirements of long-term stable storage.

And with the continuous increase of the number of three-dimensional stacking layers and the continuous reduction of the feature size, this contradiction is more significant

On the other hand, in the three-dimensional structure, the crosstalk of the floating gate structure is also very serious

[0004] In recent years, although it has been reported that nanocrystalline metals are used as floating gate materials to realize multi-valued storage and increase the storage capacity of memory, nanocrystalline metals have weak proportional reduction characteristics, and the carrier concentration decreases significantly with size reduction. Increase storage capacity space is very limited

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