Semiconductor Memory Storage Layer Metal Atom Distribution
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Solution Overview
Problem
Current semiconductor memory devices face challenges in enhancing storage density while maintaining reliable charge storage and retention characteristics, particularly due to limitations in the distribution and binding density of metal atoms in the charge storage film.
Innovation Solution
The semiconductor memory device incorporates a storage layer with a specific structure, including regions of silicon nitride and dispersed metal atoms like Ti, La, Hf, Ru, Ta, and Mo, where the binding density of metal atoms is lower than that with nitrogen, preventing clustering and ensuring uniform charge storage and retention across a reduced memory cell size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal atoms are added to the charge storage film to improve charge storage characteristics, then charge storage capability is improved, but metal atoms may cluster together which degrades performance uniformity
Solution Approach 1:
The patent applies local quality by creating different regions within the charge storage film: a first region with silicon nitride, a second region with different composition, and a third region with metal atoms having lower binding density. This spatial differentiation of properties prevents metal atom clustering while maintaining charge storage capability in specific zones.
Solution Approach 2:
The patent changes the binding density parameter of metal atoms in the third region, making it lower than in other regions. This parameter modification prevents metal atom aggregation while preserving charge storage function, directly resolving the contradiction between charge storage improvement and distribution uniformity.
2Quantity of substance
If memory cell size is reduced to increase storage density, then storage density is improved, but charge storage uniformity and retention characteristics deteriorate
Solution Approach 1:
By creating regions with different compositions and binding densities within the charge storage film, the patent maintains uniform charge storage characteristics even as memory cell size decreases. The localized properties ensure consistent performance across miniaturized cells.
Solution Approach 2:
The patent uses composite materials combining silicon nitride regions with metal atom-containing regions having different binding densities. This composite structure provides both high storage density and reliable charge retention in miniaturized memory cells.
3Reliability
If metal atom binding density is increased to improve charge storage, then charge storage capability is improved, but metal atoms cluster which increases threshold value variation
Solution Approach 1:
The patent modifies the binding density parameter of metal atoms in the third region, setting it lower than in other regions. This parameter change prevents metal atom clustering and reduces threshold value variation while maintaining adequate charge storage capability.
Data Source
AI summary
According to one embodiment, a semiconductor memory device includes a semiconductor layer, a first electrode, first and second oxide layers, and a storage layer. The first oxide layer is provided between the semiconductor layer and the first electrode. The second oxide layer is provided between the first oxide layer and the first electrode. The storage layer is provided between the first and second oxide layers. The storage layer includes a first region including silicon nitride, a second region provided between the first region and the second oxide layer and including silicon nitride, and a third region provided between the first and second regions. The third region includes a plurality of first metal atoms. A first density of bond of the first metal atoms in the third region is lower than a second density of bond of the first metal atom and a nitrogen atom in the third region.