Diffusion Suppressing Layer for Nonvolatile Memory
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Solution Overview
Problem
In nonvolatile semiconductor memory devices, impurity elements from electrode layers can diffuse into sacrifice layers during manufacturing, leading to incomplete etching and degradation of data retention due to electric fields at electrode layer edges.
Innovation Solution
Incorporating diffusion suppressing layers made of a second semiconductor material between electrode and insulating layers to prevent impurity element diffusion, ensuring complete etching and reducing electric field effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If impurity elements are present in electrode layers during manufacturing, then the memory device can be formed with standard materials, but impurity diffusion into sacrifice layers occurs causing incomplete etching and data retention degradation
Solution Approach 1:
A diffusion suppressing layer is introduced as an intermediary between the electrode layer and the sacrifice layer. This intermediate layer prevents impurity elements from the electrode layer from diffusing into the sacrifice layer, thereby maintaining etching precision without compromising manufacturing ease. The diffusion suppressing layer acts as a barrier that mediates the interaction between the electrode layer and sacrifice layer.
2Device complexity
If impurity elements diffuse into sacrifice layers, then the manufacturing process can proceed without additional layers, but etching completeness deteriorates
Solution Approach 1:
The diffusion suppressing layer serves as a mediator that blocks impurity diffusion from electrode layers to sacrifice layers. By adding this intermediate layer, etching completeness is significantly improved as the sacrifice layer remains free from impurity contamination, enabling complete removal without leaving residues.
3Device complexity
If electrode layers are formed without diffusion suppression, then the device structure remains simple, but data retention degrades due to electric field effects
Solution Approach 1:
The diffusion suppressing layer acts as an intermediary structure between the electrode layer and the memory film. This additional layer improves data retention by preventing impurity diffusion that would otherwise create electric field distortions at the edges of electrode layers, thereby enhancing reliability with only moderate increase in structural complexity.
4Manufacturing precision
If diffusion suppressing layers are added between electrode and insulating layers, then impurity diffusion is prevented improving etching precision, but device complexity increases
Solution Approach 1:
The diffusion suppressing layer is positioned strategically between the electrode layer and the sacrifice layer (and insulating layers) to prevent impurity diffusion. While this adds one more layer to the device structure, the improvement in etching precision is substantial, as the sacrifice layer can be completely removed without impurity contamination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The diffusion suppressing layers effectively prevent impurity element diffusion, allowing for precise etching and improved data retention by confining electric fields, thus enhancing the performance and reliability of nonvolatile semiconductor memory devices.
Implementation Method 1
Each of the plurality of electrode layers is a first semiconductor layer containing a first impurity element. The diffusion suppressing layer is a second semiconductor layer containing a second impurity element which is different from the first impurity element. The diffusion suppressing layer is a film having an effect of suppressing diffusion of the first impurity element.
Data Source
AI summary
According to one embodiment, a nonvolatile semiconductor memory device includes: a stacked body including a plurality of electrode layers and a plurality of insulating layers, which are alternately stacked, and diffusion suppressing layers each provided between each of the plurality of electrode layers and each of the plurality of insulating layers; and a memory film provided on a side wall of a hole penetrating the stacked body in a stacking direction. Each of the plurality of electrode layers is a first semiconductor layer containing a first impurity element. The diffusion suppressing layer is a second semiconductor layer containing a second impurity element which is different from the first impurity element. The diffusion suppressing layer is a film having an effect of suppressing diffusion of the first impurity element.