3D Memory Composite Charge Storage Structure
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Solution Overview
Problem
Current three-dimensional memory devices face challenges in achieving high charge storage density and data retention due to limitations in charge trapping materials and programming speed.
Innovation Solution
A three-dimensional memory device with a composite charge storage structure comprising a vertical stack of discrete tubular charge storage material portions and a continuous charge storage layer, where the discrete portions have a higher charge trap density and the continuous layer has a lower charge trap density, enhancing programming speed and data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single charge storage layer is used, then the device structure is simple, but the charge storage density and data retention are insufficient
Solution Approach 1:
The charge storage function is segmented into two distinct layers: a first charge storage layer with high trap density for fast programming, and a second charge storage layer with low trap density for data retention. This segmentation allows each layer to specialize in one function, resolving the contradiction between storage density and structure complexity.
Solution Approach 2:
The patent uses composite charge storage structures combining different materials (e.g., silicon nitride and silicon oxynitride) with different trap density characteristics. This composite approach enables simultaneous achievement of high charge storage capacity and good data retention without requiring a single complex material system.
2Quantity of substance
If charge trap density is increased to improve storage capacity, then programming speed decreases due to slower charge trapping
Solution Approach 1:
Different regions of the charge storage structure have different qualities: the first charge storage layer has high trap density for capacity, while the second layer has low trap density for speed. This local differentiation of properties allows the system to achieve both high storage capacity and fast programming by optimizing each layer for its specific function.
Solution Approach 2:
The charge storage function is divided into two segments with different trap densities. The first layer segments the high-capacity function, while the second layer segments the high-speed function, allowing simultaneous optimization of both capacity and programming speed without compromise.
3Speed
If discrete charge storage elements are used at each conductive layer level, then programming speed improves, but charge storage density decreases
Solution Approach 1:
The patent merges two approaches: discrete charge storage elements for speed and continuous charge storage layers for density. By combining these two configurations into a unified structure where discrete elements and continuous layers coexist, the system achieves both fast programming and high storage density simultaneously.
Solution Approach 2:
The charge storage structure uses composite configuration combining discrete tubular elements and continuous layers. This composite structural approach enables the system to leverage the speed advantages of discrete elements while maintaining the density benefits of continuous coverage.
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 composite charge storage structure improves programming speed and data retention while maintaining high charge storage density, addressing the limitations of existing technologies.
Implementation Method 1
a tunneling dielectric layer located on an inner sidewall of the composite charge storage structure
Implementation Method 2
The composite charge storage structure comprises a vertical stack of discrete tubular charge storage material portions including a first charge trapping material and vertically spaced apart from each other, and a continuous charge storage layer including a second charge trapping material
Data Source
AI summary
A memory device includes an alternating stack of insulating layers and electrically conductive layers located over a substrate, and a memory stack structure extending through the alternating stack. The memory stack structure includes a composite charge storage structure, a tunneling dielectric layer, and a vertical semiconductor channel. The composite charge storage structure may include a vertical stack of tubular charge storage material portions including a first charge trapping material located at levels of the electrically conductive layers, and a charge storage layer including a second charge trapping material extending through a plurality of electrically conductive layers of the electrically conductive layers. The first charge trapping material has a higher charge trap density than the second charge trapping material. Alternatively, the composite charge storage material portions may include discrete charge storage elements each containing a silicon nitride portion and a silicon carbide nitride liner.