Charge Trapping Film Segmentation for Data Retention
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Solution Overview
Problem
The data retention characteristics of nonvolatile memory cells degrade as they are downscaled due to charge trapping efficiency issues in three-dimensional stacked structures, where the trapping efficiency of charge in the second trapping layer is lower than in the first trapping layer, leading to poor data retention and endurance characteristics.
Innovation Solution
A semiconductor device with a charge trapping film structure that includes a first separation layer, a first trapping layer with higher charge trapping efficiency, and a second trapping layer, where the first trapping layer is positioned between the tunneling insulating film and the first separation layer, and the second trapping layer is positioned between the first conductive layer and the first separation layer, enhancing charge trapping efficiency on the tunneling insulating film side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are downscaled to increase storage density, then storage capacity is improved, but data retention characteristics deteriorate due to reduced charge trapping efficiency
Solution Approach 1:
The charge trapping film is segmented into multiple trapping layers (first trapping layer and second trapping layer) with different charge trapping efficiencies. The first trapping layer has higher charge trapping efficiency and is positioned closer to the tunneling insulating film, while the second trapping layer has lower charge trapping efficiency. This segmentation allows optimized charge distribution to maintain data retention characteristics while supporting downscaled memory cell dimensions for increased storage capacity.
Solution Approach 2:
Different regions of the charge trapping film are assigned different local qualities through the multi-layer structure. The first trapping layer exhibits high charge trapping efficiency locally near the tunneling insulating film interface, while the second trapping layer exhibits lower efficiency in other regions. This local quality differentiation ensures effective charge trapping at critical interfaces while maintaining overall device functionality in downscaled structures.
2Device complexity
If a simple charge trapping film structure is used, then device complexity is reduced, but charge trapping efficiency is insufficient leading to poor data retention
Solution Approach 1:
The charge trapping film is divided into multiple functional layers including a first trapping layer with high charge trapping efficiency and a second trapping layer with lower efficiency, separated by insulating layers. This segmentation provides a systematic approach to enhance charge trapping efficiency without creating excessive complexity, as each layer serves a distinct functional purpose in the charge trapping hierarchy.
Solution Approach 2:
The charge trapping film employs a composite structure combining multiple materials with different charge trapping characteristics. The first trapping layer material is selected for high charge trapping efficiency, while the second trapping layer material has lower efficiency, creating a composite film that achieves superior overall charge trapping performance compared to single-material structures.
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 enhanced charge trapping efficiency in the first trapping layer improves data retention characteristics by suppressing electron movement towards the tunneling insulating film, reducing the likelihood of data retention degradation and maintaining high threshold voltage, while the separation layers further suppress electron movement, maintaining good data programming and erasing characteristics.
Implementation Method 1
The charge trapping film includes a first separation layer, a first trapping layer, and a second trapping layer. The first trapping layer is positioned between the tunneling insulating film and the first separation layer. The second trapping layer is positioned between the first conductive layer and the first separation layer. A trapping efficiency of charge in the first trapping layer is higher than a trapping efficiency of charge in the second trapping layer.
Data Source
AI summary
A semiconductor device includes a semiconductor layer, a first conductive layer, a tunneling insulating film, and a charge trapping film. The tunneling insulating film is provided between the semiconductor layer and the first conductive layer. The charge trapping film is provided between the first conductive layer and the tunneling insulating film. The charge trapping film includes a first separation layer, a first trapping layer, and a second trapping layer. The first trapping layer is positioned between the tunneling insulating film and the first separation layer. The second trapping layer is positioned between the first conductive layer and the first separation layer. A trapping efficiency of charge in the first trapping layer is higher than a trapping efficiency of charge in the second trapping layer.