Semiconductor Storage Device Silicon Oxide Impurity Gettering
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Solution Overview
Problem
In three-dimensional NAND flash memory, the charge retention property of memory cells near the end of a stacked body deteriorates, leading to data retention failures, particularly when a conductive layer is present between stacked bodies.
Innovation Solution
Incorporating a silicon oxide layer with impurities such as phosphorus (P), boron (B), carbon (C), or fluorine (F) between the stacked bodies and the conductive layer to prevent the trapping of movable ions like sodium (Na) and potassium (K), which improves charge retention by gettering these ions and reducing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer is provided between stacked bodies to improve electrical connection, then electrical conductivity is improved, but charge retention property of memory cells near the end of stacked body deteriorates
Solution Approach 1:
A silicon oxide layer containing impurities (phosphorus, boron, carbon, or fluorine) is introduced as an intermediary layer between the stacked body and the conductive layer. This intermediary layer acts as a barrier to prevent movable ions from migrating into the memory cell, thereby blocking the harmful effect while maintaining the electrical connection function of the conductive layer.
Solution Approach 2:
The silicon oxide layer is modified by changing its chemical composition parameters - specifically by incorporating impurities such as phosphorus, boron, carbon, or fluorine. This parameter change transforms the silicon oxide layer into an effective barrier against movable ion migration, improving charge retention without compromising electrical conductivity.
2Productivity
If stacked bodies are closely arranged to increase integration density, then productivity is improved, but movable ions can easily migrate and cause data retention failures
Solution Approach 1:
The protection against movable ion migration is applied locally at critical interfaces - specifically at the boundaries where stacked bodies meet conductive layers. The silicon oxide layer with impurities is selectively positioned at these local regions where ion migration is most problematic, rather than uniformly throughout the entire structure, thus maintaining high integration density while providing targeted protection.
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 silicon oxide layers effectively prevent the deterioration of charge retention properties and data retention failures in memory cells, enhancing the overall performance of the semiconductor storage device.
Implementation Method 1
Incorporating a silicon oxide layer with impurities such as phosphorus (P), boron (B), carbon (C), or fluorine (F) between the stacked bodies and the conductive layer to prevent the trapping of movable ions like sodium (Na) and potassium (K), which improves charge retention by gettering these ions and reducing leakage currents.
Data Source
AI summary
A semiconductor storage device includes first and second stacked bodies, a first semiconductor layer, a first charge storage layer, a conductive layer, and a first silicon oxide layer. The first stacked body includes first insulation layers and first gate electrode layers that are alternately stacked in a first direction. The first semiconductor layer extends in the first stacked body in the first direction. The first charge storage layer is provided between the first semiconductor layer and the first gate electrode layers. The conductive layer is provided between the first stacked body and the second stacked body and extends in the first direction and a second direction. The first silicon oxide layer is provided between the conductive layer and the first gate electrode layers. The first silicon oxide layer containing an impurity being at least one of phosphorus, boron, carbon, and fluorine.