3D Flash Memory Cell Strings Protruding Horizontally
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Solution Overview
Problem
The existing three-dimensional flash memory structures have a reduced cross-sectional area of memory cell strings, leading to decreased reliability due to vertical stacking for increased integration, which affects performance and integration density.
Innovation Solution
The proposed solution involves a three-dimensional flash memory structure where memory cell strings protrude in the horizontal direction, with a channel layer and charge storage layer extending vertically, increasing the cross-sectional area of memory cells and improving integration by reducing the cell string's cross-sectional area, while maintaining a recessed structure for interlayer insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory cell strings are vertically stacked to increase integration density, then the degree of integration is improved, but the cross-sectional area of memory cell strings is reduced leading to decreased reliability
Solution Approach 1:
The patent transitions from a conventional planar memory cell layout to a three-dimensional structure where memory cell strings protrude horizontally from the substrate surface. This dimensional change allows the memory cells to occupy vertical space while maintaining adequate cross-sectional area, thereby achieving high integration density without compromising reliability
Solution Approach 2:
The patent embeds interlayer insulating layers within the memory cell string structure itself, creating a nested configuration where insulating layers are positioned inside the protruding cell strings. This nesting approach increases integration density by utilizing the vertical dimension while preserving the functional integrity and cross-sectional area of the memory cells
2Productivity
If the cross-sectional area of memory cell strings is reduced to increase integration, then the degree of integration is improved, but the cross-sectional area of memory cells decreases affecting performance
Solution Approach 1:
The patent employs vertical protrusion of memory cell strings from the substrate, transforming the layout from two-dimensional to three-dimensional. This allows the memory cells to achieve high integration through vertical stacking while maintaining sufficient cross-sectional area for optimal performance by utilizing the vertical dimension for density improvement
3Device complexity
If memory cell strings are arranged in compact vertical stacks, then manufacturing complexity is reduced, but the cross-sectional area available for memory cells is reduced
Solution Approach 1:
The patent divides the memory structure into discrete protruding cell string units that are distributed across the substrate surface. Each protruding cell string functions as an independent segment, allowing the structure to achieve compact integration while maintaining adequate cross-sectional area within each segment, thus balancing simplicity and performance
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
This approach enhances the degree of integration and increases the cross-sectional area of memory cells, improving reliability and performance by promoting horizontal scaling and simplifying the manufacturing process.
Implementation Method 1
Flash memory elements electrically control input/output of data by Fowler-Nordheim tunneling or hot electron injection
Implementation Method 2
Flash memory elements electrically control input/output of data by Fowler-Nordheim tunneling or hot electron injection
Data Source
AI summary
A three-dimensional flash memory having a structure with an extended memory cell area, and a manufacturing method therefor are disclosed. According to one embodiment, a three-dimensional memory having a structure with an extended memory cell area comprises: a plurality of word lines stacked on a substrate in the vertical direction and extending in the horizontal direction; and at least one memory cell string, which passes through the plurality of word lines and is formed on the substrate to extend in the vertical direction, wherein the at least one memory cell string comprises a channel layer formed to extend in the vertical direction and a charge storage layer formed to encompass the channel layer, forms a plurality of memory cells corresponding to the plurality of word lines, and has a structure in which regions corresponding to the plurality of memory cells protrude in the horizontal direction.