Charge-Trap Memory Cell Isolation Patterns
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Solution Overview
Problem
Charge-trap flash memory devices face issues with lateral charge spread in silicon nitride films, degrading retention characteristics, due to increased aspect ratios and interference between floating gate electrodes in highly integrated flash memory devices.
Innovation Solution
The implementation of device isolation patterns on a semiconductor substrate, with charge trap films, blocking dielectric films, and cell electrodes, along with tunnel insulation films, to electrically isolate memory cell patterns and prevent lateral charge spread, using materials like silicon nitride, aluminum oxide, and tantalum nitride, and configuring the memory cell patterns to be wider than the cell active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If floating-gate flash memory devices are highly integrated, then storage capacity increases, but lateral charge spread in silicon nitride films degrades retention characteristics
Solution Approach 1:
The patent divides the continuous silicon nitride charge trap film into separate, isolated segments using device isolation patterns and blocking dielectric films. Each memory cell's charge trap film is physically separated from adjacent cells, preventing lateral charge spread while maintaining high integration density for increased storage capacity
Solution Approach 2:
The patent introduces device isolation patterns and blocking dielectric films as intermediary structures between adjacent charge trap films. These intermediary elements act as barriers that block lateral charge migration, thereby improving retention characteristics without compromising the high integration required for storage capacity
2Device complexity
If charge trap films are used instead of floating gate electrodes, then device structure simplifies, but lateral charge spread occurs in silicon nitride films
Solution Approach 1:
The patent segments the charge trap film into isolated regions for each memory cell using device isolation patterns. This segmentation maintains the simplified charge-trap structure while preventing the lateral charge spread that would otherwise occur in continuous silicon nitride films
Solution Approach 2:
The patent applies different properties to different regions: the charge trap film maintains its continuous nature within each memory cell for simple structure, while device isolation patterns and blocking dielectric films create localized barriers at cell boundaries to prevent lateral charge spread, achieving both simplicity and reliability
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 configuration reduces the likelihood of charge lateral spread, enhancing the retention characteristics and stability of charge-trap flash memory devices by isolating memory cells and minimizing etch damage during fabrication.
Implementation Method 1
a tunnel insulation film between the memory cell pattern and the cell active region
Implementation Method 2
a blocking dielectric film on the charge trap film
Data Source
AI summary
Nonvolatile memory devices including device isolation patterns on a semiconductor substrate are provided. The device isolation patterns define a cell active region and a peripheral active region of the semiconductor substrate. Cell gate electrodes are provided that cross over the cell active regions. Memory cell patterns are provided between the cell gate electrodes and the cell active regions and extend toward the device isolation patterns. A tunnel insulation film is provided between the memory cell pattern and the cell active region. Related methods of fabricating nonvolatile memory devices are also provided herein.