3D Semiconductor Memory Anti-Diffusion Film Integration
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Solution Overview
Problem
The challenge in semiconductor memory devices is to maintain operational characteristics while reducing memory cell size, particularly in 3D structures, where voltage application and operating schemes are altered, leading to degradation issues.
Innovation Solution
The solution involves alternately stacking conductive and insulating films on a substrate, forming substantially vertical channel layers with a charge storage film interposed between them, and using anti-diffusion films to prevent impurity loss and enhance impurity concentration, thereby improving electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cell size is reduced to increase degree of integration, then integration density is improved, but operational characteristics are degraded
Solution Approach 1:
The patent transitions from planar 2D memory cell structures to three-dimensional vertical structures. Channel layers extend vertically through stacked conductive and insulating films, enabling increased integration density while maintaining operational characteristics through the third dimension. This vertical architecture allows more memory cells to be packed into the same footprint without compromising performance.
Solution Approach 2:
The patent applies different materials and structures to specific regions of the memory device. Anti-diffusion films are selectively formed on etched surfaces of conductive films where impurity concentration needs to be maintained. Charge storage films are positioned at specific locations within the vertical stack to enable local charge trapping. This localized application of different materials and structures maintains operational characteristics in critical regions while enabling overall density improvement.
2Quantity of substance
If 3D structure is implemented to reduce memory cell size, then integration density is improved, but impurity concentration is lost
Solution Approach 1:
The patent applies anti-diffusion films on etched surfaces of conductive films before subsequent processing steps. These films prevent impurities from diffusing out of the conductive films during thermal processing or implantation steps, thereby maintaining the required impurity concentration for proper device operation while enabling the 3D vertical structure.
Solution Approach 2:
The anti-diffusion films serve as intermediary layers between the conductive films and the surrounding environment. These intermediary films prevent direct interaction between impurities in the conductive films and external contaminants or processing conditions that would cause impurity loss, thereby preserving the electrical characteristics of the conductive films in the vertical stack.
3Adaptability or versatility
If voltage application scheme is changed for 3D structure, then operational characteristics are adapted, but manufacturing complexity increases
Solution Approach 1:
The patent divides the memory device into multiple discrete vertical stacks, each comprising alternating conductive and insulating films with channel layers. This segmentation allows independent formation and processing of each vertical unit, simplifying the manufacturing of complex 3D structures. The modular vertical stack architecture enables systematic fabrication while adapting to new voltage application schemes required for 3D operation.
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 operational characteristics of semiconductor memory devices by maintaining high impurity concentration and preventing impurity discharge, leading to improved erase speed and threshold voltage management.
Implementation Method 1
a first anti-diffusion film formed on etched surfaces of the conductive films
Implementation Method 2
doping impurities onto side walls of the first conductive films exposed through the channel hole
Data Source
AI summary
A semiconductor memory device includes conductive films and insulating layers alternately stacked on a substrate, substantially vertical channel layers penetrating the conductive films and the insulating layers, multilayer films including a charge storage film interposed between the conductive films and the substantially vertical channel layers, and a first anti-diffusion film formed on etched surfaces of the conductive films.