Segmented Charge Storage Films in Nonvolatile Memory
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Solution Overview
Problem
As memory cells in nonvolatile semiconductor storage devices shrink, they face reliability issues due to reduced space between cells and increased damage during processing, affecting their ability to store charges effectively.
Innovation Solution
The semiconductor storage device employs a charge storage film split into multiple strips, covered by a block insulating film made of high dielectric material, with word electrodes formed on the block insulating film, ensuring even electric field application and minimizing damage during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are shrunk to increase capacity and reduce cost, then storage density improves, but charge storage reliability deteriorates due to reduced space between cells and increased processing damage
Solution Approach 1:
The charge storage film is divided into multiple strips separated by device isolation regions. This segmentation isolates charge storage areas, preventing charge leakage between adjacent memory cells even as cell size decreases, thereby maintaining charge storage reliability while enabling higher storage density
Solution Approach 2:
Device isolation regions are introduced as intermediary structures between adjacent charge storage films. These isolation regions act as barriers that prevent harmful interactions and charge leakage between neighboring memory cells, protecting charge storage reliability during miniaturization
2Quantity of substance
If memory cells are shrunk, then storage capacity increases, but damage during processing affects memory cell characteristics more seriously
Solution Approach 1:
Dividing the charge storage film into multiple strips creates distinct, isolated processing zones. This segmentation allows for more controlled processing of each individual strip, reducing the impact of processing damage on adjacent cells and maintaining manufacturing precision even as overall cell size decreases
Solution Approach 2:
The device isolation regions create localized protective barriers at critical interfaces between memory cells. This local quality enhancement provides targeted protection against processing damage at the most vulnerable areas (cell boundaries) while allowing the rest of the structure to be miniaturized
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 enhances charge storage reliability and maintains effective memory-cell characteristics even as memory cells shrink, preventing charge leakage and improving programming and erasing speeds.
Implementation Method 1
a block insulating film disposed covering the plurality of charge storage films
Implementation Method 2
data is stored by controlling thresholds of memory cell transistors constituting memory cells. Here, the threshold voltages are controlled by injecting charges into trap sites formed in the charge storage film
Implementation Method 3
ensuring even electric field application and minimizing damage during processing
Data Source
AI summary
A semiconductor memory device includes: a semiconductor substrate; a plurality of device isolation regions being disposed in an upper-layer portion of the semiconductor substrate, and dividing the upper-layer portion into a plurality of semiconductor portions extending in a first direction; a plurality of charge storage films which are disposed on one of the plurality of the semiconductor portions and spaced apart from one another in the first direction; a block insulating film disposed covering the plurality of charge storage films; and a word electrode disposed on the block insulating film for each of rows of the plurality of charge storage films arranged in a second direction intersecting the first direction, wherein the block insulating film is disposed continuously in the first direction and in the second direction.