Nonvolatile Memory Channel Doping Profile for Charge Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional nonvolatile memory devices face issues such as lateral charge transportation, threshold voltage instability, charge loss, and the second bit effect due to insufficient isolation and short channel effects, particularly in smaller dimensions.
Innovation Solution
A multi-bit memory cell design with a varying doping profile in the channel region, featuring a higher doping concentration near the central portion to electrically separate the charge-trapping layer and reduce charge redistribution, along with lower doping concentrations near the source and drain regions to minimize electric field sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform doping concentration is used in the channel region, then the manufacturing process is simple, but lateral charge transportation occurs and threshold voltage instability arises
Solution Approach 1:
The patent applies local quality by implementing a non-uniform doping profile where the doping concentration varies across the channel region. Specifically, the channel region has a first doping concentration different from the source and drain regions, creating localized doping zones that address charge isolation issues without requiring complex multi-step doping processes
Solution Approach 2:
The patent changes the doping concentration parameter across the channel region to optimize device performance. By adjusting the doping concentration in the channel region relative to the source and drain regions, the invention mitigates lateral charge transportation and threshold voltage instability while maintaining manufacturing feasibility
2Productivity
If the channel length is reduced to increase storage capacity, then more bits can be stored, but short channel effect and second bit effect increase
Solution Approach 1:
The patent applies local quality by creating a doping profile where the channel region has a distinct doping concentration from the source and drain regions. This localized doping variation helps maintain charge isolation between adjacent bits even when the channel length is reduced, thereby preventing the second bit effect while preserving high storage capacity
Solution Approach 2:
The patent segments the doping concentration into different zones: the channel region has a first doping concentration while the source and drain regions have a second doping concentration. This segmentation creates electrical boundaries that prevent charge leakage between adjacent memory bits, enabling higher density storage without sacrificing 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 design improves charge isolation, reduces data loss, and mitigates the second bit effect and short channel effect, enhancing the reliability of multi-bit flash memory devices.
Implementation Method 1
The channel region has one of a p-type doping and an n-type doping, and the doping is configured to provide a highest doping concentration near the central portion of the channel region
Implementation Method 2
The channel region includes at least three doped regions, including a first doped region located near the central portion of the channel region; a second doped region located near one side of the first doped region; and a third doped region located near the other side of the first doped region
Data Source
AI summary
A multi-bit memory cell includes a substrate; a multi-bit charge-trapping cell over the substrate, the multi-bit charge-trapping cell having a first lateral side and a second lateral side; a source region in the substrate, a portion of the source region being under the first side of the multi-bit charge-trapping cell; a drain region in the substrate, a portion of the drain region being under the second side of the multi-bit charge-trapping cell; and a channel region in the substrate between the source region and the drain region. The channel region has one of a p-type doping and an n-type doping, and the doping is configured to provide a highest doping concentration near the central portion of the channel region.