Vertical Channel MRAM Transistor Floating Body Effect Control
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Solution Overview
Problem
Current MRAM devices face challenges in achieving high integration density and reliable operation due to limitations in transistor design and manufacturing methods, particularly in controlling the channel region to prevent floating body effects and switching failures.
Innovation Solution
The MRAM device design incorporates a vertical channel transistor with a common source region, drain region, channel body region, gate structures, word line structures, MTJ structures, and bit line structures, where the channel body region is used to control accumulated charges and reduce the risk of floating body effects, and shared signal lines are used to minimize cell size and enhance integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a vertical channel transistor is used to increase integration density, then the integration density is improved, but the control of accumulated charges in the channel region becomes difficult, leading to floating body effects
Solution Approach 1:
The channel region is segmented into a first channel region and a second channel region with different doping types. This segmentation allows independent control of charge accumulation in each region, preventing floating body effects while maintaining high integration density through the vertical channel structure.
Solution Approach 2:
Different regions of the channel are given different doping types (first doping type for the first channel region, second doping type for the second channel region). This local quality differentiation enables specific control of charge behavior in each region, addressing the floating body effect problem while preserving the benefits of vertical channel transistors for high integration.
2Ease of manufacture
If conventional transistor designs are used, then manufacturing is simpler, but the operating characteristics and reliability of the MRAM device are insufficient
Solution Approach 1:
The gate structure is designed to control both the first and second channel regions simultaneously through a single gate electrode. This multi-functional gate structure improves reliability by controlling charge in both doped regions while maintaining manufacturing simplicity by using a unified gate design rather than separate control structures.
3Reliability
If separate source and drain regions are used for each transistor, then transistor operation is more reliable, but the device area increases, reducing integration density
Solution Approach 1:
Adjacent transistors share common source and drain regions. The first channel region of one transistor shares a drain region with the second channel region of an adjacent transistor, creating a merged structure that reduces total device area while maintaining reliable transistor operation through proper doping configuration.
Solution Approach 2:
The shared doped regions serve multiple functions: they act as drain for one transistor and source for another, and provide both charge control and electrical connection functions. This multi-functionality enables high integration density while preserving transistor 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 results in a highly integrated MRAM device with improved electrical characteristics and reduced risk of switching failures, achieving good operating characteristics and increased integration density.
Implementation Method 1
Magnetoresistive random access memory (MRAM) devices and methods of manufacturing the same
Data Source
AI summary
An MRAM device may include semiconductor structures, a common source region, a drain region, a channel region, gate structures, word line structures, MTJ structures, and bit line structures arranged on a substrate. Each of the semiconductor structures may include a first semiconductor pattern having a substantially linear shape extending in a first direction that is substantially parallel to a top surface of the substrate, and a plurality of second patterns that each extend in a third direction substantially perpendicular to the top surface of the substrate. A common source region and drain region may be formed in each of the semiconductor structures to be spaced apart from each other in the third direction, and the channel region may be arranged between the common source region and the drain region. Gate structures may be formed between adjacent second semiconductor patterns in the second direction. Word line structures may electrically connect gate structures arranged in the first direction to each other. MTJ structures may be electrically connected to corresponding ones of the second semiconductor patterns. Each bit line structure may electrically connect two adjacent MTJ structures in the first direction to each other.