Floating-Body Select Transistor for MRAM Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetoresistive memory devices face challenges in achieving high integration due to the deterioration of current driving capability in select transistors when cell size is reduced, leading to difficulties in writing and reading data efficiently.
Innovation Solution
The implementation of a magnetoresistive memory cell with a select transistor that utilizes a floating-body effect, comprising a MOS transistor and a BJT connected in parallel, which enhances current driving capability by sharing a common floating body region and operating in both write and read modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If cell size is reduced to achieve high integration, then integration density is improved, but current driving capability of select transistor deteriorates
Solution Approach 1:
The patent merges MOS transistor and BJT into a single select transistor structure that shares a common floating body region. This combination allows the device to achieve both high integration density and sufficient current driving capability by utilizing the complementary strengths of MOS and BJT structures within a unified configuration.
Solution Approach 2:
The patent changes the electrical parameters of the select transistor by creating a floating body region with specific conductivity type opposite to the source and drain regions. This parameter change enables the transistor to exhibit both MOS-like switching characteristics and BJT-like current amplification, resolving the contradiction between size reduction and current capability.
2Area of stationary object
If select transistor area is reduced to improve integration, then device area is improved, but current difference during read operations decreases
Solution Approach 1:
By merging MOS and BJT structures in a single select transistor, the device achieves enhanced current modulation capability within a reduced area. The floating body region enables strong current control that maintains sufficient current difference for reliable read operations even when the transistor area is minimized for high integration.
3Area of moving object
If conventional MOS transistor is used in reduced size, then integration is improved, but writing and reading data becomes difficult
Solution Approach 1:
The patent combines MOS transistor switching capability with BJT current amplification in a single select transistor. This merger provides strong current driving capability for reliable data writing and reading operations, even when the transistor is miniaturized for high integration density.
Solution Approach 2:
By changing the structural parameters to include a floating body region with opposite conductivity type, the transistor achieves enhanced current control and driving capability. This parameter change ensures easy data writing and reading operations despite the reduced device size required for high integration.
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 allows for higher current flow and increased current difference during read operations, improving integration density and reducing the area required for the select transistor, thus enabling more efficient data storage and simplified sensing circuits.
Implementation Method 1
a part of the semiconductor layer between the first and second diffusion regions is formed as an electrically floating body region
Implementation Method 2
magnetoresistive memory (MRAM) which stores information using the difference between magnetoresistances
Data Source
AI summary
A magnetoresistive memory cell includes an MTJ device and a select transistor. The select transistor includes a first conduction-type semiconductor layer, a gate electrode formed by disposing a gate insulating layer on top of the semiconductor layer, and first and second diffusion regions formed in the semiconductor layer to be spaced apart from each other and to have a second conduction type. A part of the semiconductor layer between the first and second diffusion regions is formed as an electrically floating body region. By using a high-performance select transistor with a floating body effect, high integration of a magnetoresistive memory device may be achieved.