MTJ Block Layer Structure for Low-Power Temperature-Stable MRAM
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Solution Overview
Problem
Current magnetoresistive random access memory (MRAM) devices face issues such as high chip area, high cost, high power consumption, and sensitivity to temperature variations, limiting their performance and efficiency.
Innovation Solution
The semiconductor device incorporates a magnetic tunneling junction (MTJ) structure with a block layer made of Co-based alloy or metal nitride, and an alternative configuration with a high entropy layer, optimized through specific layer thicknesses and materials like CoW alloy, WN, and Ru, to enhance performance and prevent diffusion-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic field sensor technologies (AMR, GMR, MTJ sensors) are used, then magnetic sensing function is achieved, but chip area increases and cost increases
Solution Approach 1:
The patent combines the magnetic sensing function with the MTJ memory cell structure by integrating a block layer that serves dual purposes: as part of the MTJ stack for memory operation and as a magnetic field sensor. This merging eliminates the need for separate sensor components, thereby reducing chip area while maintaining magnetic sensing capability.
Solution Approach 2:
The block layer is designed to perform multiple functions: it acts as a magnetic barrier layer in the MTJ structure for data storage and simultaneously functions as a magnetic field sensor. This multi-functionality allows the same component to address both memory operation and sensing requirements, reducing overall device complexity and chip area.
2Reliability
If conventional magnetic field sensor technologies (AMR, GMR, MTJ sensors) are used, then magnetic sensing function is achieved, but power consumption increases
Solution Approach 1:
The patent merges the magnetic sensing function with the MTJ memory cell structure by integrating a block layer that serves dual purposes: as part of the MTJ stack for memory operation and as a magnetic field sensor. This merging eliminates the need for separate sensor components, thereby reducing chip area while maintaining magnetic sensing capability.
Solution Approach 2:
The MTJ structure with the block layer serves itself by utilizing the same magnetic tunneling mechanism for both memory operation and magnetic field sensing. The device does not require additional power-consuming sensor circuits, as the MTJ stack inherently responds to magnetic field changes through resistance variation, enabling self-service sensing with minimal additional power consumption.
3Reliability
If conventional magnetic field sensor technologies are used, then magnetic sensing function is achieved, but temperature stability deteriorates
Solution Approach 1:
The patent optimizes the block layer thickness and material composition to achieve optimal magnetic anisotropy and thermal stability. By carefully controlling the thickness of the block layer (e.g., 3-7 nm for CoFeB) and selecting appropriate materials, the device maintains stable magnetic properties across a wide temperature range, improving temperature stability while preserving sensing function.
Solution Approach 2:
The patent employs composite material structures in the MTJ stack, including combinations of CoFeB, MgO, CoFe, and other magnetic and non-magnetic layers. These composite structures provide enhanced thermal stability through controlled magnetic anisotropy and reduced sensitivity to temperature variations, while maintaining the magnetic sensing capability.
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
The solution reduces chip area, lowers power consumption, and improves temperature stability, resulting in a more efficient and cost-effective MRAM device with enhanced magnetic performance.
Implementation Method 1
Magnetoresistance (MR) effect has been known as a kind of effect caused by altering the resistance of a material through variation of outside magnetic field. The physical definition of such effect is defined as a variation in resistance obtained by dividing a difference in resistance under no magnetic interference by the original resistance.
Implementation Method 2
the block layer could be made of Co-based alloy or metal nitride, in which the Co-based alloy could further include CoW alloy whereas the metal nitride could include WN
Implementation Method 3
a high entropy layer on the MTJ
Data Source
AI summary
A semiconductor device includes a bottom electrode on a substrate, a magnetic tunneling junction (MTJ) on the bottom electrode, a first cap layer on the MTJ, a second cap layer on the first cap layer, a block layer on the second cap layer, and a top electrode on the block layer. Preferably, the block layer could be made of Co-based alloy or metal nitride, in which the Co-based alloy could further include CoW alloy whereas the metal nitride could include WN.