Three-Terminal SOT MRAM Layout for Endurance and Read Stability
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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, limited sensitivity, and susceptibility to temperature variations, which affect their performance and efficiency.
Innovation Solution
A semiconductor device and method for fabricating a spin orbit torque (SOT) MRAM device using a three-terminal MTJ-based concept, involving the formation of a magnetic tunneling junction (MTJ) with a first and second channel layer of different materials and a curved sidewall structure, utilizing a damascene process to enhance device endurance and read stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional MRAM devices are used, then data storage capability is achieved, but chip area is large and cost is high
Solution Approach 1:
The patent segments the conventional two-terminal MTJ structure into three separate terminals (first electrode, second electrode, and third electrode), allowing independent control of spin current injection and read operations. This segmentation enables more efficient use of chip space by reducing the area required for each functional unit while maintaining data storage capability.
Solution Approach 2:
The patent introduces a vertical stacking arrangement where the three electrodes are positioned at different vertical levels, with the channel layer connecting them. This three-dimensional configuration reduces the lateral footprint on the chip while preserving the magnetic tunneling junction's data storage function.
2Quantity of substance
If conventional MRAM devices are used, then data storage is achieved, but power consumption is high
Solution Approach 1:
By separating the spin current injection path (through the third electrode and channel layer) from the read path (through the first and second electrodes), the patent enables independent optimization of write and read operations. This allows low-power read operations without requiring high current densities, reducing overall power consumption while maintaining data storage capability.
Solution Approach 2:
The channel layer acts as an intermediary that carries spin current from the third electrode to modulate the magnetic state of the free layer, enabling write operations through a separate path. This mediator approach allows efficient spin transfer torque without requiring high power through the read path.
3Quantity of substance
If conventional MRAM devices are used, then data storage is achieved, but device endurance is limited
Solution Approach 1:
The patent separates the heavy current-carrying write path (through the third electrode and channel layer) from the light read path (through the first and second electrodes). This segmentation protects the read path from degradation due to high current stress, thereby improving device endurance while maintaining data storage capability.
Solution Approach 2:
The channel layer serves as a mediator that absorbs the stress of high current densities during write operations, preventing direct degradation of the magnetic tunneling junction barriers. This protective intermediary role enhances device endurance by isolating the sensitive MTJ barriers from harmful electrical stress.
4Quantity of substance
If conventional MRAM devices are used, then data storage is achieved, but read stability is insufficient
Solution Approach 1:
By providing dedicated first and second electrodes for read operations separate from the write path, the patent ensures that read operations occur through optimized low-resistance paths. This segmentation improves read stability by eliminating interference from write operations and providing consistent read conditions.
5Quantity of substance
If conventional MRAM devices are used, then data storage is achieved, but sensitivity is limited
Solution Approach 1:
The channel layer acts as a sensitive intermediary that converts spin current from the third electrode into magnetic moment changes in the free layer. This mediator mechanism enhances sensitivity by providing a direct and efficient coupling between the applied current and the magnetic state, enabling detection of subtle magnetic changes.
6Quantity of substance
If conventional MRAM devices are used, then data storage is achieved, but temperature stability is poor
Solution Approach 1:
The patent segments the current paths to allow independent optimization of thermal management for read and write operations. The separated write path through the third electrode and channel layer can be designed with specific thermal characteristics, while the read path through the first and second electrodes maintains stable operation across temperature variations, improving overall temperature stability.
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 SOT MRAM device improves device endurance and read stability by isolating the read/write path, prevents side effects like coercivity reduction and heating, and enhances write speed through spin current-induced magnetic moment switching.
Implementation Method 1
magnetic tunneling junction (MTJ)
Implementation Method 2
spin current-induced magnetic moment switching
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of: forming a first inter-metal dielectric (IMD) layer on a substrate; forming a first metal interconnection and a second metal interconnection in the first IMD layer; forming a channel layer on the first metal interconnection and the second metal interconnection; forming a magnetic tunneling junction (MTJ) stack on the channel layer; and removing the MTJ stack to form a MTJ.