STT-MRAM Cell With Soft Magnetic Coupling Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High programming current densities in Spin Torque Transfer Magnetic Random Access Memory (STT-MRAM) cells lead to increased energy consumption, thermal profile issues, and reduced reliability, affecting the scalability and integrity of the memory cells.
Innovation Solution
Incorporating a soft magnetic layer and an antiferromagnetic or ferromagnetic coupling layer in the STT-MRAM cell stack, which reduces the critical switching current density by utilizing the coupling effect to align the magnetization of the free layer with a smaller programming current, thereby decreasing energy consumption and enhancing thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high programming current density is used to switch magnetization in STT-MRAM cells, then the switching reliability is improved, but energy consumption increases and thermal stability deteriorates
Solution Approach 1:
A soft magnetic layer is introduced as an intermediary between the free layer and the bit line. This soft magnetic layer concentrates and directs the magnetic field generated by the programming current, providing a more efficient coupling mechanism that reduces the current density needed to switch the free layer magnetization, thereby lowering energy consumption while maintaining switching reliability
Solution Approach 2:
The invention changes the magnetic properties of the cell by adding the soft magnetic layer, which modifies the magnetic field distribution and coupling within the cell. This parameter change enables more efficient magnetization switching at lower current densities, resolving the contradiction between reliability and energy consumption
2Reliability
If high programming current density is used to switch magnetization in STT-MRAM cells, then the switching reliability is improved, but thermal stability deteriorates
Solution Approach 1:
The soft magnetic layer acts as a magnetic field mediator that enhances the coupling between the bit line and free layer. This intermediary structure allows for more efficient magnetization switching at lower current densities, reducing the thermal profile and heat generation while maintaining switching reliability
Solution Approach 2:
By introducing the soft magnetic layer, the magnetic field distribution parameters are changed to achieve more efficient switching. This parameter modification enables reliable magnetization switching at lower current densities, thereby improving thermal stability while maintaining switching reliability
3Reliability
If conventional MRAM programming current is used, then data storage is achieved, but write disturbances occur in adjacent cells
Solution Approach 1:
The soft magnetic layer provides localized magnetic field concentration at the target cell, creating a local quality enhancement that directs the magnetic field precisely where needed. This localized field concentration enables reliable data storage in the selected cell while minimizing write disturbances in adjacent cells
Solution Approach 2:
The soft magnetic layer serves as a localized intermediary that concentrates the magnetic field interaction at the target cell location. This intermediary structure enhances the magnetic coupling locally, enabling data storage while reducing the spread of magnetic field effects to neighboring cells, thereby minimizing write disturbances
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 approach allows for a lower programming current to switch the magnetization of the free layer, reducing energy consumption and thermal profile issues while maintaining thermal stability and improving the reliability and scalability of STT-MRAM cells.
Implementation Method 1
The pinned layer polarizes the electron spin of the programming current, and torque is created as the spin-polarized current passes through the MTJ. The spin-polarized electron current interacts with the free layer by exerting a torque on the free layer.
Implementation Method 2
Incorporating a soft magnetic layer and an antiferromagnetic or ferromagnetic coupling layer in the STT-MRAM cell stack, which reduces the critical switching current density by utilizing the coupling effect to align the magnetization of the free layer with a smaller programming current
Implementation Method 3
MRAM data is stored by magnetoresistive elements. The magnetization of one layer (the pinned layer) is fixed in its magnetic orientation, and the magnetization of the other layer (the free layer) can be changed by an external magnetic field generated by a programming current. The magnetic field of the programming current can cause the magnetic orientations of the two magnetic layers to be either parallel, giving a lower electrical resistance across the layers, or antiparallel, giving a higher electrical resistance across the layers.
Data Source
AI summary
A magnetic memory cell including a soft magnetic layer and a coupling layer, and methods of operating the memory cell are provided. The memory cell includes a stack with a free ferromagnetic layer and a pinned ferromagnetic layer, and a soft magnetic layer and a coupling layer may also be formed as layers in the stack. The coupling layer may cause antiferromagnetic coupling to induce the free ferromagnetic layer to be magnetized in a direction antiparallel to the magnetization of the soft magnetic layer, or the coupling layer may cause ferromagnetic coupling to induce the free ferromagnetic layer to be magnetized in a direction parallel to the magnetization of the soft magnetic layer. The coupling layer, through a coupling effect, reduces the critical switching current of the memory cell.