Three-Terminal Voltage Controlled Memory Cell
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Solution Overview
Problem
Conventional magnetic memory cells require high currents for programming and have slower writing/reading speeds, leading to high power consumption and poor performance in memory applications.
Innovation Solution
The implementation of a memory cell with a first and second magnetic tunnel junction (MTJ) structure, where the magnetization direction of the free layer is controlled by an electric field for writing data and the tunnel magnetoresistance of a second barrier layer is used for reading data, optimizing the design for low power consumption and high-speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional magnetic memory cells use high currents for programming, then data can be written to the free layer, but power consumption increases and writing/reading speed decreases
Solution Approach 1:
The memory cell is segmented into two separate MTJ structures: a first MTJ structure dedicated to write operations and a second MTJ structure dedicated to read operations. This segmentation allows each structure to be optimized for its specific function, enabling low-power writing through electric field control in the first MTJ while maintaining reliable reading through tunnel magnetoresistance in the second MTJ, thereby resolving the contradiction between writing capability and power consumption.
2Reliability
If conventional magnetic memory cells use high currents for programming, then data can be written to the free layer, but writing/reading speed becomes slower
Solution Approach 1:
By dividing the memory cell into separate write and read MTJ structures, the write operation can be performed rapidly through electric field application without the speed penalties associated with high current switching. The read operation independently utilizes tunnel magnetoresistance for fast detection, thus achieving both reliable data writing and high writing/reading speed simultaneously.
3Device complexity
If a single MTJ structure is used for both writing and reading, then device complexity is reduced, but switching energy increases
Solution Approach 1:
The patent employs two MTJ structures with distinct functions: the first MTJ structure optimized for write operations using electric field control with low switching energy, and the second MTJ structure optimized for read operations using tunnel magnetoresistance. This functional segmentation enables each structure to operate at optimal energy levels for its specific task, significantly reducing overall switching energy compared to a single MTJ structure that must handle both operations.
4Use of energy by moving object
If electric field control is used for magnetization switching, then switching energy is reduced, but device structure complexity increases
Solution Approach 1:
The patent implements electric field control for magnetization switching specifically in the first MTJ structure dedicated to write operations, where it reduces switching energy. The second MTJ structure for read operations maintains a conventional structure utilizing tunnel magnetoresistance. This selective application of electric field control in only one of the two MTJ structures minimizes the increase in device structure complexity while still achieving the energy reduction benefit.
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 reduces switching energy and time, achieving faster write and read operations with significantly lower current densities and energy consumption compared to traditional spin-torque techniques, while maintaining high sensing margin and flexibility in material selection.
Implementation Method 1
A portion of the first MTJ is configured to include a first barrier layer disposed between a first fixed layer and a free layer (FL). A magnetization direction of the FL is used to store data, the magnetization direction being controlled by an electric field.
Implementation Method 2
The second MTJ is coupled between the FT and a second terminal, where a portion of the second MTJ is configured to include a second barrier layer disposed between a second fixed layer and the FL, where a tunnel magnetoresistance of the second barrier layer is used to read the data.
Data Source
AI summary
Memory cell, method for operating the memory cell and method for fabricating the memory cell are disclosed. The memory cell includes at least three terminals, a first magnetic tunnel junction (MTJ) structure and a second MTJ structure. The first MTJ is coupled between a first terminal (FT) and a third terminal. A portion of the first MTJ is configured to include a first barrier layer disposed between a first fixed layer and a free layer (FL). A magnetization direction of the FL is used to store data, the magnetization direction being controlled by an electric field. The second MTJ is coupled between the FT and a second terminal, where a portion of the second MTJ is configured to include a second barrier layer disposed between a second fixed layer and the FL, where a tunnel magnetoresistance of the second barrier layer is used to read the data.