Magnetic Memory Word Line for MRAM Write and Erase
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Solution Overview
Problem
Current magnetic memory technologies face challenges in achieving high-speed data transfer and large-capacity storage while maintaining low power consumption and micropatterning capabilities, particularly in the context of magnetic random access memory (MRAM) devices.
Innovation Solution
The proposed magnetic memory design incorporates a magnetoresistive element with a fixed layer, a free layer, and a nonmagnetic tunnel barrier layer, utilizing spin-transfer magnetization reversal and a current-induced magnetic field to change the magnetization direction for data write and erase operations, allowing for efficient data recording and retrieval without the need for transistors, enabling high-speed and high-capacity storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If spin-transfer magnetization reversal is used to write data by supplying current to magnetoresistive elements, then low power consumption and micropatterning are achieved, but data erase requires complex magnetic field generation structures
Solution Approach 1:
The patent combines the write and erase functions into a single word line structure. The word line serves dual purposes: generating spin-polarized current for write operations and generating magnetic fields for erase operations. This merging eliminates the need for separate structures, reducing device complexity while maintaining low power consumption characteristics of spin-transfer magnetization reversal.
Solution Approach 2:
The word line is designed to perform multiple functions: it acts as both a current supply path for spin-transfer magnetization reversal (write operation) and a magnetic field generation source (erase operation). This multi-functionality reduces the number of components needed and simplifies the overall device structure while preserving the energy efficiency of the spin-transfer mechanism.
2Productivity
If conventional MRAM structures are used for data storage, then data read is achieved by detecting resistance change, but simultaneous data erase and write operations cannot be performed
Solution Approach 1:
The patent employs periodic action by sequentially performing erase and write operations through controlled current pulses on the word line. First, a current pulse generates a magnetic field for erase operation, then another current pulse provides spin-polarized current for write operation. This periodic switching enables both operations to be performed in sequence on the same structure, achieving high productivity while maintaining operational flexibility.
3Productivity
If magnetic field is induced by current flowing through word line for data erase, then one-time data erase is achieved, but separation of erase and write functions increases device complexity
Solution Approach 1:
The patent merges the erase function (magnetic field generation) and write function (spin-polarized current supply) into a single word line structure. By controlling the direction and magnitude of current through the word line, both erase and write operations are achieved using the same structural element, thereby maintaining one-time erase efficiency while avoiding the complexity of functionally separated structures.
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 design enables simultaneous data erase and write operations in MRAM, supporting high-speed data transfer and large-capacity storage while allowing for micropatterning, thus addressing the limitations of existing MRAM technologies.
Implementation Method 1
Data write is performed by setting the magnetization direction of the free layer in a second direction by spin-transfer magnetization reversal by supplying a current in one direction to the magnetoresistive elements
Implementation Method 2
Data erase is performed by setting the magnetization direction of the free layer in a first direction by a magnetic field induced by a current flowing through the word line
Implementation Method 3
a magnetoresistive element which includes a fixed layer in which a magnetization direction is fixed, a free layer in which a magnetization direction changes, and a nonmagnetic layer formed between the fixed layer and the free layer, and records data by a resistance value which changes on the basis of the magnetization direction of the free layer
Data Source
AI summary
A magnetic memory includes a plurality of magnetoresistive elements which include a fixed layer in which a magnetization direction is fixed, a free layer in which a magnetization direction changes, and a nonmagnetic layer formed between the fixed layer and the free layer, and a word line electrically connected to the magnetoresistive elements. Data erase is performed by setting the magnetization direction of the free layer in a first direction by a magnetic field induced by a current flowing through the word line, and data of the magnetoresistive elements are erased by one time data erase. Data write is performed by setting the magnetization direction of the free layer in a second direction by spin-transfer magnetization reversal by supplying a current in one direction to the magnetoresistive elements.