Hybrid STT SOT Magnetic Memory Write Mechanism

Solution Overview

Problem

Conventional magnetic memory devices using the STT effect consume high power and reduce durability due to large current requirements, while those using the SOT effect have larger cell sizes and complex structures, leading to inefficient write operations.

Innovation Solution

A magnetic memory device and method that simultaneously utilize both STT and SOT effects to perform write operations, reducing cell size and power consumption by combining parallel and perpendicular currents through the MTJ element, allowing for efficient data writing across multiple cells without increasing cell size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the STT effect is used for write operations, then the cell size is reduced to 6F2, but the power consumption increases and durability decreases due to large current requirements

Engineering Contradiction:

Improvecell sizeVSAvoiddurability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent merges the STT and SOT effects into a hybrid write operation. A first current is applied perpendicular to the MTJ element layers to generate STT effect, while a second current is applied parallel to the free layer to generate SOT effect via spin-hall effect material. This combination allows using smaller currents than pure STT while maintaining the compact 6F2 cell structure.

Inventive Principle:

Principle #5Merging (Combining)

2Area of stationary object

If the STT effect is used for write operations, then the cell size is reduced to 6F2, but the power consumption increases due to large current requirements

Engineering Contradiction:

Improvecell sizeVSAvoidpower consumption

Core Design Contradiction:

Area of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent merges the STT and SOT effects into a hybrid write operation. A first current is applied perpendicular to the MTJ element layers to generate STT effect, while a second current is applied parallel to the free layer to generate SOT effect via spin-hall effect material. This combination allows using smaller currents than pure STT while maintaining the compact 6F2 cell structure.

Inventive Principle:

Principle #5Merging (Combining)

3Use of energy by moving object

If the SOT effect is used for write operations, then the power consumption is reduced, but the cell size increases to 9F2 and structure becomes complex

Engineering Contradiction:

Improvepower consumptionVSAvoidcell size

Core Design Contradiction:

Use of energy by moving objectVSArea of stationary object

Solution Approach 1:

The patent merges the STT and SOT effects into a hybrid write operation. A first current is applied perpendicular to the MTJ element layers to generate STT effect, while a second current is applied parallel to the free layer to generate SOT effect via spin-hall effect material. This combination allows using smaller currents than pure STT while maintaining the compact 6F2 cell structure.

Inventive Principle:

Principle #5Merging (Combining)

4Use of energy by moving object

If the SOT effect is used for write operations, then the power consumption is reduced, but the device structure becomes complex with additional write lines

Engineering Contradiction:

Improvepower consumptionVSAvoidstructure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent merges the STT and SOT effects into a hybrid write operation. A first current is applied perpendicular to the MTJ element layers to generate STT effect, while a second current is applied parallel to the free layer to generate SOT effect via spin-hall effect material. This combination allows using smaller currents than pure STT while maintaining the compact 6F2 cell structure.

Inventive Principle:

Principle #5Merging (Combining)

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 enables reduced power consumption, improved durability, and enhanced write performance by allowing simultaneous STT and SOT effects in a single write operation, reducing stress on the MTJ element and minimizing cell size, thereby improving overall memory device efficiency and lifespan.

Implementation Method 1

current which flows in a direction parallel to the MTJ element 10 through the write line 40 causes a spin-hall effect in the spin-hall effect material layer 50, which causes the spin direction of the free layer 13 to change

Methodology Applied

Scientific EffectSpin-hall effect: Hall Effect

Implementation Method 2

The magnetic memory device using the STT effect writes data by applying a current through the MTJ element 10 to adjust the spin orientation of the free layer 13 of the MTJ element 10

Methodology Applied

Scientific EffectSpin transfer torque (STT):

Data Source

PatentUS10290339B2Operating method of a magnetic memory device

Publication Date: 2019.05.14 SK HYNIX INC

AI summary

An operating method of a magnetic memory device may include: a first step of retrieving write data to be written to a plurality of magnetic memory cells sharing a bit line according to a write request, the write data including more of a first type of data than a second type of data; a second step of writing the first type of data simultaneously to all cells of the plurality of magnetic memory cells; and a third step of writing the second type of data to a portion of the plurality of magnetic memory cells, the second type of data being different from the first type of data.