Self-Aligned SOT Memory Device with Mandrel-Based Fabrication
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Solution Overview
Problem
The scaling of spin orbit torque (SOT) memory devices poses challenges in assembling material layer stacks and aligning metallization structures, particularly in patterning and aligning SOT devices at the nanoscale, which hinders the commercialization of SOT memory technology.
Innovation Solution
The development of self-aligned SOT memory devices with a magnetic tunnel junction (MTJ) device on a spin orbit torque electrode, where contacts are laterally spaced and self-aligned to the SOT electrode, allowing for reduced footprint and increased density, utilizing materials like tantalum, tungsten, and platinum for enhanced spin hall efficiency, and a synthetic antiferromagnetic structure for improved magnetization control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional patterning and alignment methods are used for SOT devices, then manufacturing process is simpler, but manufacturing precision deteriorates at nanoscale
Solution Approach 1:
The patent implements preliminary action by forming a mandrel structure before depositing the SOT electrode material. The mandrel is patterned first, then the electrode is deposited conformally around it, ensuring precise alignment is established before subsequent fabrication steps. This preliminary structuring enables nanoscale alignment precision without requiring complex alignment procedures later in the process.
Solution Approach 2:
The patent introduces a mandrel as an intermediary structure that facilitates precise alignment. The mandrel acts as a template or mediator around which the SOT electrode is formed, enabling accurate positioning without direct complex alignment operations. This intermediary structure simplifies the overall fabrication process while achieving high precision.
2Quantity of substance
If SOT device footprint is reduced to increase density, then device density improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies the nested doll principle by forming the SOT electrode in a conformal manner around the mandrel structure. The electrode material is deposited in layers that wrap around the mandrel, creating a nested configuration. This approach enables precise positioning within a reduced footprint area, as the conformal deposition naturally follows the mandrel's geometry, achieving both high density and high precision.
Solution Approach 2:
The patent transitions from planar patterning to three-dimensional conformal deposition. Instead of defining the electrode pattern in a single plane through complex lithography, the electrode is formed by depositing material that conforms to the mandrel's three-dimensional structure. This dimensional change enables precise alignment with reduced lateral footprint, as the positioning is controlled by the vertical mandrel structure rather than lateral patterning.
3Use of energy by moving object
If non-volatile embedded memory with SOT devices is implemented, then energy efficiency improves, but device fabrication complexity increases
Solution Approach 1:
The patent extracts the alignment complexity from the main fabrication process by using a separate mandrel structure that is formed independently. The mandrel is patterned and structured first, then the SOT electrode is deposited around it. This separation of the alignment function into a distinct preparatory structure simplifies the overall fabrication process while enabling the complex non-volatile memory functionality.
Solution Approach 2:
The patent performs preliminary structuring by forming the mandrel and establishing the alignment framework before depositing the functional SOT electrode materials. This preliminary action creates a template that guides subsequent material deposition, enabling the complex multi-layer non-volatile memory structure to be fabricated with standard processes rather than requiring complex in-situ alignment procedures.
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 enables the fabrication of SOT memory devices with reduced footprint and increased density, facilitating energy and computational efficiency while overcoming the challenges of scaling and alignment, thereby advancing the commercialization of SOT memory technology.
Implementation Method 1
spin orbit torque (SOT) memory devices including a spin orbit torque electrode coupled with a compatible MTJ device
Implementation Method 2
utilizing materials like tantalum, tungsten, and platinum for enhanced spin hall efficiency
Data Source
AI summary
A spin orbit torque (SOT) memory device includes an SOT electrode on an upper end of an MTJ device. The MTJ device includes a free magnet, a fixed magnet and a tunnel barrier between the free magnet and the fixed magnet and is coupled with a conductive interconnect at a lower end of the MTJ device. The SOT electrode has a footprint that is substantially the same as a footprint of the MTJ device. The SOT device includes a first contact and a second contact on an upper surface of the SOT electrode. The first contact and the second contact are laterally spaced apart by a distance that is no greater than a length of the MTJ device.