BiSb Buffer and Interlayer Stack for Stable (012) Orientation
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Solution Overview
Problem
Existing BiSb layers in spin-orbit torque (SOT) devices suffer from Sb migration, leading to poor chemical uniformity and degradation of the (012) orientation, which affects the high spin Hall angle and conductivity required for efficient spin Hall effect and conductivity.
Innovation Solution
Incorporating a buffer layer and interlayer with specific materials such as covalently bonded amorphous, tetragonal, or textured cubic structures to inhibit Sb migration and promote the (012) orientation of the BiSb layer, enhancing its uniformity and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If BiSb layer is formed with (012) orientation for high spin Hall angle and conductivity, then spin Hall effect performance is improved, but Sb migration occurs leading to poor chemical uniformity and degradation of orientation
Solution Approach 1:
The patent introduces buffer layers and interlayers as intermediary structures between the BiSb layer and adjacent layers. These intermediary layers act as diffusion barriers that prevent Sb migration while maintaining the (012) crystallographic orientation of the BiSb layer, thus preserving both chemical uniformity and spin Hall effect performance
Solution Approach 2:
The patent employs composite material structures consisting of multiple layers with different compositions and crystal structures. The buffer layer and interlayer are designed as composite structures that combine materials with specific properties to simultaneously inhibit Sb diffusion and promote (012) orientation, resolving the contradiction between performance and stability
2Reliability
If BiSb layer is formed with (012) orientation for high conductivity, then electrical conductivity is improved, but Sb migration degrades the structural integrity
Solution Approach 1:
The buffer layer and interlayer serve as intermediary structures that physically constrain the BiSb layer and prevent Sb atoms from migrating to interfaces. This structural constraint maintains the structural integrity of the BiSb layer while preserving its high electrical conductivity associated with (012) orientation
Solution Approach 2:
The buffer layer is formed prior to the BiSb layer, and the interlayer is formed after, creating a preliminary and post-formation structural framework. This preliminary action of the buffer layer prevents Sb migration before it can degrade the structural integrity, while maintaining the conditions for high conductivity
Data Source
AI summary
The present disclosure generally relate to spin-orbit torque (SOT) magnetic tunnel junction (MTJ) devices comprising a buffer layer, a bismuth antimony (BiSb) layer having a (012) orientation disposed on the buffer layer, and an interlayer disposed on the BiSb layer. The buffer layer and the interlayer may each independently be a single layer of material or a multilayer of material. The buffer layer and the interlayer each comprise at least one of a covalently bonded amorphous material, a tetragonal (001) material, a tetragonal (110) material, a body-centered cubic (bcc) (100) material, a face-centered cubic (fcc) (100) material, a textured bcc (100) material, a textured fcc (100) material, a textured (100) material, or an amorphous metallic material. The buffer layer and the interlayer inhibit antimony (Sb) migration within the BiSb layer and enhance uniformity of the BiSb layer while further promoting the (012) orientation of the BiSb layer.