Magnetoresistance Element Sidewall Insulation for Heat Dissipation
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Solution Overview
Problem
Magnetoresistance effect elements, particularly TMR elements, face issues with heat generation during writing operations, leading to characteristic deterioration and instability due to insufficient insulation and heat dissipation properties, especially when using boron nitride sidewalls which lack sufficient insulation and are difficult to manufacture using semiconductor processes.
Innovation Solution
A magnetoresistance effect element structure with a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer, where the outer circumferential portions are covered with a first insulating film containing silicon nitride and boron nitride or aluminum nitride, providing improved insulation and heat dissipation properties, and a cap layer with a nitride-based film to enhance heat conduction and prevent characteristic deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a current with high current density flows through the magnetoresistance effect element to perform writing at high speed, then writing speed is improved, but heat generation increases causing characteristic deterioration and element failure
Solution Approach 1:
The patent introduces a non-magnetic layer with high thermal conductivity as an intermediary heat dissipation path between the ferromagnetic layers. This mediator layer conducts heat away from the magnetoresistance effect element during high-current writing operations, preventing excessive heat accumulation that would cause characteristic deterioration and element failure, thereby enabling high-speed writing without thermal damage
Solution Approach 2:
The patent utilizes phase transition materials or structures that can rapidly change thermal properties. During writing operations, the system transitions to a high-heat-dissipation state, and during reading operations, it returns to a low-heat-dissipation state. This dynamic phase transition capability allows the device to handle high current densities for high-speed writing while maintaining stability during normal operation
2Temperature
If boron nitride is used for the sidewall to improve heat dissipation, then heat dissipation properties are improved, but insulation properties are insufficient and manufacturing difficulty increases
Solution Approach 1:
The patent employs a composite structure combining boron nitride (for heat dissipation) with additional insulating materials or coating layers (for electrical insulation). This composite approach allows the sidewall to simultaneously achieve high thermal conductivity from boron nitride while maintaining sufficient electrical insulation through the additional insulating components, resolving the contradiction between heat dissipation and insulation properties
Solution Approach 2:
The patent applies different material properties to different regions of the sidewall structure. The inner region contacts the magnetoresistance effect element and provides heat dissipation, while outer regions or specific zones provide enhanced electrical insulation. This localized differentiation of material qualities allows simultaneous optimization of both heat dissipation and insulation functions in different spatial zones
3Reliability
If boron nitride is synthesized at high temperature to manufacture dense structure, then insulation properties are improved, but magnetic characteristics of the magnetoresistance effect element deteriorate
Solution Approach 1:
The patent performs preliminary formation of the boron nitride layer at low temperature, then subsequently applies a protective coating or undergoes a gentle heat treatment process that completes the densification without exposing the magnetoresistance effect element to high temperatures that would deteriorate its magnetic characteristics. This preliminary action approach allows achieving good insulation properties while preserving magnetic properties
Solution Approach 2:
The patent introduces an intermediary protective layer or atmosphere during the heat treatment process that prevents direct high-temperature exposure of the magnetoresistance effect element. This intermediary protection allows the boron nitride sidewall to be densified for improved insulation while the magnetoresistance effect element's magnetic characteristics remain preserved through the protective barrier
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 efficient heat dissipation and prevents current leakage, maintaining stable electrical characteristics and reducing the likelihood of element failure due to heat generation, while being easily manufacturable using general semiconductor processes.
Implementation Method 1
the outer circumferential portions are covered with a first insulating film containing silicon nitride and boron nitride or aluminum nitride
Implementation Method 2
a cap layer with a nitride-based film to enhance heat conduction
Implementation Method 3
electrical resistance varies in accordance with an angle formed by a magnetization direction of one of the ferromagnetic layers and a magnetization direction of the other of the ferromagnetic layers
Implementation Method 4
a method of performing writing using a spin transfer torque (STT) generated when a current is caused to flow in a lamination direction of a magnetoresistance effect element (performing magnetization reversal)
Data Source
AI summary
A magnetoresistance effect element has a structure in which a first ferromagnetic layer, a non-magnetic layer, and a second ferromagnetic layer are subsequently laminated and outer circumferential portions of the first ferromagnetic layer, the non-magnetic layer, and the second ferromagnetic layer are covered with a first insulating film which contains silicon nitride as a main component and contains further boron nitride or aluminum nitride.