Magnetoresistive Element Manganese Diffusion Barrier
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Solution Overview
Problem
Conventional magnetoresistive elements, such as tunnel and giant magnetoresistive elements, suffer from poor thermal stability due to manganese diffusion during annealing, which degrades the magnetic characteristics and MR ratio, especially in high-temperature processes used in magnetic disk drives and random access memory manufacturing.
Innovation Solution
A magnetoresistive element with a layered structure comprising an antiferromagnetic layer, a layered magnetization fixed layer with a platinum group metal and ferromagnetic material, and a magnetic free layer, where the layers are formed using sputtering and annealed to prevent manganese diffusion, enhancing thermal stability and MR ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If annealing is performed at high temperature (300°C or more) to magnetize the antiferromagnetic layer, then the magnetic characteristic is improved, but manganese diffuses to other layers causing degradation of MR ratio
Solution Approach 1:
A nonmagnetic intermediate layer is introduced between the antiferromagnetic layer and the ferromagnetic fixed layer to act as a diffusion barrier. This intermediary layer prevents manganese atoms from migrating into the ferromagnetic fixed layer during high-temperature annealing, thereby maintaining the MR ratio while allowing the annealing process to proceed for magnetic characterization.
Solution Approach 2:
The ferromagnetic fixed layer is divided into multiple sub-layers with different compositions and thicknesses. By segmenting the fixed layer, the patent creates a structure where certain layers are more resistant to manganese diffusion, allowing the overall magnetic characteristic to be maintained while protecting against composition degradation.
2Manufacturing precision
If the ferromagnetic fixed layer has a crystalline structure for good magnetic performance, then the MR ratio is improved, but manganese diffusion adversely affects the crystalline structure
Solution Approach 1:
The nonmagnetic intermediate layer serves as a protective barrier that shields the crystalline ferromagnetic fixed layer from manganese diffusion. This allows the crystalline structure to be maintained during high-temperature annealing processes without degradation from manganese contamination.
Solution Approach 2:
The patent uses composite material structures combining different ferromagnetic alloys (e.g., CoFeB, CoFe) with specific crystalline structures. These composite layers are designed to have enhanced resistance to manganese diffusion while maintaining good magnetic characteristics and crystalline order.
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 achieves higher thermal stability and MR ratio, effectively suppressing manganese diffusion and maintaining magnetic performance even at elevated temperatures, making it suitable for magnetic disk drives and random access memory applications.
Implementation Method 1
a first film formation chamber connected to the transfer chamber via a gate valve and adapted to form an antiferromagnetic layer over the substrate transferred by the robot transfer unit by sputtering using an antiferromagnetic target containing manganese (Mn)
Implementation Method 2
a magnetic head manufacturing process, a tunnel magnetoresistive element undergoes annealing at 250° C. to 300° C. in a high magnetic field of several T (tesla) for several hrs after film formation to magnetize a PtMn layer serving as an antiferromagnetic layer
Implementation Method 3
The ferromagnetic fixed layer of the giant magnetoresistive element or tunnel magnetoresistive element can use at least one of Fe, Co, and Ni as the ferromagnetic material
Implementation Method 4
The antiferromagnetic layer can use an antiferromagnetic material such as PtMn or IrMn which is obtained by adding a precious metal element to Mn
Implementation Method 5
A tunnel magnetoresistive element has an antiferromagnetic layer, ferromagnetic fixed layer, tunnel barrier layer, and ferromagnetic free layer
Data Source
AI summary
A magnetoresistive element includes an antiferromagnetic layer formed from a layer containing manganese, a layered magnetization fixed layer which includes a first magnetization fixed layer located over a side of the antiferromagnetic layer and formed from a layer containing a ferromagnetic material and a platinum group metal, a second magnetization fixed layer formed from a layer containing a ferromagnetic material, and a first nonmagnetic intermediate layer located between the first magnetization fixed layer and the second magnetization fixed layer, a magnetic free layer formed from a layer containing a ferromagnetic material, and a second nonmagnetic intermediate layer located between the layered magnetization fixed layer and the magnetic free layer.