Magnetoresistance Element Pinned Layer Ni Diffusion Barrier
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Solution Overview
Problem
Existing magnetoresistance effect elements face challenges in achieving a high MR ratio and strong exchange coupling magnetic field, with issues such as decreased yield due to etching byproducts and Ni diffusion during annealing, which affect the performance and reliability of MRAM devices.
Innovation Solution
A magnetoresistance effect element with a layered structure including a barrier layer, a reference layer, and a pinned layer with a specific stacking order of Pt, Co, Ru, and Co layers, which prevents Ni diffusion and maintains a strong exchange coupling magnetic field, thereby enhancing the MR ratio and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Pt and Pd are included in the element structure to enhance MR ratio, then the MR ratio is improved, but etching byproducts are redeposited on wall surfaces causing decreased damping constant and lower yield
Solution Approach 1:
The invention removes Pt and Pd from the element structure, extracting the harmful components that cause etching byproduct deposition while maintaining the essential functional layers needed for magnetoresistance effect
Solution Approach 2:
The invention replaces expensive Pt and Pd with more cost-effective materials that achieve similar or better performance, reducing material costs while eliminating the etching contamination problem
2Ease of manufacture
If Ni is used to replace Pt and Pd to reduce material costs, then material costs are reduced, but Ni diffuses into Co layers during annealing process decreasing exchange coupling magnetic field
Solution Approach 1:
The Ru layer serves as an intermediary barrier between Ni and Co layers, preventing Ni diffusion into Co during annealing while allowing the cost-effective Ni to be used in the structure
Solution Approach 2:
The pinned layer is segmented into distinct functional sub-layers (Ni layer, Ru layer, Co layers, Pt layer) where each layer performs a specific function, with Ru acting as a diffusion barrier
3Reliability
If Co/Pt laminate structure is used to achieve high MR ratio, then MR ratio is improved, but Pt usage increases material cost
Solution Approach 1:
The invention extracts Pt from the laminate structure, removing the expensive material while maintaining the essential magnetic and tunneling functions through alternative material combinations
Solution Approach 2:
The invention changes the material composition parameters of the laminate structure, replacing Pt with other materials and adjusting layer configurations to achieve similar or better performance at lower cost
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 a higher MR ratio, stronger exchange coupling magnetic field, and improved yield in the manufacturing process, while minimizing Pt usage and preventing magnetization reversal, thus enhancing the performance and cost-effectiveness of the magnetoresistance effect element.
Implementation Method 1
A well-known one of the magnetoresistance effect elements is a TMR (Tunnel Magneto Resistance) element (also referred to as a 'MTJ (Magnetic Tunnel Junction) element') configured to store information and detect magnetism using a TMR effect
Implementation Method 2
a pinned layer placed on an opposite side of the reference layer from the barrier layer, in which the pinned layer includes Pt, Co, Ru, Co, and Pt layers stacked in this order, and a layer including Ni
Data Source
AI summary
A magnetoresistance effect element of the present invention includes: a barrier layer; a reference layer formed on one surface of the barrier layer; a free layer formed on the other surface of the barrier layer; and a pinned layer placed on the opposite side of the reference layer from the barrier layer. The pinned layer includes a structure obtained by stacking Ni, Co, Pt, Co, Ru, Co, Pt, Co, and Ni layers in this order.