Magnetoresistive Element Manufacturing with Protection Layer
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Solution Overview
Problem
The existing methods for manufacturing magnetoresistive elements with a pair of free layers coupled to a pair of shields face challenges in achieving stable magnetic coupling, particularly when the MR stack is reduced in dimension, leading to uneven thickness of the magnetic cap layer and unstable exchange coupling magnetic fields, which affects the shielding capability and magnetization control.
Innovation Solution
The method involves forming a magnetoresistive element with a stack configuration that includes first and second main shield layers, antiferromagnetic layers, exchange coupling shield layers, and a nonmagnetic layer, where the MR stack has a spacer layer, free layers, and a magnetic cap layer, with a protection layer used to ensure a flat top surface of the magnetic cap layer, allowing for stable magnetic coupling between the free layers and shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the MR stack is reduced in dimension to reduce read gap length and track width, then recording density is improved, but the magnetic cap layer thickness becomes uneven and magnetic coupling stability deteriorates
Solution Approach 1:
A protection layer is formed on the MR stack before etching to pre-establish a flat top surface structure. This preliminary protective layer prevents the magnetic cap layer from becoming uneven during subsequent processing, ensuring stable magnetic coupling even when the MR stack dimensions are reduced for higher recording density.
Solution Approach 2:
The protection layer acts as an intermediary between the etching process and the magnetic cap layer. It mediates the etching process to prevent direct damage to the magnetic cap layer thickness uniformity, allowing dimension reduction while maintaining coupling stability.
2Length of stationary object
If the MR stack is reduced in dimension, then read gap length and track width are reduced, but exchange coupling magnetic field stability deteriorates
Solution Approach 1:
The protection layer is formed in advance to pre-establish a flat top surface on the magnetic cap layer. This preliminary structure ensures that even when the MR stack is reduced in dimension for smaller read gap length, the exchange coupling magnetic field stability is maintained through uniform magnetic cap layer thickness.
3Area of moving object
If the MR stack is reduced in dimension, then track width is reduced, but shielding capability deteriorates
Solution Approach 1:
The protection layer is formed beforehand to ensure a flat top surface of the magnetic cap layer. This preliminary structural preparation maintains uniform magnetic cap layer thickness even when track width is reduced, thereby preserving shielding capability alongside reduced track width for improved recording density.
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 stable magnetic coupling and reduced characteristic variations among MR elements, improving the shielding capability and magnetization control, while allowing for a reduction in read gap length and track width, thus enhancing recording density.
Implementation Method 1
an antiferromagnetic layer disposed on a side of the pinned layer opposite from the spacer layer. The free layer is a ferromagnetic layer whose direction of magnetization changes in response to a signal magnetic field. The pinned layer is a ferromagnetic layer whose direction of magnetization is pinned. The antiferromagnetic layer is a layer that pins the direction of magnetization of the pinned layer by means of exchange coupling with the pinned layer.
Implementation Method 2
The magnetic cap layer is in contact with the second exchange coupling shield layer and is magnetically coupled to the second exchange coupling shield layer. The second free layer is magnetically coupled to the second exchange coupling shield layer via the magnetic cap layer and thereby has a controlled direction of magnetization.
Implementation Method 3
a giant magnetoresistive (GMR) element utilizing a giant magnetoresistive effect
Implementation Method 4
a tunneling magnetoresistive (TMR) element utilizing a tunneling magnetoresistive effect
Data Source
AI summary
An MR element includes a first exchange coupling shield layer, an MR stack, and a second exchange coupling shield layer that are arranged in this order from the bottom, and a nonmagnetic layer surrounding the MR stack. The MR stack includes a first free layer, a spacer layer, a second free layer, and a magnetic cap layer that are arranged in this order from the bottom. In the step of forming the MR stack and the nonmagnetic layer, a protection layer is formed on a layered film that will be the MR stack later, and a mask is then formed on the protection layer. Next, the layered film and the protection layer are etched using the mask and then the nonmagnetic layer is formed. After removal of the mask, the protection layer is removed by wet etching.