CoZrTa Auxiliary Layer for Thin Film Magnetic Head
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Solution Overview
Problem
The existing thin film magnetic head manufacturing process faces challenges in maintaining exchange coupling strength while minimizing the thickness of the auxiliary magnetization control layer, which affects the track per inch (TPI) and read gap narrowing due to the limitations of using NiFe layers and the need for thicker film thicknesses to prevent exchange coupling strength degradation.
Innovation Solution
Incorporating a CoZrTa layer as the auxiliary magnetization control layer, which provides sufficient shielding characteristics and prevents the implantation of Ni into the CoFe layer, allowing for a thinner initial film thickness without compromising exchange coupling strength, thereby reducing the restrictions on TPI and read gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NiFe layers are used as the auxiliary magnetization control layer, then shielding characteristics are provided, but the layer thickness must be increased to prevent exchange coupling strength degradation
Solution Approach 1:
The patent changes the material composition of the auxiliary magnetization control layer from NiFe to CoZrTa, altering the physical and chemical parameters of the layer. This material substitution enables the layer to provide sufficient shielding characteristics while maintaining exchange coupling strength at reduced thicknesses, directly resolving the contradiction between reliability and layer thickness
Solution Approach 2:
The patent employs a composite material approach by using CoZrTa alloy in the auxiliary magnetization control layer. This composite material combines the advantages of high coercivity for shielding with appropriate magnetic properties for maintaining exchange coupling, eliminating the need for increased layer thickness while ensuring both shielding effectiveness and coupling strength
2Productivity
If the auxiliary magnetization control layer thickness is reduced, then TPI restrictions are minimized, but exchange coupling strength degrades when using NiFe layers
Solution Approach 1:
By changing the material parameter from NiFe to CoZrTa, the patent achieves a material that maintains exchange coupling strength at thinner thicknesses. This parameter change allows the auxiliary magnetization control layer to be thinner, thereby minimizing restrictions on TPI while preserving exchange coupling strength
Solution Approach 2:
The patent applies local quality by optimizing the magnetic properties specifically in the auxiliary magnetization control layer region. The CoZrTa material provides localized high coercivity for shielding while maintaining appropriate exchange coupling characteristics, enabling thin layer design without compromising overall head performance or TPI
3Reliability
If NiFe layers are used, then shielding is provided, but Ni implants into the CoFe layer causing exchange coupling strength degradation
Solution Approach 1:
The patent extracts the harmful element (Ni) from the auxiliary magnetization control layer composition. By removing Ni from the material composition and replacing it with CoZrTa, the source of implantation damage to the CoFe layer is eliminated, preventing exchange coupling strength degradation while maintaining shielding characteristics
Solution Approach 2:
The patent replaces the NiFe material system with CoZrTa, using a material that does not suffer from implantation issues. This substitution eliminates the harmful interaction between Ni and the CoFe layer, allowing the auxiliary magnetization control layer to fulfill its shielding function without generating harmful implantation effects
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 use of CoZrTa layers maintains exchange coupling strength and reduces the required thickness of the auxiliary magnetization control layer, minimizing TPI restrictions and enabling narrower read gaps, while avoiding the degradation of exchange coupling strength associated with NiFe layers.
Implementation Method 1
prevents the implantation of Ni into the CoFe layer
Implementation Method 2
The two magnetization free layers are exchange-coupled based on RKKY (Rudermann, Kittel, Kasuya, and Yoshida) interaction through the non-magnetic intermediate layer
Implementation Method 3
a bias magnetic layer is disposed on rear sides of the two magnetization free layers, seen from an air bearing surface (ABS), and a bias magnetic field is applied in an orthogonal direction to the ABS
Implementation Method 4
when an external magnetic field, which is in an orthogonal direction to the ABS, is applied from a recording medium, the magnetization directions of the two magnetization free layers vary, the relative angle between the magnetization directions of the two magnetization free layers varies, and an electrical resistance of a sense current varies
Data Source
AI summary
The present invention relates to a method of manufacturing a DFL type thin film magnetic head. The method includes laminating each of the layers from the lower magnetization control layer to the upper exchange coupling layer above the substrate; laminating an auxiliary magnetization control layer including at least a CoZrTa layer above the upper exchange coupling layer; forming at least each of the layers from the lower exchange coupling layer to the auxiliary magnetization control layer in pillar shape, and disposing the bias magnetic field application layer at an opposite position with respect to the ABS of each of the pillar shaped layers; trimming the auxiliary magnetization control layer by removing a part of the auxiliary magnetization control layer that is formed in the pillar shape, and disposing the upper shield layer such that the trimmed auxiliary magnetization control layer is at least covered.