Amorphous Separation Layer for Perpendicular Magnetic Recording Head Shield
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Solution Overview
Problem
In magnetic heads, the poor adhesion of materials like rhodium, ruthenium, and platinum due to chemical inertness, and the negative effects between seed layers and top shields, lead to unpredictable magnetization behavior and poor data writing performance.
Innovation Solution
A method involving the formation of an amorphous metal or insulation layer between the main pole and the seed layer to separate them, allowing for improved adhesion and reducing the impact of crystalline structures on downstream layers, thereby enhancing magnetic recording performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a seed layer is deposited to improve adhesion of the gap layer, then adhesion is improved, but the seed layer material negatively affects the magnetization behavior of the top shield
Solution Approach 1:
An amorphous metal layer is introduced as an intermediary between the crystalline seed layer and the main pole. This amorphous layer acts as a buffer that prevents the crystalline structure and magnetic properties of the seed layer from negatively affecting the magnetization behavior of the main pole, while still allowing the seed layer to provide its adhesion function.
Solution Approach 2:
The interface region between the main pole and seed layer is segmented into multiple layers: the main pole, an amorphous metal layer, and the crystalline seed layer. This segmentation allows each layer to perform its specific function independently - the amorphous layer maintains uniform magnetic properties while the crystalline seed layer provides adhesion.
2Strength
If a crystalline seed layer is used to improve adhesion, then adhesion is improved, but the crystalline structure creates unpredictable magnetization behavior
Solution Approach 1:
The amorphous metal layer serves as a mediator that decouples the crystalline seed layer from the main pole. It transmits the adhesion benefit while blocking the transmission of crystalline structure effects that cause unpredictable magnetization behavior.
Solution Approach 2:
Different layers are assigned different structural qualities: the amorphous metal layer has a non-crystalline structure to ensure uniform magnetic properties, while the seed layer maintains its crystalline structure for adhesion. This local differentiation of structural quality allows each layer to optimize its specific function.
3Reliability
If gap layer materials like rhodium, ruthenium, or platinum are used, then corrosion resistance is improved, but adhesion is poor due to chemical inertness
Solution Approach 1:
The amorphous metal layer acts as an intermediary that bridges the gap between the main pole and the chemically inert gap layer materials. It provides a surface that promotes adhesion while allowing the gap layer materials to maintain their corrosion resistance properties.
Solution Approach 2:
The structure employs a composite material approach by combining the amorphous metal layer with the corrosion-resistant gap layer materials (rhodium, ruthenium, or platinum). This composite structure leverages the adhesion properties of the amorphous layer and the corrosion resistance of the gap layer materials.
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 amorphous layer mitigates the negative effects of seed layer materials on the main pole, ensuring predictable magnetization and improved data writing capabilities in magnetic heads, particularly in perpendicular magnetic recording.
Implementation Method 1
forming an amorphous metal layer above the write pole, wherein the metal layer is electrically conductive... forming a trailing shield such that the amorphous metal layer is between the trailing shield and the write pole
Data Source
AI summary
Depositing a seed layer for a high-moment shield onto a write pole may have a deleterious effect on the magnetic response of the write pole. Instead, an amorphous separation layer may be deposited between the write pole and the seed layer. In one embodiment, the seed layer is formed directly on the amorphous layer. In addition to separating the seed layer from the write pole, the amorphous separation layer permits the seed layer to dictate the crystallographic orientation of the shield which is subsequently deposited on the magnetic head. That is, the amorphous layer provides a substrate that allows the seed layer to have a crystalline structure independent of the layers that were deposited previously. The amorphous separation layer may comprise an amorphous metal—e.g., NiNb or NiTa—or an insulative material—e.g., alumina or silicon dioxide.