Thin Film Magnetic Head Insulating Layer Composition for Noise Reduction
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Solution Overview
Problem
Existing thin film magnetic heads face challenges in maintaining high sensitivity and output due to variations in magnetic characteristics of bias magnetic field application layers, particularly in narrow shield gaps, leading to noise issues and reduced thermal stability.
Innovation Solution
A novel thin film magnetic head design featuring a CPP structure with bias magnetic field application layers formed at tapered parts via insulating and foundation layers, where the insulating layers are composed of Si oxide with specific Si content and oxygen-to-Si ratios, and the foundation layers are made of Cr or Cr alloys, enhancing thermal stability and reducing noise occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the shield gap is narrowed to increase recording density, then the recording density increases, but the magnetic characteristics of bias magnetic field application layers become unstable causing noise and waveform variation
Solution Approach 1:
The patent changes the material composition parameters of the insulating layer, specifically controlling the Si content (30-56 at%) and O/Si ratio (0.8-1.3) of the Si oxide layer. This parameter optimization stabilizes the magnetic characteristics of the bias magnetic field application layers while maintaining narrow shield gap structure, thereby preventing noise and waveform variation even at high recording densities
Solution Approach 2:
The patent employs a composite insulating layer structure consisting of multiple materials including Si oxide with specific composition ratios, combined with other insulating materials. This composite structure provides both the electrical insulation needed for narrow shield gaps and the magnetic field stabilization needed to prevent characteristics degradation, resolving the contradiction between high density and stability
2Ease of manufacture
If conventional insulating layers are used in bias magnetic field application layers, then manufacturing is simplified, but thermal stability deteriorates after annealing treatment
Solution Approach 1:
The patent optimizes the compositional parameters of the Si oxide insulating layer, controlling Si content (30-56 at%) and O/Si ratio (0.8-1.3), which maintains manufacturing feasibility while dramatically improving thermal stability after annealing treatment. The specific parameter range ensures the layer withstands annealing without degradation
Solution Approach 2:
The patent applies different material compositions to different regions of the insulating layer structure. The Si oxide layer with optimized composition is placed specifically where thermal stability is critical, while maintaining overall manufacturing simplicity. This localized optimization resolves the contradiction between ease of manufacture and thermal stability
3Ease of manufacture
If residual magnetization of bias magnetic field application layers is small, then layer formation becomes easier, but magnetic field response control becomes insufficient causing waveform variation and Barkhausen noise
Solution Approach 1:
The patent optimizes the material composition parameters of the insulating layer (Si content 30-56 at%, O/Si ratio 0.8-1.3) which indirectly controls the magnetic properties of adjacent layers. This parameter optimization ensures sufficient residual magnetization for proper magnetic field response control while maintaining reasonable manufacturing ease
Solution Approach 2:
The insulating layer acts as an intermediary between the bias magnetic field application layers and the substrate. By optimizing its composition, it mediates the magnetic field distribution and stabilizes the magnetic characteristics, ensuring proper response control without requiring extreme manufacturing complexity
4Ease of manufacture
If retentivity of bias magnetic field application layers is small, then manufacturing is simplified, but bias magnetic field is reduced under external influences causing waveform variation and Barkhausen noise
Solution Approach 1:
The patent optimizes the insulating layer composition parameters (Si content 30-56 at%, O/Si ratio 0.8-1.3) which stabilizes the magnetic environment for the bias magnetic field application layers. This ensures sufficient retentivity and bias field stability against external influences while maintaining manufacturing simplicity
Solution Approach 2:
The optimized insulating layer serves as a protective intermediary that shields the bias magnetic field application layers from external magnetic influences. Its specific composition creates a stable magnetic environment, preventing field reduction under external influences while keeping the overall structure manufacturable
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 design significantly reduces noise occurrence rates and improves thermal stability by optimizing the layer configuration, ensuring consistent magnetic characteristics and performance even after annealing treatment.
Implementation Method 1
the insulating layers are configured of a Si oxide such that the Si content of the Si oxide is in the range of 30 ̃56 at % (atom %) and that the atom ratio of oxygen to Si (O/Si) is in the range of 0.8 ̃1.3
Implementation Method 2
the foundation layers are configured of Cr or Cr alloy, and the insulating layers are configured of a Si oxide... the bias magnetic field application layers are configured to apply a vertical bias magnetic field to the free layer
Implementation Method 3
a magneto-resistive (MR) effect element having an MR effect film formed by sequentially layering a magnetic pinned layer, a nonmagnetic layer and a free layer... the free layer is configured to change its magnetization direction in accordance with an external magnetic field
Implementation Method 4
ensuring consistent magnetic characteristics and performance even after annealing treatment
Data Source
AI summary
Foundation layers of a thin film magnetic head are disposed between insulating layers and bias magnetic field application layers, and are configured of Cr or Cr alloy. The insulating layers are configured of a Si oxide such that the Si content of the Si oxide is in the range of 30˜56 at % (atom %) and that the atom ratio of oxygen to Si (O/Si) is in the range of 0.8˜1.3. With the configuration, the occurrence rate of noise is reduced.