Fill-in Contact Layer for Slider Air Bearing Surface
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Solution Overview
Problem
The existing magnetic data recording technologies face challenges in achieving a smooth air bearing surface for magnetic heads due to surface roughness caused by processing procedures like polishing and ion milling, which can lead to interference in the measurement of seed and protective layers and affect sensor performance.
Innovation Solution
A refill material without silicon or carbon is used to fill the troughs on the slider's surface, accompanied by a seed layer of silicon for adhesion and a protective overcoat of carbon, allowing precise control of layer thickness and enhancing sensor protection with materials like AlOx, TaOx, CrOx, TaN, CrN for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polishing and ion milling are used to recess magnetic heads, then magnetic head positioning is improved, but surface roughness increases causing measurement interference
Solution Approach 1:
The protective coating is divided into multiple distinct layers: a seed layer (5-20 nm), a refill layer (50-200 nm), and a protective overcoat (20-100 nm). This segmentation allows each layer to serve a specific function and enables independent measurement and control of thickness for each layer, resolving the measurement interference problem caused by surface roughness.
Solution Approach 2:
A refill layer made of aluminum oxide (AlOx) is introduced as an intermediary between the rough slider body surface and the seed layer. This refill layer fills the surface troughs and provides a smoother base, enabling accurate thickness measurement of the subsequent seed and protective layers without interference from the underlying roughness.
2Shape
If a refill layer containing silicon or carbon is used, then surface filling is achieved, but layer thickness measurement becomes inaccurate
Solution Approach 1:
The refill layer uses aluminum oxide (AlOx) as an intermediary material that is chemically distinct from both the slider body and the carbon-based protective overcoat. This material choice ensures that thickness measurement techniques like XRF and Auger can accurately measure the carbon-containing protective layer without interference from the refill layer composition.
Solution Approach 2:
The invention changes the compositional parameters of the refill layer by selecting aluminum oxide instead of silicon or carbon-based materials. This parameter change enables the subsequent protective overcoat thickness to be measured accurately using standard techniques, while still achieving the desired surface filling and smoothing effect.
3Reliability
If protective overcoat is applied directly on rough surface, then protection is provided, but sensor performance deteriorates due to interference
Solution Approach 1:
The seed layer and refill layer are deposited beforehand to create a smooth, uniform base surface before applying the protective overcoat. This preliminary action ensures that the protective overcoat can be applied uniformly at the precise thickness required for optimal sensor performance, while still providing the necessary corrosion protection.
Solution Approach 2:
The protective coating structure uses a composite material approach with multiple layers: a silicon-containing seed layer for adhesion, an aluminum oxide refill layer for surface smoothing and corrosion resistance, and a carbon-based protective overcoat for final protection. This composite structure achieves both protection and precise sensor performance.
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 results in a smoother air bearing surface, accurate control of layer thickness, and improved sensor performance by preventing interference in measurements and providing effective protection against corrosion and thermal expansion.
Implementation Method 1
The seed layer can also be referred to as an adhesion layer. This layer promotes adhesion of the carbon layer.
Implementation Method 2
During deposition, the thickness of the seed layer and protective overcoat can be measured and controlled using an ellipsometer.
Implementation Method 3
After deposition, the thickness of the seed layer and protective overcoat can be measured by a process such as XRF or Auger measurement
Implementation Method 4
After deposition, the thickness of the seed layer and protective overcoat can be measured by a process such as XRF or Auger measurement
Data Source
AI summary
A magnetic slider for magnetic data recording constructed by a process that allows for careful control of seed layer and overcoat thickness. The slider is treated by a process that result in surface pits and scratches. A refill layer is used to fill in the pits and scratches, the refill layer being constructed of a material that does not include Si or carbon. An angled ion beam etching can be used to remove portions of the refill layer that extend outside of the pits and scratches. Then, a seed layer comprising Si and a protective layer comprising C are deposited over the surface. Because the refill layer does not contain either of Si or C, the thickness of the seed layer and carbon overcoat can be acurately measured and controlled, without the refill layer being mistaken for seed or overcoat material.