Read Sensor Layer Composition for Etch-Rate-Matched Carbon Coating
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Solution Overview
Problem
Magnetic recording heads face instability and failure due to protrusions or recesses forming in the reader sensor, which are caused by using materials that are too hard or too soft in the spacer and capping layers, leading to corrosion and carbon coating defects.
Innovation Solution
Laminating, co-sputtering, or using alloys with hard materials (Ta, Ru, Hf, and/or W) and soft materials (Al, Ti, Cr, and/or Ni) in the spacer and capping layers to adjust the etch rate and prevent protrusions and recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If hard materials (CoHf or Ru) are used in the spacer or capping layer, then the structural stability is improved, but protrusions form on the MFS causing carbon coating defects and sensor failure
Solution Approach 1:
The patent changes the material parameters of the spacer and capping layers by using specific alloy compositions (TaRu, TaHf, RuAl, NiAl) with controlled hardness and etch rates. This parameter adjustment allows the layers to maintain structural stability while forming uniform carbon coatings without protrusions during the lapping process.
Solution Approach 2:
The patent employs composite material structures by combining hard materials (Ta, Ru, Hf, W) with soft materials (Al, Ti, Cr, Co, Ni) in specific ratios within the spacer and capping layers. This composite approach balances the opposing requirements of structural stability and carbon coating uniformity by leveraging the complementary properties of different materials.
2Manufacturing precision
If soft materials (IrMn) are used in the spacer or capping layer, then the carbon coating uniformity is improved, but recesses form on the MFS causing corrosion and sensor failure
Solution Approach 1:
The patent adjusts the material parameters by selecting alloys with specific hardness and etch rate characteristics. The chosen materials (TaRu, TaHf, RuAl, NiAl) have optimized properties that prevent recess formation while maintaining carbon coating uniformity, resolving the contradiction between coating quality and structural stability.
Solution Approach 2:
The patent uses composite material compositions that blend soft and hard materials in controlled ratios. This composite structure provides both the carbon coating uniformity associated with soft materials and the structural stability associated with hard materials, eliminating the formation of harmful recesses.
3Ease of manufacture
If the etch rate of the spacer layer does not match the etch rate of the magnetic layers, then the manufacturing process is simpler, but protrusions or recesses form causing sensor failure
Solution Approach 1:
The patent optimizes the etch rate parameter of the spacer and capping layers by selecting specific material compositions (TaRu, TaHf, RuAl, NiAl) that etch at matched rates relative to the magnetic layers. This parameter matching prevents protrusion and recess formation during etching, ensuring sensor reliability while maintaining manufacturing feasibility.
Solution Approach 2:
The patent applies different material compositions to different layers (spacer and capping) with specific local etch rate characteristics. Each layer is designed with appropriate local properties to match the etching behavior of adjacent magnetic layers, ensuring uniform profiles and preventing defects that would compromise sensor reliability.
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
Mitigates the formation of protrusions and recesses, maintaining a stable carbon coating and preventing sensor failure by matching the etch rate of the spacer and capping layers with the free layers.
Implementation Method 1
Laminating, co-sputtering, or using alloys with hard materials (Ta, Ru, Hf, and/or W) and soft materials (Al, Ti, Cr, and/or Ni) in the spacer and capping layer of the sensor
Data Source
AI summary
The present disclosure generally relates to magnetic recording heads of magnetic recording devices. To protect and lubricate magnetic elements of the magnetic recording heads (e.g., reader sensors), a coating of carbon is applied to the magnetic element. When there are defects in the carbon coating, the sensor is exposed to air and may corrode causing reader sensor failure. Protrusions and/or recesses may form on the MFS of the sensor when materials that are too hard (e.g., CoHf or Ru) or too soft (e.g., IrMn) are used in the spacer or capping layer of the sensor. By laminating, co-sputtering, or using an alloy with hard materials (e.g., Ta, Ru, and/or Hf) and/or soft materials (e.g., Al, Ti, Cr, and/or Ni) in the spacer and capping layer of the sensor, the formation of protrusion and recesses in the reader sensor may be mitigated.