Magnetic Write Head Narrow Pitch Coil Fabrication
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Solution Overview
Problem
Existing methods for fabricating magnetic write heads with smaller pitch coils are limited by overplating issues, which prevent the achievement of narrower coil pitches necessary for higher recording density and frequency extendibility in magnetic recording media.
Innovation Solution
A photoresist etching method is employed that includes the use of a thin, non-metallic insulating stopper layer to prevent overplating by blocking redeposition of Cu onto the sidewalls, allowing for the formation of coils with a narrower pitch by ensuring that plating only occurs from the seed layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoresist etching method is used to fabricate coils, then manufacturing process is simple, but overplating occurs on sidewalls preventing narrower coil pitch
Solution Approach 1:
A thin non-metallic insulating stopper layer is introduced as an intermediary between the seed layer and photoresist. This stopper layer acts as a mediator that blocks Cu redeposition onto the sidewalls during plating, preventing overplating while allowing the plating process to proceed normally from the seed layer.
Solution Approach 2:
The photoresist structure is segmented into multiple functional layers: a thick lower photoresist layer for etching protection, a thin non-metallic insulating stopper layer for sidewall protection during plating, and an upper photoresist layer for final patterning. This segmentation allows each layer to perform its specific function without interfering with others.
2Manufacturing precision
If magnetic fine particles are made smaller to reduce bit boundary irregularities, then recording density increases, but thermal stability of magnetization deteriorates
Solution Approach 1:
The magnetic anisotropy energy KU is increased to compensate for the reduced volume V of smaller magnetic particles. By changing the material parameters (increasing KU through compositional or structural modifications), the thermal stability index KUV/kBT is maintained even as particle size decreases, enabling higher recording density without sacrificing thermal stability.
3Speed
If pitch coil is reduced to improve frequency extendibility, then writing frequency increases, but manufacturing precision deteriorates due to overplating
Solution Approach 1:
The thin non-metallic insulating stopper layer serves as a protective intermediary on the sidewalls during the plating process. It prevents Cu atoms from redepositing on sidewalls, thereby maintaining precise coil dimensions even when fabricating narrower pitch coils for higher writing frequency applications.
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 enables the fabrication of magnetic write heads with a narrower pitch coil, enhancing writing frequency and addressing the thermal stability issues associated with high coercivity magnetic media, thereby improving recording density and frequency extendibility.
Implementation Method 1
blocking redeposition of Cu onto the sidewalls
Data Source
AI summary
A magnetic write head has a plated coil with narrow pitch and is suitable for writing at high frequencies on magnetic media with high coercivity. The narrow pitch is obtained without such disadvantages as overplating that has adversely affected prior art attempts to produce such narrow pitches. The process that produces the magnetic write head is characterized by an RIE plasma etch using O2/N2 to etch plating trenches into a baked layer of photoresist with the ratio of gases being 5/45 sccm so that a dilute O2 concentration does not create unwanted side etching of the plating trenches. In addition, a Cu seed layer is coated with an insulating layer of Al2O3 which redeposits on the trench sidewalls to inhibit redeposition of any Cu from the seed layer and prevent outward growth of the plated Cu that would result in overplating.