Magnetic Head TFC Structure Planarization for Shield Stability
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Solution Overview
Problem
In magnetic hard disk drives, the uneven lower sensor shield shape caused by thermal fly-height control (TFC) structures leads to instability in magnetic domain structures, affecting data reproduction at high recording densities due to reduced clearance between the magnetic disk and head.
Innovation Solution
A method involving forming a conducting material above an insulating film, applying a mask to create a TFC structure, depositing a second insulating film, and planarizing to ensure a planar upper surface, which stabilizes the lower sensor shield and restricts magnetic charge distribution, thereby maintaining a stable magnetic domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a TFC structure is placed under the lower sensor shield to control fly height, then the magnetic spacing is reduced and recording density is improved, but the lower sensor shield shape becomes uneven causing instability in magnetic domain structures
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the TFC structure and the lower sensor shield. This mediator allows the TFC structure to perform its fly height control function while preventing direct contact that would cause unevenness and magnetic domain instability. The insulating film acts as a buffer that decouples the thermal expansion effects from the magnetic shield structure.
Solution Approach 2:
The structure is segmented into distinct functional layers: the TFC structure for thermal control, the insulating film for isolation, and the lower sensor shield for magnetic function. This segmentation allows each component to perform its specific function without interfering with others, particularly preventing the TFC-induced unevenness from affecting the magnetic domain stability of the sensor shield.
2Length of moving object
If the clearance between the magnetic disk and head is reduced to improve recording density, then the flying height is reduced, but the magnetic domain structure becomes unstable due to TFC structure unevenness
Solution Approach 1:
The insulating film serves as a mediator that enables reduced flying height through TFC while preventing the transmission of unevenness to the lower sensor shield. This intermediary layer allows the thermal fly height control to achieve smaller clearances without compromising the stability of the magnetic domain structure in the sensor shield.
3Temperature
If a TFC structure is formed directly under the lower sensor shield, then the thermal protrusion is achieved, but the insulation thickness is compromised and conduction between layers may occur
Solution Approach 1:
The insulating film is introduced as a mediator between the TFC structure and the lower sensor shield, ensuring that thermal protrusion is achieved while maintaining proper insulation. This intermediary layer prevents direct thermal and electrical contact that would compromise insulation reliability, allowing the TFC structure to generate thermal protrusion without causing conduction between layers.
4Stability of the object's composition
If the lower sensor shield is made planar to stabilize magnetic domains, then the magnetic domain structure is stabilized, but the TFC structure cannot effectively control fly height
Solution Approach 1:
The system is segmented into separate functional layers where the TFC structure handles fly height control through thermal expansion, while the lower sensor shield maintains a planar geometry for magnetic domain stability. The insulating film enables this functional separation by allowing the TFC structure to have non-planar geometry without transferring unevenness to the sensor shield.
Solution Approach 2:
The insulating film acts as an intermediary that decouples the geometric requirements of the TFC structure from those of the lower sensor shield. This allows the TFC structure to achieve thermal protrusion for fly height control while the lower sensor shield maintains a planar surface for stable magnetic domains, with the insulating film preventing transmission of geometric irregularities.
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 ensures a stable magnetic domain structure and improved data reproduction by maintaining a planar surface, enhancing recording density without compromising insulation thickness or causing conduction between layers.
Implementation Method 1
using the thermal expansion of the magnetic head due to heat produced by the resistor
Implementation Method 2
planarizing at least the second insulating film to form a planar upper surface of at least the second insulating film
Data Source
AI summary
In one embodiment, a method includes forming a conducting material above an insulating film, applying a mask to portions of the conducting material in a shape of a TFC structure, removing exposed portions of the conducting material to form the TFC structure, depositing an insulating film above the TFC structure, and planarizing the insulating film to form a planar upper surface of the insulating film. In another embodiment, a magnetic head includes a TFC structure positioned between insulating films and a magnetic element positioned above the TFC structure, the TFC structure configured for providing localized thermal protrusion of the magnetic head on a media facing surface thereof, wherein an upper surface of an upper of the insulating films is planar, the magnetic element includes at least one of a main magnetic pole and a read sensor, and the TFC structure is configured for providing thermal protrusion of the magnetic element.