Tunneling Magnetic Sensing Element Two-Layer Insulating Film
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Solution Overview
Problem
Conventional tunneling magnetic sensing elements face challenges in maintaining proper bias magnetic field strength and preventing short-circuiting due to inadequate thickness control of insulating films, leading to alignment issues and insulation degradation.
Innovation Solution
A magnetic sensing element with a laminate structure featuring first insulating films thinner than second insulating films, ensuring proper bias magnetic field supply and insulation between layers, while preventing short-circuiting through controlled thickness and deposition angles, and using oxidation-inhibiting inner insulating layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the first insulating film is increased to ensure insulation between the hard bias layer and the laminate, then insulation is improved, but the bias magnetic field supplied from the hard bias layer to the free magnetic layer is decreased
Solution Approach 1:
The patent introduces a two-layer insulating film structure where the first insulating film (in contact with laminate) and second insulating film (in contact with hard bias layer) have different thicknesses. The second insulating film is made thicker than the first, distributing the insulation function across two dimensions of thickness control rather than using a single uniform thickness, thereby maintaining both insulation and magnetic field strength.
Solution Approach 2:
Different regions of the insulating structure are given different thicknesses to serve different functions. The first insulating film (thinner) is optimized for maintaining magnetic field strength, while the second insulating film (thicker) is optimized for providing insulation. This local differentiation of quality resolves the contradiction between insulation and magnetic field strength.
2Force
If the thickness of the second insulating film is decreased to match the first insulating film thickness, then the bias magnetic field is maintained, but short-circuiting between the hard bias layer and lower shielding layer occurs more easily
Solution Approach 1:
The patent uses a two-layer insulating film structure with different thicknesses to resolve the contradiction. The second insulating film is made thicker to provide adequate insulation over the large area, while the first insulating film remains thinner to maintain magnetic field strength. This dimensional differentiation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The insulating structure is locally optimized with different thicknesses in different regions. The second insulating film (under hard bias layer) is thicker to prevent short-circuiting over the large area, while the first insulating film (near laminate) is thinner to maintain magnetic field strength. This local quality differentiation resolves the contradiction.
3Reliability
If the first insulating film is made thick to prevent short-circuiting, then insulation is improved, but the resist layer cannot be lifted off due to filling of undercut portions
Solution Approach 1:
The patent changes the thickness parameter of the first insulating film to a specific range (5-20 nm) that balances two conflicting requirements: thick enough to provide insulation but thin enough to allow resist layer lift-off. This parameter optimization resolves the contradiction between insulation and manufacturability.
Solution Approach 2:
Instead of making the first insulating film uniformly thick throughout, the patent applies a controlled thin thickness (5-20 nm) specifically in the region where resist lift-off occurs, while the second insulating film provides the main insulation thickness. This partial application of thickness resolves the contradiction.
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 solution effectively supplies a proper bias magnetic field to the free magnetic layer while maintaining satisfactory insulation and reducing the probability of short-circuiting, ensuring reliable operation of the magnetic sensing element.
Implementation Method 1
the inner insulating layer functions as an oxidation-inhibiting layer that inhibits oxidation of the laminate
Implementation Method 2
the bias magnetic field supplied from the hard bias layer 10 to the free magnetic layer 5
Data Source
AI summary
A magnetic sensing element is provided. The magnetic sensing element includes a laminate disposed on a conductive layer. The laminate having a structure including a pinned magnetic layer, a nonmagnetic layer, and a free magnetic layer disposed in that order from the bottom, first insulating films disposed at both sides in the track width direction of the laminate, second insulating films disposed on the conductive layer, the second insulating films being connected to the respective first insulating films, bias layers disposed over the respective first insulating films and the respective second insulating films, wherein the thickness in the track width direction of the first insulating film is smaller than the thickness of the second insulating film.