CPP Magnetoresistive Device Shield Gap Precision
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Solution Overview
Problem
Conventional magnetoresistive (MR) heads with a current-in-plane structure face challenges in maintaining insulation and precision when reducing the shield gap length, leading to difficulties in forming precise upper electrode layers and maintaining the desired thickness and shape, especially in current-perpendicular-to-plane (CPP) structures.
Innovation Solution
A magnetoresistive device with a CPP structure is developed, featuring a magnetoresistive element between two electrode layers with a difference in level, allowing for precise formation without a thick insulating layer around the element, and a method involving a layered structure with insulating and bias field applying layers to enhance precision and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the shield gap length is reduced to enhance linear recording density in CIP structure, then the linear recording density is improved, but the insulation between GMR element and shield layers becomes difficult to maintain
Solution Approach 1:
The patent transitions from CIP (current-in-plane) structure to CPP (current-perpendicular-to-plane) structure, fundamentally inverting the current flow direction. This inversion eliminates the need for insulating films between the GMR element and shield layers, as the current now flows perpendicular to the layer planes through the GMR element itself, thereby solving the insulation problem while maintaining reduced shield gap length
Solution Approach 2:
The patent changes the critical parameter of current flow direction from in-plane to perpendicular-to-plane orientation. This parameter change fundamentally alters the structural requirements, allowing the GMR element to be directly adjacent to shield layers without insulation, thus enabling reduced shield gap length while maintaining reliability
2Reliability
If a thick insulating layer is formed around the magnetoresistive element in conventional manufacturing methods, then the insulation is maintained, but the precision and desired thickness/shape of the upper electrode layer cannot be achieved
Solution Approach 1:
The patent extracts and removes the insulating film from the structure by forming contact holes through it. This extraction eliminates the interference of the thick insulating layer with the upper electrode layer formation, allowing precise control of the upper electrode layer's thickness and shape while maintaining necessary insulation through the contact hole structure
Solution Approach 2:
The patent introduces a vertical dimension solution by forming contact holes that extend through the insulating layer. This dimensional approach allows the upper electrode layer to be formed with precise thickness and shape control in the horizontal plane, while insulation is maintained vertically through the contact hole structure
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 solution enables the precise formation of MR devices with improved shield gap length definition and reduced noise in output signals, addressing the insulation and precision issues of conventional MR heads.
Implementation Method 1
giant magnetoresistive (GMR) elements utilizing a giant magnetoresistive effect
Implementation Method 2
tunnel magnetoresistive (TMR) elements utilizing a tunnel magnetoresistive effect
Implementation Method 3
bias field applying layers for applying a bias magnetic field to the MR element
Data Source
AI summary
A magnetoresistive device comprises: a first shield layer and a second shield layer disposed with a space from each other in the direction of thickness; an MR element disposed between the first and second shield layers; and a layered structure disposed between the first and second shield layers on both sides of the MR element. The layered structure includes an insulating layer and bias field applying layers. The second shield layer has a surface facing toward the first shield layer. This surface includes a first portion touching the top surface of the MR element and second portions located on both sides of the MR element, the sides being opposed to each other in the direction of track width. A difference in level is created between the first and second portions such that the second portions are closer to the first shield layer than the first portion.