High Junction Angle Read Sensors for Magnetic Recording
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Solution Overview
Problem
Conventional magnetic recording read apparatuses face performance issues at higher areal densities due to reduced track widths and shield-to-shield spacing, which affect the stability and functionality of the read sensor, particularly the free layer, as the layers become thinner and narrower.
Innovation Solution
The method involves fabricating a read sensor with high junction angles by using ion milling techniques to define the sensor stack, allowing for increased free layer volume and improved magnetic behavior, while maintaining thin layers and reducing redeposition damage through controlled ion mill energies and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If track width is reduced for higher areal density recording, then storage density is improved, but read sensor performance deteriorates due to reduced layer volumes
Solution Approach 1:
The patent changes the geometric parameters of the read sensor by increasing the junction angle from conventional lower angles to higher angles (e.g., 75-90 degrees or more). This parameter change modifies the sensor's volume distribution, allowing the free layer to maintain adequate volume even at reduced track widths, thus preserving sensor performance while enabling higher areal density recording
2Productivity
If shield-to-shield spacing is reduced for higher density recording, then storage density is improved, but read sensor stability deteriorates
Solution Approach 1:
The patent modifies the read sensor's junction angle parameter to higher values, which changes the sensor's geometric configuration. This allows the sensor to maintain stable magnetic properties and adequate free layer volume even when shield-to-shield spacing is reduced, thereby enabling higher storage density without compromising sensor stability
3Device complexity
If layer thickness is reduced to maintain thin structure, then device compactness is improved, but free layer volume is reduced affecting sensor functionality
Solution Approach 1:
The patent changes the junction angle parameter to higher values (e.g., 75-90 degrees or more), which fundamentally alters the geometric relationship between layers. This parameter change allows the free layer to achieve adequate volume through improved geometric configuration rather than increased thickness, enabling thin-layer structures while maintaining sufficient free layer volume for sensor functionality
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 enhances the stability and performance of the read sensor at lower track widths, achieving improved magnetic behavior and cross-track resolution by maintaining large junction angles and minimizing additional damage during fabrication.
Implementation Method 1
using ion milling techniques to define the sensor stack, allowing for increased free layer volume and improved magnetic behavior, while maintaining thin layers and reducing redeposition damage through controlled ion mill energies and angles
Data Source
AI summary
A method provides a magnetic read apparatus. A sensor stack is deposited. The read sensor is defined from the stack such that the sensor has sides forming a junction angle of 75 degrees-105 degrees from a sensor bottom. Defining the sensor includes performing a first ion mill at a first angle and a first energy and performing a second ion mill at a second angle greater than the first angle and at a second energy less than the first energy. The first angle is 5 degrees-30 degrees from normal to the top surface. After the first ion mill, less than half of the stack's bottom layer depth remains unmilled. Magnetic bias structure(s) adjacent to the sides may be formed. The magnetic bias structure(s) include a side shielding material having at least one of the saturation magnetization greater than 800 emu/cm3 and an exchange length less than five nanometers.