VCSEL Wafer Bonding for EAMR Head Laser Integration
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Solution Overview
Problem
Existing energy-assisted magnetic recording (EAMR) systems face challenges in integrating a reliable heat source without increasing the complexity and cost of magnetic recording head fabrication, particularly due to the need for semiconducting materials or complex optical fiber alignments.
Innovation Solution
The integration of a vertical cavity surface emitting laser (VCSEL) bonded directly to the magnetic recording head during wafer processing, utilizing reliable wafer bonding techniques and light redirecting structures to efficiently emit laser light for heating, thereby reducing costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a laser diode is fabricated inside the slider using semiconducting materials, then a heat source for EAMR is provided, but the fabrication process becomes complicated and cost increases
Solution Approach 1:
The system is divided into separate components: the VCSEL is fabricated on a separate semiconductor wafer, while the magnetic head is fabricated on a separate slider substrate. These components are then integrated through wafer bonding, allowing each component to be optimized independently while simplifying the overall fabrication process
Solution Approach 2:
Wafer bonding serves as an intermediary process that connects the VCSEL wafer to the magnetic head slider. This bonding interface allows thermal and optical coupling between the laser and head while maintaining separate fabrication processes for each component
2Device complexity
If a laser diode is mounted remote from the head with optical fibers, then integration complexity is reduced, but cost and production time increase
Solution Approach 1:
The VCSEL and magnetic head are merged into a single integrated assembly through wafer bonding, creating a unified component that functions as both a heat source and recording device. This integration eliminates the need for separate optical fiber connections while maintaining simple manufacturing processes
Solution Approach 2:
The VCSEL serves multiple functions: it provides the heat source for EAMR, acts as a light emitter for potential read operations, and integrates the optical and magnetic functions into a single component that simplifies the overall system architecture
3Quantity of substance
If magnetic grain size is reduced to increase areal storage density, then storage capacity increases, but thermal stability decreases due to superparamagnetic limit
Solution Approach 1:
The system dynamically changes the temperature parameter of the magnetic grains during write operations. By locally heating the grains with the VCSEL, the coercivity is reduced temporarily, allowing magnetic switching at lower fields. After heating ceases, the grains return to their stable high-anisotropy state, maintaining data retention
Solution Approach 2:
The EAMR process employs periodic heating cycles during write operations. The VCSEL is activated briefly to heat the magnetic grains, enabling magnetic transition, then deactivated to allow the grains to cool and stabilize. This periodic thermal action allows small grains to be written while maintaining their thermal stability
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 provides a reliable and cost-effective heat source for EAMR systems, enhancing thermal stability and areal storage density without requiring cooling systems, and simplifying the manufacturing process by using mature wafer bonding technologies.
Implementation Method 1
a small spot where data is to be written is locally heated to reduce the coercivity of the magnetic grains therein
Implementation Method 2
a small spot where data is to be written is locally heated
Implementation Method 3
one or more light redirecting structures for redirecting the laser light towards the end surface
Data Source
AI summary
An energy-assisted magnetic recording apparatus comprises a magnetic recording head having an end surface and an interface surface perpendicular to the end surface. The apparatus further comprises a vertical cavity surface emitting laser (VCSEL) bonded to the interface surface and configured to emit laser light through the interface surface and into the magnetic recording head. The magnetic recording head includes one or more light redirecting structures for redirecting the laser light towards the end surface. A method of making an energy-assisted magnetic recording apparatus comprises the steps of aligning a first wafer including a plurality of VCSELs with a second wafer including a plurality of magnetic recording heads, such that an emitting region of each of the plurality of VCSELs is disposed over a light redirecting structure of a corresponding one of the plurality of magnetic recording heads, and bonding the first wafer to the second wafer.