Self-Aligned MAMR Head STO and Main Pole Alignment
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Solution Overview
Problem
Existing microwave-assisted magnetic recording (MAMR) technologies face challenges in accurately aligning the spin torque oscillator (STO) with the main pole (MP) during the formation of the MAMR head, leading to potential accidental erasure of adjoining tracks and degradation of the oscillating field quality due to non-planarity and separate photolithography processes.
Innovation Solution
A method involving ion beam etching with a single mask to self-align the STO and MP, ensuring perfect alignment and coplanar sidewalls, along with optional side and leading shields to reduce flux leakage and improve stack quality, allowing for precise formation of the MAMR head structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate photolithography processes are used to form STO and MP, then fabrication flexibility is improved, but alignment precision deteriorates leading to track erasure
Solution Approach 1:
The patent combines the formation of STO and MP into a single photolithography process using one mask layer. The mask defines both the STO region and MP region simultaneously, ensuring they are formed in the same processing step. This merging of operations eliminates alignment errors between separate lithography steps while maintaining fabrication flexibility through unified process control.
Solution Approach 2:
The patent introduces a common mask layer as an intermediary element that mediates the formation of both STO and MP. This mask serves as a reference framework that simultaneously defines the positions of both structures, acting as a mediator that ensures their precise relative alignment without requiring separate alignment procedures.
2Power
If STO is placed close to write pole for MAMR recording, then oscillating field strength is improved, but alignment difficulty increases
Solution Approach 1:
The patent merges the positioning of STO relative to the write pole into a single lithography step. The mask defines both structures with their precise relative positions predetermined in the mask design, eliminating the need for complex post-fabrication alignment procedures while maintaining the close proximity required for strong oscillating field generation.
3Manufacturing precision
If ion beam etching is used with single mask, then alignment precision is improved, but process complexity increases
Solution Approach 1:
The patent combines multiple functions into the single ion beam etching step: it simultaneously etches the STO structure, the MP structure, and creates the precise alignment between them all in one process. This consolidation reduces the total number of process steps and mask applications, simplifying the overall fabrication sequence despite the sophistication of the ion beam etching technique itself.
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 self-aligned MAMR head maintains cross-track resolution and enhances the quality of the oscillating field, preventing accidental erasure of adjoining tracks and improving device performance by ensuring perfect alignment and reducing sideways flux leakage.
Implementation Method 1
Ion beam etching is then used (in combination with this mask) to remove extraneous material all the way down to the substrate, thereby forming the units
Implementation Method 2
Because of ferromagnetic resonance (FMR), it becomes possible to switch media grains at fields below their normal coercivity
Implementation Method 3
Spin torque oscillation then occurs in the FGL, producing the oscillating field
Implementation Method 4
When electrons transit the SIL their spins become polarized by the magnetization present in the SIL. The resulting spin polarization is carried into the FGL by electrons that have crossed interlayer 13
Data Source
AI summary
The invention discloses a MAMR head that has the STO stack placed at the trailing side of the write element, with both STO and write element completely self-aligned in the cross track direction. A method for defining both the MP and the STO stack geometries in a single step is also described.