Near-field light generating element etching stopper layers
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Solution Overview
Problem
The formation of near-field light generating elements for thermally-assisted magnetic recording faces challenges in suppressing surface unevenness and distortion within the waveguide, leading to increased light propagation loss and limitations in writing data due to the etching process creating significant steps between the plasmon antenna and the waveguide.
Innovation Solution
A method involving the use of first and second etching stopper layers to manage etching endpoints and prevent over-etching, followed by planarization of the waveguide surface, which includes forming inclined side surfaces on the plasmon antenna and using a stopper multilayer with specific refractive index settings to minimize surface irregularities and optimize light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an etching process is used to form a plasmon antenna on a substrate, then the plasmon antenna can be formed with the required shape, but a substantially large step is created between the plasmon antenna and the surrounding area
Solution Approach 1:
The etching process is divided into two stages: first etching to create the basic plasmon antenna shape and initial step, then second etching after planarization to refine the side surfaces. This segmentation allows the step to be managed and reduced through controlled processing steps.
Solution Approach 2:
A planarization layer is formed over the waveguide structure before the final etching process. This preliminary planarization action flattens the surface and reduces the step height created by the first etching, enabling more precise control in the subsequent etching step.
2Manufacturing precision
If the step height is reduced through planarization, then surface unevenness is suppressed, but the waveguide may develop distortion within its structure
Solution Approach 1:
The refractive index of the planarization layer is specifically selected to be between those of the waveguide and the etching stopper layer. This local optimization of material properties enables the planarization layer to flatten the surface while minimizing optical distortion within the waveguide structure.
Solution Approach 2:
The refractive index parameter of the planarization layer is carefully controlled to fall within a specific range. This parameter change optimizes the optical properties, allowing surface planarization while maintaining waveguide integrity and minimizing distortion.
3Shape
If the waveguide surface is made uneven to accommodate the plasmon antenna, then the antenna can be properly formed, but light propagation loss increases
Solution Approach 1:
The waveguide surface is planarized before the final etching of the plasmon antenna. This preliminary action ensures a flat, smooth surface that minimizes light scattering and propagation loss, while still allowing the antenna to be formed through controlled etching.
Solution Approach 2:
The planarization layer acts as an intermediary between the waveguide and the plasmon antenna. It provides a smooth optical interface that reduces light loss while enabling the formation of the antenna structure through subsequent etching processes.
4Reliability
If the anisotropic magnetic field of the magnetic recording medium is increased to improve thermal stability, then data can be held longer, but the write field intensity of the thin-film magnetic head becomes insufficient
Solution Approach 1:
Heat is supplied to the magnetic recording medium to induce a phase transition or thermal state change that temporarily reduces the anisotropic magnetic field. This allows the write field to effectively modify the magnetization despite the medium's inherent thermal stability properties.
Solution Approach 2:
Near-field light generated by the plasmon antenna acts as an intermediary to transfer energy to the magnetic recording medium. This light-mediated energy transfer enables localized heating that reduces the anisotropic magnetic field, allowing data writing without requiring increased write field intensity.
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 effectively reduces surface unevenness and distortion within the waveguide, minimizing light propagation loss and enabling proper irradiation of the plasmon antenna, thereby enhancing the performance of thermally-assisted magnetic recording heads.
Implementation Method 1
a plasmon antenna for generating near-field light by being irradiated with light
Implementation Method 2
a waveguide for guiding light to the plasmon antenna
Data Source
AI summary
Provided is a method for forming a near-field light generating element, which is capable of sufficiently suppressing the unevenness of a waveguide surface and the distortion within the waveguide. The forming method comprises the steps of: forming a first etching stopper layer on a lower waveguide layer; forming a second etching stopper layer; forming, on the second etching stopper layer, a plasmon antenna material layer; performing etching with the second etching stopper layer used as a stopper, to form a first side surface of plasmon antenna; forming a side-surface protecting mask so as to cover the first side surface; and performing etching with the first and second etching stopper layers used as stoppers, to form the second side surface. By providing the first and second etching stopper layer, over-etching can be prevented even when each etching process takes enough etch time, which allows easy management of etching endpoints.