Etch Stop Layer for HAMR Optical Device Feature Size Control
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Solution Overview
Problem
Current etching processes for HAMR heads lack strict control over feature size, which affects the precision of optical articles used in heat-assisted magnetic recording, impacting areal density and thermal stability.
Innovation Solution
A method involving the deposition of an etch stop material with a higher refractive index than the core material, followed by a halide-based etching process, where the etch rate of the core material is at least five times higher than that of the etch stop material, allowing for precise control of feature sizes in optical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If typical etching processes are used for HAMR heads, then the manufacturing process is simple, but the feature size control is not strict enough
Solution Approach 1:
An etch stop layer is introduced as an intermediary material between the core layer and the substrate. This etch stop layer has a refractive index n1 that is less than or equal to the refractive index n2 of the core material, and exhibits selective etching behavior where the etch rate of the core material is at least five times higher than the etch rate of the etch stop material. This intermediary layer enables precise control of feature sizes by stopping the etching process at the desired depth while maintaining process feasibility.
2Manufacturing precision
If feature size control is improved through selective etching, then manufacturing precision increases, but the etching process becomes more complex
Solution Approach 1:
The etch stop layer is designed with specific parameter characteristics: refractive index n1 ≤ n2 (where n2 is the refractive index of the core material), and selective etch rate ratio (core material etch rate / etch stop material etch rate ≥ 5). These parameter changes enable precise feature size control through the etching process while maintaining ease of manufacture by using standard deposition and etching techniques with controlled parameters.
3Reliability
If the etch stop material has lower refractive index than core material, then optical performance is improved, but material selection becomes more constrained
Solution Approach 1:
The etch stop layer is designed with local quality characteristics specific to its function: refractive index n1 ≤ n2 of the core material, and selective etch rate properties. This local quality optimization for optical performance and etch selectivity is achieved without constraining overall material selection flexibility, as various materials can be chosen to meet these local requirements depending on the specific application needs.
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 enables tighter control over feature sizes, enhancing precision and reducing variability, thereby improving areal densities in recording media and maintaining thermal stability.
Implementation Method 1
etching the core layer using a halide based etch process, wherein the etch stop material has an etch rate in the halide based etch process and the core material has an etch rate in the halide based etch process, wherein the etch rate of the core material is at least about five times higher than the etch rate of the etch stop material
Implementation Method 2
depositing an etch stop material to form an etch stop layer, wherein the etch stop material has a refractive index in the infrared wavelength range, n1; depositing a core material to form a core layer, wherein the core material has a refractive index in the infrared wavelength range, n2
Data Source
AI summary
Disclosed herein is a method for fabricating an optical device that includes depositing an etch stop material to form an etch stop layer, wherein the etch stop material has a refractive index in the infrared wavelength range, n1; depositing a core material to form a core layer, wherein the core material has a refractive index in the infrared wavelength range, n2; and etching the core layer using a halide based etch process, wherein the etch stop material has an etch rate in the halide based etch process and the core material has an etch rate in the halide based etch process, wherein the etch rate of the core material is at least about five times higher than the etch rate of the etch stop material, and wherein n1 is not greater than n2.