Amorphous SiC:H Waveguide for HAMR Light Focusing
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Solution Overview
Problem
Current methods for heating storage media in thermally assisted magnetic/optical recording struggle to achieve high storage density due to limitations in focusing energy, particularly in achieving a small heated spot size using existing waveguide materials with high refractive index and low optical loss.
Innovation Solution
A Plasma Enhanced Chemical Vapor Deposition (PECVD) process is used to deposit amorphous hydrogenated silicon carbide (SiC:H) layers with a refractive index greater than 2.4 and low optical loss, specifically by controlling gas ratios and plasma conditions, to enhance light confinement and focusing in near-field transducers (NFTs) for heat-assisted magnetic recording (HAMR) devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional waveguide materials are used, then the device structure is simpler, but the refractive index is insufficient and optical loss is high, resulting in poor light confinement and focusing
Solution Approach 1:
The patent changes the material composition parameters by controlling the atomic concentration ratios of Si (50-60 at%), C (3-13 at%), and H (32-42 at%) in the silicon carbide layer, and adjusting gas flow rates and plasma power (100-700 W) to achieve the desired refractive index (>2.4) and low optical loss (<180 dB/cm) characteristics
Solution Approach 2:
The patent uses composite material structure with amorphous hydrogenated silicon carbide (a-SiC:H) as the core layer, combining it with cladding layers to form a waveguide structure that achieves both high refractive index and low optical loss, resolving the contradiction between material simplicity and performance requirements
2Area of moving object
If the heated spot size is not reduced, then the energy focusing is easier to achieve, but the storage density cannot be increased
Solution Approach 1:
The patent creates local quality enhancement by fabricating a waveguide structure with spatially varying refractive index distribution, where the core layer has higher refractive index than cladding layers, enabling localized light confinement and intense energy focusing at the target spot, thus reducing heated spot size while maintaining energy focusing capability
Solution Approach 2:
The patent changes the optical parameters of the waveguide materials, specifically achieving refractive index >2.4 in the silicon carbide core layer, which enhances the light confinement effect and enables tighter focusing of the heated spot, thereby increasing storage density
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 process results in amorphous hydrogenated silicon carbide layers with refractive indices of not less than 2.4 and optical losses of not more than 180 dB/cm at 825 nm, enabling more confined light propagation and increased thermal gradient, thereby improving storage density and focusing capabilities in HAMR devices.
Implementation Method 1
A Plasma Enhanced Chemical Vapor Deposition ('PECVD') Silicon Carbide ('SiC') process is disclosed
Implementation Method 2
The reactive gas is reacted in the presence of a plasma under defined conditions
Data Source
AI summary
In a method for depositing a layer of amorphous hydrogenated silicon carbide (SiC:H), a gas mixture comprising a reactive gas to inert gas volume ratio of 1:12 to 2:3 is introduced into a reaction chamber of a plasma-enhanced chemical vapor deposition apparatus. The reactive gas has a ratio of Si of 50 to 60, C of 3 to 13, and H of 32 to 42 at %. The inert gas comprises i) a first inert gas selected from helium, neon and mixtures; and ii) a second inert gas selected from argon, krypton, xenon and mixtures. The reaction plasma is at a power frequency of 1-16 MHz at a power level of 100 W to 700 W. The resulting layer exhibits a refractive index of not less than 2.4 and a loss of not more than 180 dB/cm at an indicated wavelength within 800 to 900 nm.