In-Slider Waveguide Lithography for HAMR Sub-Micron Patterns
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Solution Overview
Problem
Current manufacturing techniques for heat-assisted magnetic recording (HAMR) hard disk drives struggle to form precise sub-micron patterns on the air-bearing surface of sliders due to issues with stray light and alignment, which affects the performance of near-field transducers.
Innovation Solution
Coating the air-bearing surface of sliders with a photoresist having high optical absorbance at the operational wavelength and using an integrated waveguide to direct light, forming a feature proximate the near-field transducer, which enables the creation of precise sub-micron patterns through the photoresist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing techniques are used to form patterns on the air-bearing surface, then the manufacturing process is simple, but the pattern size cannot achieve sub-micron precision and alignment with near-field transducers is poor
Solution Approach 1:
The patent replaces conventional mechanical lithography systems with an optical-based waveguide lithography system. Light is guided through a waveguide structure integrated into the slider to directly expose the photoresist at the air-bearing surface, enabling sub-micron pattern formation without complex mechanical alignment systems. This substitution of mechanical alignment with optical guidance resolves the contradiction by achieving high precision through optical confinement rather than mechanical positioning.
Solution Approach 2:
The patent introduces a waveguide as an intermediary structure that couples the light source to the photoresist at the air-bearing surface. The waveguide acts as a mediator that confines and directs light precisely to the target location, enabling sub-micron pattern formation. This intermediary structure eliminates the need for complex external alignment systems while achieving the required precision, thus resolving the contradiction between precision and complexity.
2Manufacturing precision
If conventional lithography methods are used, then the process is straightforward, but stray light causes poor pattern definition and reduced near-field transducer performance
Solution Approach 1:
The patent applies local quality by confining the light exposure to a highly localized region at the air-bearing surface through the waveguide structure. The light is delivered precisely where needed (at the photoresist location) while being excluded from surrounding areas, thereby eliminating stray light interference. This localized light delivery enables excellent pattern definition without the harmful effects of stray light that plague conventional lithography methods.
Solution Approach 2:
The patent extracts the light delivery function from a conventional external lithography system and integrates it directly into the slider structure through the waveguide. By taking out the light source and guiding it through the waveguide to the exact location needed, the system eliminates stray light that would otherwise be generated by external illumination systems. This extraction and reintegration of the light path resolves the contradiction between pattern definition quality and stray light interference.
3Reliability
If larger patterns are formed using conventional methods, then the manufacturing process is easier, but the near-field transducer performance and thermal protection are insufficient
Solution Approach 1:
The patent replaces conventional mechanical lithography with optical waveguide-based lithography to achieve sub-micron pattern sizes (60% smaller than conventional methods). These smaller, precisely formed patterns are critical for optimizing near-field transducer performance and providing adequate thermal protection. The optical substitution enables manufacturing of these small patterns with sufficient precision, resolving the contradiction between transducer performance requirements and manufacturing ease.
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 allows for the formation of sub-micron patterns that are 60% smaller than those achieved with conventional methods, reducing stray light and improving alignment with the near-field transducer, enhancing thermal protection and operational efficiency.
Implementation Method 1
coating an air-bearing surface of a slider with a photoresist having a high optical absorbance at or near an operational wavelength of the slider
Implementation Method 2
Light is directed at a target wavelength through an entry of a waveguide integrated into the slider. The light exiting the waveguide forms a feature
Implementation Method 3
Light is directed at a target wavelength through an entry of a waveguide integrated into the slider
Data Source
AI summary
An air-bearing surface of a slider is coated with a photoresist having a high optical absorbance at or near an operational wavelength of the slider. Light is directed at a target wavelength through an entry of a waveguide integrated into the slider. The light exiting the waveguide forms a feature through the photoresist, the feature proximate a near-field transducer of the slider. A sub-micron pattern is formed using the feature.