Angular Alignment Gratings for Precise 3D Writing in Glass Substrates
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Solution Overview
Problem
The challenge in fabricating devices using glass substrates lies in maintaining accurate angular alignment of laser voxels in three dimensions due to small dimensions and angular variations during wafer placement, which affects processing accuracy.
Innovation Solution
The implementation of on-the-fly angular alignment features on glass substrates using retro-reflective optical probes to determine the local angle of the substrate surface, allowing for precise compensation of tilt during laser micromachining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alignment methods are used for laser inscription on glass substrates, then the processing speed is maintained, but the angular alignment accuracy deteriorates due to substrate tilt variations
Solution Approach 1:
The patent applies preliminary action by pre-forming angular alignment features (gratings or markers) on the glass substrate before laser inscription. These features are created during substrate fabrication and serve as reference points for subsequent alignment operations, eliminating the need for complex real-time alignment systems during laser processing.
Solution Approach 2:
The patent uses angular alignment features as an intermediary element between the substrate and the laser inscription system. These features act as a mediator that translates substrate orientation into measurable angular deviations, enabling precise alignment without requiring direct complex measurement of substrate tilt during processing.
2Manufacturing precision
If real-time angular measurement is implemented during laser inscription, then the processing accuracy is improved, but the processing time increases
Solution Approach 1:
The alignment features are prepared in advance during substrate fabrication, so no additional measurement time is required during laser inscription. The pre-formed gratings or markers provide immediate reference for alignment calculations, maintaining high processing speed while ensuring accuracy.
Solution Approach 2:
The patent replaces complex mechanical alignment systems with optical measurement of pre-formed features. By using optical probes to detect the angular orientation of pre-existing alignment features, the system achieves high precision without the mechanical complexity and time consumption of traditional alignment methods.
3Manufacturing precision
If angular alignment features are added to the substrate, then the laser voxel alignment is improved, but the substrate fabrication complexity increases
Solution Approach 1:
The patent merges the alignment feature fabrication with the existing substrate manufacturing process. Angular alignment gratings or markers are formed using the same lithography and etching steps already employed for creating optical waveguides and other substrate features, thereby adding minimal complexity to the overall fabrication process.
Solution Approach 2:
The alignment features serve multiple functions: they provide angular reference for laser inscription alignment, serve as test structures for substrate quality verification, and can potentially function as optical elements in the final device. This multi-functionality justifies the additional fabrication steps.
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
Enhances the accuracy of laser inscription processes on glass substrates by providing real-time angular alignment, improving the precision of feature writing and optical waveguide formation.
Implementation Method 1
an angular alignment grating to reflect a selected spectrum of light incident on the angular alignment grating at an angle
Implementation Method 2
emitting light at an incident angle on an angular alignment feature or grating on or within a top surface of a glass substrate being processed; receiving reflected light from the emitted light at the incident angle on the angular alignment feature or grating
Data Source
AI summary
Apparatuses, systems, and techniques related to angular alignment of a substrate for writing 3D features are described. Angled incident light is emitted onto an angular alignment grating on or within a surface of a substrate workpiece. Reflected light is received from the angular alignment grating and an angle of at least a portion of the surface in the local vicinity of the angular alignment grating is determined based on the received reflected light. A voxel location within the substrate workpiece is adjusted based on the surface angle of the substrate workpiece.