Alpha-BBO Acousto-Optic Deflector for UV Patterning
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Solution Overview
Problem
Current acousto-optic deflectors (AODs) lack high resolution for laser beam deflection, are not transparent to ultraviolet light, and require additional optical elements to compensate for deficiencies, increasing system complexity and cost.
Innovation Solution
Development of an AOD system using an α-BBO crystal with a transducer plane aligned for slow acoustic wave propagation, allowing for high-resolution patterning with reduced beam width and increased transparency to UV light, eliminating the need for additional optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional AOD designs are used, then the system is simpler and cheaper, but the resolution is insufficient and UV transparency is poor
Solution Approach 1:
The patent changes the acoustic wave propagation speed parameter by rotating the transducer plane relative to the crystal axes, achieving slower sound velocity in the interaction region. This parameter change enables higher resolution patterning while maintaining system simplicity through a single crystal element
Solution Approach 2:
The patent uses a composite approach by combining α-BBO crystal with specific transducer configurations to create an AOD that simultaneously achieves UV transparency, high resolution, and compact size. The α-BBO crystal serves as both the diffractive element and the acoustic waveguide
2Manufacturing precision
If additional optical elements are added to compensate for AOD deficiencies, then beam profile can be narrowed, but system complexity and cost increase
Solution Approach 1:
The AOD system performs self-service by using the α-BBO crystal's intrinsic properties (slow acoustic wave propagation, UV transparency) to simultaneously achieve beam narrowing, high resolution, and UV compatibility without requiring separate compensating optical elements. The single crystal element serves multiple functions
3Adaptability or versatility
If AOD is designed for UV transparency, then UV patterning is enabled, but resolution and beam width control become challenging
Solution Approach 1:
The patent achieves both UV transparency and high resolution by changing the acoustic wave propagation parameter through crystal orientation. The rotated transducer plane creates slower sound velocity that enhances diffraction efficiency and resolution while the α-BBO crystal material provides UV transparency
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 AOD system achieves higher resolution patterning with reduced system complexity and cost by utilizing the α-BBO crystal's properties to enhance UV transparency and beam focusing, enabling efficient microlithographic applications.
Implementation Method 1
Acousto-optic deflectors (AODs) are used for laser beam scanning in optical lithography
Data Source
AI summary
The technology disclosed relates to developing an acousto-optic device (AOD) using an alpha-barium borate (αBBO) crystal. An AOD using αBBO enables high-resolution microlithographic patterning. The AOD includes a slab of αBBO coupled to an RF transducer that drives an acoustic wave through the crystal structure. A laser source emits a beam of light that is incident on the crystal surface. The propagated acoustic wave acts as a diffraction grating that diffracts the incident wave. Using an αBBO crystal allows for high resolution of light in the ultraviolet and visible spectra. The low speed of acoustic wave propagation through the crystal allows for more laser spots to be imaged than AODs made using other types of crystals.