Acousto-Optic Modulator Light Source Stabilization
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Solution Overview
Problem
Existing light source apparatuses for semiconductor defect inspection face challenges in stabilizing deep ultraviolet light output, with previous methods using electro-optical elements being prone to degradation and having limited efficiency, and acousto-optical elements resulting in reduced output and beam quality issues.
Innovation Solution
A light source apparatus configuration that uses a laser light source, nonlinear optical crystals, and an acousto-optic modulator to generate and stabilize wavelength-converted light beams, specifically using a zero-order light beam to minimize losses and maximize output, with control mechanisms to adjust the light intensity based on detection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first-order diffracted light beam is used as output, then beam quality is maintained, but output efficiency is reduced to 0-80% of incident light
Solution Approach 1:
The patent segments the diffracted light into multiple orders and combines them. Instead of using only the first-order diffracted beam, the system collects and combines light from multiple diffraction orders (zero-order, first-order, second-order, etc.), thereby increasing the total output efficiency while maintaining acceptable beam quality through proper optical combining.
Solution Approach 2:
The patent merges multiple diffracted light beams (from different orders) into a single output beam. By using optical elements to combine the energy from various diffraction orders, the system achieves higher overall efficiency while preserving the beam quality characteristics needed for the application.
2Reliability
If a first-order diffracted light beam is used as output, then beam quality is maintained, but the output angle is inconvenient (twice the Bragg angle)
Solution Approach 1:
The patent separates the diffraction orders spatially and then selectively combines them. By segmenting the light paths and using appropriate optical elements (mirrors, beam combin ers), the system can redirect the combined beam to a convenient output angle while maintaining the quality characteristics of the diffracted beams.
Solution Approach 2:
The patent uses a portion of the diffracted beams (including zero-order and multiple higher orders) rather than relying solely on the first-order beam at the inconvenient angle. By selectively combining multiple orders, the system achieves both convenient output geometry and maintained beam quality.
3Productivity
If the acousto-optical element operates at high efficiency, then output intensity is improved, but the configuration becomes more complex
Solution Approach 1:
The patent designs the acousto-optical system to perform multiple functions with a single element. The AOM simultaneously modulates the light intensity, selects specific wavelengths, and directs the beam to the desired angle. This multi-functionality reduces the need for additional separate components, thereby simplifying the overall configuration while maintaining high output intensity.
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 configuration allows for stable and efficient generation of deep ultraviolet light with improved output stability and reduced costs, maintaining high beam quality and increasing the range of output control, thus addressing the limitations of previous technologies.
Implementation Method 1
at least one nonlinear optical crystal that generates a wavelength converted light beam using the fundamental light beam or a harmonic laser beam of the fundamental light beam as an incident light beam
Implementation Method 2
an acousto-optic modulator that is disposed in an optical path of the incident light beam in such a way that a zero-order light beam enters the nonlinear optical crystal
Data Source
AI summary
Provided are a light source apparatus and an inspection apparatus that can stably output a wavelength converted light beam. A light source apparatus includes a laser light source that generates a first fundamental light beam, at least one nonlinear optical crystal that generates a wavelength converted light beam using the fundamental light beam or a harmonic laser beam of the fundamental light beam as an incident light beam, a detector that detects the wavelength converted light beam, an acousto-optic modulator that is disposed in an optical path of the incident light beam in such a way that a zero-order light beam enters the nonlinear optical crystal, and a controller that controls an output intensity of the wavelength converted light beam according to a detection signal from the detector.