Laser Apparatus Photodetector for EUV Return Beam Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In EUV light generation systems, the increased power of laser beams to produce smaller feature sizes in semiconductor devices leads to issues with return beams and self-oscillation beams damaging optical elements, requiring effective detection and mitigation strategies to prevent damage and ensure stable operation.
Innovation Solution
A laser apparatus with a master oscillator, amplifiers, a photodetector device, and a controller that analyzes temporal variations in detection signals to distinguish between return beams and self-oscillation beams, allowing for appropriate measures such as focus adjustment or immediate shutdown to prevent damage to optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser beam power is increased to produce smaller feature sizes, then manufacturing precision is improved, but harmful factors increase due to return beams and self-oscillation beams damaging optical elements
Solution Approach 1:
The system performs preliminary detection of return beams and self-oscillation beams before they can damage optical elements. The photodetector device continuously monitors the laser beam path, and the controller identifies harmful beams early, enabling preventive action (focus adjustment or shutdown) before damage occurs.
Solution Approach 2:
The system implements a feedback mechanism where the photodetector device continuously monitors the laser beam path for return beams and self-oscillation beams. The controller receives detection signals, analyzes beam characteristics, and automatically adjusts focus or shuts down the laser to prevent damage to optical elements.
2Reliability
If detection sensitivity is increased to distinguish between return beams and self-oscillation beams, then reliability is improved, but device complexity increases due to multiple photodetectors and complex control logic
Solution Approach 1:
The photodetector device is segmented into multiple detection units, each with a different spectral response characteristic. This segmentation allows the system to detect and distinguish between return beams and self-oscillation beams by comparing signals from different photodetectors, improving reliability while distributing the complexity across modular components.
Solution Approach 2:
Different photodetectors are assigned different local qualities (spectral responses) to detect specific beam characteristics. The controller analyzes the pattern of responses from photodetectors with different spectral characteristics to identify whether a return beam or self-oscillation beam is present, enabling accurate differentiation.
3Reliability
If real-time detection and response is implemented to prevent damage, then reliability is improved, but response time is constrained by the need for rapid focus adjustment or shutdown
Solution Approach 1:
The system continuously monitors the laser beam path in advance, maintaining readiness to detect return beams and self-oscillation beams before they reach critical levels. This preliminary detection capability enables the controller to initiate protective actions (focus adjustment or shutdown) with minimal delay, balancing reliability with response time constraints.
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 system effectively determines and addresses return and self-oscillation beams, preventing damage to optical elements and ensuring stable operation of the laser apparatus, even at higher power levels, by performing focus adjustments or stopping the laser when necessary.
Implementation Method 1
The photodetector device may include a first photodetector configured to detect energy of a light beam traveling back along the laser beam path and a second photodetector configured to detect power of the light beam traveling back along the laser beam path
Data Source
AI summary
A laser apparatus may include a master oscillator, a plurality of amplifiers, a photodetector device configured to detect a light beam traveling back along a laser beam path, and a controller. The photodetector device may include a first photodetector configured to detect energy of a light beam traveling back along the laser beam path and a second photodetector configured to detect power of the light beam traveling back along the laser beam path. The controller may be configured to determine that a return beam is generated when the intensity of the energy detection signal exceeds a first threshold. The controller may be configured to determine that a self-oscillation beam is generated when the intensity of the power detection signal exceeds a second threshold.