Burst-Mode Supercontinuum Source for Fiber Lifetime and Thermal Stability
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Solution Overview
Problem
Current broadband radiation sources for metrology applications in integrated circuit manufacturing, such as scatterometers and alignment sensors, face challenges in generating high-quality, stable supercontinuum radiation with limited lifetime and high repetition rate limitations, leading to frequent component replacements and thermal instabilities.
Innovation Solution
A supercontinuum radiation source utilizing a hollow-core photonic crystal fiber with a modulated pump laser radiation, where the pump laser pulses are delivered in a burst mode rather than a continuous train, reducing exposure and heat load, and a processor generates control signals to synchronize the burst mode with measurement operations, extending the fiber's lifetime and improving stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If continuous train of pump laser pulses is used, then high output power is achieved, but fiber lifetime is reduced and thermal instabilities occur
Solution Approach 1:
The patent applies periodic action by switching from continuous pulse train operation to burst mode operation, where pump laser pulses are delivered in periodic bursts separated by longer idle periods. This allows the fiber to cool down between bursts, reducing cumulative thermal damage and extending fiber lifetime while maintaining high peak power output during the burst periods.
2Productivity
If high repetition rate is used, then productivity is improved, but thermal issues and stability deteriorate
Solution Approach 1:
The burst mode operation uses periodic action with high repetition rates during active measurement bursts, followed by longer idle periods for thermal management. This allows the system to achieve high productivity during measurement periods while using the idle periods to dissipate heat and maintain thermal stability, resolving the contradiction between high repetition rate and thermal issues.
3Duration of action of stationary object
If burst mode operation is implemented, then fiber lifetime is extended, but measurement continuity is reduced
Solution Approach 1:
The system uses preliminary action by synchronizing the burst mode operation with the measurement process. The pump laser bursts are timed to coincide with when measurements are being performed, ensuring measurement continuity during the burst periods. The idle periods between bursts are scheduled during transitions or non-critical measurement phases, thus extending fiber lifetime without significantly impacting overall measurement continuity.
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 burst mode operation significantly extends the lifetime of the hollow-core photonic crystal fiber, reduces thermal issues, and allows for higher repetition rates, enhancing the stability and performance of metrology devices by maintaining high output power and coherence of the supercontinuum radiation.
Implementation Method 1
a hollow-core photonic crystal fiber being operable to receive the modulated pump laser radiation and excite a working medium contained within the hollow-core photonic crystal fiber so as to generate supercontinuum radiation
Implementation Method 2
hollow-core photonic crystal fiber
Data Source
AI summary
A supercontinuum radiation source including a modulator being operable to modulate pump laser radiation including a train of radiation pulses to provide modulated pump laser radiation, the modulation being such to selectively provide a burst of the pulses; and a hollow-core photonic crystal fiber being operable to receive the modulated pump laser radiation and excite a working medium contained within the hollow-core photonic crystal fiber so as to generate supercontinuum radiation.