EUV Light Source Burst Control for Thermal Stability
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Solution Overview
Problem
Current extreme ultraviolet (EUV) light source apparatuses face challenges in maintaining stable EUV light emission and reducing damage to optical elements when transitioning between emission and pause periods, leading to heat load variations and potential instability in EUV light production.
Innovation Solution
The EUV light source apparatus incorporates a burst control unit that controls the irradiation of a target material with a laser beam, allowing for successive pulsed emission and pause periods, shifting the oscillation timing or beam axis of the laser beam to prevent plasma generation during pause periods, thereby stabilizing the optical system and reducing heat load variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the laser beam continuously irradiates the target material to maintain EUV light emission readiness, then the EUV light emission can be maintained, but heat load variations occur and optical elements suffer damage
Solution Approach 1:
The patent applies periodic action by controlling the laser beam to irradiate the target material in pulsed sequences rather than continuously. The burst control unit manages periods of irradiation followed by pause periods, creating a periodic pattern that reduces cumulative heat load on optical elements while maintaining EUV light emission capability during active periods.
Solution Approach 2:
The patent implements preliminary action by adjusting oscillation timing or beam axis positioning before the pause period begins. This preliminary adjustment prevents plasma generation from residual laser energy during pause periods, ensuring clean transitions between emission and pause states without unintended heat accumulation or plasma formation.
2Object-affected harmful factors
If the laser beam is outputted in pulses to reduce heat load, then heat load variations are reduced, but EUV light emission stability may be affected during transitions
Solution Approach 1:
The patent employs feedback mechanisms through the burst control unit that monitors and adjusts laser beam parameters dynamically. By detecting the state of plasma generation and EUV emission, the system provides feedback to optimize pulse timing and duration, ensuring stable EUV light emission while maintaining reduced heat load through adaptive pulse control.
Solution Approach 2:
The patent applies dynamics by making the laser beam parameters adjustable and adaptive rather than fixed. The oscillation timing and beam axis position are dynamically modified based on operational requirements, allowing the system to optimize performance during both emission and pause periods while maintaining stability through real-time adjustments.
3Object-affected harmful factors
If the oscillation timing is shifted during pause periods to prevent plasma generation, then damage from residual plasma is reduced, but control complexity increases
Solution Approach 1:
The patent replaces complex mechanical control systems with optical and temporal control mechanisms. Instead of physically moving components to prevent plasma generation, the system uses oscillation timing adjustments and beam axis positioning - essentially using the laser's inherent properties and temporal modulation to achieve plasma suppression during pause periods, thereby reducing mechanical complexity.
4Object-affected harmful factors
If the beam axis is shifted during pause periods to prevent plasma generation, then optical element damage is reduced, but alignment precision requirements increase
Solution Approach 1:
The patent applies partial action by shifting the beam axis only sufficiently to prevent plasma generation during pause periods, rather than maintaining perfect alignment at all times. During emission periods, full alignment precision is restored. This partial adjustment during pauses reduces optical element damage while the temporary nature of the misalignment minimizes the impact on overall system precision requirements.
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 approach extends the lifetime of optical elements, ensures stable EUV light emission by maintaining thermal stability during the burst operation, and reduces damage from heat load variations, while allowing for efficient control of EUV light emission.
Implementation Method 1
a laser apparatus configured to irradiate a target material, wherein the target material is turned into plasma and emits extreme ultraviolet light
Implementation Method 2
the target material is turned into plasma and emits extreme ultraviolet light
Data Source
AI summary
An extreme ultraviolet light source apparatus, in which a target material is irradiated with a laser beam from a laser apparatus and the target material is turned into plasma, thereby emitting extreme ultraviolet light, may include a burst control unit configured to control irradiation of the target material is irradiated with the laser beam outputted successively in pulses from the laser apparatus when the extreme ultraviolet light is emitted successively in pulses. The target material is prevented from being turned into plasma by the laser beam while the laser beam is outputted successively in pulses from the laser apparatus when the successive pulsed emission is paused.