Optical Shutter Control for Stable EUV Laser Burst Output
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Solution Overview
Problem
In the production of semiconductor devices, existing EUV light generation systems face challenges in stabilizing the output of pulsed laser beams for burst operations, leading to thermal instability and unstable EUV light generation, which affects the precision and efficiency of microfabrication processes.
Innovation Solution
A laser apparatus with a master oscillator and amplifiers, equipped with optical shutters controlled by a controller, is used to manage the pulsed laser beam output, ensuring stable burst operations by switching the shutters to maintain thermal stability and consistent energy levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the master oscillator operates in burst mode to generate pulsed laser beams, then the productivity of EUV light generation is improved, but thermal instability occurs leading to worsened reliability
Solution Approach 1:
The master oscillator operates in periodic burst mode, alternating between active pulse generation and idle periods. This periodic operation allows the system to accumulate thermal energy during bursts while dissipating heat during idle periods, preventing thermal runaway and maintaining stability over time.
Solution Approach 2:
Optical shutters are introduced as intermediary components between the master oscillator and the beam path. These shutters control the timing and duration of laser beam extraction, enabling precise management of thermal load on the master oscillator while maintaining high productivity during active periods.
2Manufacturing precision
If the laser beam energy is increased for better microfabrication precision, then the manufacturing precision is improved, but the thermal load on the master oscillator increases causing worsened thermal stability
Solution Approach 1:
The laser beam generation process is segmented into multiple amplification stages (first amplifier, second amplifier, third amplifier) with the master oscillator operating at lower energy. Each stage progressively amplifies the beam, allowing high final energy for precision work while the master oscillator remains thermally manageable throughout.
3Reliability
If optical shutters are added to control burst operations, then the reliability is improved, but the device complexity increases
Solution Approach 1:
Multiple optical shutters are merged into a coordinated control system managed by a single controller. This integration allows the shutters to work together as a unified thermal management solution, improving reliability through coordinated operation while minimizing the complexity increase that would result from independent control systems.
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 solution enables the generation of stable pulsed EUV light with consistent energy, improving the precision and efficiency of microfabrication processes, particularly in the production of semiconductor devices with feature sizes below 32 nm.
Implementation Method 1
at least one optical shutter disposed on the beam path of the pulsed laser beam
Implementation Method 2
at least one amplifier disposed on a beam path of the pulsed laser beam
Data Source
AI summary
A laser apparatus may include: a master oscillator configured to output a pulsed laser beam at a repetition rate; at least one amplifier disposed on a beam path of the pulsed laser beam; at least one optical shutter disposed on the beam path of the pulsed laser beam; and a controller configured to switch the at least one optical shutter.