Laser System Phase Optical Element Coherence Control
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Solution Overview
Problem
Current semiconductor exposure systems face challenges in reducing coherence and preventing amplified spontaneous emission (ASE) in laser beams due to spatial and temporal division of pulse laser beams, which affects the resolution and intensity of the exposure process.
Innovation Solution
Incorporating a random phase plate or phase optical elements with spatial random phase shift functions within the optical path of the laser system, such as in the delay optical path or optical resonator, to spatially and randomly shift the phase of the pulse laser beam, thereby reducing coherence and preventing ASE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a random phase plate is introduced in the optical path, then coherence is reduced and ASE is prevented, but device complexity increases
Solution Approach 1:
A random phase plate is introduced as an intermediary optical element in the optical path to modify the phase distribution of the laser beam. This mediator reduces spatial coherence and prevents ASE without requiring complex rotary mechanisms or high-reflectivity mirrors, thus resolving the contradiction between reliability improvement and device complexity increase.
2Manufacturing precision
If spatial and temporal division of pulse laser beams is implemented, then resolution is improved, but intensity is reduced
Solution Approach 1:
The pulse laser beam is divided into multiple spatially separated sub-beams through temporal and spatial division. This segmentation improves exposure resolution by reducing coherence effects, while the random phase plate compensates for intensity loss by optimizing phase distribution across the divided beams.
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 effectively reduces speckles and ASE, ensuring higher coherence and intensity of the laser beam, which enhances the resolution and efficiency of the semiconductor exposure process without the need for complex rotary mechanisms or increased reflectivity, thus improving the overall performance of the laser system.
Implementation Method 1
a phase optical element included in the delay optical path and having a function of spatially and randomly shifting a phase of the pulse laser beam
Data Source
AI summary
A laser system including: A. a laser apparatus configured to output a pulse laser beam; B. an optical pulse stretcher including a delay optical path for expanding a pulse width of the pulse laser beam; and C. a phase optical element included in the delay optical path and having a function of spatially and randomly shifting a phase of the pulse laser beam. The phase optical element includes a plurality of types of cells providing different amounts of phase shift to the pulse laser beam and arranged irregularly in any direction.