Dual-Pulse Laser Beam Overlap for Semiconductor Exposure Throughput
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Solution Overview
Problem
Existing laser systems face challenges in maintaining high throughput while minimizing chromatic aberration and beam size divergence, particularly when using KrF and ArF excimer lasers, which can lead to increased beam size and inappropriate polarization for semiconductor exposure.
Innovation Solution
A laser system incorporating a first and second pulse laser apparatus, a first polygon mirror, and a processor to control the output timing and direction of laser beams such that they are partially overlapped and oriented in the same direction, using a beam steering device and a beam measuring instrument to optimize beam power and size for semiconductor exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If KrF and ArF excimer lasers are used to achieve shorter wavelength for improved resolution, then resolution is improved, but chromatic aberration occurs due to wide spectral linewidth (350-400 pm) causing beam size divergence and inappropriate polarization
Solution Approach 1:
The patent divides the single laser beam into two separate laser beams with different wavelengths (first and second pulse laser beams). Each beam is generated by a separate pulse laser apparatus, allowing independent control and optimization of each wavelength component to reduce chromatic aberration effects.
Solution Approach 2:
The patent overlays the two laser beams spatially so that they occupy the same optical path and focus at the same location. The beams are nested in terms of their spatial distribution, with both beams passing through the same projection lens and exposing the photosensitive substrate at the same position, thereby reducing beam size divergence.
2Object-affected harmful factors
If line narrowing module is added to narrow spectral linewidth and reduce chromatic aberration, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent changes the approach from modifying the spectral parameters of a single beam (using line narrowing modules) to using multiple beams with different wavelengths. By changing from a single-wavelength optimization approach to a multi-wavelength approach, the patent avoids adding complex spectral filtering components while still achieving reduced chromatic aberration through proper beam combination.
3Productivity
If multiple laser beams are combined to increase throughput, then throughput is improved, but beam size divergence increases
Solution Approach 1:
The patent spatially overlays the two laser beams so that they are nested within the same optical path and focus at the same location. This nesting approach allows multiple beams to be combined without increasing the overall beam size at the focus, thereby maintaining tight focus while achieving increased throughput through the combination of multiple beams.
Solution Approach 2:
The patent combines laser beams in the temporal dimension by using pulsed lasers with different pulse timing, while maintaining spatial overlap. The first and second pulse laser beams are output with a shift of 1/2 of the predetermined cycle, allowing temporal multiplexing without spatial separation, thus increasing throughput without beam size divergence.
4Productivity
If pulse laser beams are output in predetermined cycle with 1/2 cycle shift, then throughput is improved by effective utilization of polygon mirror reflection surfaces, but synchronization control complexity increases
Solution Approach 1:
The patent employs a processor that receives synchronization signals from the polygon mirror rotation and uses this feedback to precisely control the timing of pulse laser beam output. The processor adjusts the pulse timing based on the actual rotation state of the polygon mirror, ensuring accurate 1/2 cycle phase shift while accommodating variations in rotation speed, thereby simplifying the overall control system through adaptive feedback control.
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 configuration enhances throughput by reducing beam size divergence and ensuring appropriate polarization, facilitating efficient semiconductor device manufacturing without enlarging the exposure apparatus design.
Implementation Method 1
The first polygon mirror is configured to reflect the first pulse laser beam and the second pulse laser beam
Implementation Method 2
optical paths of the first pulse laser beam and the second pulse laser beam reflected by the first polygon mirror are oriented in a first direction and at least partially overlapped
Data Source
AI summary
A laser system includes a first pulse laser apparatus configured to output a first pulse laser beam in a predetermined cycle, a second pulse laser apparatus configured to output a second pulse laser beam in the predetermined cycle, a first polygon mirror configured to reflect the first pulse laser beam and the second pulse laser beam, and a processor configured to control the first pulse laser apparatus, the second pulse laser apparatus, and the first polygon mirror such that the first pulse laser beam and the second pulse laser beam are output with a shift of ½ of the predetermined cycle between them and optical paths of the first pulse laser beam and the second pulse laser beam reflected by the first polygon mirror are oriented in a first direction and at least partially overlapped.