Excimer Laser Burst Timing Control for Narrow-Linewidth Amplification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor exposure technology is the occurrence of chromatic aberrations due to wide spectral linewidth in excimer laser apparatuses, leading to reduced resolution, and the inefficiency and potential damage from shortening pulse widths in ultraviolet laser processing.
Innovation Solution
A laser apparatus that converts seed pulsed light into burst pulses synchronized with discharge timing in the excimer amplifier, using optical sensors to adjust the trigger delay period, ensuring precise timing and maximizing amplification efficiency while minimizing spontaneous radiation and optical element damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the spectral linewidth of excimer laser apparatus is wide, then the laser can be operated at high repetition frequencies, but chromatic aberrations occur resulting in decreased resolution
Solution Approach 1:
The laser output is segmented into multiple pulses (burst pulses) within a broader temporal window. The seed laser generates multiple pulses that are then amplified together by the excimer amplifier, effectively segmenting the amplification process to accommodate high repetition frequencies while maintaining narrow spectral linewidth through the original seed laser characteristics
Solution Approach 2:
The system employs periodic burst pulse generation where groups of pulses are emitted in synchronized sequences. The solid-state laser produces periodic burst patterns that match the excimer amplifier's discharge timing, enabling high repetition frequency operation while maintaining precise spectral control through the periodic structure
2Productivity
If the pulse width of ultraviolet laser light is shortened to improve processing speed, then productivity increases, but optical elements may be damaged due to excessive peak power
Solution Approach 1:
The laser system uses periodic burst pulse generation instead of continuous short pulses. By distributing energy across multiple pulses in a burst pattern with appropriate timing, the peak power of individual pulses is reduced while maintaining overall processing efficiency through the cumulative effect of multiple pulses
Solution Approach 2:
The seed laser pre-generates multiple pulses with controlled parameters before amplification. This preliminary pulse generation allows optimization of pulse characteristics to avoid excessive peak power while ensuring the pulses are ready for efficient amplification by the excimer amplifier, preventing optical element damage from the outset
3Ease of operation
If the timing between seed pulsed light output and discharge in excimer amplifier is not synchronized, then the system operation is simplified, but amplification efficiency decreases and spontaneous radiation increases
Solution Approach 1:
The system employs feedback control where the timing of the seed laser's burst pulse output is adjusted based on the discharge timing of the excimer amplifier. This feedback mechanism ensures precise synchronization between seed pulse arrival and amplifier discharge, maximizing amplification efficiency while maintaining automated operation that preserves ease of use
Solution Approach 2:
The system replaces complex mechanical timing adjustment mechanisms with electronic control and synchronization methods. By using electronic timing control and feedback loops, precise synchronization is achieved without mechanical complexity, maintaining ease of operation while optimizing amplification efficiency
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 enhances resolution by reducing chromatic aberrations and improves amplification efficiency, maintaining optical element longevity through synchronized burst pulse generation.
Implementation Method 1
amplifies the burst seed pulsed light and outputs the amplified light as amplified burst pulsed light
Implementation Method 2
a first optical sensor that receives the burst seed pulsed light outputted from the solid-state laser apparatus and that outputs a first detection signal according to a timing at which the burst seed pulsed light is outputted
Implementation Method 3
a discharge space in which discharge occurs; amplifies the burst seed pulsed light that has entered the discharge space
Data Source
Figure 1
Figure 2
Figure 3~4A
AI summary
A laser apparatus includes: (A) a solid-state laser apparatus that outputs burst seed pulsed light containing a plurality of pulses; (B) an excimer amplifier that amplifies the burst seed pulsed light in a discharge space in a single occurrence of discharge and outputs the amplified light as amplified burst pulsed light; (C) an energy sensor that measures the energy of the amplified burst pulsed light; and (D) a laser controller that corrects the timing at which the solid-state laser apparatus is caused to output the burst seed pulsed light based on the relationship of the difference between the timing at which the solid-state laser apparatus outputs the burst seed pulsed light and the timing at which the discharge occurs in the discharge space with a measured value of the energy.