XeCl Excimer Laser Gas Mixture Deuterium Stabilization
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Solution Overview
Problem
Excimer lasers experience performance degradation due to chemical and electrical erosion in the halogen-containing atmosphere, leading to contamination and interruptions, and their pulse delivery has a characteristic two-portion amplitude profile that is problematic for processes requiring precise temporal energy delivery, such as excimer-laser recrystallization of silicon.
Innovation Solution
Replacing the hydrogen additive in the lasing gas mixture with deuterium, which is present at a concentration greater than 10 parts-per-million, to stabilize the laser performance and reduce the amplitude difference between the first and second portions of the laser pulses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If hydrogen additive is used in the lasing gas mixture, then the lasing gas lifetime is extended, but the amplitude difference between first and second portions of laser pulses is not reduced
Solution Approach 1:
The patent changes the chemical parameter of the stabilizing additive from hydrogen (H2) to deuterium (D2). This isotopic substitution modifies the pulse amplitude profile while maintaining the gas lifetime extension benefit. The deuterium concentration is optimized at 1-100 ppm to achieve both extended lifetime and reduced amplitude difference between pulse portions.
2Stability of the object's composition
If deuterium concentration is increased above optimal level, then pulse amplitude uniformity improves, but laser output energy is reduced
Solution Approach 1:
The patent applies partial action by using deuterium at low concentrations (1-100 ppm) rather than high concentrations. This partial substitution is sufficient to achieve the desired pulse amplitude uniformity while avoiding the negative impact on laser output energy that would occur at higher deuterium concentrations.
3Power
If beam-mixing optics and synchronization are used to combine multiple lasers, then greater pulse energy is achieved, but system complexity increases
Solution Approach 1:
The patent extracts the pulse amplitude uniformity improvement from the complex beam-mixing approach and achieves it directly at the single-laser level through deuterium addition. This eliminates the need for additional beam-mixing optics and synchronization systems, reducing overall system complexity while maintaining the ability to achieve high pulse energies.
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 deuterium additive improves pulse-to-pulse and long-term stability, maintains total energy-per-pulse, and significantly reduces the amplitude difference between the first and second portions of the pulses, enhancing the suitability for processes like silicon recrystallization by improving energy delivery uniformity.
Implementation Method 1
Performance degradation can eventually develop due to chemical and electrical erosion of the discharge electrodes and other surfaces in the highly-reactive halogen-containing atmosphere in the chamber
Implementation Method 2
Replacing the hydrogen additive in the lasing gas mixture with deuterium, which is present at a concentration greater than 10 parts-per-million, to stabilize the laser performance and reduce the amplitude difference between the first and second portions of the laser pulses
Implementation Method 3
Operation of excimer lasers is based on an optical transition between different electronically excited states of noble-gas molecules. Relaxation of the excited molecules to the ground state results in the emission of high-intensity UV light in a laser-resonator
Implementation Method 4
The noble-gas halide molecules are created in the excited state by a short and powerful electrical excitation (gas discharge) of between about 1 nanosecond (ns) and 1000 ns duration
Data Source
AI summary
A xenon chloride (XeCl) excimer laser includes a lasing-gas mixture including a buffer gas, a noble gas, a halogen-donating gas, and deuterium. The deuterium is present in a concentration greater than about 10 parts-per-million.