Excimer Laser Discharge Control for Fluorocarbon Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chromatic aberrations in projection lenses of semiconductor exposure apparatuses due to wide spectral linewidths of laser light emitted from KrF and ArF excimer lasers, leading to decreased resolution, are addressed by incorporating a line narrowing module to narrow the spectral linewidth.
Innovation Solution
A gas laser apparatus with a laser chamber containing fluorine gas, a primary electrode, a preliminary ionization electrode, and a processor that controls discharge to perform first and second discharge controls, allowing the preliminary ionization electrode to discharge independently of the primary electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a line narrowing module is provided in the laser resonator to narrow the spectral linewidth, then chromatic aberrations are reduced and resolution is improved, but fluorocarbon accumulates in the laser gas leading to energy loss
Solution Approach 1:
The patent implements periodic discharge cycles alternating between laser output mode (both electrodes discharge) and fluorocarbon removal mode (only preliminary ionization electrode discharges). This periodic action allows the system to maintain narrow spectral linewidth for high resolution while periodically eliminating fluorocarbon accumulation that causes energy loss.
Solution Approach 2:
The preliminary ionization electrode performs preliminary ionization of the laser gas before main laser discharge. During non-output periods, it continues to discharge to decompose fluorocarbon compounds formed during laser operation, preventing energy loss while maintaining the line narrowing effect.
2Power
If the preliminary ionization electrode and primary electrode both perform discharge, then laser light is generated, but fluorocarbon concentration increases reducing laser efficiency
Solution Approach 1:
The system alternates between laser generation phase (both electrodes discharge to produce laser light) and fluorocarbon removal phase (only preliminary ionization electrode discharges to decompose fluorocarbon). This periodic operation maintains laser efficiency by preventing fluorocarbon accumulation while ensuring sufficient laser power output.
Solution Approach 2:
The fluorocarbon byproduct of laser operation is converted from a harmful accumulation into a manageable condition through controlled decomposition. The preliminary ionization electrode's discharge during non-output periods transforms the harmful fluorocarbon accumulation into beneficial gas purification, maintaining laser 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
The solution effectively reduces fluorocarbon concentration in the laser gas, maintaining pulse laser light energy by decomposing fluorocarbon during periods of non-output, thereby enhancing the resolution of the semiconductor exposure apparatus.
Implementation Method 1
a preliminary ionization electrode disposed in the laser chamber, a power supplier configured to supply power to the primary electrode and the preliminary ionization electrode, and a processor configured to control the power supplier to perform first discharge control that causes the preliminary ionization electrode and the primary electrode to perform discharge
Data Source
AI summary
A gas laser apparatus according to an aspect of the present disclosure includes a laser chamber, a primary electrode, a preliminary ionization electrode, a power supplier, and a processor. The laser chamber is configured to encapsulate a laser gas containing a fluorine gas. The primary electrode is disposed in the laser chamber. The preliminary ionization electrode is disposed in the laser chamber. The power supplier is configured to supply power to the primary electrode and the preliminary ionization electrode. The processor is configured to control the power supplier to perform first discharge control that causes the preliminary ionization electrode and the primary electrode to perform discharge, and second discharge control that causes only the preliminary ionization electrode to perform discharge without causing the primary electrode to perform discharge.