Excimer Laser Window Holder Layout to Protect Sealing Members
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas laser apparatuses used in semiconductor exposure face challenges due to wide spectral linewidths of KrF and ArF excimer laser light, leading to chromatic aberrations in projection lenses and decreased resolution. To mitigate this, a line narrowing module is often employed, but it can lead to issues with sealing members deteriorating prematurely due to reflected light exposure.
Innovation Solution
The gas laser apparatus incorporates a tubular window holder with a window inclined relative to the optical axis, a ring-shaped sealing member, and an extending surface that reflects and absorbs the reflected light, preventing it from reaching the sealing member and reducing deterioration.
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 the chromatic aberrations are reduced and resolution is improved, but the sealing member deteriorates prematurely due to reflected light exposure
Solution Approach 1:
The harmful reflected light is extracted from the optical path by the extending surface, which is specifically designed to intercept and absorb the reflected light before it can reach the sealing member. This separates the harmful radiation from the functional optical path, allowing the line narrowing module to maintain its resolution-improving function while protecting the sealing member from deterioration
Solution Approach 2:
The extending surface acts as an intermediary element between the window and the sealing member. It intercepts the reflected light that would otherwise travel directly to the sealing member, converting the harmful light energy into heat and preventing it from reaching the sealing member, thus mediating between the optical function and the sealing requirement
2Productivity
If the window is positioned to allow light passage, then the laser light can exit the resonator, but reflected light reaches the sealing member causing deterioration
Solution Approach 1:
The extending surface is positioned at a specific location where reflected light converges, providing localized protection only where needed. This local intervention allows the window to maintain its light-transmitting function while the extending surface specifically addresses the reflected light issue at its point of concern, without affecting overall laser output
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 effectively suppresses the deterioration of sealing members, thereby extending their service life and maintaining the usable period of the gas laser apparatus, ensuring consistent performance and resolution in semiconductor exposure processes.
Implementation Method 1
an extending surface that is located on a side toward which reflected light travels, the reflected light being a part of the light traveling to the window via the opening and reflected off the window
Implementation Method 2
the extending surface irradiated with the reflected light from the window
Data Source
AI summary
A gas laser apparatus includes an enclosure, a window holder, a window, and a sealing member. The window holder further having an extending surface located on the side toward which reflected light travels, the reflected light being reflected off the window, the extending surface being continuous with the end surface and extending in a direction away from the window, the extending surface irradiated with the reflected light. A line is obtained by symmetrically folding back the optical axis of the reflected light at the position, on the extending surface, that is irradiated with the reflected light with respect to a reference line passing through the irradiated position and perpendicular to the extending surface. The line 602 extends across a normal to the window in the direction from the extending surface toward the window from the side facing the outer circumference of the window toward the center axis of the window.