Laser Wavelength Tuning for Exposure Apparatus Chromatic Aberration
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Solution Overview
Problem
Current semiconductor exposure apparatuses face challenges in achieving high resolving power due to chromatic aberration caused by the natural oscillation amplitudes of KrF and ArF excimer laser apparatuses, which are exacerbated by the use of conventional exposure lenses, leading to limitations in pattern resolution and depth of focus.
Innovation Solution
The exposure apparatus employs a laser light source capable of varying wavelength and spectrum line width, along with precise control of the distance between the mask and substrate, to utilize the Talbot effect for high-resolution patterning, allowing for adjustable imaging distance and depth of focus through the use of a beam forming unit and a controller that adjusts the laser parameters to achieve optimal interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional exposure lens is used with KrF or ArF excimer laser apparatus, then the apparatus can perform exposure, but chromatic aberration occurs due to natural oscillation amplitudes, lowering resolving power
Solution Approach 1:
The patent changes the wavelength parameter of the laser beam dynamically. By adjusting the wavelength to match specific absorption peaks of the photoresist material, the system achieves high resolving power without chromatic aberration. The wavelength is varied within a controlled range (e.g., 192-194 nm for ArF laser) to optimize exposure while eliminating the harmful effects of natural oscillation amplitudes.
2Manufacturing precision
If the spectrum width of the laser beam is narrowed using a line narrow module, then chromatic aberration is reduced, but the device complexity increases
Solution Approach 1:
Instead of using complex line narrow modules to reduce spectrum width, the patent changes the approach by dynamically adjusting the central wavelength of the laser beam. This wavelength variation method achieves the same effect of reducing chromatic aberration while avoiding the need for additional optical components like etalons or gratings, thus maintaining simpler device architecture.
3Manufacturing precision
If immersion exposure is performed to shorten apparent wavelength, then resolving power is improved, but the depth of focus is reduced
Solution Approach 1:
The patent varies the wavelength parameter of the laser beam to achieve optimal exposure conditions. By tuning the wavelength to match the absorption characteristics of the photoresist, the system achieves high resolving power equivalent to immersion exposure without actually requiring immersion, thereby maintaining a larger depth of focus and avoiding the trade-off between resolution and focus depth.
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 enables high-accuracy control of imaging position and depth of focus, maintaining high resolving power by varying the wavelength and spectrum line width of the laser beam, thereby overcoming chromatic aberration issues and enhancing exposure precision.
Implementation Method 1
a mask on which a pattern is formed, the pattern being configured to generate diffracted light by being irradiated with the laser beam
Implementation Method 2
exposure apparatus configured to perform exposure using the Talbot effect
Implementation Method 3
a laser light source capable of varying a wavelength of a laser beam that is emitted from the laser light source
Data Source
AI summary
An exposure apparatus may include a laser light source capable of varying a wavelength of a laser beam that is emitted from the laser light source, a mask on which a pattern is formed, the pattern being configured to generate diffracted light by being irradiated with the laser beam, and a controller configured to control, in accordance with a distance between the mask and a substrate, the wavelength of the laser beam that is emitted from the laser light source, wherein the mask is irradiated with the laser beam emitted from the laser light source to perform proximity exposure on a surface of the substrate.