Exposure System Pupil Shift for Lateral Chromatic Aberration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chromatic aberration in semiconductor exposure systems, particularly due to wide spectral linewidths of KrF and ArF excimer laser beams, leads to reduced resolution and magnification distortion, which are not effectively addressed by existing line narrowing modules.
Innovation Solution
An exposure system with an illumination optical system that shifts the position of its pupil relative to the projection optical system's pupil to correct for lateral chromatic aberration and magnification telecentric error, using a pulse laser beam with multiple center wavelengths.
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 aberration is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the chromatic aberration correction function from the laser resonator (line narrowing module) and relocates it to the illumination optical system by shifting the pupil position. This separates the laser source requirements from the optical system requirements, allowing simpler laser hardware while achieving the same resolution improvement through optical design.
Solution Approach 2:
The patent introduces an intermediary approach by using the illumination optical system as a mediator to correct chromatic aberration. Instead of modifying the laser resonator directly, the system uses the illumination optical path (with pupil shift) to compensate for the wide spectral linewidth effects, achieving aberration correction without changing the laser hardware.
2Manufacturing precision
If the spectral linewidth of the laser beam is narrowed, then chromatic aberration is reduced, but the laser resonator complexity increases
Solution Approach 1:
The patent extracts the correction function from the laser resonator and implements it in the illumination optical system. By shifting the pupil position in the illumination optical system, the system achieves imaging position accuracy without requiring a complex line narrowing module in the laser resonator.
3Adaptability or versatility
If a projection lens is formed of a material that transmits ultraviolet light, then the laser beam can pass through, but chromatic aberration occurs
Solution Approach 1:
The patent changes the parameter of the illumination optical system by shifting the pupil position. This parameter change allows the system to compensate for the chromatic aberration introduced by the ultraviolet-transmitting projection lens, maintaining resolution while using appropriate lens materials for UV transmission.
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 reduces imaging position deviation and enhances resolution by compensating for chromatic aberration, improving the quality of pattern transfer on photosensitive substrates.
Implementation Method 1
deviation of an imaging position due to lateral chromatic aberration on the photosensitive substrate
Implementation Method 2
illuminate a photomask with a pulse laser beam including a plurality of center wavelengths
Implementation Method 3
project an image of the photomask
Data Source
AI summary
An exposure system includes an illumination optical system configured to illuminate a photomask with a pulse laser beam including a plurality of center wavelengths, and a projection optical system configured to illuminate a photosensitive substrate with the pulse laser beam that has passed through the photomask and to project an image of the photomask. A position of a first pupil that is a pupil of the illumination optical system is shifted from a reference position in a conjugate relationship with a second pupil that is a pupil of the projection optical system in a direction of reducing, by a magnification telecentric error, deviation of an imaging position due to lateral chromatic aberration on the photosensitive substrate.