Narrowed Bandwidth Pulsed Light for Lithography Contrast
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Solution Overview
Problem
Current lithographic processes face challenges in achieving high contrast and precision when printing features smaller than the classical resolution limit, particularly due to limitations in wavelength and numerical aperture, which affect the reproduction of patterns on substrates for semiconductor manufacturing.
Innovation Solution
The method involves narrowing the bandwidth of a pulsed light beam used in photolithography to improve imaging quality by iteratively varying the optical spectrum, mask design, and light source design, allowing for a single exposure pass to generate distinct aerial images on a substrate with different wavelengths, thereby optimizing the optical spectrum, mask pattern, and pupil design to enhance contrast and depth of focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a broader optical spectrum is used in lithography, then the imaging speed and throughput are improved, but the contrast and manufacturing precision of the imaged features deteriorate
Solution Approach 1:
The patent segments the optical spectrum into multiple discrete wavelength components (e.g., first wavelength λ1 and second wavelength λ2) rather than using a continuous broad spectrum. This segmentation allows selective use of specific wavelength bands that optimize both imaging speed and contrast, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent changes the spectral parameters by narrowing the bandwidth of the light source to specific wavelength ranges (e.g., 50-275 fm bandwidth) while maintaining multiple wavelength components. This parameter optimization enables high-contrast imaging without sacrificing imaging speed, as the narrowed spectrum reduces chromatic aberrations while preserving essential wavelength diversity for efficient patterning.
2Manufacturing precision
If the bandwidth of light pulses is reduced to improve contrast, then the manufacturing precision is improved, but the imaging speed and throughput may deteriorate
Solution Approach 1:
The patent employs pulsed illumination with periodic temporal structure, where light is delivered in controlled pulses rather than continuous illumination. This periodic action allows the system to use narrowed bandwidth for high contrast during each pulse while maintaining high average imaging speed through optimized pulse frequency and duty cycle, effectively resolving the contradiction between manufacturing precision and productivity.
Solution Approach 2:
The patent dynamically adjusts the bandwidth and temporal characteristics of the light source to match the specific imaging requirements. The system can modulate the spectral width and pulse duration in real-time, enabling high contrast when needed while maintaining high speed through rapid switching and optimized exposure timing, thus resolving the static contradiction between precision and speed.
3Manufacturing precision
If multiple wavelengths are used in a single exposure pass, then the depth of focus and manufacturing precision are improved, but the device complexity increases
Solution Approach 1:
The patent makes the light source multi-functional by designing it to emit multiple discrete wavelengths simultaneously or in rapid succession from a single source architecture. This universal light source can serve multiple imaging functions (different depths, different feature sizes) without requiring separate optical systems for each wavelength, thus improving depth of focus while minimizing the increase in device complexity.
Solution Approach 2:
The patent merges multiple wavelength channels into a single integrated optical path and exposure system. By combining the generation, delivery, and control of multiple wavelengths within one unified optical train rather than using separate systems, the patent achieves extended depth of focus through multi-wavelength imaging while avoiding the proportional increase in device complexity that would result from multiple independent systems.
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 improves imaging quality metrics such as contrast, image log slope, and exposure latitude by adjusting the bandwidth of the light pulses to between 50 fm and 275 fm, enabling more precise and detailed pattern reproduction on substrates, even at sub-wavelength scales.
Implementation Method 1
The method comprises directing a pulsed light beam along a direction of propagation toward a patterning device, the pulsed light beam comprising a plurality of pulses of light
Data Source
AI summary
Systems, methods, and computer programs for increasing a contrast for a lithography system are disclosed. In one aspect, a method of optimizing a process for imaging a feature on a substrate using a photolithography system is disclosed, the method including obtaining an optical spectrum of a light beam for the imaging, wherein the light beam includes pulses having a plurality of different wavelengths, and narrowing the optical spectrum of the pulses of the light beam for the imaging to improve a quality metric of the imaging.