LED Array Peak Intensity Control in Lithography
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Solution Overview
Problem
Lithographic apparatuses using arrays of LEDs face issues due to fluctuations in peak intensity emission wavelength, leading to degraded imaging quality, as the peak intensity drifts with temperature changes, current variations, and degradation over time, causing inconsistent radiation emission across the array.
Innovation Solution
A lithographic apparatus with a radiation peak intensity detection apparatus that identifies and controls the emission spectrum of individually controllable elements, ensuring a uniform peak intensity across the array by adjusting properties such as current, and using optical elements to modify the emission profile, thereby maintaining consistent radiation emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an array of LEDs is used as a radiation source, then the lithographic apparatus can provide I-line radiation, but the peak intensity of the emission spectrum drifts and fluctuates due to temperature changes, current variations, and degradation over time
Solution Approach 1:
The patent implements a feedback control system where a detection apparatus continuously monitors the peak intensity wavelength of the LED emission spectrum. Based on the detected drift, the control system automatically adjusts the current supplied to individual LEDs or applies temperature compensation to maintain the peak intensity at the desired wavelength, thereby resolving the reliability issue while preserving the radiation emission capability
Solution Approach 2:
The patent changes the operating parameters of the LEDs by dynamically adjusting the drive current and temperature conditions. By modifying these parameters in response to detected spectral drift, the system maintains consistent peak intensity wavelength despite inherent LED instability, thus improving reliability without sacrificing radiation emission
2Adaptability or versatility
If the peak emission wavelength drifts from the desired wavelength, then the bandwidth of the radiation source increases, but the imaging quality degrades due to inconsistent radiation emission across the array
Solution Approach 1:
The detection apparatus provides real-time feedback on the peak emission wavelength, enabling the control system to adjust individual LED currents or temperature conditions to maintain all LEDs operating at the desired wavelength. This feedback mechanism ensures narrow bandwidth and consistent imaging quality while preserving the adaptability of the LED array
Solution Approach 2:
The patent applies local quality control by individually adjusting the current or temperature conditions of specific LEDs within the array based on their unique spectral characteristics. This localized adjustment ensures that each LED contributes to a consistent overall emission profile, maintaining both the versatility of the array and the precision of the imaging
3Quantity of substance
If individual LEDs in the array have varying peak emission wavelengths, then the overall bandwidth of the radiation source becomes larger, but the reception, transmission, and reflection of radiation at the specific wavelength deteriorates
Solution Approach 1:
The system uses feedback from the detection apparatus to monitor and adjust the emission characteristics of individual LEDs. By continuously measuring peak wavelengths and adjusting drive currents or temperature, the system ensures all LEDs in the large array maintain consistent wavelength, preserving both the quantity of radiation sources and the reliability of wavelength-specific optical interactions
Solution Approach 2:
The patent segments the LED array into individually controllable units, each with its own current control and temperature management. This segmentation allows precise independent adjustment of each LED's emission characteristics, ensuring wavelength consistency across the entire array while maintaining the benefit of having multiple radiation sources
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 solution ensures a uniform emission profile across the LED array, improving imaging quality by maintaining peak intensity at a desired wavelength, enhancing pattern application on radiation-sensitive substrates.
Implementation Method 1
the use of an array of LEDs has been proposed as a radiation source for providing 365 nm (I-line) radiation
Implementation Method 2
the peak intensity of an emission spectrum of an LED is known to drift, or in other words fluctuate
Implementation Method 3
A radiation peak intensity detection apparatus is configured to detect a peak in the intensity of an emission spectrum of one or more individually controllable elements of the radiation source
Data Source
AI summary
A lithographic arrangement allows for controlling radiation characteristics. An illumination system provides a beam of radiation from radiation provided by a radiation source. The radiation source includes an array of individually controllable elements, each individually controllable element being capable of emitting radiation. A support structure supports a patterning device. The patterning device imparts the radiation beam with a pattern. A projection system projects the patterned radiation beam onto a target portion of a substrate held by a substrate table. A radiation peak intensity detection apparatus detects a peak in the intensity of an emission spectrum of one or more of the individually controllable elements of the radiation source.