EUV Target Sensor Segmentation for Droplet Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing EUV light generation systems face challenges in accurately detecting and synchronizing with small-diameter droplets, leading to reduced S/N ratio and expanded detection range, which complicates the generation of extreme ultraviolet light for microfabrication processes.
Innovation Solution
A timing sensor with multiple sensor elements and a signal generator that compares sensor signals with thresholds, improving the S/N ratio and enabling detection of small-diameter droplets or expanding the detection range by positioning light-receiving surfaces differently relative to the droplet trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor element is used for droplet detection, then the device complexity is low, but the measurement precision and detection range are insufficient for small-diameter droplets
Solution Approach 1:
The sensor is divided into multiple sensor elements (first, second, third, and fourth sensor elements) arranged in a specific pattern. Each element detects light from different angular positions relative to the droplet trajectory, enabling more precise detection of small-diameter droplets through spatial segmentation of the detection function.
2Adaptability or versatility
If the light-receiving surfaces are positioned along the droplet trajectory direction, then the detection range is limited, but the S/N ratio is maintained; however, to expand detection range, the positioning must change which complicates the system
Solution Approach 1:
The light-receiving surfaces are positioned not only along the droplet trajectory direction but also in a direction orthogonal to the trajectory. This two-dimensional arrangement allows the sensor to detect droplets over a broader angular range, effectively expanding the detection range without requiring complex mechanical adjustments or multiple sensor assemblies.
3Measurement precision
If the illumination light beam diameter is reduced to match small-diameter droplets, then the measurement precision improves, but the S/N ratio deteriorates making detection difficult
Solution Approach 1:
By segmenting the sensor into multiple elements positioned at different angular positions, the system can integrate signals from multiple detection points. This segmentation allows precise measurement of small droplet dimensions while maintaining reliable detection through signal integration across the sensor array, overcoming the S/N ratio problem associated with reduced beam diameter.
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
Enhances the detection accuracy and range of small-diameter droplets, improving the synchronization of laser pulses with droplet passage, thereby enhancing the efficiency of EUV light generation for microfabrication.
Implementation Method 1
a light-emitting unit configured to illuminate the predetermined region with illumination light
Implementation Method 2
a target sensor configured to receive the illumination light from the light-emitting unit
Implementation Method 3
a plurality of sensor elements, each of the plurality of sensor elements being configured to output a sensor signal that varies in accordance with an amount of light received on a light-receiving surface
Implementation Method 4
generate extreme ultraviolet light by irradiating a target with a pulse laser beam outputted from a laser apparatus to generate plasma
Implementation Method 5
irradiating a target with a pulse laser beam outputted from a laser apparatus to generate plasma
Data Source
AI summary
A target sensor may include: a plurality of sensor elements, each of the plurality of sensor elements being configured to output a sensor signal that varies in accordance with an amount of light received on a light-receiving surface; and a signal generator configured to process the sensor signals from the plurality of sensor elements. The light-receiving surfaces of the plurality of sensor elements may be disposed at different positions in a second direction different from a first direction along which an image of the target illuminated by the illumination light may move. The signal generator may be configured to compare each of the sensor signals from the plurality of sensor elements with a threshold and output the signal indicating detection of a target to the controller in a case where at least one of the sensor signals from the plurality of sensor elements may exceed the threshold.