EUV Light Generation Target Detection via Optical Projection
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Solution Overview
Problem
Current extreme ultraviolet light generation methods for semiconductor microfabrication, such as LPP, DPP, and SR systems, face challenges in accurately timing the irradiation of targets with pulse laser beams to generate EUV light, especially at finer scales like 32 nm or less, due to shifts in the target's actual path relative to the optical path, leading to inconsistencies in plasma generation and EUV light emission.
Innovation Solution
The proposed method involves a target sensor and light-emitting unit configuration where the light source irradiates a region with a transverse optical path longer than the target's movement direction, and a transfer optical system forms an image of the target within a slit or detector, allowing for precise detection and timing of the target's passage, thereby ensuring consistent irradiation with the pulse laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional target detection method is used, then the detection system is simple, but the detection timing shifts due to target path deviations, reducing manufacturing precision
Solution Approach 1:
The patent transforms the detection approach by projecting the target image onto a two-dimensional detector plane through an optical system. This dimensional transformation allows simultaneous measurement of target position in multiple directions, enabling accurate detection timing even when the target deviates from its nominal path. The optical projection system converts spatial position information into detectable optical signals on the detector surface.
Solution Approach 2:
The patent introduces an optical system as an intermediary between the moving target and the detector. This intermediary component (comprising lenses, mirrors, or other optical elements) transfers the target's positional information to the detector without requiring direct contact or complex sensor arrays near the target path. The optical intermediary enables precise timing detection while maintaining system modularity and reducing direct interference with the target trajectory.
2Reliability
If the target path is not precisely controlled, then the system operation is simpler, but the irradiation timing becomes inconsistent, reducing reliability
Solution Approach 1:
The patent implements a feedback mechanism where the detector continuously monitors the target's actual position and timing, and this information is used to adjust the laser irradiation timing dynamically. The system measures the target's passage through the detection region and triggers the laser pulse based on the actual detected position rather than a predetermined timer, ensuring consistent irradiation timing regardless of path variations.
Solution Approach 2:
The patent performs preliminary detection of the target's position and velocity before the actual laser irradiation occurs. The optical detection system captures target information in advance, allowing the control system to calculate the optimal irradiation timing and prepare the laser system accordingly. This preliminary measurement and calculation phase ensures that the subsequent irradiation occurs at the precise moment when the target is in the correct position.
3Measurement precision
If a simple detection region is used, then the device complexity is reduced, but the detection precision decreases due to target path shifts
Solution Approach 1:
The patent employs an optical projection system that maps the three-dimensional target trajectory onto a two-dimensional detector plane. This dimensional transformation allows the system to measure target position and timing with high precision by detecting the target's image position on the detector, regardless of small deviations in the target's actual path. The optical system effectively converts difficult-to-measure spatial deviations into easily detectable position shifts on the detector surface.
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 suppresses shifts in detection timing and irradiation timing, ensuring accurate and consistent generation of EUV light by aligning the target's actual path with the optical path, enhancing the precision and reliability of EUV light production for finer semiconductor features.
Implementation Method 1
detecting the target passing through a second predetermined region by irradiating the second predetermined region with light and by detecting light incident on an optical sensor from the second predetermined region
Implementation Method 2
irradiating the target with a pulse laser beam introduced into the first predetermined region through the through-hole on a basis of a timing of detecting the target passing through the second predetermined region, to turn the target into plasma
Implementation Method 3
turn the target into plasma
Data Source
AI summary
An extreme ultraviolet light generation device may comprise: a chamber provided with a through-hole; an introduction optical system configured to introduce the pulse laser beam into a first predetermined region inside the chamber through the through-hole; a target supply device configured to output the target toward the first predetermined region; a light source configured to irradiate a second predetermined region with light whose optical path in the second predetermined region has a transverse section that is longer along a direction perpendicular to a direction of movement of the target than along the direction of movement of the target, the second predetermined region including part of a trajectory of the target between the target supply device and the first predetermined region; and an optical sensor configured to detect light incident on the optical sensor from the second predetermined region to detect the target passing through the second predetermined region.