EUV Light Generation Apparatus with Scattered Light Alignment Control
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Solution Overview
Problem
Existing extreme ultraviolet light generation systems for semiconductor microfabrication face challenges in accurately irradiating targets with pulse laser beams, leading to inefficiencies in EUV light production due to misalignment between the target center and the optical path axis.
Innovation Solution
The implementation of a system that includes a chamber, a target generation unit, a focusing optical system, and scattered light detectors to detect and adjust the optical path of the pulse laser beam, ensuring alignment between the target center and the optical path axis, and utilizing a pre-pulse and main pulse laser device configuration to enhance EUV light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pulse laser beam is used to irradiate the target, then EUV light generation is enabled, but misalignment between the target center and optical path axis reduces efficiency
Solution Approach 1:
The patent implements a feedback control system where scattered light detectors monitor the position of the target relative to the optical path axis in real-time. The detected scattered light signals are fed back to the laser control unit, which adjusts the laser beam position accordingly to maintain precise alignment with the target center, thereby resolving the alignment precision issue while maintaining high EUV generation efficiency
Solution Approach 2:
The patent replaces mechanical alignment adjustment mechanisms with an optical detection and control system. Instead of physically adjusting the target or laser position through mechanical means, the system uses scattered light detection to monitor alignment and electronically controls the laser beam positioning, achieving higher precision and efficiency
2Power
If the target is irradiated with a pulse laser beam, then plasma is generated for EUV light production, but inaccurate irradiation leads to energy loss
Solution Approach 1:
The scattered light detectors provide real-time feedback on target position and laser beam alignment. The control unit uses this feedback to optimize the laser beam positioning on the target, ensuring maximum energy transfer to plasma generation and minimizing wasted laser energy, thereby improving both EUV output and energy efficiency
Solution Approach 2:
The system performs preliminary detection of the target position using scattered light detectors before the main laser irradiation. This preliminary action allows the control unit to pre-adjust the laser beam positioning to ensure accurate irradiation, preventing energy loss from misalignment before the high-power laser pulse is delivered
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 the accuracy and efficiency of EUV light generation by ensuring precise alignment and optimal irradiation, thereby enhancing the production of extreme ultraviolet light for semiconductor microfabrication processes.
Implementation Method 1
a focusing optical system configured to concentrate a pulse laser beam to the predetermined region
Implementation Method 2
an LPP (laser produced plasma) type system using plasma generated by irradiating a target material with a laser beam
Implementation Method 3
a plurality of scattered light detectors each configured to detect scattered light from the target irradiated with the pulse laser beam
Data Source
AI summary
An extreme ultraviolet light generation apparatus may include: a chamber; a target generation unit configured to output a target to a predetermined region inside the chamber; a focusing optical system configured to concentrate a pulse laser beam to the predetermined region; and a plurality of scattered light detectors each configured to detect scattered light from the target irradiated with the pulse laser beam. The extreme ultraviolet light generation apparatus may further include: an optical path changer configured to change an optical path of the pulse laser beam; and an optical path controller configured to control the optical path changer on a basis of results of detection by the plurality of scattered light detectors.