EUV Plasma Position Detection Using Visible Light Intermediary
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Solution Overview
Problem
The challenge is to stabilize the optical axis of EUV light generated during plasma irradiation with laser light, as changes in the target's position affect the EUV light's optical axis, leading to malfunctions in inspection and exposure apparatuses.
Innovation Solution
A position detection apparatus and method that uses a visible light optical system to condense visible light generated with EUV light, employing a position detection sensor and processing unit to detect changes in the plasma's position, allowing for correction of the EUV light optical axis by analyzing changes in the spot of visible light detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target position is stabilized during laser irradiation, then the EUV light optical axis remains stable, but the complexity of the position control system increases
Solution Approach 1:
The patent introduces a visible light optical system as an intermediary to detect plasma position. Instead of directly monitoring the EUV light or the target position, the system uses visible light (which accompanies EUV light generation) as a mediator to indicate plasma position changes. This intermediary approach simplifies the detection system while maintaining reliability in stabilizing the EUV light optical axis.
Solution Approach 2:
The patent creates an optical copy of the plasma position using visible light. The visible light optical system forms an optical image (spot) of the plasma on a detection sensor, providing a simplified copy representation of the plasma position. This optical copying mechanism allows indirect but effective monitoring of plasma position without complex direct measurement systems.
2Measurement precision
If a visible light optical system is added to detect plasma position, then the position detection capability is improved, but the device complexity increases
Solution Approach 1:
The patent applies multi-functionality by having the visible light optical system serve multiple purposes: it detects plasma position changes, provides optical axis stabilization information, and enables real-time monitoring. The same visible light detection mechanism is used for both positioning and stabilization functions, reducing the need for separate dedicated systems and thereby limiting the increase in device complexity.
Solution Approach 2:
The visible light acts as an intermediary that provides measurement information without requiring direct EUV light detection. Since visible light has longer wavelength and is easier to detect than EUV light, using it as a mediator improves measurement precision while avoiding the technical challenges and complexity associated with direct EUV detection 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 effectively stabilizes the EUV light's optical axis, enabling accurate detection and correction of plasma position changes, thereby ensuring consistent performance in inspection and exposure applications.
Implementation Method 1
plasma generated by condensing laser light onto a target with a condensing lens
Implementation Method 2
a visible light optical system configured to condense visible light generated together with EUV light from plasma
Data Source
AI summary
Provided are a position detection apparatus and a position detection method capable of detecting a position of plasma on a target. The position detection apparatus according to the present disclosure includes: a visible light optical system configured to condense visible light generated together with EUV light from plasma generated by condensing laser light onto a target with a condensing lens; a position detection sensor configured to detect the visible light condensed by the visible light optical system; and a position detection processing unit configured to detect a change in a position of the plasma on the target, from a change in a spot of the visible light detected by the position detection sensor.