EUV Plasma Imaging Feedback for Circular Intermediate Focus
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Solution Overview
Problem
Existing EUV light generation apparatuses face challenges in achieving high circularity of the EUV light profile at the intermediate focal point due to the elliptical shape of the plasma, which complicates the shaping of EUV light in external apparatuses.
Innovation Solution
Incorporating a camera to image the plasma generation region, utilizing correlation information to adjust control parameters such as delay time, pulse energies, and pulse widths of the laser device to improve the circularity of the EUV light profile at the intermediate focal point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the plasma is generated by laser irradiation in the conventional manner, then the plasma generation process is simple, but the EUV light profile at the intermediate focal point becomes non-circular (elliptical), which complicates shaping in external apparatuses
Solution Approach 1:
The system images the plasma generation region and uses the obtained image data to feedback-adjust laser control parameters (delay time, pulse energies, pulse widths) to improve the circularity of the EUV light profile at the intermediate focal point
Solution Approach 2:
The invention changes laser control parameters (delay time between first and second pulse laser light, pulse energies, pulse widths) to transform the plasma shape from elliptical to more circular, thereby improving the EUV light profile circularity
2Manufacturing precision
If the plasma shape is not controlled, then the apparatus operation is simple, but the EUV light profile circularity is poor, requiring complex shaping in external apparatuses
Solution Approach 1:
The system uses imaging of the plasma generation region with feedback control to automatically adjust laser parameters and achieve the desired circular plasma shape, eliminating the need for manual intervention and complex external shaping apparatuses
Solution Approach 2:
The apparatus performs self-adjustment by using the imaged plasma shape information to automatically modify laser control parameters, achieving circular plasma shape control without requiring external intervention or complex mechanical adjustment mechanisms
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
The apparatus achieves improved circularity of the EUV light profile, enabling effective shaping and utilization of EUV light in external apparatuses.
Implementation Method 1
a laser produced plasma (LPP) type apparatus using plasma generated by irradiating a target with laser light
Implementation Method 2
irradiating a target with laser light has been developed
Implementation Method 3
an EUV light concentrating mirror configured to reflect EUV light emitted from the plasma and concentrate the EUV light on an intermediate focal point
Data Source
AI summary
An EUV light generation apparatus includes a chamber; a target supply device supplying a first target; a laser device outputting first pulse laser light to be incident on the first target, outputting second pulse laser light to be incident on a second target, and adjusting a control parameter correlated with a shape of plasma generated by the second pulse laser light being incident on the second target; an EUV light concentrating mirror reflecting EUV light emitted from the plasma and concentrating the EUV light on an intermediate focal point; a camera imaging the EUV light and generating a picture including an image of the plasma; and a processor obtaining a value of the control parameter for improving circularity of a profile of the EUV light at the intermediate focal point using the picture and correlation information including a correlation between the shape of the plasma and the control parameter.