Coherent EUV Light Source Using High-Order Harmonics for Defect Detection
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Solution Overview
Problem
Conventional EUV radiation sources for lithography are incoherent, leading to reduced optical converting efficiency and increased complexity in defect detection, with plasma generation processes causing pollution and requiring additional optical elements, which are not suitable for the small feature sizes and high precision needed in semiconductor manufacturing.
Innovation Solution
An EUV radiation light source generation apparatus comprising a pump laser, pulse shaping units, a wavelength conversion unit, and a high-order harmonics generation unit, which processes the pulse laser radiation beam to extend its spectrum, adjust its center wavelength, and compensate its phase, resulting in a high-order harmonic radiation beam suitable for coherent EUV light generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If incoherent EUV radiation sources (LPP or DPP) are used, then EUV light can be generated, but optical converting efficiency is reduced and additional optical elements are required
Solution Approach 1:
The patent changes the fundamental parameter of light coherence from incoherent to coherent by using high-order harmonics generation. This transforms the optical source characteristics, enabling direct focusing without additional optical elements and improving optical converting efficiency while maintaining EUV light generation
Solution Approach 2:
The patent extracts and eliminates the need for additional optical elements by generating coherent EUV light through high-order harmonics. The coherent nature of the light allows direct use without the optical gathering elements required for incoherent sources, simplifying the overall system
2Measurement precision
If incoherent light is used for defect detection, then defect detection can be performed, but additional optical elements are required and complexity increases
Solution Approach 1:
The patent changes the coherence parameter of the light source to coherent, which fundamentally improves defect detection capability while eliminating the need for additional optical elements. The coherent light enables direct focusing and imaging with simpler optical paths
3Illumination intensity
If conventional laser wavelength is used, then laser can be generated, but subtle defects on mask cannot be observed for feature sizes less than 10nm
Solution Approach 1:
The patent changes the wavelength parameter from conventional laser wavelengths to EUV wavelengths through high-order harmonics generation. This wavelength reduction enables resolution of subtle defects on masks for feature sizes less than 10nm, achieving the required manufacturing precision
4Power
If plasma generation process is used, then EUV radiation can be generated, but pollution is produced
Solution Approach 1:
The patent converts the harmful plasma generation process into a beneficial alternative by using high-order harmonics generation with coherent light. This eliminates pollution while maintaining EUV radiation output, transforming the harmful approach into a clean solution
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 solution provides a high-power EUV light source capable of performing at-wavelength optical metrology with improved precision and reduced complexity, enhancing defect detection accuracy and reducing pollution by generating coherent EUV light with increased intensity.
Implementation Method 1
a pump laser, configured to provide a pulse laser radiation beam
Implementation Method 2
The wavelength conversion unit is configured to conduct a center wavelength conversion operation to the pulse laser radiation beam
Implementation Method 3
The high-order harmonics generation unit is configured to receive the pulse laser radiation beam processed by the at least one pulse shaping unit and the center wavelength conversion operation, and is configured to focus the received pulse laser radiation beam to a high order harmonic generation medium to generate a high order harmonic radiation beam
Data Source
AI summary
An EUV radiation light source generation apparatus includes a pump laser, at least one pulse shaping unit, a wavelength conversion unit, and a high-order harmonics generation unit. The pump laser provides a pulse laser radiation beam. Each pulse shaping unit conducts a spectrum extending operation and a phase compensation operation to the pulse laser radiation beam. The phase compensation operation makes multiple frequency components of the pulse laser radiation beam emitted by the pulse shaping unit to be substantially in phase. The wavelength conversion unit conducts a center wavelength conversion operation to the pulse laser radiation beam. The high-order harmonics generation unit receives the pulse laser radiation beam processed by the pulse shaping unit and the center wavelength conversion operation, and focuses the received pulse laser radiation beam to a high order harmonic generation medium to generate a high order harmonic radiation beam.