EUV Light Generator Electron Bunch Length Control
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Solution Overview
Problem
Current EUV light generators face challenges in generating EUV light with a pulse width that suppresses abrasion and speckles on optical elements and wafers, while maintaining high transmission efficiency, due to the high coherence of the EUV light and the large size of the undulator required for microfabrication features smaller than 16 nm.
Innovation Solution
The EUV light generator incorporates an electron storage ring with a high-frequency acceleration cavity and undulators, where the electron bunch length and pulse width are optimized to produce EUV light with a longer pulse width and reduced coherence, eliminating the need for pulse stretching optics and allowing for improved transmission efficiency and reduced generator size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electron bunch is accelerated to produce high coherence EUV light, then the EUV light quality is improved, but the pulse width becomes too short causing abrasion and speckles on optical elements and wafers
Solution Approach 1:
The patent changes the temporal parameters of the electron bunch by controlling its length (0.09m ≤ Lez ≤ 3m) and the pulse width of the generated EUV light (0.3 to 10 ns). This parameter adjustment transforms the EUV light from high coherence with short pulse width to low coherence with extended pulse width, eliminating abrasion and speckles while maintaining optical quality
Solution Approach 2:
The patent introduces dynamic control of the electron bunch characteristics through the high-frequency acceleration cavity, which modulates the electron bunch length and timing. This dynamic adjustment allows optimization of the EUV pulse width to achieve the desired low coherence effect without sacrificing light quality
2Manufacturing precision
If a large size undulator is used to generate EUV light for microfabrication features smaller than 16 nm, then the manufacturing precision is improved, but the device complexity and size increase
Solution Approach 1:
The patent changes the operational parameters of the undulator by optimizing the electron bunch length and energy in conjunction with the high-frequency acceleration cavity. This parameter optimization enables the undulator to achieve the required EUV light properties for sub-16nm fabrication with a reduced device size and lower complexity
Solution Approach 2:
The patent applies preliminary acceleration and conditioning of the electron bunch in the high-frequency acceleration cavity before the electrons enter the undulator. This preliminary action optimizes the electron beam parameters, allowing the undulator to generate the required EUV light with smaller size and reduced complexity
3Object-affected harmful factors
If pulse stretching optics are added to extend the EUV light pulse width, then the harmful effects are reduced, but the device complexity and transmission efficiency decrease
Solution Approach 1:
The patent performs the pulse width extension action preliminarily, during the electron bunch acceleration phase in the high-frequency acceleration cavity, before the EUV light is generated. By controlling the electron bunch length and timing in advance, the system directly generates extended pulse width EUV light, eliminating the need for subsequent pulse stretching optics
Solution Approach 2:
The patent extracts and removes the pulse stretching optics from the system by implementing the pulse width extension function in the electron acceleration stage. This extraction simplifies the overall device complexity while maintaining the beneficial low coherence effect
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 optimized EUV light generator achieves low coherence EUV light with a pulse width ranging from 0.3 to 10 ns, reducing abrasion and speckles, and enhancing transmission efficiency, while also minimizing the size of the EUV light generator.
Implementation Method 1
a high-frequency acceleration cavity disposed in the first linear section and configured to accelerate the electron bunch in such a way that a length Lez of the electron bunch satisfies Expression (a) below
Implementation Method 2
an undulator disposed in the second linear section and configured to output EUV light when the electron bunch enters the undulator
Data Source
AI summary
An EUV light generator including the following components: A. an electron storage ring including a first linear section and a second linear section; B. an electron supplier configured to supply the electron storage ring with an electron bunch; C. a high-frequency acceleration cavity disposed in the first linear section and configured to accelerate the electron bunch in such a way that a length Lez of the electron bunch satisfies “0.09 m≤Lez≤3 m;” and D. an undulator disposed in the second linear section and configured to output EUV light when the electron bunch enters the undulator.