EUV Radiation Source Triggering via Remote Photoionization
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Solution Overview
Problem
Existing methods for generating EUV radiation and soft X-ray radiation face challenges in achieving reliable ignition and high repetition frequencies due to charge carrier depletion and thermal erosion of trigger devices, especially at high frequencies and during extended operating pauses.
Innovation Solution
Introducing radiation from a remote radiation source into the discharge space to generate charge carriers, using coherent or incoherent radiation sources, and focusing radiation on electrodes to optimize plasma formation and stability, with materials like tungsten and molybdenum for improved thermal conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trigger device is arranged in the immediate spatial vicinity of the plasma for controlled generation of gas discharge, then reliable ignition control is achieved, but the trigger device is exposed to high thermal loads and ion bombardment causing strong erosion and shortened product life
Solution Approach 1:
The trigger device is extracted from the immediate vicinity of the plasma and relocated to a position outside the discharge space. Radiation generated by the trigger device is directed into the discharge space to provide pre-ionization, allowing reliable ignition control without exposing the trigger device to thermal loads and ion bombardment, thus extending its operational life
Solution Approach 2:
Radiation serves as an intermediary between the trigger device and the plasma. The trigger device generates radiation that travels through a vacuum or air gap to provide pre-ionization in the discharge space, enabling controlled ignition without direct physical contact between the trigger device and the plasma, thereby avoiding thermal and ion damage
2Duration of action of stationary object
If the trigger device is cooled to withstand thermal loads, then device durability is improved, but a comparatively strong erosion of the auxiliary electrode still takes place during subsequent discharge operation
Solution Approach 1:
The trigger device is extracted from the discharge space to a location outside it, eliminating exposure to thermal loads and ion bombardment. This removes the need for cooling systems and prevents electrode erosion while maintaining ignition control functionality through radiation-based pre-ionization
3Productivity
If high repetition frequencies are used to increase productivity, then EUV radiation output is improved, but charge carrier depletion occurs leading to insufficient pre-ionization and reduced discharge stability
Solution Approach 1:
The trigger device provides preliminary action by generating radiation that creates pre-ionization in the discharge space before the main discharge occurs. This pre-ionization ensures sufficient charge carriers are available even at high repetition frequencies, maintaining discharge stability and enabling sustained high productivity
Solution Approach 2:
The radiation from the trigger device provides continuous pre-ionization between discharges, ensuring that charge carriers are continuously replenished. This maintains discharge stability even at high repetition frequencies where charge carrier depletion would normally occur, allowing continuous useful action without interruption
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 ensures reliable and efficient ignition of the gas discharge at high repetition frequencies and extended operating pauses, reducing electrode erosion and maintaining radiation source longevity by protecting it from thermal loads.
Implementation Method 1
at least one radiation source (28) which generates at least one radiation (30) for making available the charge carriers (24)
Implementation Method 2
generating in particular EUV radiation (12) and/or soft X-ray radiation (12a) by means of an electrical gas discharge
Implementation Method 3
a so-termed pinch plasma 26 is created which is heated to a certain temperature by ohmic heating
Implementation Method 4
focusing radiation on electrodes to optimize plasma formation and stability
Data Source
AI summary
A method of generating in particular EUV radiation (12) and/or soft X-ray radiation (12a) emitted by a plasma (26) is described. The plasma (26) is formed by an operating gas (22) in a discharge space (14) which comprises at least one radiation emission window (16) and an electrode system with at least one anode (18) and at least one cathode (20). This electrode system transmits electrical energy to the plasma (26) by means of charge carriers (24) introduced into the discharge space (14). It is suggested for obtaining a reliable ignition of the plasma (26) at high repetition frequencies that a radiation (30) generated by at least one radiation source (28) is introduced into the discharge space (14) for making available the discharge carriers (24).