EUV Light Source Synchronized Microwave Ionization
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Solution Overview
Problem
In EUV light source apparatuses, the inefficient use of microwave energy for ionizing neutral particles leads to thermal energy emission, instability in target material states, and the generation of X-rays, which pose safety and environmental concerns.
Innovation Solution
A pulse-operated EUV light source apparatus that synchronizes plasma generation with microwave radiation to cause electron cyclotron resonance, efficiently ionizing neutral particles and minimizing thermal energy emission, using magnetic fields to trap and exhaust charged particles and ionized particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If microwave is continuously radiated to ionize neutral particles, then ionization effect is improved, but thermal energy emission increases and target material stability deteriorates
Solution Approach 1:
The patent applies periodic pulsed microwave radiation synchronized with plasma generation cycles. The microwave is radiated only during specific time windows when neutral particles are present and need ionization, rather than continuous radiation. This periodic action maintains ionization efficiency while allowing thermal energy to dissipate between pulses, preventing target material instability and X-ray generation.
2Use of energy by moving object
If microwave energy is increased to improve ionization of neutral particles, then ionization efficiency is improved, but X-ray generation increases posing safety concerns
Solution Approach 1:
The patent uses synchronized pulsed microwave radiation that operates only during specific phases of the plasma generation cycle when ionization is needed. By limiting microwave exposure to brief periodic intervals and ensuring complete ionization of neutral particles before the next pulse, the system achieves high ionization efficiency without allowing electrons to accumulate excessive energy that would lead to X-ray generation.
Solution Approach 2:
The patent implements a control system that monitors plasma generation status and adjusts microwave radiation timing and intensity accordingly. The feedback mechanism ensures microwaves are applied only when neutral particles are present and need ionization, and are stopped when ionization is complete, preventing over-ionization that would lead to harmful X-ray emission while maintaining efficient ionization during active phases.
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
Improves the utility efficiency of microwave energy for ionization, stabilizes the target material state, reduces X-ray generation, and extends the life of EUV collector mirrors, enhancing exposure performance and safety.
Implementation Method 1
microwave radiating means that radiates microwave through pulse operation into a space in which a magnetic field is formed to cause electron cyclotron resonance, and thereby ionizes neutral particles emitted from the plasma
Implementation Method 2
magnetic field forming means that forms the magnetic field and a magnetic field for trapping at least ionized particles
Implementation Method 3
LPP (laser produced plasma) light source using plasma generating by applying a laser beam to a target
Data Source
AI summary
In an extreme ultra violet light source apparatus that exhausts debris including fast ions and neutral particles by the effect of a magnetic field, neutral particles emitted from plasma are efficiently ionized. The extreme ultra violet light source apparatus includes a plasma generating unit that generates plasma, that radiates at least extreme ultra violet light, through pulse operation; collective optics that collects the extreme ultra violet light radiated from the plasma; a microwave generating unit that radiates microwave through pulse operation into a space in which a magnetic field is formed to cause electron cyclotron resonance, and thereby ionizes neutral particles emitted from the plasma; a magnetic field forming unit that forms the magnetic field and a magnetic field for trapping at least ionized particles; and a control unit that synchronously controls at least the plasma generating unit and the microwave generating unit.