Dual Energy Beam EUV Light Source for Gas Density Control

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Solution Overview

Problem

Existing extreme ultraviolet light source devices face challenges in controlling the gas density of plasma raw material in the discharge zone, leading to inefficient generation of EUV radiation at 13.5 nm wavelength due to uneven evaporation and diffusion of raw materials between electrodes.

Innovation Solution

The device employs a dual energy beam irradiation system, where a first energy beam evaporates the raw material, and a second energy beam further evaporates it just before discharge initiation, controlling the gas density within 300 nanoseconds to ensure high-density plasma formation, thereby optimizing EUV radiation generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single energy beam is used to evaporate raw material, then the process is simple, but the gas density of plasma raw material in the discharge zone cannot be controlled appropriately

Engineering Contradiction:
Improveevaporation processVSAvoidgas density of plasma raw material
Core Design Contradiction:
Device complexityVSQuantity of substance

Solution Approach 1:

The evaporation process is divided into two distinct stages using two separate energy beams: a first energy beam for initial evaporation and a second energy beam for final evaporation just before discharge. This segmentation allows independent control of each evaporation stage, enabling precise control of the gas density of plasma raw material in the discharge zone.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first energy beam performs preliminary evaporation of the raw material, creating an initial vapor cloud. Then, the second energy beam is applied at a precisely controlled timing (within 300 nanoseconds before discharge) to further evaporate and concentrate the raw material, ensuring optimal gas density is achieved just before the discharge occurs.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If raw material is evaporated and allowed to diffuse freely between electrodes, then the process is simple, but the gas density becomes uneven and inappropriate for efficient EUV generation

Engineering Contradiction:
Improveraw material supplyVSAvoidgas density uniformity
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The system uses periodic, pulsed energy beam irradiation instead of continuous evaporation. The first energy beam irradiates the raw material, then after a controlled interval (within 300 nanoseconds), the second energy beam irradiates the same region. This periodic action prevents excessive diffusion and maintains uniform, appropriate gas density in the discharge zone.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The two energy beams are applied in rapid succession with a timing interval of within 300 nanoseconds, which is short enough to prevent significant diffusion of the evaporated material. This continuous action ensures that the gas density remains uniform and appropriate throughout the discharge zone, maximizing EUV generation efficiency.

Inventive Principle:
Principle #20Continuity of useful action

3Productivity

If electrodes are used continuously without interruption, then productivity is maintained, but thermal loading and wear increase, reducing electrode lifetime

Engineering Contradiction:
ImproveEUV radiation generationVSAvoidelectrode lifetime
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The energy beams are applied in a precisely timed sequence: the first beam evaporates raw material, then within 300 nanoseconds the second beam further evaporates it before discharge initiation. This preliminary, controlled evaporation prevents excessive material accumulation and reduces thermal shock to the electrodes during discharge, thereby extending electrode lifetime while maintaining productivity.

Inventive Principle:
Principle #10Preliminary action

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 allows for efficient EUV radiation production by maintaining suitable gas density in the discharge zone, enhancing the conversion efficiency of EUV radiation and extending electrode lifetime by reducing thermal loading and wear.

Implementation Method 1

a first energy beam is radiated towards raw material supplied onto discharge electrodes for causing the raw material to evaporate

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

the raw material in the region irradiated by the first energy beam is irradiated by the second energy beam and the raw material is further evaporated

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a discharge is initiated in the gap between the pair of discharge electrodes by the evaporated raw material, and the discharge heats and excites high-temperature plasma raw material

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 4

the EUV radiation emitted from this plasma is extracted

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Data Source

PatentEP2170020B1Extreme ultraviolet light source device and method for generating extreme ultraviolet radiation
Publication Date: 2011.06.08 USHIO INC
  • EP2170020B1 patent drawingFigure 1
  • EP2170020B1 patent drawingFigure 2
  • EP2170020B1 patent drawingFigure 3

AI summary

An extreme ultraviolet light source device comprising a pair of mutually opposed discharge electrodes, pulsed power supplying means adapted to supply pulsed power to said discharge electrodes, raw material supplying means for supplying liquid or solid raw material to said electrodes in order to cause extreme ultraviolet radiation to be emitted at said discharge electrodes, and energy beam irradiation means adapted to emit an energy beam for irradiating the raw material supplied to said discharge electrodes in order to initiate a discharge in the gap between said pair of discharge electrodes by said raw material being evaporated, wherein said energy beam irradiation means is comprised of a first energy beam irradiation means adapted to emit a first energy beam for irradiating said raw material supplied to said discharge electrodes and causing said raw material to evaporate, and a second energy beam irradiation means adapted to emit a second energy beam for irradiating the raw material in the region irradiated by said first energy beam for further evaporating the raw material after irradiation of said first energy beam and in the interval before the discharge is initiated in the gap between said pair of discharge electrodes.