EUV Radiation Source Droplet Coalescence Control

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Solution Overview

Problem

Existing radiation sources for lithographic apparatuses face challenges in delivering fuel droplets of precise size and separation, which affects the generation of extreme ultraviolet (EUV) radiation for miniaturization in IC manufacturing, as the current methods struggle to control the size and spacing of droplets effectively.

Innovation Solution

A radiation source fuel droplet generator is developed, utilizing a fuel droplet emitter connected to a modulating voltage source and electrodes to apply varying voltages, creating an electric field that accelerates or decelerates droplets, promoting coalescence and controlling their relative speeds to achieve desired droplet sizes and separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional droplet delivery methods are used, then the radiation source can operate, but the droplet size and separation cannot be precisely controlled

Engineering Contradiction:

Improvedroplet size and separation controlVSAvoidelectrode and voltage control system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies voltage modulation to change the electrical parameters of the droplet stream, using electric field effects to control droplet size and separation. By varying voltage parameters in real-time, the system achieves precise control over droplet characteristics without mechanical adjustments.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical droplet generation and separation mechanisms with an electrical field-based system. Instead of using physical structures to control droplet size and spacing, the invention uses electric fields to manipulate droplet behavior, reducing mechanical complexity while improving precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Quantity of substance

If droplet size is increased to improve coalescence, then radiation generation is enhanced, but droplet separation becomes more difficult to control

Engineering Contradiction:

Improvedroplet size for coalescenceVSAvoiddroplet separation control

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent makes the droplet generation system dynamic by applying time-varying voltages that adapt droplet size and separation in real-time. The system can dynamically adjust between producing larger droplets for coalescence and maintaining proper separation, allowing both objectives to be achieved through temporal control rather than static constraints.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs periodic voltage application to the droplet stream, creating rhythmic patterns of droplet formation, growth, and separation. This periodic modulation allows droplets to grow to desired sizes for coalescence while maintaining controlled separation through timing-based electrical actuation.

Inventive Principle:

Principle #19Periodic action

3Manufacturing precision

If voltage modulation is applied to control droplet speed, then droplet delivery precision is improved, but energy consumption increases

Engineering Contradiction:

Improvedroplet delivery precisionVSAvoidvoltage source energy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies voltage modulation only when and where needed in the droplet trajectory, rather than continuously throughout the entire system. By applying electrical control selectively at critical points in the droplet delivery process, the system achieves precise control while minimizing unnecessary energy consumption from continuous voltage application.

Inventive Principle:

Principle #16Partial or excessive 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 enables precise control over droplet size and separation, enhancing the generation of EUV radiation, thereby improving the miniaturization capabilities in IC manufacturing by facilitating the formation of larger droplets with controlled velocities and charges, leading to improved pattern printing in lithography.

Implementation Method 1

A voltage source is configured to apply a potential difference between the first and second electrodes and thereby generate an electric field between the first and second electrodes

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

The electric field applies a decelerating force to one of the first and second portions of the stream of fuel droplets and applies an accelerating force to the other of the first and second portions of the stream of fuel droplets

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 3

promoting coalescence and controlling their relative speeds to achieve desired droplet sizes and separation

Methodology Applied

Scientific EffectDroplet coalescence: Coagulation

Data Source

PatentUS9310689B2Radiation source and lithographic apparatus

Publication Date: 2016.04.12 ASML NETHERLANDS BV

AI summary

Methods and apparatus are provided for promoting the coalescence of fuel droplets in a stream generated by a radiation source droplet stream generator for use in lithographic apparatus. Various examples are described in which a modulating voltage source is applied to the emitter so that the electrical characteristics of the droplets may be controlled. This results in acceleration and deceleration of droplets in the stream which causes them to merge and promotes coalescence.