EUV Target Expansion Rate Control via Radiant Exposure

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Solution Overview

Problem

Current methods for producing extreme ultraviolet (EUV) light in laser-produced plasma sources face challenges in controlling the expansion rate of target materials, which affects the conversion efficiency of EUV light production, leading to suboptimal performance in photolithography processes.

Innovation Solution

A method is developed to control the expansion rate of a target material by adjusting the radiant exposure delivered by a first beam of radiation, which modifies the geometric distribution of the target, forming a modified target that interacts with a second beam to enhance EUV light production. This involves measuring characteristics such as energy, position, and size of the target, and adjusting parameters like pulse width and power of the first beam to maintain optimal radiant exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If radiant exposure from the first beam is increased to modify geometric distribution of the target material, then the expansion rate control and EUV conversion efficiency improve, but the energy consumption and system complexity increase

Engineering Contradiction:

ImproveEUV conversion efficiencyVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The first beam of radiation is applied to the target material before the second beam to pre-modify the geometric distribution and control the expansion rate. This preliminary action prepares the target in an optimal state for subsequent EUV light generation, improving conversion efficiency while separating the control function from the generation function

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The first beam acts as an intermediary that mediates between the control system and the target material. By using this intermediate step to modify the target's geometric distribution, the system achieves precise expansion rate control without directly complicating the EUV generation process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

Engineering Contradiction:

ImproveEUV conversion efficiencyVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The first beam delivers a controlled amount of radiant exposure that is sufficient to modify the geometric distribution and control expansion rate, but not excessive. This partial action approach achieves the necessary target modification with minimal energy input, avoiding waste while maintaining optimal EUV conversion efficiency

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If characteristics of the target material are measured to control radiant exposure, then the expansion rate precision improves, but the measurement precision requirements and system complexity increase

Engineering Contradiction:

Improveexpansion rate precisionVSAvoidmeasurement precision requirements

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The system measures characteristics of the target material (such as position, size, or geometric distribution) and uses this feedback information to adjust the radiant exposure from the first beam. This closed-loop feedback mechanism ensures precise expansion rate control while adapting to variations in target material properties in real-time

Inventive Principle:

Principle #23Feedback

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 controlled expansion rate of the target material increases the conversion efficiency of EUV light production, improving the usable EUV light output and maintaining it within a predetermined range, thereby enhancing the performance of EUV light sources for applications like photolithography.

Implementation Method 1

directing a first beam of radiation toward the target material to deliver energy to the target material to modify a geometric distribution of the target material

Methodology Applied

Scientific EffectRadiant heating: Heating

Implementation Method 2

directing a second beam of radiation toward the modified target, the second beam of radiation converting at least part of the modified target to plasma that emits EUV light

Methodology Applied

Scientific EffectLaser-produced plasma: Plasma

Implementation Method 3

measuring one or more characteristics associated with one or more of the target material and the modified target relative to the first beam of radiation

Methodology Applied

Scientific EffectOptical detection:

Data Source

PatentUS11096266B2Target expansion rate control in an extreme ultraviolet light source

Publication Date: 2021.08.17 ASML NETHERLANDS BV

AI summary

A method includes providing a target material that comprises a component that emits extreme ultraviolet (EUV) light when converted to plasma; directing a first beam of radiation toward the target material to deliver energy to the target material to modify a geometric distribution of the target material to form a modified target; directing a second beam of radiation toward the modified target, the second beam of radiation converting at least part of the modified target to plasma that emits EUV light; measuring one or more characteristics associated with one or more of the target material and the modified target relative to the first beam of radiation; and controlling an amount of radiant exposure delivered to the target material from the first beam of radiation based on the one or more measured characteristics to within a predetermined range of energies.