Angled Laser Beam EUV Source Power Optimization

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Solution Overview

Problem

In extreme ultraviolet (EUV) photolithography systems, the protection bar used to prevent the CO2 laser beam from entering downstream optics reduces the EUV radiation power by blocking a portion of the EUV radiation, limiting the power output and throughput.

Innovation Solution

An angled primary laser beam is configured to intersect the fuel droplets at a non-perpendicular angle, with a collector mirror focusing the EUV radiation to an exit aperture not aligned with the primary laser beam, allowing the protection element to absorb the remnant laser beam without blocking EUV radiation, thus maximizing power output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection bar is used to prevent the CO2 laser beam from entering downstream optics, then the laser beam is blocked from damaging optics, but the EUV radiation power is reduced due to blocking

Engineering Contradiction:

Improveprotection of downstream opticsVSAvoidEUV radiation power output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the spatial arrangement by angling the primary laser beam at a non-perpendicular angle (e.g., 45 degrees) relative to the fuel droplet trajectory, rather than using a perpendicular intersection. This dimensional change in beam orientation allows the protection bar to be positioned without blocking the EUV radiation path, resolving the contradiction between optical protection and power output.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces asymmetry in the beam-droplet interaction geometry by using a non-perpendicular angle between the primary laser beam and fuel droplet trajectory. This asymmetric configuration allows the protection bar to be strategically positioned in the laser beam path without interfering with the EUV radiation collection and transmission, thereby maintaining both protection functionality and high power output.

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If the exit aperture is aligned with the primary laser beam trajectory, then the system configuration is simplified, but the protection element blocks a significant portion of EUV radiation

Engineering Contradiction:

Improvesystem configuration simplicityVSAvoidEUV radiation power

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent resolves the contradiction by changing the spatial relationship between the exit aperture and laser beam trajectory. The exit aperture is positioned at an angle relative to the laser beam path, creating a separated geometry that simplifies the overall system configuration while preventing the protection bar from blocking EUV radiation and maintaining high power output.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 configuration increases the EUV radiation power and throughput by preventing the protection element from blocking the EUV radiation, enhancing the performance of the EUV photolithography system.

Implementation Method 1

A primary laser is configured to generate a primary laser beam along a second trajectory that intersects the first trajectory. The primary laser beam has an energy sufficient to ignite a plasma that emits extreme ultraviolet (EUV) radiation

Methodology Applied

Scientific EffectLaser-induced plasma generation: Plasma

Implementation Method 2

The primary laser beam has an energy sufficient to ignite a plasma that emits extreme ultraviolet (EUV) radiation from the plurality of fuel droplets

Methodology Applied

Scientific EffectEUV radiation emission from plasma: Luminescence

Implementation Method 3

A collector mirror is configured to focus the EUV radiation to an exit aperture of the source vessel. The exit aperture is not linearly aligned with a line of the primary laser beam

Methodology Applied

Scientific EffectEUV radiation focusing: Focusing

Implementation Method 4

A protection element is linearly aligned with the primary laser beam at a position that is external to a path of the EUV radiation. The protection element is configured to absorb the remnant primary laser beam

Methodology Applied

Scientific EffectLaser beam absorption: Absorption (EM radiation)

Data Source

PatentUS9992856B2Solution for EUV power increment at wafer level

Publication Date: 2018.06.05 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure relates to a photolithography radiation source having an angled primary laser, and an associated method of formation. In some embodiments, the photolithography radiation source has a fuel droplet generator that provides fuel droplets to a source vessel along a first trajectory. A primary laser is configured to generate a primary laser beam along a second trajectory that intersects the first trajectory. The primary laser beam is configured to ignite a plasma from the plurality of fuel droplets that emits radiation. A collector mirror is configured to focus the radiation to an exit aperture of the source vessel. The primary laser beam does not intersect the exit aperture.