Movable Mirror Focusing for Flexible EUV Laser Focal Positioning

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Solution Overview

Problem

Existing EUV radiation generating apparatuses face challenges in adjusting the focal position of laser beams within a target area without adding additional optical elements, which leads to power losses and space constraints, especially when using actuatable deflection mirrors.

Innovation Solution

A focusing device comprising a paraboloid mirror for beam widening and an ellipsoid or hyperboloid mirror for focusing, with a movement device that allows for the relative or combined movement of these mirrors to adjust the focal position within the target area, eliminating the need for additional optical elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an actuatable deflection mirror is added to change the focal position, then the focal position can be adjusted, but the device complexity increases and power losses occur

Engineering Contradiction:

Improvefocal position adjustmentVSAvoidnumber of optical elements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the focusing function and focal position adjustment function into a single ellipsoid mirror by making it movable. Instead of adding a separate deflection mirror to adjust the focal position, the ellipsoid mirror itself is made movable along its optical axis, thereby merging two functions (focusing and focal position adjustment) into one component, reducing device complexity and eliminating additional power losses

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ellipsoid mirror serves multiple functions: it focuses the laser beam and simultaneously adjusts the focal position when moved. This multi-functional design eliminates the need for separate optical elements dedicated solely to focal position adjustment, thereby reducing the overall number of components and associated power losses

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If additional optical elements are added to adjust focal position, then focal flexibility improves, but installation space requirements increase

Engineering Contradiction:

Improvefocal position flexibilityVSAvoidinstallation space

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges the focal position adjustment function into the existing ellipsoid mirror assembly by making it movable. This eliminates the need for additional optical elements and their associated mounting spaces, thereby maintaining focal flexibility while minimizing installation space requirements

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If multiple reflective optical elements are used, then beam focusing capability improves, but power losses increase

Engineering Contradiction:

Improvebeam focusing capabilityVSAvoidpower losses

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent combines the focusing function and focal position adjustment function into a single ellipsoid mirror that can move along its optical axis. This merging eliminates the need for additional reflective optical elements that would otherwise be required for focal position adjustment, thereby reducing the number of reflection surfaces and associated power losses while maintaining beam focusing capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The movable ellipsoid mirror performs both focusing and focal position adjustment functions, eliminating the need for separate optical elements. This multi-functionality reduces the total number of reflective surfaces in the optical path, thereby minimizing cumulative power losses from multiple reflections

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables flexible positioning of the focal point in space without increasing installation space or adding optical elements, maintaining imaging quality and reducing aberrations, thus enhancing the efficiency of EUV radiation generation.

Implementation Method 1

a paraboloid mirror configured to widen the laser beam

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

an ellipsoid mirror or ahyperboloid mirror configured to focus the widened laser beam at a focal position within the target area

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11835699B2Focusing device and EUV radiation generating device having same

Publication Date: 2023.12.05 TRUMPF LASER SYSTEMS FOR SEMICONDUCTOR MANUFACTURING GMBH

AI summary

A focusing device for focusing a laser beam in a target area. The focusing device includes a paraboloid mirror configured to widen the laser beam; an ellipsoid mirror or a hyperboloid mirror configured to focus the widened laser beam at a focal position within the target area; and a movement device. The movement device is configured to move the ellipsoid mirror or the hyperboloid mirror relative to the paraboloid mirror, or together with the paraboloid mirror, to change the focal position within the target area.