Illumination Device With Deflection Member For Uniform Lithography

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Solution Overview

Problem

Conventional illumination apparatuses for lithography processes suffer from light quantity loss due to the absorption of illumination light by correction optical systems, leading to non-uniform light intensity distributions on the projection master.

Innovation Solution

An illumination apparatus featuring a deflection member that forms a periodic illuminance distribution along a predetermined direction, combined with an optical integrator system of wavefront division facets, which adjusts the periodic pattern to achieve uniform or desired light intensity distributions while minimizing light loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a correction optical system is used to correct non-uniform illuminance distribution, then uniformity of light intensity distribution is improved, but light quantity is lost due to absorption

Engineering Contradiction:

Improveuniformity of light intensity distributionVSAvoidlight quantity loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent replaces the correction optical system (which uses optical elements like filters or lenses to correct illuminance distribution) with a programmable illumination system that uses multiple light sources and control circuits. This substitution eliminates the need for physical correction elements that absorb light, thereby reducing light quantity loss while achieving uniform illuminance distribution through electronic control of multiple light sources.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the illumination parameters by using multiple light sources with independently controllable intensities. By adjusting the emission parameters (intensity, timing) of each light source according to the specific illuminance requirements at different positions, the system achieves uniform distribution without the light absorption inherent in traditional correction optical systems.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If a correction optical system is arranged to correct angular intensity distributions, then uniformity of illuminance on projection master is improved, but device complexity increases

Engineering Contradiction:

Improveuniformity of illuminance on projection masterVSAvoidcomplexity of optical system

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent replaces the complex correction optical system with a programmable array of multiple light sources. Instead of using intricate optical elements to correct angular intensity distributions, the system uses electronic control of light source intensities to directly achieve the desired illuminance uniformity, thereby simplifying the overall device structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent segments the illumination function into multiple independent light sources, each responsible for illuminating a specific region or aspect of the projection master. This segmentation allows independent optimization and control of each light source, eliminating the need for a complex monolithic correction optical system and enabling more flexible and simpler system architecture.

Inventive Principle:

Principle #1Segmentation

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 solution enables uniform or desired light intensity distributions on the illumination target surface, reducing light quantity loss and improving the accuracy of the lithography process.

Implementation Method 1

a deflection member arranged in an optical path of the illumination apparatus and configured to form an illuminance distribution with a periodic pattern

Methodology Applied

Scientific EffectLight deflection: Reflection

Implementation Method 2

an optical integrator system having a plurality of wavefront division facets arrayed on the predetermined face and configured to form secondary light sources with use of a beam from the deflection member

Methodology Applied

Scientific EffectWavefront division: Refraction

Data Source

PatentUS10459343B2Illumination device

Publication Date: 2019.10.29 NIKON CORP

AI summary

An object is to provide an illumination apparatus that achieves illumination with a uniform illuminance distribution, while reducing a light quantity loss. An illumination apparatus for illuminating an illumination target surface has: a deflection member configured to form an illuminance distribution with a periodic pattern along a predetermined direction on a predetermined face traversing an optical path; and an optical integrator system having a plurality of wavefront division facets arrayed on the predetermined face and configured to form secondary light sources with use of a beam from the deflection member; the deflection member forms the illuminance distribution with the periodic pattern of an integer times or a unit fraction times an array period of the plurality of wavefront division facets.