Polarization-Influencing Optical Element for Microlithography

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Solution Overview

Problem

Microlithographic projection exposure apparatuses face challenges in efficiently providing desired polarization distributions with existing technologies, which often result in light loss and complex production requirements.

Innovation Solution

An optical system comprising a mirror arrangement with independently adjustable mirror elements and a polarization-influencing optical element that generates a continuously varying polarization distribution, allowing for flexible and cost-effective setting of polarization states in the pupil plane, including tangential and radial polarization distributions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If existing technologies are used to provide desired polarization distributions, then polarization control is achieved, but light loss increases and production requirements become complex

Engineering Contradiction:

Improveproduction requirementsVSAvoidlight loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent replaces complex mechanical mirror arrangements with a polarization-influencing optical element that uses optical properties (birefringence, optical activity) to control polarization distributions. This substitution eliminates the need for mechanically adjustable mirror elements while achieving the same polarization control function, thereby reducing light loss and simplifying production

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the approach from mechanically adjusting mirror angles to optically controlling polarization parameters through material properties. The polarization-influencing optical element modifies light polarization states by changing optical parameters such as birefringence orientation and optical rotation, providing a more efficient and manufacturable solution

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If mirror arrangements with independently adjustable mirror elements are used, then angular distribution of reflected light can be changed, but device complexity increases

Engineering Contradiction:

Improveflexibility in setting polarization distributionsVSAvoidcomplexity of mirror arrangement

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex mechanical system of independently adjustable mirror elements with a single polarization-influencing optical element that achieves the same adaptability through optical material properties. This element can generate various polarization distributions (tangential, radial, circular) without requiring multiple mechanically adjustable components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The polarization-influencing optical element serves multiple functions that previously required separate components: it controls polarization direction, adjusts angular distribution, and generates different polarization patterns (tangential, radial, circular) all within a single element, thereby reducing device complexity while maintaining versatility

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 and efficient setting of polarization distributions with reduced light loss and simplified production, allowing for precise control of illumination settings in microlithographic processes.

Implementation Method 1

the polarization-influencing optical element has linear birefringence having a direction of the fast axis of birefringence that varies over the optically effective surface

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 2

the polarization-influencing optical element is produced from optically active material

Methodology Applied

Scientific EffectOptical activity:

Implementation Method 3

at least one mirror arrangement having a plurality of mirror elements which are adjustable independently of one another for the purpose of changing an angular distribution of the light reflected by the mirror arrangement

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS9405202B2Optical system of a microlithographic projection exposure apparatus

Publication Date: 2016.08.02 CARL ZEISS SMT GMBH

AI summary

The invention relates to an optical system of a microlithographic projection exposure apparatus, comprising at least one mirror arrangement having a plurality of mirror elements which are adjustable independently of one another for the purpose of changing an angular distribution of the light reflected by the mirror arrangement, and a polarization-influencing optical element, which generates, for impinging light having a constantly linear or a circular input polarization distribution, an output polarization distribution having a direction of polarization that varies continuously over the light beam cross section.