Block Copolymer Polarizing Elements for Deep-UV Light

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Solution Overview

Problem

Current polarizing elements, such as wire grid polarizers, are ineffective for shorter wavelengths like those used in ArF and F2 excimer lasers due to limitations in machining technology, which restricts their application in semiconductor manufacturing and other fields that require deep-UV light polarization.

Innovation Solution

The development of a polarizing element with an anisotropic striped structure formed by block copolymer lithography, where the striped structure has an average continuous distance of two or more times the light wavelength in the longitudinal direction and an average interval less than half the wavelength in the transverse direction, allowing for effective polarization of ultraviolet light with wavelengths below 300 nm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional wire grid polarizers are used, then they can polarize infrared and visible light, but they are ineffective for ultraviolet light with wavelengths below 300 nm due to machining limitations

Engineering Contradiction:

Improvewavelength rangeVSAvoidgrid interval

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent replaces conventional mechanical machining methods with block copolymer self-assembly to create the wire grid structure. The block copolymer naturally forms nanoscale periodic patterns through phase separation, eliminating the need for precision mechanical machining and enabling grid intervals suitable for deep-UV wavelengths.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the material state from solid metal wires to polymer-based structures formed through self-assembly. By controlling the block copolymer composition and processing conditions, the grid interval parameter can be precisely tuned to match the required wavelength scale for deep-UV polarization.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If prism-type polarizers are used, then high degree of polarization is achieved, but substantial deflection between incoming and outgoing light rays occurs and larger installation space is required

Engineering Contradiction:

Improvepolarization degreeVSAvoidbeam deflection

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent uses a thin film wire grid structure deposited on a substrate, which allows the polarizing function to be achieved in a compact, planar configuration. This eliminates the need for thick prism structures and associated beam deflection, while maintaining effective polarization through the sub-wavelength grid pattern.

Inventive Principle:

Principle #30Flexible shells and thin films

3Volume of moving object

If filter-type polarizers with rolled glass and conductive particles are used, then thin device formation is achieved with smaller installation space, but they are ineffective for ultraviolet light because materials transparent to UV light cannot be rolled to produce orientation of embedded particles

Engineering Contradiction:

Improveinstallation spaceVSAvoidUV light effectiveness

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical rolling process with a chemical self-assembly process using block copolymers. The polymer blocks naturally segregate into oriented structures through thermodynamic phase separation, creating the anisotropic conductivity pattern needed for polarization without requiring mechanical deformation of UV-transparent materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables the polarization of deep-UV light, expanding the applications of polarizing elements to semiconductor fabrication, nanolithography, astrophysics, and other fields by overcoming the limitations of conventional machining technologies.

Implementation Method 1

the polarization layer having polarization characteristics for the light

Methodology Applied

Scientific EffectPolarization: Polarisation

Implementation Method 2

Prism-type polarizers use the birefringence of optically transmissive crystals

Methodology Applied

Scientific EffectBirefringence: Birefringence

Implementation Method 3

the polarization layer is formed by block copolymer lithography in which a pattern of block copolymer microdomains is transferred to the polarization layer

Methodology Applied

Scientific EffectSelf-assembly: Self-Assembly

Data Source

PatentUS8687274B2Short-wavelength polarizing elements and the manufacture and use thereof

Publication Date: 2014.04.01 KK TOSHIBA

AI summary

While gold wire grids have been used to polarize infrared wavelengths for over a hundred years, they are not appropriate for shorter wavelengths due to their large period. With embodiments of the present invention, grids with periods a few tens of nanometers can be fabricated. Among other things, such grids can be used to polarize visible and even ultraviolet light. As a result, such wire grid polarizers have a wide variety of applications and uses, such as, e.g., in the fabrication of semiconductors, nanolithography, and more.