Super-Resolution Photoetching via Evanescent Wave Conversion

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Solution Overview

Problem

Conventional near-field optical photolithography and super lens imaging technologies face challenges in achieving contactless super-resolution imaging due to rapid decay of evanescent waves in gap spaces, leading to reduced imaging resolution and contrast, and potential damage to high-precision mask structures.

Innovation Solution

The implementation of high numerical aperture (NA) off-axis illumination and surface plasmon (SP) wave illumination modes, combined with accessory structures, to convert high-frequency evanescent wave components into low-frequency components, allowing for effective imaging through a larger gap without physical contact between the mask and substrate, thereby enhancing imaging contrast and resolving power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If contacting mode is used to achieve super-resolution imaging, then imaging resolution is improved, but mask damage increases

Engineering Contradiction:
Improveimaging resolutionVSAvoidmask damage
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an evanescent wave field as an intermediary to transfer pattern information from mask to substrate without direct physical contact. The evanescent waves carry sub-wavelength spatial frequency information through the gap space, enabling super-resolution imaging while preventing mask abrasion and damage that would occur in contacting modes.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical contacting system with an optical field-based system. Instead of relying on physical contact between mask and substrate, the invention uses evanescent wave coupling to transfer pattern information, substituting mechanical interaction with electromagnetic field interaction to eliminate wear and damage.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Duration of action of stationary object

If air distance between mask and substrate is increased to prevent contact, then mask lifecycle is extended, but imaging resolution deteriorates

Engineering Contradiction:
Improvemask lifecycleVSAvoidimaging resolution
Core Design Contradiction:
Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The patent changes the working parameters of the optical system by operating in the evanescent wave regime rather than far-field optical regime. By utilizing the exponential decay characteristics of evanescent waves and matching the gap distance to the decay length, the system achieves super-resolution imaging at larger separations (tens of nanometers to micrometers) compared to conventional near-field techniques.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from near-field imaging (where resolution is limited by extremely small gap distances) to a regime where the gap dimension is effectively decoupled from resolution limits. By using evanescent waves that can propagate through larger gaps and by employing techniques like aperture coupling and phase matching, the invention extends the useful imaging distance into a new dimensional regime.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Device complexity

If conventional optical photolithography is used, then device complexity is reduced, but resolution is limited to quarter wavelength

Engineering Contradiction:
Improvesystem simplicityVSAvoidline width resolution
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent exploits the phase transition from propagating waves to evanescent waves by controlling the gap distance and optical coupling conditions. In the evanescent wave regime, spatial frequency components beyond the diffraction limit can be sustained and transferred, enabling resolution beyond the conventional quarter-wavelength limit while maintaining relative system simplicity.

Inventive Principle:
Principle #36Phase transitions

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 approach enables contactless super-resolution imaging photolithography with improved resolution and contrast, extending the lifecycle of mask structures and reducing abrasion, while maintaining high imaging quality even at larger air distances between the mask and substrate.

Implementation Method 1

surface plasmon (SP) wave illumination mode

Methodology Applied
Scientific EffectSurface plasmon (SP) wave:

Implementation Method 2

a high-frequency evanescent wave component of spatial spectrum information for the light is converted to a low-frequency evanescent wave component after being transmitted through the mask pattern

Methodology Applied
Scientific EffectEvanescent wave:

Data Source

PatentEP3051351B1Super-resolution image photoetching
Publication Date: 2019.06.12 INST OF OPTICS & ELECTRONICS CHINESE ACAD OF SCI
  • EP3051351B1 patent drawingFigure 1
  • EP3051351B1 patent drawingFigure 2
  • EP3051351B1 patent drawingFigure 3(a)~3(b)

AI summary

Provided are apparatuses and methods for super resolution imaging photolithography. An exemplary apparatus may includean illumination light generation device configured to generate illumination light for imaging a pattern included in a mask through the mask. The illumination light may include a high-frequency spatial spectrum such that a high-frequency evanescent wave component of spatial spectrum information for the light is converted to a low-frequency evanescent wave component after being transmitted through the mask pattern. For example, the illumination light generation device may be configured to form the illumination in accordance with a high numerical aperture (NA) illumination mode and/or a surface plasmon (SP)wave illumination mode.