Displacement Talbot Lithography Large Pattern Printing

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Solution Overview

Problem

Existing methods for printing very large periodic patterns using Displacement Talbot lithography (DTL) and DTL-related techniques face challenges in achieving high uniformity and throughput due to the requirement for large, high-quality collimating optics and the complexity of scanning strategies, especially for patterns exceeding 300x300mm in size.

Innovation Solution

A method involving an elongated beam of monochromatic light with a range of angles of incidence, where the power per incremental distance falls to zero at the ends according to specific profiles, allowing for sub-exposures that overlap to achieve uniform exposure energy densities, enabling the printing of large periodic patterns with high uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If DTL is used to print very large periodic patterns (exceeding 300x300mm), then the pattern size is increased, but the uniformity and throughput deteriorate due to requirements for large high-quality collimating optics and complex scanning strategies

Engineering Contradiction:
Improvepattern sizeVSAvoiduniformity
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent divides the large periodic pattern into multiple smaller sub-patterns that can be printed separately using standard-sized optics. These sub-patterns are then overlapped and combined to form the complete large-scale pattern, thereby avoiding the need for large collimating optics while maintaining uniformity across the entire pattern area

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension to the printing process by sequentially printing different sub-patterns at different time points and then combining them. This allows the system to achieve large spatial coverage through time-multiplexed exposure rather than requiring all areas to be exposed simultaneously with a large beam

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

2Area of stationary object

If DTL is used to print very large periodic patterns (exceeding 300x300mm), then the pattern size is increased, but the throughput deteriorates due to complex scanning strategies

Engineering Contradiction:
Improvepattern sizeVSAvoidthroughput
Core Design Contradiction:
Area of stationary objectVSProductivity

Solution Approach 1:

The patent segments the large pattern printing task into multiple independent sub-pattern printing operations. Each sub-pattern can be printed using standard scanning strategies, and the segmentation allows for parallel processing or optimized sequential processing, thereby improving overall throughput compared to attempting to print the entire large pattern in a single complex scanning operation

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary planning and decomposition of the large pattern into sub-patterns before the actual printing process. This preliminary action allows for optimization of the scanning strategy for each sub-pattern individually, avoiding the need for complex real-time control during the printing process and thereby improving throughput

Inventive Principle:
Principle #10Preliminary action

3Manufacturing precision

If sub-exposures with overlapping regions are used to achieve uniform exposure energy densities, then the uniformity is improved, but the exposure time increases

Engineering Contradiction:
ImproveuniformityVSAvoidexposure time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies different exposure strategies to different regions of the pattern. In overlap regions where multiple sub-exposures converge, the exposure parameters are locally adjusted to ensure uniform energy density accumulation. In non-overlap regions, standard exposure parameters are used, thereby minimizing the total exposure time while maintaining uniformity where required

Inventive Principle:
Principle #3Local quality

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 allows for the efficient printing of large periodic patterns with high uniformity and short exposure times, suitable for high-throughput production processes, by ensuring uniformity across the overlap regions and accurate alignment of features.

Implementation Method 1

the mask pattern diffracts the incident light to form an intensity distribution at the substrate plane

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

a photosensitive layer is disposed at the substrate and the periodic pattern is printed into the photosensitive layer

Methodology Applied
Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentEP3781989B1Methods and systems for printing large periodic patterns by overlapping exposure fields
Publication Date: 2023.06.14 EULITHA
  • EP3781989B1 patent drawingFigure 1
  • EP3781989B1 patent drawingFigure 2~3
  • EP3781989B1 patent drawingFigure 4~5

AI summary

A method for printing a periodic pattern of linear features into a photosensitive layer which includes providing a mask bearing a pattern of linear features, arranging the substrate parallel to the mask, generating an elongated beam for illuminating the mask with a range of angles of incidence in a plane parallel to the linear features and with a uniform power per incremental distance along the length of the beam except at its ends where the power per incremental distance falls to zero according to first and second profiles over a fall-off distance, scanning said beam in first and second sub-exposures to print first and second parts of the desired pattern such that the first and second parts overlap by the fall-off distance, wherein the first and second profiles are selected so that their summation across the fall-off distance produces a uniform power per incremental distance.