Capillary Self-Assembly for Sub-100nm Micro-Pipe Fabrication

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Solution Overview

Problem

Conventional methods for producing micro-pipes are unsuitable for trenches with widths less than 100 nm and are limited in producing micro-pipes with small cross-sectional dimensions, which are necessary for various industrial applications, including semiconductor manufacturing and fluid control.

Innovation Solution

A method involving the formation of elongated cavities on a substrate by creating a pair of features with a specific gap width, allowing them to stick together when contacted with a liquid that forms a contact angle of less than 90° with the material, enabling the creation of micro-pipes with cross-sectional dimensions less than 100 nm, suitable for semiconductor and biotechnological applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional filling methods are used to form micro-pipes in trenches, then micro-pipes can be produced in larger trenches, but the method is unsuitable for trenches with width less than 100 nm due to limited filling characteristics

Engineering Contradiction:
Improvemicro-pipe dimensional controlVSAvoidmanufacturing feasibility
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces conventional mechanical filling methods with a capillary action-based self-assembly process. By controlling the contact angle between liquid precursor material and trench walls to be less than 90 degrees, the liquid automatically wets and fills narrow trenches through capillary forces, eliminating the need for external filling mechanisms and enabling precise formation of micro-pipes with widths below 100 nm.

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

Solution Approach 2:

The patent changes the physical-chemical parameters of the filling process by controlling the contact angle of the liquid precursor material. By selecting materials and processing conditions that achieve a contact angle less than 90 degrees, the system transitions from incomplete filling in narrow trenches to complete self-filled micro-pipes, resolving the contradiction between trench width and filling effectiveness.

Inventive Principle:
Principle #35Parameter changes

2Volume of moving object

If photoresist layer thickness is increased to 1 um to 100 um for ionizing radiation method, then large micro-pipes can be produced, but the method is not suited for small cross-section micro-pipes less than 100 nm

Engineering Contradiction:
Improvemicro-pipe sizeVSAvoidcross-sectional dimension control
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent replaces ionizing radiation deformation methods with capillary-driven self-assembly. Instead of using thick photoresist layers (1-100 um) that require complex radiation processing, the system uses thin liquid precursor layers that automatically form micro-pipes through capillary action, achieving precise cross-sectional dimensions below 100 nm without the need for thick material layers or radiation equipment.

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

3Shape

If trench height is made larger than width for conventional micro-pipe formation, then micro-pipes can be formed by lining and covering the trench, but the method cannot produce micro-pipes with width less than 100 nm

Engineering Contradiction:
Improvetrench geometryVSAvoidmicro-pipe width control
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional approach by not trying to fill trenches from the bottom up with solid materials. Instead, it introduces a liquid precursor material that flows into the trench and forms micro-pipes through capillary action during drying. This inversion of the filling mechanism allows precise control of micro-pipe width regardless of trench dimensions, overcoming the limitation of conventional lining methods.

Inventive Principle:
Principle #13The other way round (Inversion)

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 method allows for the production of micro-pipes with precise control over dimensions and spacing, enabling their use in semiconductor fabrication, fluid control, and filtering applications, improving efficiency and throughput in industries requiring small-scale fluid management.

Implementation Method 1

The liquid is suitable for making a contact angle of less than 90° with the material of the elongated sidewalls

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 2

Subsequent to the rinsing, the substrate and the first pair of features are dried

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3281910B1Method of forming micro-pipes on a substrate and a structure formed therewith
Publication Date: 2019.10.02 INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW)
  • EP3281910B1 patent drawingFigure 1~2(f)
  • EP3281910B1 patent drawingFigure 3~4
  • EP3281910B1 patent drawingFigure 5(a)~6

AI summary

A method for producing a structure comprising, on a main surface of a substrate, at least one elongated cavity having openings at opposing ends. The method comprises providing a substrate having a main surface. On the main surface, a first pair of features are formed that protrude perpendicularly from the main surface. The features have elongated sidewalls and a top surface, are parallel to one another, are separated by a gap having a width sl and a bottom area, and have a width wl and a height h1. A ratio of h1/w1 is in the range of 3 to 30 and wherein the separation gap sl is less than twice the height of h1. At least the main surface of the substrate and the first pair of features are brought in contact with a liquid, suitable for making a contact angle of less than 90° with the material of the elongated sidewalls and subsequently, the substrate is dried.