Nanostructure Deposition via Evaporative Droplet Alignment

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Solution Overview

Problem

Current methods for depositing and orienting elongated nanostructures, such as nanowires, in electronic devices are inefficient, leading to random orientation and significant material waste, making the production of large-area devices like displays prohibitively expensive due to excessive material usage and complexity in achieving arbitrary patterns with good registration.

Innovation Solution

A method involving the controlled deposition and evaporation of fluid droplets containing nanostructures on a substrate with controlled surface treatments to align and orient nanostructures, utilizing printheads and surface chemistry to achieve precise alignment and orientation, either at the droplet center or edge, minimizing material waste and enabling cost-effective production of high-performance electronic devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If spin coating or microfluidic channels are used to deposit nanostructures, then coverage and orientation control are achieved, but substantial nanostructure material is wasted

Engineering Contradiction:
Improvenanostructure orientation controlVSAvoidnanostructure material waste
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The substrate is pre-patterned with hydrophobic regions and hydrophilic channels before nanostructure deposition. This preliminary surface preparation creates predetermined pathways that guide nanostructure orientation during droplet evaporation, ensuring material is deposited only where needed with correct orientation, thereby minimizing waste

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Surface chemistry (hydrophobic/hydrophilic patterns) acts as an intermediary between the deposited droplet and the substrate. This chemical mediator directs the flow and evaporation of the droplet containing nanostructures, controlling their final position and orientation without requiring excessive material

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If microfluidic channels are used to control nanowire orientation, then some level of patterning is achieved, but device fabrication complexity substantially increases

Engineering Contradiction:
Improvenanowire orientationVSAvoidfabrication complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The complex three-dimensional microfluidic channel structure is extracted and replaced with a simple two-dimensional surface pattern on the substrate. This extraction eliminates the need for building complex 3D fluidic systems while retaining the orientation control function through hydrophobic/hydrophilic surface chemistry

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The mechanical microfluidic channel structure is replaced with a chemical surface pattern system. Instead of using physical channels to guide flow, the invention uses hydrophobic/hydrophilic surface chemistry to direct droplet evaporation and nanostructure deposition, simplifying the fabrication process

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

3Manufacturing precision

If arbitrary patterns with good registration are achieved using microfluidic channels, then nanowire positioning is improved, but the system complexity and material usage increase

Engineering Contradiction:
Improvenanowire pattern registrationVSAvoidsystem complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The substrate surface is divided into regions with different local properties (hydrophobic regions versus hydrophilic channels). This local differentiation allows precise control of droplet evaporation and nanostructure deposition in specific areas, achieving arbitrary patterns with good registration while using a simple overall system architecture

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 method allows for precise control over the orientation and deposition of nanostructures, reducing material waste and increasing the efficiency of device fabrication, enabling the cost-effective production of high-performance electronic devices with improved pattern registration and reduced complexity.

Implementation Method 1

A method involving the controlled deposition and evaporation of fluid droplets containing nanostructures on a substrate with controlled surface treatments to align and orient nanostructures

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

A method involving the controlled deposition and evaporation of fluid droplets containing nanostructures on a substrate with controlled surface treatments to align and orient nanostructures

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP1936711B1Method of forming a transistor
Publication Date: 2016.07.13 PALO ALTO RESEARCH CENTER INC
  • EP1936711B1 patent drawingFigure 1~3
  • EP1936711B1 patent drawingFigure 4~5
  • EP1936711B1 patent drawingFigure 6~9

AI summary

A method of depositing elongated nanostructures that allows accurate positioning and orientation is described. The method involves printing or otherwise depositing elongated nanostructures in a carrier solution. The deposited droplets are also elongated, usually by patterning the surface upon which the droplets are deposited. As the droplet evaporates, the fluid flow within the droplets is controlled such that the nanostructures are deposited either at the edge of the elongated droplet or the center of the elongated droplet. The described deposition technique has particular application in forming the active region of a transistor.