Redox Atomic Layer Deposition Using Aqueous Solutions
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Solution Overview
Problem
Current Atomic Layer Deposition (ALD) techniques face limitations, including the need for expensive and unstable gas-phase precursors, restricted applicability to conductive substrates, and requirement for sophisticated equipment and anhydrous conditions, which hinder efficient and scalable deposition of inorganic films.
Innovation Solution
A liquid-phase ALD method using aqueous solutions with organic compounds and inorganic ions or ion complexes, where each cycle involves adsorption of an organic compound followed by oxidation with an inorganic ion complex, allowing for self-limiting deposition of inorganic materials like metal or metal oxides without the need for vacuum equipment or electrical potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas-phase ALD is used, then deposition precision is improved, but equipment complexity and cost increase
Solution Approach 1:
The patent changes the phase parameter of precursors from gas to liquid, enabling ALD deposition without vacuum equipment. Liquid precursors are delivered through simple pumping systems, dramatically reducing device complexity while maintaining monolayer-level deposition precision through the self-limited surface reaction mechanism
Solution Approach 2:
The patent replaces the complex vacuum mechanical system with a liquid delivery system using simple pumps and flow controllers. The liquid-phase precursors are delivered through capillary action or pressure-driven flow, eliminating the need for vacuum chambers, throttle valves, and complex pumping systems while preserving ALD precision
2Adaptability or versatility
If electrochemical ALD is used, then substrate applicability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes the electrochemical power supply system (potentiostat, reference electrode, counter electrode) from the ALD process. Instead of using electrochemical reduction, the invention employs simple liquid-phase chemical reduction with stoichiometric control, eliminating complex electrical hardware while maintaining broad substrate compatibility including dielectrics and semiconductors
Solution Approach 2:
The patent implements self-limited surface reactions where the substrate surface itself controls the reaction extent. The liquid-phase precursors react autonomously with surface sites until saturation, providing self-regulating deposition without external electrical control. This self-service mechanism simplifies the device while enabling deposition on diverse substrates
3Stability of the object's composition
If anhydrous conditions are used, then deposition stability is improved, but process complexity increases
Solution Approach 1:
The patent changes the solvent parameter from anhydrous organic solvents to aqueous solutions. This parameter change eliminates the need for moisture-exclusion equipment (glove boxes, molecular sieves, dried gas systems) while maintaining stable deposition. The aqueous precursors are designed with hydrolysis resistance or controlled hydrolysis, providing stable monolayer formation in ambient conditions
4Ease of operation
If liquid-phase ALD is used, then ease of operation is improved, but growth rate decreases
Solution Approach 1:
The patent employs periodic pulsed delivery of liquid precursors to maintain high surface concentration during each pulse, maximizing reaction rate. The cyclic immersion and withdrawal of the substrate, combined with pulsed precursor flow, creates periodic high-rate deposition events that increase overall growth rate while maintaining the simplicity of liquid-phase operation
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 enables stable, scalable, and conformal deposition of inorganic films at ambient conditions, with growth rates close to one monolayer per cycle, suitable for a variety of substrates, and eliminates the risks of air-induced ignition and organic solvent use, offering precise thickness control and environmental benefits.
Implementation Method 1
contacting the substrate surface with a first aqueous liquid solution comprising an organic compound having a functional group permitting its adsorption on the substrate
Implementation Method 2
contacting the substrate surface having the organic compound adsorbed thereon with a second liquid aqueous solution comprising an inorganic ion or an ion complex suitable for oxidizing the organic compound
Implementation Method 3
The redox replacement is possible thanks to the sufficiently high difference between the reduction potential of zinc and copper
Implementation Method 4
having an insoluble reduction product which is the inorganic material
Data Source
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AI summary
Method to deposit a layer of inorganic material on a substrate surface, comprising one or more cycles, each cycle comprising the steps of: a) contacting the substrate surface with a first aqueous liquid solution comprising an organic compound having a functional group permitting its adsorption on the substrate, followed by b) contacting the substrate surface having the organic compound adsorbed thereon with a second liquid aqueous solution comprising an inorganic ion or an ion complex suitable for oxidizing the organic compound and having an insoluble reduction product which is the inorganic material.