Organic Reactants for Selective Metal Oxide ALD
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Solution Overview
Problem
The use of water as a reactant in atomic layer deposition (ALD) processes at low temperatures leads to undesirable sticking to surfaces, making purging inefficient and potentially oxidizing substrates, which complicates selective deposition schemes.
Innovation Solution
Employing organic reactants such as formic acid or other carboxylic acids that are non-polar and thermally stable, allowing for selective formation of metal oxide layers through cyclic processes like ALD or sequential CVD, with controlled purging to avoid surface oxidation and enhance selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water is used as a reactant in ALD processes at low temperatures, then oxide formation is achieved, but purging efficiency deteriorates due to water sticking to surfaces
Solution Approach 1:
The patent changes the chemical parameters of the reactant from water to organic carboxylic acids (formic acid, acetic acid, propanoic acid). This parameter change fundamentally alters the molecular properties - organic acids are non-polar and less adhesive to hydrophilic surfaces compared to polar water molecules, enabling efficient purging even at low temperatures while maintaining oxide formation capability
Solution Approach 2:
The patent employs volatile organic carboxylic acids that can be easily removed through purging. These reactants are designed to be temporarily present during deposition but completely removable afterward, leaving no residual sticking effects that would compromise subsequent process cycles or selectivity
2Stability of the object's composition
If water is used as a reactant, then oxide formation is achieved, but selectivity deteriorates due to surface oxidation
Solution Approach 1:
The patent changes the chemical reactivity parameters by substituting water with organic carboxylic acids. These organic reactants exhibit different surface interaction characteristics - they form metal oxides on dielectric surfaces while being less prone to oxidize metal surfaces, thereby achieving selective deposition based on substrate material type
Solution Approach 2:
The patent achieves different reaction outcomes on different surface types (dielectric vs. metal) using the same organic reactant. The reactant displays locally adapted behavior - reacting with dielectric surfaces to form oxides while leaving metal surfaces in their elemental state, enabling spatial and material-selective deposition
3Manufacturing precision
If water-based processes are applied for selective deposition, then oxide formation is achieved, but process complexity increases due to purging difficulties
Solution Approach 1:
The patent simplifies the purging process by changing from water to volatile organic carboxylic acids. The organic reactants have favorable vapor pressure and volatility characteristics that enable complete removal through simple gas flow purging, eliminating the need for complex heating, vacuum, or extended purge sequences required for water-based processes
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 efficient purging and selective deposition of metal oxide films, maintaining the elemental state of metal surfaces and achieving high selectivity, even at temperatures where water-based processes are problematic, by reducing oxidized copper to its elemental state and preventing unwanted surface reactions.
Implementation Method 1
exposing the substrate to an organic reactant; and exposing the substrate to a purging gas and/or the vacuum; wherein a reaction between the metal or semi-metal precursor and the organic reactant selectively forms a metal oxide layer
Implementation Method 2
exposing the substrate to a purging gas and/or a vacuum
Data Source
AI summary
A method for selectively depositing a metal oxide film is disclosed. In particular, the method comprises pulsing a metal or semi-metal precursor onto the substrate and pulsing an organic reactant onto the substrate. A reaction between the metal or semi-metal precursor and the organic reactant selectively forms a metal oxide film on either a dielectric layer or a metal layer.