ScAlN CVD Films With Nucleation Layers for Low-Segregation Growth
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Solution Overview
Problem
Existing methods for forming ScxAl1-xN films for piezoelectric layers in electronic devices face challenges in achieving uniform wurtzite crystal structure and low temperature processing without segregation, while maintaining low impurity and oxygen concentrations.
Innovation Solution
The method involves using Chemical Vapor Deposition (CVD) at temperatures between 750°C and 950°C with specific metalorganic precursors containing cyclopentadienyl and amidinate ligands, controlling the precursor ratios, and employing a nucleation layer to form ScxAl1-xN films with improved morphology and low carbon content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional CVD methods are used to form ScxAl1-xN films, then high temperature processing is achieved, but segregation occurs and uniform wurtzite crystal structure cannot be maintained
Solution Approach 1:
The patent applies parameter changes by optimizing the CVD processing temperature to a specific range (700-950°C) and controlling precursor flow rates and ratios. These parameter adjustments enable the formation of uniform ScxAl1-xN films with wurtzite crystal structure while preventing segregation that occurs at higher temperatures.
Solution Approach 2:
The patent uses composite metalorganic precursors containing both aluminum and scandium elements along with specific ligands (amido, alkyl, aryl groups). This composite precursor approach allows simultaneous deposition of multiple elements in controlled ratios, achieving uniform composition without segregation.
2Stability of the object's composition
If low temperature CVD is used to prevent segregation, then uniform composition is achieved, but impurity and oxygen concentrations increase
Solution Approach 1:
The patent optimizes multiple parameters including temperature (700-950°C), precursor flow rates, and pressure conditions to achieve the right balance. These parameter changes enable low-temperature processing that prevents segregation while maintaining low impurity and oxygen concentrations through enhanced precursor reactivity and surface kinetics.
Solution Approach 2:
The patent employs specific metalorganic precursors with amido, alkyl, and aryl ligands as intermediaries that facilitate controlled decomposition and reaction at lower temperatures. These intermediary compounds enable precise compositional control while minimizing unwanted side reactions that would introduce impurities.
3Manufacturing precision
If metalorganic precursors with amido, alkyl, and aryl ligands are used, then uniform wurtzite crystal structure is formed, but process complexity increases
Solution Approach 1:
The patent uses composite metalorganic precursors that combine multiple ligand types (amido, alkyl, aryl) with aluminum and scandium centers. These composite molecules provide controlled decomposition pathways that yield uniform wurtzite crystal structures while the complexity is managed through systematic synthesis approaches.
Solution Approach 2:
The patent applies local quality by using different ligand types at specific positions around the metal center in the precursor molecules. This local differentiation of ligand properties (amido for nitrogen donation, alkyl/aryl for steric control) enables precise control of crystal structure formation while keeping the overall process manageable.
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 results in ScxAl1-xN films with a uniform wurtzite crystal structure, reduced segregation, and low impurity concentrations, suitable for use as piezoelectric layers in devices such as Bulk Acoustic Wave resonators and High Electron Mobility Transistors, enhancing their performance and reliability.
Implementation Method 1
heating a CVD reactor chamber containing a substrate to a temperature range between about 750 degrees Centigrade and about 950 degrees Centigrade, providing a first precursor comprising Al to the CVD reactor chamber in the temperature range, providing a second precursor comprising Sc to the CVD reactor chamber in the temperature range, providing a third precursor comprising nitrogen to the CVD reactor chamber in the temperature range, and forming the film comprising ScxAl1-xN on the substrate
Data Source
AI summary
A method of forming a film can include heating a CVD reactor chamber containing a substrate to a temperature range between about 750 degrees Centigrade and about 950 degrees Centigrade, providing a first precursor comprising Al to the CVD reactor chamber in the temperature range, providing a second precursor comprising Sc to the CVD reactor chamber in the temperature range, providing a third precursor comprising nitrogen to the CVD reactor chamber in the temperature range, and forming the film comprising ScAlN on the substrate.