Thick Crystalline AlN Layer Formation via MX2 Bond Conversion
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Solution Overview
Problem
Existing methods for forming thick crystalline aluminium nitride (AlN) layers result in poor crystalline quality and delamination issues, particularly when manufacturing components like acoustic filters.
Innovation Solution
A method involving a substrate with a dichalcogenide surface film bonded by van der Waals bonds, followed by a polycrystalline AlN film with grain boundaries, and diffusing metal elements to convert van der Waals bonds into covalent bonds through a redox reaction, facilitating the formation of a thick crystalline layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thick aluminium nitride AlN crystalline layer (greater than 200 nm) is formed directly on a dielectric layer, then the layer thickness is sufficient for acoustic filter manufacture, but the crystalline quality is poor and delamination occurs
Solution Approach 1:
The patent introduces a surface film made of a dichalcogenide of a transition metal (MX2) as an intermediary layer between the dielectric layer and the aluminium nitride crystalline layer. This intermediate layer acts as a nucleation layer that improves the interface adhesion and reduces delamination, while also improving the crystalline quality of the AlN layer by providing a suitable template for crystal growth.
Solution Approach 2:
The patent segments the interface structure into multiple distinct layers: a dielectric layer, a surface film layer (MX2), and an aluminium nitride crystalline layer. This segmentation allows each layer to perform its specific function optimally - the dielectric layer provides electrical isolation, the surface film provides nucleation and adhesion, and the AlN layer provides the desired piezoelectric or acoustic properties.
2Manufacturing precision
If a surface film made of a dichalcogenide of a transition metal (MX2) is inserted between the dielectric layer and the aluminium nitride AlN crystalline layer, then the crystalline quality is improved, but the interface bonding strength is insufficient for thick layers
Solution Approach 1:
The patent changes the bonding parameter of the surface film by introducing metal elements that react with the MX2 to convert the van der Waals bonds into covalent bonds. This parameter change (from weak van der Waals bonding to strong covalent bonding) significantly enhances the interface bonding strength while preserving the crystalline quality improvement provided by the MX2 layer.
3Strength
If metal elements are diffused into the surface film through grain boundaries to convert van der Waals bonds into covalent bonds, then the interface bonding strength is improved, but the process complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where metal elements are introduced onto the surface and automatically diffuse into the MX2 layer through the grain boundaries of the polycrystalline AlN film. The grain boundaries act as natural diffusion pathways, eliminating the need for complex external diffusion equipment or processes. The system uses its own structural features (grain boundaries) to facilitate the bonding enhancement.
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 reduces delamination risks and enhances crystalline quality, allowing for the production of thick AlN layers suitable for components such as acoustic filters.
Implementation Method 1
diffusing metal elements into the surface film, through the grain boundaries of the polycrystalline aluminium nitride AlN film
Implementation Method 2
the metal elements being chosen to react chemically with MX2 by a redox reaction so as to convert the van der Waals bonds into covalent bonds
Implementation Method 3
the surface film comprising a set of monolayers bonded together by van der Waals bonds
Data Source
AI summary
A method for manufacturing a crystal layer includes using a substrate having a surface film made of a dichalcogenide of a transition metal, designated MX2, where “M” denotes a transition metal and “X” denotes a chalcogen, the surface film including a set of monolayers bonded together by van der Waals bonds; forming a polycrystalline aluminium nitride AlN film, having grain boundaries, on the surface film; and diffusing metal elements into the surface film, through the grain boundaries of the polycrystalline aluminium nitride AlN film, the metal elements being chosen to react chemically with MX2 by a redox reaction so as to convert the van der Waals bonds into covalent bonds, A crystalline layer is formed on the polycrystalline aluminium nitride AlN film after the diffusing.