RF Filter Thin-Film Cavity Sealing With Low-Cost Supporting Electrodes
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Solution Overview
Problem
The existing methods for preparing radio frequency filters are lengthy and costly, requiring complex processes and expensive materials like gold, which hinders large-scale application and market competitiveness.
Innovation Solution
A method involving the formation of a resonant structure on a substrate, followed by the creation of a supporting electrode and a thin film structure spaced by the supporting electrode, using materials like copper and titanium for cost reduction and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional protective substrate methods (silicon, glass, ceramic, metal housing) are used with wafer level bonding and welding, then the filter is isolated and protected from external moisture and particles, but the preparation process becomes lengthy and complex with multiple complicated processes
Solution Approach 1:
The patent extracts the protective cavity formation from the complex conventional process by directly utilizing the resonant structure cavity. Instead of creating a separate protective substrate with multiple bonding and welding steps, the invention uses the existing resonant structure cavity as the protective cavity, eliminating the need for separate protective substrate preparation and simplifying the overall process while maintaining protection from moisture and particles.
Solution Approach 2:
The patent merges the protective cavity function with the resonant structure by forming the supporting electrode on the resonant structure and using the resonant structure's cavity as the protective cavity. This consolidation eliminates the need for separate protective substrates and reduces the number of process steps while maintaining the protective function against external moisture and particles.
2Reliability
If conventional protective substrate methods with through hole electrode processing, deep hole electrode filling, and wafer bonding are used, then the filter is protected, but the preparation cost becomes expensive
Solution Approach 1:
The patent extracts the protective cavity formation from the expensive conventional process by directly utilizing the resonant structure cavity. Instead of creating a separate protective substrate requiring through hole electrode processing, deep hole electrode filling, and wafer bonding, the invention uses the existing resonant structure cavity, eliminating costly materials and processes while maintaining protection.
Solution Approach 2:
The patent replaces expensive conventional protective substrates (silicon, glass, ceramic, metal housing) with a simpler supporting electrode structure formed on the resonant structure. This substitution uses less expensive materials and processes while achieving the same protective function, significantly reducing preparation cost.
3Reliability
If gold is used as wafer bonding and electrode material, then the filter is protected and electrodes are formed, but the preparation cost increases significantly
Solution Approach 1:
The patent replaces expensive gold materials with less expensive alternatives for the supporting electrode and sealing structure. By forming the supporting electrode directly on the resonant structure and using cost-effective sealing methods, the invention maintains reliable bonding and electrode formation while significantly reducing material costs.
Solution Approach 2:
The patent changes the material parameters from expensive gold to more cost-effective materials for the supporting electrode and sealing structures. This substitution maintains the functional requirements for bonding and electrode formation while reducing the overall preparation cost of the filter.
4Reliability
If expensive wafer bonding and physical vapor deposition apparatus with lateral deposition capability are used, then the protective cavity is formed, but the preparation cost of a single BAW device becomes expensive
Solution Approach 1:
The patent extracts the protective cavity formation from the expensive wafer bonding and physical vapor deposition processes by directly utilizing the resonant structure cavity. This approach eliminates the need for costly specialized apparatus and reduces the preparation cost per device while maintaining reliable protective cavity formation.
Solution Approach 2:
The patent replaces expensive wafer bonding and physical vapor deposition processes with simpler, more cost-effective methods for forming the protective cavity. By using the resonant structure cavity directly and forming the supporting electrode through less expensive processes, the invention significantly reduces the preparation cost per BAW device.
Data Source
AI summary
The present disclosure provides a method of preparing a radio frequency filter, including: a substrate; a supporting electrode protruded on a front surface of the substrate; and a thin film structure formed on the substrate and spaced with the substrate by the supporting electrode. An end surface of a top end of the supporting electrode is in sealing contact with a front surface of the thin film structure.