Wafer-Level SAW Filter Package for Size and Temperature Stability
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Solution Overview
Problem
Current surface acoustic wave filters face challenges in achieving smaller size and higher temperature stability, particularly with the increasing complexity of RF front-end components in 5G technologies, where traditional packaging methods are difficult to process and fail to meet stringent size and stability requirements.
Innovation Solution
A wafer-level surface acoustic wave filter design that combines a substrate layer and a piezoelectric thin film layer via wafer bonding, with a cover plate using the same material as the substrate, forming a sealed cavity to enhance temperature stability and reduce size, and incorporating a supporting wall and electrode layers for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional packaging methods are used for surface acoustic wave filters, then the manufacturing process is simpler, but the package size is larger and temperature stability is poor
Solution Approach 1:
The patent merges the filter structure with the package structure by forming the filter directly on the package substrate. The package substrate serves dual functions as both the packaging platform and the filter resonator substrate, eliminating the need for separate filter and package structures. This integration achieves both small package size and improved temperature stability through the substrate's inherent acoustic wave propagation characteristics
Solution Approach 2:
The patent employs composite material structures including piezoelectric thin film layers bonded to substrate layers with specific acoustic impedance matching. The use of composite materials with tailored thermal and acoustic properties enables the filter to achieve high temperature stability while maintaining a compact form factor suitable for modern RF applications
2Reliability
If the piezoelectric thin film layer thickness is increased, then the filter performance is improved, but the temperature stability deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the piezoelectric thin film layer to a specific range that balances filter performance and temperature stability. By precisely controlling the film thickness and selecting appropriate material compositions, the filter achieves high Q-factor and selectivity while the substrate's thermal characteristics compensate for temperature variations, maintaining stable operation across temperature ranges
3Reliability
If wafer bonding is used to combine substrate layer and piezoelectric thin film layer, then temperature stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs wafer bonding between the substrate layer and piezoelectric thin film layer during the wafer fabrication stage before dicing into individual devices. This preliminary bonding action creates a thermally and mechanically stable integrated structure that maintains temperature stability throughout subsequent packaging and assembly processes, while the bonding is executed using established semiconductor manufacturing techniques
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
The wafer-level package effectively reduces the size of the surface acoustic wave filter, enhances temperature stability, and improves reliability by minimizing the influence of temperature changes on the filter's performance, making it suitable for high-integration RF front-end modules.
Implementation Method 1
the wafer includes a substrate layer and a piezoelectric thin film layer, and the substrate layer and the piezoelectric thin film layer are combined together by wafer bonding therebetween. The electrode layer is arranged on a surface of the piezoelectric thin film layer
Implementation Method 2
the supporting wall is located between the piezoelectric thin film layer and the cover plate, and the supporting wall surrounds between the piezoelectric thin film layer and the cover plate to form a sealed cavity
Implementation Method 3
the substrate layer and the piezoelectric thin film layer are combined together by wafer bonding therebetween
Data Source
AI summary
Embodiments of the present application provide a wafer level surface acoustic wave filter and a package method, the surface acoustic wave filter includes a wafer, an electrode layer, a supporting wall and a cover plate; wherein, the wafer includes a substrate layer and a piezoelectric thin film layer combined together by wafer bonding, the electrode layer is arranged on a surface of the piezoelectric thin film layer, the supporting wall surrounds between the piezoelectric thin film layer and the cover plate to form a sealed cavity; and the cover plate includes at least a first material layer, which uses the same material as the substrate layer.