Mass-Loaded Piezoelectric Resonator for Wafer-Level Frequency Tuning
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Solution Overview
Problem
Existing film bulk acoustic resonators require external element tuning, which leads to significant performance loss due to the inability to manufacture multiple resonators operating at different frequencies on a single wafer.
Innovation Solution
A method involving a device wafer with a piezoelectric layer, bottom and top electrodes, and mass loading layers, where the sacrificial layer is released to form a cavity, allowing the resonator to be tuned by controlling the ratio of the mass loading layers' areas, enabling multiple resonators with different frequencies to be manufactured on the same wafer without external element tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external element tuning is used to adjust the frequency of the film bulk acoustic resonator, then the resonator frequency can be tuned, but significant performance loss occurs
Solution Approach 1:
The resonator structure is segmented into multiple functional layers including mass loading layers that can be independently configured. By dividing the resonator into separable components with different mass loading configurations, multiple resonant frequencies can be achieved without external tuning elements, thus maintaining performance while enabling frequency adjustment.
Solution Approach 2:
The patent transitions from one-dimensional frequency adjustment (external element tuning) to two-dimensional frequency control by varying both the mass loading layer area and the cavity depth. This dimensional expansion allows frequency tuning through structural parameters rather than external elements, eliminating performance loss while maintaining adaptability.
2Productivity
If a single wafer is used to manufacture resonators, then manufacturing efficiency is improved, but only one resonant frequency can be produced per wafer
Solution Approach 1:
The resonator structure is designed with universal mass loading layers and cavity configurations that can be adjusted to produce different resonant frequencies. By making the mass loading layers and cavity dimensions variable parameters, a single wafer can manufacture multiple resonators with different frequencies, achieving both high productivity and frequency diversity.
Solution Approach 2:
The patent employs parameter changes in the mass loading layer area and cavity depth to achieve different resonant frequencies. By varying these structural parameters across different regions of the same wafer, multiple frequency resonators can be manufactured simultaneously, resolving the contradiction between manufacturing efficiency and frequency variety.
3Ease of manufacture
If the resonator frequency is determined by thickness only, then manufacturing is simplified, but multiple frequencies cannot be achieved on one wafer
Solution Approach 1:
The patent applies local quality by creating mass loading layers with different areas and densities at different locations on the resonator structure. This localized variation in mass distribution allows different regions to resonate at different frequencies while maintaining a unified manufacturing process, thus preserving ease of manufacture while expanding frequency capability.
Solution Approach 2:
The invention extends frequency control from the single dimension of thickness to multiple dimensions by incorporating mass loading layer area and cavity depth as additional frequency-determining parameters. This multi-dimensional approach maintains manufacturing simplicity through standardized layer deposition while enabling diverse frequency output.
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 avoids performance loss by allowing resonators with different resonant frequencies to be produced on the same wafer, ensuring good performance by eliminating the need for external tuning and expanding the tunable frequency range.
Implementation Method 1
a piezoelectric layer, a bottom electrode and a top electrode are arranged on the supporting layer in sequence
Implementation Method 2
A first mass loading layer is formed on a side surface of the bottom electrode close to the cavity, and a second mass loading layer is formed on a side surface of the top electrode facing away from the cavity; and the first mass loading layer, the second mass loading layer, and the cavity are all located in an effective working region of the resonator. The resonator is correspondingly tuned by controlling a ratio of an area of the first mass loading layer in an effective working region of the resonator to an area of the second mass loading layer in an effective working region of the resonator
Implementation Method 3
releasing the sacrificial layer to form a cavity between the first mass loading layer and the supporting layer, wherein the first mass loading layer, the second mass loading layer, and the cavity are all located in an effective working region of the resonator
Data Source
AI summary
The present application provides a resonator and a method of preparing same, and relates to the field of semiconductor technologies. The method includes: providing a device wafer, wherein the device wafer includes a first substrate and a piezoelectric layer, a bottom electrode, and a first mass loading layer formed in sequence on the first substrate; forming, on the bottom electrode, a sacrificial layer covering the first mass loading layer; forming a supporting layer on one side of the device wafer with the sacrificial layer; forming a second substrate on the supporting layer through a bonding process; removing the first substrate to expose the piezoelectric layer; forming a top electrode and a second mass loading layer in sequence on the piezoelectric layer; and releasing the sacrificial layer to form a cavity between the first mass loading layer and the supporting layer. Therefore, the resonator is correspondingly tuned by controlling a ratio of an area of the first mass loading layer in an effective working region of the resonator to an area of the second mass loading layer in the effective working region of the resonator, thereby manufacturing resonators with different resonant frequencies, effectively avoiding loss caused by tuning with an external element, and ensuring good performance of the resonator.