Bulk-Mode Resonator Cavity Filling for Frequency Stabilization
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Solution Overview
Problem
Bulk mode resonators face uncontrollable variations in resonance frequency, making it difficult to achieve desired nominal frequencies, especially in high-frequency applications like portable devices, due to manufacturing method fluctuations and complexity in existing correction methods.
Innovation Solution
Introducing a method to manufacture bulk mode resonators by deliberately decreasing the mass and dimensions of the resonant element, measuring the frequency, and compensating for any differences by filling open cavities with materials like silicon or metal oxides to achieve a desired frequency accuracy of better than 0.01 to 1%. This involves forming open cavities in the resonant element and partially filling them with materials that can adjust the mass and Young's modulus to stabilize the frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bulk mode resonators are manufactured using conventional methods, then manufacturing simplicity is maintained, but resonance frequency accuracy deteriorates with uncontrollable variations of 5 to 10%
Solution Approach 1:
The patent applies preliminary action by intentionally creating cavities in the resonant element before final assembly. These cavities are pre-positioned to allow subsequent mass adjustment through filling operations. The cavities are formed at defined locations that enable precise control over the resonant frequency without requiring complex real-time adjustments during manufacturing.
Solution Approach 2:
The patent implements parameter changes by modifying the mass of the resonant element through selective filling of cavities with materials having different densities. By controlling the amount and type of filling material, the resonant frequency can be precisely tuned within a wide range while maintaining manufacturing simplicity. This allows frequency adjustment from 5-10% deviation down to better than 0.01% accuracy.
2Manufacturing precision
If frequency correction is performed by modifying bias voltage, then frequency adjustment is achieved, but power consumption increases unrealistically for battery-powered devices
Solution Approach 1:
The patent replaces the electrical correction method (modifying bias voltage) with a mechanical correction method (adjusting mass through cavity filling). This substitution eliminates the need for continuous power consumption during frequency adjustment, as the mass modification is a one-time manufacturing process rather than an ongoing operational adjustment. The mechanical approach achieves frequency correction without the unrealistic bias levels required by electrical methods.
3Manufacturing precision
If frequency correction is performed by heating a filament, then frequency adjustment is achieved, but device power consumption increases which is undesirable in battery-powered devices
Solution Approach 1:
The patent substitutes the thermal correction method (heating filament) with a mechanical mass adjustment method. Instead of continuously heating a filament to change frequency, the invention uses cavity filling to permanently adjust the resonant frequency during manufacturing. This eliminates ongoing power consumption for frequency correction while maintaining the ability to achieve precise frequency targets in battery-powered portable devices.
4Manufacturing precision
If laser vaporization is used to decrease mass for frequency correction, then frequency accuracy is improved, but manufacturing complexity and cost increase due to dedicated equipment requirements
Solution Approach 1:
The patent applies the extraction principle by removing material in the form of cavities that are then selectively filled. Instead of using complex laser vaporization equipment to precisely remove material, the invention extracts material by creating cavities through standard semiconductor fabrication processes, then adds material back in controlled amounts through filling operations. This approach achieves frequency precision using conventional manufacturing equipment rather than specialized laser systems.
Solution Approach 2:
The patent implements parameter changes by controlling the mass of the resonant element through cavity filling rather than material removal. This allows frequency adjustment using standard deposition and filling processes that are already part of conventional semiconductor manufacturing, avoiding the need for expensive and complex laser vaporization equipment while achieving comparable or better frequency accuracy.
5Manufacturing precision
If ion bombarding is used to increase mass for frequency correction, then frequency accuracy is improved, but the process lacks flexibility as it must be performed before device packaging
Solution Approach 1:
The patent applies preliminary action by creating cavities in advance during standard fabrication, but the actual frequency correction through cavity filling can be performed at any stage before final packaging. This staged approach provides flexibility unlike ion bombarding which must be done early in the process. The cavities are prepared beforehand, allowing frequency adjustment to occur at the optimal point in the manufacturing sequence without constraining the overall process timing.
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 allows for accurate frequency stabilization within a wide correction range, compatible with standard technological processes, and can be performed before or after cap installation, reducing power consumption and complexity in industrial environments.
Implementation Method 1
Element 1 then enters a mode of bulk vibration at its resonance frequency, which corresponds to a bulk wave oscillation around central neutral line 5 of element 1
Implementation Method 2
The voltage difference between element 1 and electrodes 10 and 11 creates electrostatic forces which cause a deformation of element 1
Implementation Method 3
The deformation of element 1 causes a variation of the capacitance of the capacitor formed by element 1 and electrodes 10 and 11
Data Source
AI summary
A method for forming a resonator including a resonant element, the resonant element being at least partly formed of a body at least partly formed of a first conductive material, the body including open cavities, this method including the steps of measuring the resonator frequency; and at least partially filling said cavities.