Piezoelectric Resonator Groove Layout for Electrode Insulation
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Solution Overview
Problem
Existing resonators face the risk of electrode short-circuiting due to uneven etching rates during the manufacturing process, particularly when the release width varies, leading to potential exposure of upper electrodes and increased risk of short-circuiting between electrodes and protective films.
Innovation Solution
The resonator design incorporates a vibration portion with a substrate, lower electrode, piezoelectric film, and upper electrode, surrounded by a holding frame with opening grooves of varying widths, where the gap between the upper electrode and substrate is adjusted based on the release width to prevent short-circuiting by maintaining adequate insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the release width is increased to improve etching rate, then the etching speed increases, but the electrode insulation deteriorates due to excessive etching of the piezoelectric film
Solution Approach 1:
The patent applies local quality by making the gap width between the upper electrode and substrate edge variable rather than uniform. Specifically, the gap width is increased in regions where the release width is large to compensate for excessive piezoelectric film etching, while maintaining a standard gap width in regions with smaller release widths. This localized adjustment ensures adequate electrode insulation is maintained throughout the device despite variations in release width across different regions.
Solution Approach 2:
The patent changes the geometric parameter of the gap width between the upper electrode and substrate edge based on the release width. By making the gap width a variable parameter that correlates with the release width, the design compensates for the increased etching rate in wider release regions, thereby maintaining consistent electrode insulation performance across the entire device structure.
2Productivity
If the release width is increased to improve manufacturing efficiency, then the etching process becomes faster, but the manufacturing precision deteriorates due to uneven piezoelectric film removal
Solution Approach 1:
The patent addresses manufacturing precision by implementing local quality through spatially varying gap widths. In regions with larger release widths where excessive etching occurs, the gap width is increased to provide a larger safety margin, compensating for the non-uniform piezoelectric film removal. This ensures that even with faster etching rates, the final electrode structure maintains proper insulation and dimensional accuracy.
3Device complexity
If the gap between upper electrode and substrate edge is kept constant, then the device structure is simpler, but the electrode insulation becomes insufficient in regions with large release width
Solution Approach 1:
The patent resolves this contradiction by applying local quality - the gap width between the upper electrode and substrate edge is made non-uniform, specifically being increased in regions where the release width is large. This localized variation in gap width provides enhanced insulation protection precisely where the risk of electrode short-circuiting is highest due to excessive piezoelectric film etching, while maintaining simpler structures in regions where standard gap widths are sufficient.
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 design effectively prevents electrode short-circuiting by ensuring sufficient gap width between electrodes, even with varying release widths, thereby enhancing insulation resistance and maintaining the resonator's operational integrity.
Implementation Method 1
a piezoelectric film F3 formed on the lower electrode E1
Data Source
AI summary
A resonator includes a vibration portion that has a substrate having a main surface, a lower electrode on the main surface of the substrate, a piezoelectric film on the lower electrode, and an upper electrode on the piezoelectric film. A frame surrounds at least part of the vibration portion. Opening grooves having different widths in a first direction in a plan view of the main surface are provided in a periphery of the vibration portion. In a plan view of the main surface, the upper electrode is provided so as to be spaced from an outer edge of the substrate by a gap which is along the first direction, such that a length of the gap in a region where a width of the opening groove is large is larger than a length of the gap in a region where a width of the opening groove is small.