Quartz Vibrator Groove Etching for Higher Angular Velocity Sensitivity
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Solution Overview
Problem
Existing methods for manufacturing quartz crystal vibrators do not effectively form grooves of different depths for vibration arms, which limits the detection sensitivity and accuracy of angular velocity detection.
Innovation Solution
A method involving the use of micro loading effect in dry etching to form grooves of varying depths on quartz crystal substrates, where the first and second protective films with different opening widths are used to control etching rates, allowing for the formation of first and second vibration arms with distinct groove configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dry etching is used to form grooves on vibration arms, then the grooves are formed with uniform depth, but the detection sensitivity and accuracy of angular velocity detection are limited
Solution Approach 1:
The patent applies local quality by forming grooves with different depths at different locations on the vibration arms. Specifically, first grooves are formed with a first depth and second grooves are formed with a second depth that is greater than the first depth. This non-uniform groove configuration optimizes the vibration characteristics locally at different positions, thereby improving angular velocity detection sensitivity while maintaining manufacturing feasibility through selective etching processes.
2Measurement precision
If grooves of different depths are formed on vibration arms, then detection sensitivity is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent employs preliminary action by forming a protective film over the quartz crystal substrate before etching. The protective film has a first region with a first thickness and a second region with a second thickness that is greater than the first thickness. This pre-formed thickness variation in the protective film allows subsequent etching to produce grooves of different depths in a single etching step, thereby achieving complex groove configurations without proportionally increasing process complexity.
Solution Approach 2:
The patent utilizes parameter changes by varying the thickness of the protective film across different regions. The protective film thickness parameter is changed from a first thickness in the first region to a second thickness in the second region. This parameter variation enables differential etching rates and final groove depths, allowing the formation of vibration arms with optimized mechanical properties for enhanced detection sensitivity.
3Ease of manufacture
If uniform grooves are formed on all vibration arms, then the manufacturing process is simple, but the amplitude of vibration arms is reduced and thermoelastic loss increases
Solution Approach 1:
The patent implements local quality by creating non-uniform groove depths where first grooves have a first depth and second grooves have a second depth greater than the first depth. This local variation in groove geometry optimizes the vibration characteristics of different arms, increasing vibration amplitude and reducing thermoelastic loss in regions where enhanced performance is beneficial, while maintaining manufacturing simplicity through a unified etching process applied to a pre-patterned protective film.
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 enhances the detection sensitivity of angular velocity by increasing the amplitude of vibration arms and reducing thermoelastic loss, leading to improved accuracy in angular velocity detection.
Implementation Method 1
a first dry etching step of dry etching the quartz crystal substrate from the first surface through the first protective film
Implementation Method 2
The micro loading effect refers to an effect in which, at a dense portion having a small processing width and a sparse portion having a large processing width, a processing depth is larger, that is, an etching rate is larger, in the sparse portion than in the dense portion even when dry etching is performed under the same condition
Data Source
AI summary
A method for manufacturing a vibrator includes a preparation step of preparing a quartz crystal substrate having a first surface and a second surface that are in a front and back relationship, a first protective film formation step of forming a first protective film in an element formation region of the first surface, the first protective film having a first opening overlapping a first groove formation region and a second opening overlapping a second groove formation region, in which a region of the quartz crystal substrate where the vibrator is formed is referred to as the element formation region, a region where the first groove is formed is referred to as the first groove formation region, and a region where the second groove is formed is referred to as the second groove formation region, and a first dry etching step of dry etching the quartz crystal substrate from the first surface through the first protective film. Wa<Wb, in which Wa represents a width of the first opening and Wb represents a width of the second opening.