Tuning-Fork Vibration Element Etching for Precise Groove Alignment
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Solution Overview
Problem
Existing methods for manufacturing tuning-fork type vibration elements face complications due to separate wet and dry etching steps, leading to positional deviations and restricted design freedom, or restricted dimensions when using the micro-loading effect in a single etching step.
Innovation Solution
A method involving dual dry etching steps with protective films of varying thicknesses on both substrate surfaces to form vibration arms and grooves, allowing for independent control of etching depths and widths without relying on the micro-loading effect, thereby enhancing design freedom and manufacturing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate wet etching and dry etching steps are used to form the outer shape and groove, then the manufacturing process can form both features, but the manufacturing step becomes complicated and positional deviation occurs
Solution Approach 1:
The patent combines the formation of the outer shape and the groove into a single dry etching step by using a resist pattern that defines both features simultaneously. This merging eliminates the need for separate wet etching and dry etching steps, reducing process complexity while maintaining positional accuracy between the groove and outer shape.
Solution Approach 2:
The patent segments the etching process into two independent dry etching steps: first forming the outer shape, then forming the groove. This segmentation allows each feature to be formed with precise control while avoiding the complications of combining them in a single step or using separate wet etching, thus reducing overall process complexity.
2Ease of manufacture
If outer shape and groove are collectively formed using micro-loading effect in dry etching, then manufacturing steps are simplified, but dimension setting is restricted and design freedom is reduced
Solution Approach 1:
The patent applies preliminary action by forming a thickness difference in the protective film before the dry etching process. The protective film is made thicker in the groove formation region compared to the outer shape formation region. This preliminary thickness variation enables independent control of etching depths for the groove and outer shape during the dry etching process, providing design freedom while maintaining process simplicity.
Solution Approach 2:
The patent implements local quality by creating a protective film with spatially varying thickness: a first thickness in the groove formation region and a second thickness (different from the first) in the outer shape formation region. This local variation in protective film thickness allows different etching rates and depths in different regions, enabling flexible dimension control for both the groove and outer shape within a single dry etching step.
3Ease of manufacture
If uniform protective film thickness is used in dry etching, then the process is simple, but independent control of groove depth and width is not achieved
Solution Approach 1:
The patent changes the parameter of protective film thickness from uniform to non-uniform. By making the protective film thickness a variable parameter that differs between the groove formation region and outer shape formation region, the process enables independent control of groove depth and width while maintaining relative simplicity. The thickness ratio between the two regions is specifically controlled to achieve the desired dimensional precision.
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 enables precise formation of vibration elements with improved dimensional accuracy and reduced thermoelastic loss, allowing for flexible design without positional deviations and unrestricted dimensions.
Implementation Method 1
a first protective film forming step of forming a first protective film on the first substrate surface; a second protective film forming step of forming a second protective film on the second substrate surface
Implementation Method 2
a first dry etching step of dry-etching the crystal substrate from a side on the first substrate surface via the first protective film to form the first surface, the first groove, and outer shapes of the first vibration arm and the second vibration arm
Data Source
AI summary
A method of manufacturing a vibration element includes: a first protective film forming step of forming a first protective film on a first substrate surface of a crystal substrate; a first dry etching step of dry-etching the crystal substrate via the first protective film; a second protective film forming step of forming a second protective film on a second substrate surface of the crystal substrate; and a second dry etching step of dry-etching the crystal substrate via the second protective film. A relationship of T1<T2<T3 or T4<T5<T6 is satisfied, in which T1 and T4 are thicknesses of the first and second protective films in an inter-arm region, respectively, T2 and T5 are thicknesses of the first and second protective films in first and second groove forming regions, respectively, and T3 and T6 are thicknesses of the first and second protective films in first and second bank portion forming regions, respectively.