Quartz Vibration Element Etching to Eliminate Arm Sidewall Steps
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Solution Overview
Problem
The existing method for manufacturing vibration elements using dry etching results in stepped portions at the side surfaces of vibrating arms, leading to unwanted vibration and damage such as cracking and chipping due to positional shifts between photoresist films on the substrate surfaces.
Innovation Solution
A manufacturing method involving dry etching from both sides of a quartz crystal substrate followed by wet etching to form inclining surfaces, ensuring a depth ratio of D1/D ≥0.80, which reduces the size of stepped portions and improves the Q value of the vibration element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is performed from both front and rear surfaces to form grooves, then the grooves can be formed simultaneously with outer shapes, but stepped portions are formed at side surfaces due to positional shift between photoresist films
Solution Approach 1:
The patent divides the etching process into two separate stages: first forming the outer shapes of vibrating arms, then forming grooves. This segmentation eliminates the positional alignment issue between photoresist films by performing groove formation after outer shape formation, ensuring high positioning accuracy while maintaining productivity.
Solution Approach 2:
The patent performs preliminary formation of outer shapes before forming grooves. By establishing the outer shape structure first, subsequent groove formation can be precisely positioned relative to the already-formed outer shapes, eliminating stepped portions caused by misalignment.
2Ease of manufacture
If photoresist films are formed on both surfaces for dry etching, then grooves can be etched from both sides, but positional shifts cause stepped portions that lead to unwanted vibration and damage
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: outer shape formation first, then groove formation. This eliminates the need for simultaneous dual-surface photoresist alignment, preventing stepped portions that cause vibration and damage, thereby improving reliability while maintaining ease of manufacture.
Solution Approach 2:
The patent converts the potential harm of stepped portions into a benefit by using sequential etching. The controlled removal of material in stages allows precise formation of grooves without creating harmful stepped portions, transforming the manufacturing complexity into a quality improvement.
3Manufacturing precision
If dry etching is used to form grooves, then precise dimensional control is achieved, but stepped portions are created at side surfaces
Solution Approach 1:
The patent segments the etching process to first form outer shapes with precise dimensions, then form grooves separately. This sequential approach maintains dimensional accuracy while avoiding stepped portions on side surfaces, achieving both precise dimensions and smooth surface shapes.
Solution Approach 2:
Instead of forming grooves first and then outer shapes (which causes stepped portions), the patent inverts the sequence by forming outer shapes first and then grooves. This reversal eliminates the stepped portion problem while maintaining both dimensional accuracy and surface smoothness.
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
The method effectively minimizes unwanted vibration and damage by reducing the size of stepped portions, maintaining accurate dimensions, and enhancing the Q value of the vibration element.
Implementation Method 1
a first dry etching step of dry-etching the quartz crystal substrate from a first surface side to form the first grooves and outer shapes of the first and second vibrating arms, a second dry etching step of dry-etching the quartz crystal substrate from a second surface side to form the second grooves and the outer shapes of the first and second vibrating arms
Implementation Method 2
a subsequent wet etching step of wet-etching the side surfaces of the first and second vibrating arms, the first grooves, and the second grooves to form inclining surfaces that couple bottom surfaces to in-groove side surfaces of the first and second grooves
Data Source
AI summary
A vibration element manufacturing method includes a first dry etching step of dry-etching a quartz crystal substrate from the first surface side to form first grooves and the outer shapes of first and second vibrating arms, a second dry etching step of dry-etching the quartz crystal substrate from the second surface side to form second grooves and the outer shapes, and a wet etching step of wet-etching the side surfaces of the first and second vibrating arms, the first grooves, and the second grooves to form inclining surfaces that couple bottom surfaces to in-groove side surfaces of the first and second grooves, and the first and second grooves satisfy the relationship of D1/D ≥0.80, where D represents the depth of each of the first and second grooves, and D1 represents the result of subtraction of the length of the inclining surfaces in a direction Z from the depth in each of the first and second grooves.