Silicon MEMS Vibrator Structure for Low-Cost Frequency Stability
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Solution Overview
Problem
Existing vibrators with MEMS structures using expensive SOI substrates face challenges in reducing production costs due to high material expenses.
Innovation Solution
A method for manufacturing a vibrator device using a single crystal silicon substrate with a recessed base portion, support portion, and vibrating arms, where the vibrating arms are formed through dry etching and wet etching processes to create a triangular cross-sectional shape, allowing for a piezoelectric film to be disposed on the opposite surface, and utilizing a temperature characteristic adjusting film to reduce the temperature coefficient of frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SOI substrate is used to manufacture vibrator, then frequency-temperature characteristics are improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive SOI substrates with inexpensive single crystal silicon substrates. The single crystal silicon substrate serves as a cost-effective alternative that maintains the necessary mechanical and thermal properties for vibrator fabrication, thereby reducing manufacturing cost while preserving frequency-temperature characteristics.
Solution Approach 2:
The patent modifies the substrate material parameter from SOI to single crystal silicon. This parameter change fundamentally alters the cost structure while maintaining the functional requirements for frequency-temperature stability through appropriate substrate thickness and structure design.
2Manufacturing precision
If wet etching is used to form vibrating arms, then manufacturing precision is improved, but production time increases
Solution Approach 1:
The patent performs preliminary patterning by forming bottomed long grooves through dry etching before the final vibrating arm formation. This preliminary action defines the basic structure and position, allowing the subsequent wet etching to focus only on completing the vibrating arms, thereby reducing overall production time while maintaining precision.
Solution Approach 2:
The patent divides the vibrating arm formation process into two segments: first forming bottomed long grooves by dry etching to establish the basic structure, then completing the vibrating arms by wet etching. This segmentation allows each process to be optimized independently, balancing precision and production time.
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 approach enables the production of a low-cost vibrator with improved frequency-temperature characteristics and efficient etching processes, utilizing inexpensive single crystal silicon substrates while maintaining effective vibration performance.
Implementation Method 1
an excitation unit including a piezoelectric thin film is formed on a silicon semiconductor layer
Implementation Method 2
forming, based on dry etching, at least two bottomed long grooves arranged at a predetermined interval on a second surface
Implementation Method 3
forming the vibrating arm between the second surface and a bottom surface of the long groove in a thickness direction of the silicon substrate by wet etching side surfaces of the long groove
Data Source
AI summary
A method for manufacturing a vibrator device including a base portion having a first surface, a support portion protruding from the first surface in a normal direction of the first surface, and a vibrating arm that extends from the support portion along the first surface and that has a gap with the first surface, the method including: preparing a single crystal silicon substrate having a flat plate shape; forming, by dry etching, at least two bottomed long grooves arranged at a predetermined interval on a second surface which is one surface of the silicon substrate; and forming the vibrating arm between the second surface and a bottom surface of the long groove in a thickness direction of the silicon substrate by wet etching side surfaces of the long groove and communicating the two long grooves with each other.