MEMS Comb Tooth Structure with Asymmetric Line Widths
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Solution Overview
Problem
Existing micro-electro-mechanical systems (MEMS) face challenges in balancing electrostatic driving force and stability of comb teeth structures, particularly in achieving optimal dimensions and configurations for efficient movement and stability.
Innovation Solution
The proposed MEMS system incorporates a comb tooth structure with alternating first and second comb teeth, a spring structure connected to the second comb teeth, and an electrode structure with specific line widths, ratios, and thicknesses to achieve balanced electrostatic driving and stability. The system includes a cantilever beam connected to the spring structure and a baffle with vias to enhance stability and movement capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the comb tooth dimensions are reduced to increase the number of teeth, then the electrostatic driving force is improved, but the stability and risk of collapse deteriorate
Solution Approach 1:
The patent applies different line widths to different comb teeth: first comb teeth have a line width of 3-7 microns while second comb teeth have a line width of 7-15 microns. This local differentiation allows thinner first teeth to generate sufficient electrostatic force while thicker second teeth provide enhanced stability and reduced collapse risk, resolving the contradiction between driving force and stability.
2Force
If the line width of comb teeth is decreased to increase electrostatic force, then the driving force is improved, but the manufacturing precision and structural integrity worsen
Solution Approach 1:
The patent specifies precise line width ranges for different comb tooth types: first comb teeth at 3-7 microns and second comb teeth at 7-15 microns, with the distance between adjacent teeth controlled at 2-4 microns. This local quality approach ensures that each region has the appropriate dimensions for its function while maintaining manufacturability within defined tolerances.
Solution Approach 2:
The patent employs a composite structure where comb teeth are formed from multiple materials including silicon dioxide layers (200-500 nanometers thick) and sacrificial materials. This composite construction allows for precise dimensional control and structural integrity while achieving the required electrostatic performance.
3Force
If the overlapping ratio of comb teeth is increased to improve electrostatic force, then the driving force is improved, but the device complexity increases
Solution Approach 1:
The patent divides the comb tooth structure into two distinct segments: first comb teeth with line width 3-7 microns and second comb teeth with line width 7-15 microns. This segmentation allows independent optimization of each segment's properties, achieving high electrostatic force through the first teeth while maintaining stability through the second teeth, without requiring complex overlapping configurations.
Solution Approach 2:
The patent introduces asymmetry in the comb tooth design by using different line widths for first and second comb teeth, and positioning them at different heights (second comb teeth extend 1-5 microns higher). This asymmetric configuration simplifies the overall structure compared to uniform designs while achieving superior electrostatic performance and stability.
4Stability of the object's composition
If the cantilever beam width is increased to improve stability, then the structural integrity is improved, but the ease of operation and movement range deteriorate
Solution Approach 1:
The patent applies local quality by making the cantilever beam width equal to or greater than the line width of the second comb teeth (7-15 microns), providing localized structural support where needed. This ensures stability at the connection point while allowing the comb teeth themselves to maintain thinner profiles for ease of movement and operation.
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 described MEMS system effectively balances electrostatic driving force and stability by optimizing the dimensions and configurations of the comb teeth, spring structure, and electrode structure, ensuring reliable movement and reduced risk of collapse.
Implementation Method 1
the first comb tooth portion includes a plurality of first comb teeth... the second comb tooth portion includes a plurality of second comb teeth... the plurality of first comb teeth and at least part of the plurality of second comb teeth are arranged alternately... the second comb tooth portion is a suspended structure and configured to be movable
Data Source
AI summary
A micro-electro-mechanical system and a manufacturing method thereof. The micro-electro-mechanical system includes a comb tooth structure, a spring structure, and an electrode structure. The comb tooth structure includes first comb teeth and second comb teeth arranged alternately. A cantilever beam connecting the second comb teeth is connected to the spring structure; line widths of a first comb tooth and a second comb tooth are 3-7 microns, and are not less than a distance between the adjacent first comb tooth and the second comb tooth a ratio of the length of the first comb tooth to a length of the second comb tooth is 0.7-1.5, a width of the cantilever beam is not less than the line width of the second comb tooth, and thickness of the first comb tooth and a thickness of the second comb tooth are both 300 nanometers to 500 microns.