MEMS Self-Aligned High-Low Comb Teeth via Lifting Structure
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Solution Overview
Problem
The existing high/low comb teeth structures in MEMS devices require complex and high-precision alignment processes, leading to low yield ratios and increased processing difficulties due to the need for bonding or repeated etching.
Innovation Solution
The introduction of a self-aligning high/low comb teeth design featuring a lifting structure with bent and straight beam sections, where one end is fixed to a substrate and the other end connected to movable or fixed comb teeth, allowing vertical displacement and out-of-plane movement without the need for repeated etching or bonding, using a SOI silicon wafer and controlling stress in the film layer for formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bonding or repeated etching is used to form high/low comb teeth, then out-of-plane movement capability is achieved, but process complexity increases and yield ratio decreases
Solution Approach 1:
The lifting structure is divided into multiple beam sections (first beam section, second beam section, third beam section) with different orientations and functions. This segmentation allows each section to contribute to the overall out-of-plane displacement while maintaining manufacturability through standard photolithography processes, resolving the contradiction between achieving complex 3D movement and keeping the process simple.
Solution Approach 2:
The patent transitions from planar 2D comb teeth to 3D high/low comb teeth by introducing vertical displacement through the lifting structure. The bent beam configuration enables out-of-plane movement without requiring complex bonding or repeated etching processes, achieving dimensional enhancement while maintaining process simplicity.
2Manufacturing precision
If high-precision alignment is required for bonding or repeated etching, then high/low comb teeth can be formed, but manufacturing difficulty increases and yield ratio decreases
Solution Approach 1:
The lifting structure is designed to be formed in a single etching step along with the comb teeth, making the structure self-forming without requiring separate alignment steps. The continuous material layer and integrated design enable the lifting structure to automatically align with the comb teeth during a single fabrication process, eliminating the need for high-precision alignment between separate steps.
Solution Approach 2:
The lifting structure and comb teeth are combined into a single integrated structure formed in one etching step. This merging of formation processes eliminates the need for separate bonding or repeated etching steps, thereby removing the requirement for high-precision alignment between multiple steps and significantly reducing manufacturing difficulty.
3Manufacturing precision
If SOI technique is used to achieve self-alignment, then alignment problem is solved, but repeated etching and complex processing remain
Solution Approach 1:
The patent changes the material parameter by using a continuous material layer for the lifting structure that can be etched in a single step. This parameter change allows the lifting structure to be formed simultaneously with the comb teeth without requiring SOI techniques or repeated etching, achieving self-alignment while simplifying the processing steps.
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 solution simplifies the manufacturing process, reduces processing costs and difficulties, and improves yield ratios by forming self-aligning high/low comb teeth in a single etching procedure, enabling out-of-plane movement in MEMS devices like electrostatic actuators and capacitive displacement transducers.
Implementation Method 1
the bent beam makes the folded beam structure displace in the vertical direction, and thereby drives the movable comb teeth/fixed comb teeth connected to the lifting structure to displace out of the plane of the fixed comb teeth/movable comb teeth
Data Source
AI summary
A MEMS self-aligned high-and-low comb tooth and manufacturing method thereof, the comb tooth having a lifting structure, the lifting structure generating a displacement in the vertical direction to drive the movement of a movable comb tooth or a fixed comb tooth attached thereto. The manufacturing method thereof adopts a silicon wafer, the lifting structure and the comb tooth are sequentially formed on a mechanical structure layer, the fixed comb tooth and the movable comb tooth are formed with the same etching process, and the stress in the lifting structure displaces the fixed comb tooth and the movable comb tooth in the vertical direction, thus forming the self-aligned high-and-low comb tooth.