Homogenous Silicon Multi-Level MEMS Comb Structure
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Solution Overview
Problem
Existing MEMS devices with non-homogenous comb structures face accuracy issues due to electrostatic differences and misalignment problems, leading to decreased precision and inefficient use of die area.
Innovation Solution
A manufacturing method that creates self-aligned critical structures on a single layer of homogenous device wafer material using deep silicon etching, eliminating the need for electrical biasing and ensuring uniform vertical surfaces, allowing for precise and efficient capacitive detection with multi-layer comb structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-homogenous comb structures are used in MEMS devices, then manufacturing flexibility is improved, but electrostatic differences and misalignment issues occur leading to decreased accuracy
Solution Approach 1:
The patent applies homogeneity by forming both the stator and rotor comb structures from the same homogenous device wafer material using deep silicon etching. This eliminates electrostatic differences between different materials while maintaining manufacturing flexibility through a unified etching process that can create complex multi-level structures from a single homogeneous substrate.
2Measurement precision
If multi-layer comb structures with recessed fingers are created, then capacitive detection precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the comb structure into multiple recessed levels with stator and rotor fingers at different depths. This segmentation enables precise capacitive detection by creating multiple sensing zones while the entire structure is formed from homogenous material through a systematic etching process that manages the complexity.
Solution Approach 2:
The patent merges the formation of stator and rotor structures into a single deep silicon etching process from homogenous device wafer material. This combining approach reduces manufacturing steps and eliminates alignment issues between separate layers while still achieving the complex multi-level comb structure geometry.
3Manufacturing precision
If deep silicon etching is used to create self-aligned structures, then misalignment issues are eliminated, but manufacturing process difficulty increases
Solution Approach 1:
The patent applies self-service through self-aligned deep silicon etching where the etching process automatically defines the relative positions of stator and rotor structures. The method uses the structure itself as the alignment reference, eliminating the need for separate alignment steps and reducing manufacturing complexity despite the advanced etching technique required.
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 enhances the accuracy and efficiency of MEMS devices by eliminating electrostatic differences and misalignment issues, enabling precise and dense comb structures with improved material optimization for specific applications.
Implementation Method 1
A manufacturing method that creates self-aligned critical structures on a single layer of homogenous device wafer material using deep silicon etching
Implementation Method 2
The amount of deflection can be sensed from changes in capacitance from the changes in the gap between the two electrodes due to deflection
Data Source
Figure 1a~1d
Figure 1e~1h
Figure 2a~2d
AI summary
The present invention relates to a micromechanical device comprising a multi-layer micromechanical structure including only homogenous silicon material. The device layer comprises at least a rotor and at least two stators. At least some of the rotor and the at least two stators are at least partially recessed to at least two different depths of recession from a first surface of the device layer and at least some of the rotor and at least two stators are at least partially recessed to at least two different depths of recession from a second surface of the device layer.