3D MEMS Shell Resonators With Openings for Gyroscope Q Tuning
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Solution Overview
Problem
Current methods for fabricating three-dimensional microstructures, particularly from high-melting-temperature materials like fused silica, face challenges in achieving high precision and quality due to expensive and time-consuming processes, such as mechanical grinding and laser ablation, which limit the production of micro- and millimeter-scale structures with high mechanical quality factors and low noise levels required for advanced sensors like gyroscopes.
Innovation Solution
The development of techniques to create three-dimensional microstructures with selectively removed regions using methods like blowtorch molding and chemical etching, allowing for the formation of structures with high quality factors and low noise levels, including the use of shadow masks for selective coating and etching to achieve conformal electrode configurations and stacked resonator structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical grinding and laser ablation are used to fabricate three-dimensional microstructures, then manufacturing precision can be achieved, but the process becomes expensive and time-consuming
Solution Approach 1:
The fabrication process is divided into multiple stages: initial shaping through molding, followed by selective removal of material through chemical etching. This segmentation allows different aspects of the process to be optimized independently - molding provides rapid bulk formation while etching provides precise final geometry
Solution Approach 2:
A sacrificial layer is introduced as an intermediary element that enables the formation of complex three-dimensional structures. The sacrificial layer is deposited conformally and then selectively removed through chemical etching, allowing creation of hollow and internally complex geometries that would be difficult to achieve directly
2Manufacturing precision
If mechanical grinding and laser ablation are used to fabricate microstructures, then high precision can be achieved, but the cost increases
Solution Approach 1:
Mechanical grinding and laser ablation processes are replaced with chemical etching processes. The chemical etching uses selective removal of material through chemical reactions, which can achieve high precision without the equipment costs and operational expenses associated with mechanical and laser-based methods
Solution Approach 2:
The etching process parameters (etchant composition, temperature, time) are carefully controlled and optimized to achieve the desired precision. By adjusting these parameters, high manufacturing precision is achieved while maintaining cost-effectiveness through a simpler chemical process rather than expensive mechanical or laser systems
3Ease of manufacture
If conventional fabrication methods are used, then manufacturing is simpler, but mechanical quality factor and noise level performance deteriorate
Solution Approach 1:
The structure is designed with selectively removed regions that create specific local geometries optimized for mechanical resonance performance. These localized structural features, achieved through selective chemical etching, enhance the mechanical quality factor by reducing energy loss pathways while maintaining overall structural integrity
Solution Approach 2:
The fabrication process creates composite structures combining different material layers (sacrificial layer, structural material) with different properties. The selective removal of the sacrificial layer creates hollow regions and complex internal geometries that improve mechanical quality factor while the remaining structure maintains the benefits of the base material
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
These techniques enable the production of micro- and millimeter-scale structures with high mechanical quality factors and low noise levels, improving the performance of sensors like gyroscopes by reducing energy loss and enhancing signal sensitivity and frequency matching.
Implementation Method 1
blowtorch molding
Implementation Method 2
high-melting-temperature materials like fused silica
Implementation Method 3
chemical etching
Implementation Method 4
use of shadow masks for selective coating and etching
Data Source
AI summary
Three-dimensional (3D) micro-scale shells are presented with openings of various sizes and geometries on the surface. The shell consist of a suspended ring-shaped resonator, multiple support beams, a support post, and a cap region that connects the support beams to the support post. Shells with openings of various sizes and geometries allow the creation of micro electromechanical systems (MEMS) sensors and actuators with a wide range of engineered mechanical and electrical properties. The openings on the shell surface can, for example, control the mechanical quality factor (Q) and resonance frequencies of the shell when the shell is used as a suspended proof mass of a mechanical resonator of a vibratory gyroscope. The shells can also serve as mechanical supporting layers and/or an electrode connection layer for MEMS actuators and sensors that use 3D shells as proof masses.