Silicon Hemispherical Resonance Gyroscope for Low Noise and Cost
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Solution Overview
Problem
Traditional hemispherical resonance gyroscopes are limited by high cost, large size, and low accuracy due to their quartz material, restricting their widespread application in inertial measurement systems.
Innovation Solution
A MEMS hemispherical resonance gyroscope is developed using silicon micromachining, featuring a hemispherical shell made of in-situ doped polysilicon, silicon oxide, or diamond, with silicon spherical electrodes and a processing method involving isotropic etching and deep reactive ion etching to create capacitors, reducing noise and increasing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional quartz material is used for hemispherical resonance gyroscope, then high accuracy is achieved, but cost becomes very high and size becomes large
Solution Approach 1:
The patent replaces expensive fused quartz with inexpensive silicon-based materials that can be mass-produced through standard semiconductor manufacturing processes. The hemispherical shell is fabricated using silicon-on-insulator (SOI) wafers with thicknesses of 50-200 micrometers, enabling batch production at low cost while maintaining sufficient mechanical Q-factor for gyroscope operation
Solution Approach 2:
The patent changes the material parameter from fused quartz to silicon-based materials (single-crystal silicon, polysilicon, or silicon-on-insulator) and adjusts the size parameter from 20mm diameter to 5-15mm diameter. This parameter change enables compatibility with standard semiconductor manufacturing processes, achieving both cost reduction and miniaturization while preserving the hemispherical resonance gyroscope's high accuracy characteristics
2Measurement precision
If traditional quartz material is used for hemispherical resonance gyroscope, then high accuracy is achieved, but size becomes large
Solution Approach 1:
The patent changes the size parameter from 20mm diameter to 5-15mm diameter by utilizing silicon-based materials with higher mechanical Q-factors that allow operation at smaller dimensions. The hemispherical shell thickness is optimized to 50-200 micrometers, achieving miniaturization while maintaining the structural integrity and resonance characteristics necessary for accurate gyroscope operation
3Ease of manufacture
If silicon-based materials are used instead of quartz, then cost and size are reduced, but manufacturing precision becomes more challenging
Solution Approach 1:
The patent replaces traditional mechanical machining and bonding processes with semiconductor manufacturing techniques including photolithography, plasma etching, and vapor deposition. These processes enable precise fabrication of hemispherical shells with 50-200 micrometer thickness and accurate electrode positioning, achieving manufacturing precision of several micrometers through batch processing
Solution Approach 2:
The patent utilizes standard semiconductor manufacturing equipment and processes that serve multiple functions: photolithography patterns both the hemispherical shell structure and electrode positions, plasma etching creates both the hemispherical cavity and releases the membrane, and vapor deposition deposits both structural layers and conductive electrodes. This multi-functionality reduces the need for specialized equipment and processes, improving manufacturing precision through proven semiconductor processes
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 silicon-based gyroscope achieves higher accuracy and lower noise levels, enabling smaller size and lower production costs, with batch production capabilities, thus overcoming the limitations of traditional quartz-based gyroscopes.
Implementation Method 1
the hemispherical shell and the several silicon spherical electrodes which surround the hemispherical shell constitute several capacitors
Implementation Method 2
the shielded electrodes separate the driving electrodes and the equilibrium electrodes from the signal detection electrodes
Implementation Method 3
during a hemispherical cup body rotates around the centreline of the cup, its four antinodes vibration pattern will deflect
Data Source
AI summary
The present invention relates to a micromachined hemispherical resonance gyroscope, which includes a resonant layer, wherein the resonant layer comprises a hemispherical shell whose top point of the hemispherical shell is its anchor point; several silicon hemispherical electrodes are arranged around the hemispherical shell, the silicon hemispherical electrodes include driving electrodes, equilibrium electrodes, shielded electrodes and signal detection electrodes or quadrature correction electrodes, the hemispherical shell and the several silicon spherical electrodes which surround the hemispherical shell constitute several capacitors. The hemispherical resonance micromechanical gyroscope utilizes a processing method on the basis of silicon micromachining, which leads to small size and low production cost, as well as batch production capacity, meanwhile its sensitivity is independent of amplitude and its driving voltage could be very low, as a result its output noise could be significantly reduced, and its accuracy is better than the gyroscope products in the prior art.