Cavity MEMS Proof Mass Layout for Thin TWS Vibration Sensing
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Solution Overview
Problem
Existing MEMS accelerometer designs are too thick and large for applications in true wireless stereo (TWS) earphones, failing to meet the minimized requirements for acoustic transducers.
Innovation Solution
A MEMS device with a minimized proof mass having a thickness smaller than the substrate, formed by creating a cavity and interconnection structure on a substrate, and connecting a proof mass with a reduced thickness to the interconnection structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional MEMS accelerometer design is used, then the device has sufficient structural strength and stability, but the device becomes too thick and large for TWS earphones
Solution Approach 1:
The patent transitions from traditional planar MEMS structures to a three-dimensional cavity-based architecture. The proof mass is positioned within a cavity formed in the substrate, allowing the sensing element to be suspended in three-dimensional space rather than confined to a planar layout. This dimensional change enables reduced overall device thickness while maintaining structural integrity through the cavity walls and support structures.
Solution Approach 2:
The proof mass is nested within the cavity formed in the substrate, creating a compact hierarchical structure. The cavity itself is formed by removing material from the substrate, and the proof mass is positioned inside this cavity and connected to the substrate through support structures. This nesting arrangement maximizes space utilization and reduces the overall footprint and thickness of the MEMS device.
2Length of moving object
If proof mass size is reduced for miniaturization, then the device fits TWS earphones, but the sensitivity and measurement precision decrease
Solution Approach 1:
The patent optimizes the geometric parameters of the proof mass and cavity structure to achieve miniaturization while preserving sensitivity. By carefully controlling the dimensions, shape, and positioning of the proof mass within the cavity, the device achieves reduced size suitable for TWS earphones while maintaining adequate voice vibration sensing capability through parameter optimization rather than simple scaling.
Solution Approach 2:
The cavity structure provides localized structural support and defines a specific sensing zone where the proof mass is positioned. The cavity walls and support structures are designed with specific local properties that enhance the sensitivity of the proof mass to voice vibrations while maintaining overall device miniaturization. The local quality of the cavity region is optimized for acoustic sensing rather than uniform structural strength throughout the entire device.
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
Enables the MEMS device to be applied in TWS earphones for supplying voice vibration, with improved sensitivity and sensor accuracy due to precise control of cavity and proof mass dimensions.
Implementation Method 1
MEMS structures are often applied to microelectronics such as accelerometer, gyroscope, mirror, and acoustic sensor, etc.
Implementation Method 2
MEMS structures are often applied to microelectronics such as accelerometer, gyroscope, mirror, and acoustic sensor, etc.
Data Source
AI summary
A method of forming a micro-electromechanical system (MEMS) device includes: providing a substrate comprising a first surface and a second surface opposite to the first surface; forming a cavity in the substrate, the cavity extending between the first surface and the second surface; forming an interconnection structure on the first surface of the substrate and over the cavity; and forming a proof mass in the cavity, connected to the interconnection structure, the proof mass having a thickness which is smaller than a thickness of the substrate.