Cavity-Suspended MEMS Proof Mass for Thin TWS Accelerometers
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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 integrating a proof mass with reduced thickness through precise etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional MEMS accelerometer design is used, then the device has sufficient structural strength and stability, but the device thickness and size become too large for TWS earphone applications
Solution Approach 1:
The patent transitions from conventional thick planar MEMS structures to a three-dimensional cavity-based design where the proof mass is suspended within a cavity formed in the substrate. This dimensional change allows the proof mass to achieve sufficient structural strength through its suspended configuration and connection to the substrate via support structures, while dramatically reducing the overall device thickness to meet TWS earphone requirements.
Solution Approach 2:
The substrate is segmented by forming a cavity that separates the proof mass from the bulk substrate material. The proof mass is connected to the substrate through support structures rather than being a solid continuous structure. This segmentation allows the proof mass to be thin and lightweight while maintaining structural integrity through the support connections and cavity configuration.
2Length of moving object
If proof mass thickness is reduced to minimize device size, then the device fits TWS earphones, but manufacturing precision requirements increase
Solution Approach 1:
The cavity is formed in the substrate before the proof mass is deposited or assembled. This preliminary formation of the cavity structure provides a pre-defined geometric framework that guides subsequent manufacturing steps. The cavity dimensions and shape are established in advance, ensuring that when the proof mass is added, the overall device achieves the target thickness with controlled tolerances.
Solution Approach 2:
The cavity acts as an intermediary structure between the substrate and the proof mass. By controlling the cavity dimensions and configuration, the design mediates the relationship between the thick substrate and the thin proof mass, allowing precise control of the final device thickness while maintaining structural strength through the cavity's geometric design and support structures.
Data Source
AI summary
The present disclosure relates to a micro-electromechanical system (MEMS) device and a method of forming the same. The MEMS device includes a substrate, a cavity, an interconnection structure and a proof mass. The substrate includes a first surface and a second surface opposite to the first surface. The cavity is disposed in the substrate, extending between the first surface and the second surface. The interconnection structure is disposed on the first surface of the substrate, over the cavity. The proof mass is disposed in the cavity, connected to the interconnection structure, the proof mass having a thickness which is smaller than a thickness of the substrate.