MEMS Microphone Diaphragm Clamping for Larger Area and Low Noise
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Solution Overview
Problem
The use of stress-free films as diaphragms in MEMS microphones faces limitations in mechanical resonance frequency and size, leading to increased size and cost, reduced yield, and inconsistent manufacturing, while stress films introduce manufacturing uncertainties.
Innovation Solution
A diaphragm design combining stress-free and stress films, where the diaphragm is simply supported during manufacturing to eliminate stress and clamped during operation, utilizing electrostatic interaction to constrain the periphery, thereby maintaining manufacturing consistency and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a stress-free film is used as a diaphragm to eliminate manufacturing stress uncertainty, then manufacturing consistency and yield are improved, but the diaphragm size and thickness are limited
Solution Approach 1:
The patent applies a dynamic support mechanism where the supporting electrode can switch between simply supporting the diaphragm periphery during manufacturing and clamping it through electrostatic interaction during operation. This dynamic transition allows the diaphragm to achieve both manufacturing consistency (simply supported) and larger area (clamped)
Solution Approach 2:
The patent changes the boundary condition parameter of the diaphragm from simply supported to clamped by applying electrostatic force. This parameter change enables the stress-free film to maintain its manufacturing advantages while achieving the mechanical properties needed for larger diaphragm areas
2Manufacturing precision
If a stress-free film is used as a diaphragm to eliminate manufacturing stress uncertainty, then manufacturing consistency and yield are improved, but the acoustic properties are limited
Solution Approach 1:
The patent dynamically changes the boundary condition of the diaphragm from simply supported during manufacturing to clamped during acoustic operation. This dynamic transition allows the stress-free film to maintain manufacturing consistency while achieving superior acoustic properties through the clamped configuration
3Reliability
If the diaphragm periphery is fixed to the supporting structure in a clamped manner, then the mechanical resonance frequency and acoustic properties are improved, but manufacturing stress accumulates in the diaphragm
Solution Approach 1:
The patent applies preliminary action by first simply supporting the diaphragm periphery during the manufacturing process to prevent stress accumulation, then subsequently applying electrostatic force to achieve the clamped configuration for optimal acoustic performance. This sequential approach eliminates manufacturing stress while maintaining acoustic properties
4Reliability
If a larger diaphragm area is used to improve signal-to-noise ratio, then the microphone sensitivity is improved, but the chip size increases
Solution Approach 1:
The patent changes the boundary condition parameter from simply supported to clamped, which fundamentally alters the mechanical and acoustic properties of the diaphragm. This parameter change enables larger diaphragm areas to be achieved without proportionally increasing chip size, as the clamped configuration provides better mechanical support and acoustic performance
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 design enhances yield and reliability by allowing a larger diaphragm area without increasing chip size, reducing noise, and improving signal-to-noise ratio, sensitivity, and dynamic range.
Implementation Method 1
when being applied a bias, the supporting electrode constrains the periphery of the diaphragm on the supporting portion through electrostatic interaction so as to support the diaphragm in a clamped manner
Data Source
AI summary
A MEMS microphone, a microphone unit and an electronic device are disclosed by the present disclosure. The micro-electro-mechanical system microphone comprises: a substrate; a back electrode plate comprising a supporting structure; and a diaphragm located between the substrate and the back electrode plate, wherein the supporting structure comprises a supporting portion used for supporting a periphery of a diaphragm, and a supporting electrode being insulated from the supported diaphragm, and wherein the diaphragm is a stress-free film when being applied no bias, and when being applied a bias, the supporting electrode constrains the periphery of the diaphragm on the supporting portion through electrostatic interaction so as to support the diaphragm in a clamped manner.