Tensioned Membrane MEMS Microphone Fabrication
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Solution Overview
Problem
Existing MEMS microphones face challenges in selectively controlling sensitivity and frequency properties, requiring changes in membrane thickness and deposition processes that increase costs and complexity.
Innovation Solution
Applying a controlled amount of tension to the membrane during fabrication, using temperatures to achieve desired sensitivity and frequency characteristics, allowing for standard components to produce microphones with varying properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If membrane thickness and deposition processes are varied to control sensitivity and frequency properties, then MEMS microphone performance is improved, but manufacturing costs and process complexity increase
Solution Approach 1:
The patent applies parameter changes by controlling the tension amount of the membrane as a key parameter to selectively control sensitivity and frequency properties. By adjusting the tension amount during fabrication, the patent achieves different microphone characteristics without changing membrane thickness or deposition processes, thus resolving the contradiction between manufacturing precision and process complexity
Solution Approach 2:
The patent makes the membrane tension mechanism serve multiple functions: it controls both sensitivity level and frequency properties (resonant frequency, audio bandwidth) simultaneously. This multi-functionality allows a single fabrication parameter (tension amount) to control multiple performance characteristics, reducing the need for separate process variations
2Reliability
If multiple membrane specifications are used to achieve different sensitivity levels, then performance requirements are met, but inventory costs and manufacturing complexity increase
Solution Approach 1:
Instead of using different membrane thicknesses or materials, the patent changes the tension parameter applied to a standard membrane to achieve different sensitivity levels. This allows a single membrane specification to serve multiple performance requirements, eliminating the need for inventory management of multiple membrane types
Solution Approach 2:
The patent applies preliminary tensioning to the membrane during fabrication to preset the sensitivity level before the microphone is used. This preliminary action of tensioning allows the same membrane to be configured for different performance levels, reducing manufacturing complexity and inventory requirements
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 production of MEMS microphones with different sensitivity and frequency properties using a single membrane size and thickness, reducing manufacturing costs and complexity while maintaining high performance.
Implementation Method 1
The membrane and the back plate form a capacitor. Receipt of an audible signal (e.g. sound pressure) causes the membrane to vibrate, which generates a signal that represents the audio signal.
Implementation Method 2
stretching the membrane to obtain the tension amount
Data Source
AI summary
A micro electro-mechanical system (MEMS) microphone is provided. The MEMS microphone is configured to operate at a predetermined range of frequencies. The MEMS microphone has a tensioned membrane preset at a tension amount selected to cause the MEMS microphone to operate at a predetermined sensitivity level that is above a threshold sensitivity level. The tension amount is controlled based on a temperature applied to the tensioned membrane during a fabrication process. At least a portion of the tensioned membrane is sandwiched between a first conductive layer and a second conductive layer configured to equalize stress of the tensioned membrane.