Piezoelectric MEMS Microphone Spring Region for Stress-Stable Sensitivity
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Solution Overview
Problem
Conventional capacitive MEMS microphones suffer from high power consumption and reliability issues in harsh environments, while existing piezoelectric MEMS microphones face sensitivity degradation due to residual stress in the diaphragm, leading to unpredictable performance.
Innovation Solution
A piezoelectric MEMS microphone design featuring a spring region formed from the membrane or a separate material, with slits and joins to reduce intrinsic stress, allowing the membrane greater freedom and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid membrane structure is used in piezoelectric MEMS microphone, then structural strength is improved, but intrinsic stress increases causing sensitivity degradation
Solution Approach 1:
The membrane structure is segmented by introducing slits that divide the continuous membrane into separate regions. These slits create discrete piezoelectric elements that can independently respond to acoustic pressure while reducing the propagation of intrinsic stress through the membrane, thereby maintaining sensitivity without compromising structural integrity.
Solution Approach 2:
The spring region is formed with different material properties than the main membrane body. By using a separate material or modified structure in the spring region, the design achieves localized flexibility to accommodate stress while maintaining the rigid characteristics of the membrane in areas requiring structural strength, thus balancing both requirements.
2Measurement precision
If the membrane is made more flexible to reduce stress, then sensitivity is improved, but structural strength decreases
Solution Approach 1:
By segmenting the membrane through slits, the structure achieves flexibility in specific regions without compromising overall strength. The segmented structure can deform locally to reduce stress while maintaining rigidity in areas that require structural support, thus balancing flexibility and strength requirements.
Solution Approach 2:
The spring region utilizes composite material construction, combining different materials with complementary properties. This allows the spring region to provide necessary flexibility and stress relief while the main membrane maintains its structural strength through appropriate material selection and design.
3Measurement precision
If a spring region is added to reduce stress, then sensitivity is improved, but device complexity increases
Solution Approach 1:
The spring region is merged with the membrane structure rather than being a completely separate component. By integrating the spring functionality into the membrane assembly through shared materials and manufacturing processes, the design reduces overall device complexity while still achieving stress reduction and sensitivity improvement.
Solution Approach 2:
The spring region serves multiple functions simultaneously: it acts as a stress relief mechanism, provides structural support, and maintains flexibility for acoustic response. This multi-functionality reduces the need for additional separate components, thereby reducing device complexity while achieving multiple performance goals.
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 spring region reduces intrinsic stress, resulting in more predictable sensitivity, higher yield, and increased output energy, making the microphone more reliable and efficient.
Implementation Method 1
Piezoelectric MEMS microphones work on the principle of piezoelectric effect, so that they convert acoustic signals to electric signals when sound waves vibrate the piezoelectric sensor. The sound waves bend the piezoelectric film layers of a membrane or cantilevered beam, causing stress and strain, resulting in charges being generated in the piezoelectric film layers.
Data Source
AI summary
A piezoelectric microelectromechanical systems microphone is provided comprising a substrate including at least one wall defining a cavity, the at least one wall defining an anchor region around a perimeter, a piezoelectric film layer forming a membrane, the piezoelectric film layer being supported at the anchor region by a spring region, and an electrode disposed over the piezoelectric film layer. A method of manufacturing such a MEMS microphone is also provided.