Corrugated MEMS Diaphragms for High Sensitivity Microphones
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microelectromechanical system microphones face challenges in designing dual membrane structures that minimize deformation between pillars while maintaining responsiveness to acoustic pressure, due to significant pressure differences causing tensile stress and increased stiffness.
Innovation Solution
A microelectromechanical system comprising a spacer layer with alternately arranged counter electrode walls and support walls, and two corrugated conductive diaphragms forming sealed chambers with aligned crests and troughs, which reduces residual stress and deformation, allowing for increased acoustic compliance without additional stiffening pillars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pressure within the sealed volume is reduced to significantly below atmospheric pressure, then the acoustic damping is reduced and microphone SNR is improved, but the pressure difference causes membrane deformation between pillars and increases membrane stiffness
Solution Approach 1:
The patent applies corrugated (curved) structures to both the first and second membranes instead of flat planar membranes. The corrugations provide structural reinforcement that resists deformation under pressure differential while maintaining the membrane's ability to respond to acoustic pressure. The curvature distributes stress more evenly, preventing localized tensile stress between pillars.
Solution Approach 2:
The patent uses thin corrugated membrane structures that are flexible enough to respond to acoustic pressure but stiffened by their corrugated geometry to resist deformation from the pressure differential. The corrugations act as structural reinforcement within the thin film, allowing the membrane to maintain its shape under vacuum while remaining acoustically responsive.
2Stability of the object's composition
If additional pillars are added to reduce membrane deformation, then membrane stability is improved, but acoustic compliance is reduced and sensitivity is degraded
Solution Approach 1:
The corrugated structure provides inherent stiffness through its geometry, eliminating the need for additional pillars. The curved ridges and valleys of the corrugations create structural reinforcement that stabilizes the membrane under pressure differential without requiring extra support elements that would restrict acoustic motion.
Solution Approach 2:
The patent changes the physical parameters of the membrane by introducing corrugations with specific geometries (ridge height, valley depth, spacing). This modifies the membrane's mechanical properties, increasing its resistance to deformation while maintaining acoustic compliance. The corrugation parameters are optimized to balance structural stability with acoustic responsiveness.
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 solution enhances acoustic compliance and microphone sensitivity by reducing residual stress and deformation, enabling thinner diaphragm materials with improved resistance to pressure differentials, resulting in a more compliant and sensitive electro-acoustic conversion device.
Implementation Method 1
a first capacitance is formed between the first corrugated conductive diaphragm and the conductive elements disposed on the first surface of the spacer layer and a second capacitance is formed between the second corrugated conductive diaphragm and the conductive elements disposed on the second surface of the spacer layer
Implementation Method 2
If the pressure within the sealed volume is reduced to significantly below atmospheric pressure i.e. less than 10% of atmospheric pressure, the acoustic damping associated with the airflow through the counter electrode will be reduced significantly. The reduction of the acoustic damping results in an increase in microphone SNR (Signal to Noise Ratio).
Implementation Method 3
The first crests are respectively aligned with the second troughs and the first troughs are respectively aligned with the second crests. The support walls are respectively sandwiched between the aligned first troughs and second crests. This alignment reduces residual stress and deformation between the pillars.
Data Source
AI summary
A microelectromechanical system includes a spacer layer, a first corrugated conductive diaphragm, and a second corrugated conductive diaphragm. The spacer layer includes counter electrode walls, slots and support walls extending along a first direction. The counter electrode walls, slots and support walls are arranged alternately in a second direction. The first corrugated conductive diaphragm includes first crests and first troughs arranged alternately in the second direction. The second corrugated conductive diaphragm includes second crests and second troughs arranged alternately in the second direction. The spacer layer is received in a cavity formed by the first and second corrugated conductive diaphragms. The support walls are respectively sandwiched between the aligned first troughs and second crests. The counter electrode walls are respectively suspended in the corresponding chambers formed between the aligned first crests and second troughs. The microelectromechanical system of the present disclosure has a high level of acoustic compliance and sensitivity.