MEMS Microphone Vibration Membrane Slit Pattern Design
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Solution Overview
Problem
Conventional MEMS microphones face challenges in achieving high sensitivity and robustness due to limitations in vibration membrane structures, such as increased chip size and process complexity with slot and spring patterns, which affect vibration displacement and product yield.
Innovation Solution
A high-sensitivity MEMS microphone with a vibration membrane structure featuring minute slit patterns crossing in a horizontal direction, formed along the circular edge, which improves vibration displacement and robustness, and a manufacturing method involving a substrate with a through hole, a vibration membrane with a slit pattern, a fixed membrane with air inlets, and a support layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a slot pattern is formed in the vibration membrane to reduce rigidity and improve sensitivity, then sensitivity is improved, but chip size increases
Solution Approach 1:
The vibration membrane is segmented into multiple regions by forming a cross-shaped slot pattern that divides the membrane into four quadrants. This segmentation reduces the overall rigidity of the membrane while maintaining a compact chip size, as the slots are integrated within the existing membrane area rather than requiring additional space
Solution Approach 2:
The slot pattern transitions from conventional linear slots to a cross-shaped configuration that extends in multiple dimensions (both horizontal and vertical directions). This multi-dimensional slot arrangement maximizes the rigidity reduction effect within the available membrane area, improving sensitivity without proportionally increasing chip size
2Stress or pressure
If a spring pattern is applied to the vibration membrane to reduce stress, then stress is reduced, but process complexity increases
Solution Approach 1:
The vibration membrane is segmented into multiple regions by forming a cross-shaped slot pattern that divides the membrane into four quadrants. This segmentation reduces the overall rigidity of the membrane while maintaining a compact chip size, as the slots are integrated within the existing membrane area rather than requiring additional space
Solution Approach 2:
The slot pattern transitions from conventional linear slots to a cross-shaped configuration that extends in multiple dimensions (both horizontal and vertical directions). This multi-dimensional slot arrangement maximizes the rigidity reduction effect within the available membrane area, improving sensitivity without proportionally increasing chip size
3Measurement precision
If the vibration membrane rigidity is reduced to improve sensitivity, then sensitivity is improved, but vibration displacement decreases
Solution Approach 1:
The cross-shaped slot pattern is positioned specifically at the center of the vibration membrane, creating local flexibility zones that allow for greater vibration displacement in the central region while maintaining adequate rigidity in the outer regions. This localized modification optimizes both sensitivity and vibration displacement
Solution Approach 2:
The slot pattern creates asymmetric stress distribution in the vibration membrane, with the cross-shaped configuration allowing different regions to vibrate with different amplitudes. This asymmetric design enables the central region to achieve larger displacement while the outer regions maintain structural integrity
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 proposed solution achieves improved vibration displacement and sensitivity by forming minute slit patterns, enhancing the microphone's performance index while maintaining low rigidity and robustness, compared to conventional spring and slot structures.
Implementation Method 1
when a sound pressure (sound source) is applied from outside to the vibration membrane
Implementation Method 2
a capacitance value varies as a distance between the fixed membrane and the vibration membrane varies. A thus-generated electric signal is used to measure a sound pressure
Data Source
AI summary
A microphone includes: a substrate configured to have a through hole formed at a central portion thereof; a vibration membrane disposed to cover the through hole on the substrate to include a slit pattern in which slit patterns are arranged in a plurality of lines along a circular edge thereof; a fixed membrane separately mounted at an upper portion of the vibration membrane with an air layer therebetween to have a plurality of air inlets that extend therebetween in a direction of the air layer; and a support layer configured to support the fixed membrane separately mounted on the vibration membrane.