MEMS Microphone Phase Delay Structure for Directional Sensitivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing microphones, particularly MEMS microphones, face challenges in achieving improved sensitivity and directionality while maintaining a downsized form factor and cost-effectiveness, as they often require multiple digital MEMS microphones and DSP chips for directional functionality.
Innovation Solution
The development of a microphone structure incorporating a phase delay membrane made of a wafer level package, featuring a vibrating membrane with slots, a fixed membrane with air intake apertures, and a phase delay unit with zigzag sound passages, which delays sound phase and enhances directionality without the need for multiple digital MEMS microphones and DSP chips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional functionality is achieved using multiple digital MEMS microphones and DSP chips, then directionality is improved, but device complexity and cost increase
Solution Approach 1:
The single microphone is segmented into multiple functional regions: a first receiving region for receiving sound waves and a second receiving region for receiving reference sound waves. This segmentation allows different parts of the same device to perform different functions, achieving directional capability without multiple separate microphones or digital processing chips.
Solution Approach 2:
A phase delay unit is introduced as an intermediary component between the sound wave reception and the capacitive sensing. This phase delay unit delays the sound waves by a predetermined time, creating a phase difference that enables directional detection. The intermediary component allows analog directionality to be achieved through physical phase manipulation rather than digital signal processing.
2Measurement precision
If multiple digital MEMS microphones and DSP chips are used for directional functionality, then directionality is improved, but manufacturing cost increases
Solution Approach 1:
Multiple functional elements are merged into a single integrated device: sound wave reception, phase delay, reference sound wave reception, and capacitive sensing are all combined in one microphone structure. This merging eliminates the need for multiple separate microphones and DSP chips, significantly reducing manufacturing cost while maintaining directional capability.
Solution Approach 2:
The patent replaces the digital signal processing system (DSP chips and multiple microphones) with an analog mechanical/acoustic system. The phase delay unit uses physical sound wave propagation delays and the capacitive sensing uses electrical field changes, both of which are analog phenomena. This substitution eliminates expensive digital processing hardware while achieving the same directional functionality.
3Volume of moving object
If the microphone is downsized using MEMS technology, then device size is reduced, but achieving improved sensitivity and directionality becomes more difficult
Solution Approach 1:
The patent transitions from a single-point sensing approach to a distributed sensing approach across two-dimensional surfaces. The first and second receiving regions are distributed across different locations and orientations, allowing the small MEMS device to capture spatial sound information. This dimensional expansion enables sensitivity improvement without increasing overall device volume.
Solution Approach 2:
The patent changes the operating parameters of the capacitive sensing system by introducing phase-delayed sound waves. The phase difference created by the delay unit modifies the temporal and spatial parameters of sound wave interaction with the membranes, enhancing the sensitivity of the capacitive sensing to directional sound sources even in the downsized MEMS structure.
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 approach enables the creation of a downsized microphone with improved sensitivity and directionality, reducing the need for costly digital processing and allowing for analog directionality, thus lowering production costs and enhancing sound quality.
Implementation Method 1
a phase delay unit (100) disposed on the fixed membrane (5), the phase delay unit (100) having a sound aperture (120) through which the sound wave (SW) may travel inside from the exterior and a sound passage (130) connected with the sound aperture (120)
Implementation Method 2
the capacitive MEMS microphone includes a fixed membrane and a vibrating membrane, thus when a sound pressure is applied to the vibrating membrane from the outside, the gap between the fixed membrane and the vibrating membrane changes and the capacitance changes accordingly
Implementation Method 3
the piezoelectric MEMS microphone includes a vibrating membrane. When the vibrating membrane is deformed by external sound pressure, an electrical signal is generated by the piezoelectric effect and the sound pressure is measured
Data Source
AI summary
A microphone and a method of manufacturing the microphone are provided. The method includes; preparing a substrate and forming a vibrating membrane having an oxide film and a plurality of slots onto the substrate. A sacrificial layer and a fixed membrane is formed over the vibrating membrane and air intake apertures are formed through the fixed membrane. A first pad is connected to the fixed membrane, a second pad is connected to the vibrating membrane, and a phase delay unit is bonded to the bonding pad. A penetration aperture may be formed by etching the rear side of the substrate and bonding the phase delay unit on the bonding pad. A sound passage, is formed by connecting passage patterns, and sound apertures with the sound passages by sequentially stacking phase delay layers on the bonding pad and simultaneously forming the passage patterns in the phase delay layers.