MEMS Microphone Semiconductor-Insulator Diaphragm
Solution Overview
Problem
Conventional MEMS microphones, such as piezoelectric and piezoresistive types, suffer from low sensitivity and high noise, while capacitive-type microphones face design complexity and high manufacturing costs due to precise electrode placement and stress requirements.
Innovation Solution
A MEMS microphone design utilizing a semiconductor-on-insulator structure with resistors and vent holes, where the first openings form diaphragms connected to resistors, allowing resistance changes to convert sound waves into electrical signals without the need for piezoelectric or piezoresistive materials, fabricated using conventional semiconductor processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric or piezoresistive materials are used to form the diaphragm, then the MEMS microphone can convert sound waves into electrical signals, but the sensitivity is low and noise is high
Solution Approach 1:
The patent replaces piezoelectric and piezoresistive materials with standard semiconductor materials and uses a different detection mechanism. Instead of relying on material-specific piezoelectric or piezoresistive effects that produce low signal and high noise, the invention uses a capacitor formed by doped regions in the semiconductor substrate, enabling electrical signal generation through mechanical vibration without the harmful effects of specialized materials.
2Reliability
If capacitive-type MEMS microphone uses precise electrode placement, then sound wave conversion is achieved, but design complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the semiconductor substrate serve multiple functions: it acts as both the structural base and the capacitor formation medium. The doped regions within the substrate create the capacitor, eliminating the need for separate electrode structures. This multi-functionality reduces design complexity and manufacturing cost while maintaining accurate sound wave conversion capability.
3Manufacturing precision
If the distance between two electrodes in capacitive-type MEMS is made exact, then capacitance changes accurately with sound waves, but manufacturing yield decreases due to stress and bending
Solution Approach 1:
The patent merges the capacitor structure into the semiconductor substrate itself using doped regions, eliminating the need for separate fixed and flexible electrodes. This integration removes the stress and bending issues that affect electrode distance precision in conventional capacitive designs, thereby improving manufacturing yield while maintaining accurate capacitance changes in response to sound waves.
4Ease of manufacture
If conventional semiconductor processes are used to fabricate the MEMS microphone, then manufacturing cost and complexity are reduced, but specific piezoelectric or piezoresistive materials are still required
Solution Approach 1:
The patent uses homogeneous standard semiconductor materials throughout the substrate and doped regions, eliminating the need for specialized piezoelectric or piezoresistive materials. This material uniformity allows the use of conventional semiconductor fabrication processes, reducing manufacturing complexity and cost while simplifying the material supply chain.
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 design enhances sensitivity and reduces manufacturing complexity and costs by leveraging semiconductor processes, eliminating the need for specific materials and simplifying the fabrication process.
Implementation Method 1
the diaphragm is connected to the resistors. When the diaphragm vibrates due to the sound wave, resistor deformation is caused. Consequently, resistance of the resistor connected to the diaphragm is changed.
Data Source
AI summary
A microelectromechanical system microphone includes a semiconductor-on-insulator structure, a plurality of resistors, a plurality of first openings, and a vent hole. The semiconductor-on-insulator structure includes a substrate, an insulating layer and a semiconductor layer. The resistors are formed in the semiconductor layer, the first openings are formed in the semiconductor layer, and the vent hole is formed in the insulating layer and the substrate. The resistors are connected to each other to form a resistor pattern, and the first openings are all formed within the resistor pattern.