MEMS Microphone Recess Design for Back Volume
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Solution Overview
Problem
MEMS microphones face limitations in sensitivity due to the space occupied by the MEMS device and integrated circuit, which restricts the back volume and thus the performance of the microphone.
Innovation Solution
Creating a recess in the substrate to house the MEMS device and/or integrated circuit, thereby increasing the back volume without occupying additional space, allowing for improved sensitivity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the MEMS device and integrated circuit are disposed in a flat substrate configuration, then the assembly is compact and easy to manufacture, but the back volume is reduced which limits sensitivity
Solution Approach 1:
The patent introduces a recess into the substrate, transitioning from a flat two-dimensional surface to a three-dimensional structure with depth. This dimensional change creates additional back volume without increasing the overall footprint of the device, effectively resolving the contradiction between compactness and sensitivity enhancement.
Solution Approach 2:
The MEMS device and integrated circuit are nested within the recess of the substrate, utilizing the vertical space created by the recess. This nesting approach allows components to be housed within the substrate structure itself, maximizing the use of available space and increasing back volume without proportionally increasing device complexity.
2Measurement precision
If the back volume is increased to improve sensitivity, then the microphone performance is enhanced, but the space required for components increases
Solution Approach 1:
By creating a recess with depth, the patent exploits the third dimension (vertical space) to increase back volume. This allows sensitivity to be improved without proportionally increasing the horizontal footprint or overall component space requirements, as the additional volume is achieved through vertical integration rather than lateral expansion.
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 increased back volume results in enhanced sensitivity and transduction efficiency of the MEMS microphone, as demonstrated by the correlation between increased back volume and improved sensitivity in the provided graphs.
Implementation Method 1
sound energy enters through a sound port and vibrates a diaphragm and this action creates a corresponding change in electrical potential (voltage) between the diaphragm and a back plate disposed near the diaphragm
Data Source
AI summary
A microelectromechanical system (MEMS) microphone assembly includes a base and a cover. The cover is coupled to the base and together with the base defines a cavity. The base forms a recess and the recess has dimensions and a shape so as to hold a MEMS die. The MEMS die includes a diaphragm and back plate.