MEMS Acoustic Sensor Back Cavity Integration
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Solution Overview
Problem
Existing MEMS microphones are costly to manufacture and require complex packaging, limiting their cost-effectiveness and adaptability to existing manufacturing processes.
Innovation Solution
A MEMS device design featuring a first and second plate with a linkage system, situated in an enclosure formed by substrates, where the plates are displaced by acoustic pressure differentials, and pressure equalization channels ensure ambient pressure equality, reducing manufacturing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS microphones are manufactured using two separate chips (ASIC and MEMS) enclosed by conductive cover and substrate, then acoustic sensing function is achieved, but manufacturing cost increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the MEMS microphone structure with the substrate by integrating the back cavity formation directly into the substrate manufacturing process. The substrate serves dual purposes: as the mechanical support structure and as the enclosure forming the back cavity, eliminating the need for separate ASIC chip assembly and reducing manufacturing steps.
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: it provides mechanical support, forms the acoustic back cavity enclosure, and serves as part of the acoustic sensing structure. This multi-functionality reduces the number of separate components needed and simplifies the manufacturing process.
2Reliability
If MEMS microphones are manufactured using two separate chips (ASIC and MEMS) enclosed by conductive cover and substrate, then acoustic sensing function is achieved, but device complexity increases
Solution Approach 1:
The patent merges the back cavity formation with the substrate structure itself. By forming the back cavity as an integrated part of the substrate through standard semiconductor fabrication processes, the design eliminates complex packaging requirements and reduces the number of discrete components that need to be assembled and enclosed.
3Reliability
If acoustic back cavity is formed by volume under MEMS chip and substrate, then acoustic sensing is enabled, but package footprint increases
Solution Approach 1:
The patent utilizes the vertical dimension by forming the back cavity as an etched region within the substrate thickness rather than requiring lateral expansion. This three-dimensional integration allows the acoustic cavity to be contained within the substrate volume, reducing the horizontal package footprint while maintaining the necessary acoustic sensing volume.
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 design allows for cost-effective manufacturing and improved acoustic sensitivity, with reduced sensitivity to accelerations and enhanced flexibility in design, resulting in a smaller package footprint and improved reliability.
Implementation Method 1
The MEMS device further includes a second plate with a third surface and a fourth surface attached to the first plate. A linkage connects the anchor to the first plate, wherein the first plate and second plate are displaced in the presence of an acoustic pressure differential between the first and second surfaces of the first plate.
Data Source
AI summary
A MEMS device is disclosed. The MEMS device comprises a first plate with a first surface and a second surface; and an anchor attached to a first substrate. The MEMS device further includes a second plate with a third surface and a fourth surface attached to the first plate. A linkage connects the anchor to the first plate, wherein the first plate and second plate are displaced in the presence of an acoustic pressure differential between the first and second surfaces of the first plate. The first plate, second plate, linkage, and anchor are all contained in an enclosure formed by the first substrate and a second substrate, wherein one of the first and second substrates contains a through opening to expose the first surface of the first plate to the environment.