MEMS Microphone Sidewall Support for Membrane Breakage
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Solution Overview
Problem
Conventional MEMS microphones face issues with vibration membrane breakage during the wet etch process due to deformation, and reducing the substrate's critical dimension to prevent breakage adversely affects audio signal quality by increasing the contact area between the substrate and the membrane.
Innovation Solution
Incorporating support members on the sidewalls of the opening in the substrate, which are symmetrically arranged and have a smaller lateral width than the opening, to provide mechanical support to the vibration membrane and prevent breakage, while maintaining a minimal contact area to avoid signal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the critical dimension of the substrate is reduced to provide support to the vibration membrane, then the vibration membrane breakage is prevented, but the contact area between the substrate and the membrane increases which adversely affects the audio signal
Solution Approach 1:
The substrate is segmented by forming openings that expose lower surface portions of the vibration membrane, creating distinct supported regions. Support members are strategically positioned within these openings to provide localized support only where needed, rather than increasing overall substrate contact area. This segmentation allows the membrane to maintain large-area contact with the cover layer for signal quality while receiving targeted support to prevent breakage.
Solution Approach 2:
Support members are placed at specific locations within the openings on the substrate, providing localized mechanical support precisely where the vibration membrane needs reinforcement. The support members have controlled dimensions and positions that ensure support is applied only to lower surface portions of the membrane, maintaining minimal contact area while preventing breakage during wet etch processes.
2Reliability
If support members are added to provide mechanical support to the vibration membrane, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The support members are integrated into the substrate structure during the semiconductor manufacturing process, combining the substrate formation and support member creation into a unified process flow. The support members are formed as part of the substrate fabrication sequence, utilizing existing process steps such as deposition and patterning, rather than requiring separate manufacturing operations.
Solution Approach 2:
The support members are designed to automatically provide the required mechanical support function through their geometric configuration and material properties, without requiring additional control systems or adjustment mechanisms. The support members' dimensions and positions are determined during manufacturing to inherently provide the necessary support during wet etch processes, eliminating the need for post-manufacturing adjustments or complex control systems.
Data Source
AI summary
A semiconductor device includes a substrate having an opening extending through the substrate and at least one support member on a sidewall of the opening, a vibration membrane on the substrate, a cover layer on the vibration membrane. The substrate, the vibration membrane, and the cover layer define a cavity. The opening exposes a lower surface portion of the vibration membrane. The at least one support member on the sidewall of the opening provides support to the vibration membrane in a deformation of the vibration membrane to prevent breakage.