MEMS Microphone Backbone Structure for Diaphragm Flatness
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Solution Overview
Problem
Prior art piezoelectric MEMS microphones with cantilever diaphragms lack a base structure, leading to curvature due to stress/stress gradients, impacting acoustic performance and manufacturability, and result in fragile and unreliable devices with low manufacturing yield.
Innovation Solution
A MEMS microphone design featuring a pressure sensing element supported by a robust backbone, where the pressure sensing element can be piezoelectric and attached to a diaphragm, with the backbone providing structural support and minimizing acoustic damping, enhancing the structural integrity and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If piezoelectric thin films are used for cantilever diaphragms without a base structure, then the device can be fabricated using standard MEMS processes, but stress/stress gradient causes diaphragm curvature that impacts acoustic performance and manufacturability
Solution Approach 1:
The diaphragm is segmented into a piezoelectric film layer and a separate backbone structure. The backbone is divided into multiple beams that are selectively removed to create the final diaphragm structure, allowing stress management while maintaining fabrication compatibility.
Solution Approach 2:
The invention transitions from a traditional single-layer cantilever diaphragm to a multi-layer structure with the piezoelectric film deposited on a backbone structure. This adds a vertical dimension to the design, enabling stress compensation through the backbone while maintaining the thin-film piezoelectric layer for sensing.
2Device complexity
If piezoelectric thin films without base structure are used, then device complexity is reduced, but the cantilever diaphragms become fragile and unreliable with low manufacturing yield
Solution Approach 1:
The backbone structure serves as a pre-established support framework that protects the fragile piezoelectric film during fabrication and operation. This prior cushioning structure prevents diaphragm breakage before the final product is completed, thereby improving manufacturing yield and reliability.
Solution Approach 2:
The invention combines the piezoelectric film material with a backbone structure material to create a composite diaphragm system. The backbone provides mechanical strength and reliability, while the piezoelectric film maintains its sensing function, achieving both simplicity and robustness.
3Strength
If a backbone structure is added to support the pressure sensing element, then structural integrity and robustness are improved, but device complexity increases
Solution Approach 1:
The backbone is segmented into multiple identical beams arranged in a grid pattern. This segmentation allows for standardized fabrication processes and simplifies the design while providing comprehensive support to the piezoelectric film, balancing structural integrity with design simplicity.
Solution Approach 2:
The backbone structure serves multiple functions simultaneously: it provides mechanical support to prevent film breakage, acts as a stress compensation structure to maintain diaphragm flatness, and serves as the substrate for piezoelectric film deposition. This multi-functionality reduces the need for additional components.
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 new structure improves the robustness and manufacturability of MEMS microphones, increasing the signal-to-noise ratio and reducing acoustic resistance, resulting in a more reliable and efficient acoustic performance.
Implementation Method 1
the pressure sensing element is a piezoelectric element
Data Source
AI summary
Disclosed are a MEMS microphone and an electronic apparatus. The MEMS microphone comprises: a pressure sensing element, for sensing pressure applied thereon; a diaphragm attached to the pressure sensing element and applying pressure to the pressure sensing element; and a backbone attached to the pressure sensing element and supporting the pressure sensing element.