MEMS Microphone Plate with Corrugations and Anti-Stiction Coating
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Solution Overview
Problem
Micro-electro mechanical system (MEMS) devices in microphones face challenges such as surface tension-induced stiction between the plate and membrane, leading to noise, decreased signal-to-noise ratio (SNR), and sensitivity issues due to residual tensile stress and parasitic capacitance from CMOS integration.
Innovation Solution
A semiconductor structure with a thin, stiff plate made of epitaxial silicon or silicon-on-insulator substrate, supported by a handle substrate, and featuring apertures and corrugations to reduce stress and stiction, along with an anti-stiction coating, which is bonded with a CMOS device to minimize noise and enhance SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin plate is used to reduce form factor and thickness, then the device size is reduced, but the plate becomes more susceptible to bending and residual stress
Solution Approach 1:
The patent introduces corrugations (curved structures) in the plate to provide structural rigidity while maintaining thin overall thickness. The curved geometry resists bending forces and reduces the impact of residual stress, allowing the plate to remain straight and stable despite being thin.
Solution Approach 2:
The patent uses a composite structure combining the thin plate with supporting elements and anti-stiction coatings. This composite approach provides both the thickness reduction benefit and the structural stability needed to resist bending and stress.
2Volume of moving object
If the plate and membrane are placed close together to reduce device thickness, then form factor is reduced, but surface tension causes stiction between plate and membrane
Solution Approach 1:
The patent introduces an anti-stiction coating as an intermediary layer between the plate and membrane. This coating reduces surface tension and prevents direct contact adhesion, allowing the components to be placed close together without suffering from stiction problems.
Solution Approach 2:
The patent uses thin film structures for both the plate and membrane, which allows them to be positioned close together while maintaining their structural integrity and reducing the overall device thickness. The thin film nature combined with anti-stiction treatment prevents harmful adhesion.
3Adaptability or versatility
If integration with CMOS devices is added to enhance functionality, then device performance is improved, but manufacturing complexity and yield loss increase
Solution Approach 1:
The patent merges the MEMS device structure with CMOS device integration, combining multiple functionalities into a single unified structure. This integration allows enhanced functionality while using shared manufacturing processes and materials, though it does increase overall manufacturing complexity.
Data Source
AI summary
A semiconductor structure includes a first device and a second device. The first device includes a plate including a plurality of apertures, a membrane disposed opposite to the plate and including a plurality of corrugations facing the plurality of apertures, and a conductive plug extending from the plate through the membrane. The second device includes a substrate and a bond pad disposed over the substrate, wherein the conductive plug is bonded with the bond pad to integrate the first device with the second device, and the plate is an epitaxial (EPI) silicon layer or a silicon-on-insulator (SOI) substrate.