MEMS Chip Annular Protrusions Reduce Stiffness
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Solution Overview
Problem
MEMS chips face reduced sensitivity and resonance frequency due to increased membrane stiffness when fully edge-fixed, and compromised low frequency properties when partially fixed, leading to suboptimal performance in acoustic applications.
Innovation Solution
A MEMS chip design featuring a substrate with a back cavity and capacitance system, including a membrane and back plate, with annular protruding portions and elastic arms to suspend the membrane and back plate, reducing internal stress and stiffness while minimizing air leakage, thereby enhancing sensitivity and resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the whole edge of the membrane is fixed on the substrate, then the stiffness of the membrane is improved, but the sensitivity of the MEMS chip reduces
Solution Approach 1:
The membrane edge fixation is segmented into two distinct regions: a first fixation region that fixes part of the membrane edge to the substrate, and a second fixation region that fixes the back plate to the substrate. This segmentation allows different portions of the structure to have different fixation characteristics, enabling the membrane to maintain adequate stiffness while preserving sensitivity through the suspended region.
2Reliability
If the edge of the membrane is partially fixed on the substrate, then the sensitivity is improved, but a leakage path forms reducing resonance frequency and low frequency property
Solution Approach 1:
The back plate serves as an intermediary structure that is fixed to the substrate in the second fixation region. This back plate provides structural support and seals the acoustic cavity, preventing air leakage paths that would otherwise form when the membrane edge is partially fixed. The intermediary back plate thus enables sensitivity improvement while maintaining resonance frequency stability.
3Stability of the object's composition
If the membrane is fully fixed on the substrate, then structural stability is improved, but air leakage occurs reducing low frequency performance
Solution Approach 1:
The fixation structure is segmented into two functional regions: the first fixation region for the membrane edge and the second fixation region for the back plate. This segmentation allows the back plate to be firmly fixed to the substrate, providing structural stability and sealing the acoustic cavity to prevent air leakage, while the membrane maintains its vibration characteristics through the separate fixation arrangement.
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 achieves higher sensitivity, resonance frequency, and low frequency performance by reducing membrane stiffness and air leakage, improving the overall acoustic properties of the MEMS chip.
Implementation Method 1
a capacitance system disposed on the substrate, including: a back plate; a membrane opposite to the back plate forming an inner cavity
Data Source
AI summary
The present invention discloses a MEMS chip including a substrate with a back cavity; a capacitance system disposed on the substrate including a back plate, a membrane opposite to the back plate forming an inner cavity; a protruding portion accommodated in the inner cavity, fixed on one of the back plate and the membrane and spaced apart from the other along a vibration direction; a support system configured to support the capacitance system, including a first fixation portion suspending the membrane on the substrate, and a second fixation portion suspending the back plate on the substrate; the protruding portion comprises an annular first protruding portion and an annular second protruding portion surrounding the first protruding portion. The MEMS chip has higher sensitivity, higher resonance frequency and higher low frequency property.