MEMS Chip Membrane Stiffness and Leakage Control
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Solution Overview
Problem
MEMS chips face reduced sensitivity and resonance frequency due to high membrane stiffness when fully fixed, and leakage issues when partially fixed, affecting their acoustic performance.
Innovation Solution
A MEMS chip design featuring a substrate with a back cavity, a capacitance system including a membrane and back plate, a protruding portion, and a reinforce portion with strip-shaped ribs, where the membrane is partially fixed via elastic arms and the back plate is suspended, allowing for adjustable stiffness and resonance frequency optimization.
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 patent applies local quality by providing a reinforce portion only at specific locations on the membrane rather than fixing the entire edge. The reinforce portion has a smaller area than the membrane and is positioned to provide localized stiffness enhancement while leaving other areas flexible for sensitivity maintenance.
2Reliability
If the edge of the membrane is partially fixed on the substrate, then the sensitivity of the MEMS chip is improved, but a leakage path is formed between the substrate and the membrane
Solution Approach 1:
The protruding portion acts as an intermediary element between the membrane and the inner cavity. It prevents the formation of leakage paths by providing a barrier structure that seals the space while allowing the membrane to remain partially unfixed for sensitivity maintenance.
3Reliability
If the edge of the membrane is partially fixed on the substrate, then the sensitivity of the MEMS chip is improved, but the resonance frequency and low frequency property are reduced
Solution Approach 1:
The reinforce portion provides localized stiffness enhancement at specific positions on the membrane, allowing the membrane to maintain flexibility for high sensitivity while having reinforced areas that preserve resonance frequency and low frequency properties.
4Object-generated harmful factors
If a protruding portion is provided in the inner cavity, then the leakage path is prevented, but the space in the inner cavity is occupied
Solution Approach 1:
The protruding portion is designed with dimensions that are sufficient to prevent leakage paths but minimized to occupy minimal space in the inner cavity. The protruding portion extends from the membrane toward the back plate but maintains a spacing that prevents excessive space occupation.
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 enhances sensitivity, resonance frequency, and low-frequency properties by reducing membrane stiffness and maintaining resonance frequency, while preventing leakage, thus improving overall acoustic performance.
Implementation Method 1
A sound hole is provided on the shell communicating the back cavity, thus allowing the membrane to move under external pressure wave
Implementation Method 2
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 Micro-Electro-Mechanical System 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 reinforce portion fixed to the membrane, having an area smaller than that of the membrane; 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 MEMS chip has higher sensitivity, higher resonance frequency and higher low frequency property.