MEMS Chip Support Pillar Resonance Frequency
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Solution Overview
Problem
Existing MEMS chips face challenges in increasing resonance frequency and signal noise ratio (SNR) due to limitations in the package structure, where increasing membrane stiffness reduces sensitivity and decreasing back cavity volume increases noise and lowers SNR.
Innovation Solution
The MEMS chip design includes a substrate with a back cavity and a capacitance system featuring a back plate with through holes and a support structure with annular support pillars that extend along the vibration direction, allowing for a sealed space that maintains high SNR even with decreased back cavity volume, enhancing membrane stability and resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If membrane stiffness is increased to improve resonance frequency, then resonance frequency is improved, but sensitivity and signal noise ratio reduce
Solution Approach 1:
The patent applies local quality by providing support portions only at specific locations (two ends along the vibration direction) rather than uniformly across the membrane. This localized support structure allows the membrane to maintain appropriate stiffness for high resonance frequency while preserving its sensitivity and signal noise ratio characteristics in the unsupported vibration regions.
2Speed
If back cavity volume is decreased to improve resonance frequency, then resonance frequency is improved, but overlapped area between membrane and substrate increases resulting in more noise and lower SNR
Solution Approach 1:
The patent resolves the contradiction by transitioning from a single-dimensional volume reduction approach to a multi-dimensional solution. It maintains a sufficient back cavity volume while compensating for resonance frequency enhancement through the addition of support portions in the spatial dimension, thereby preventing membrane-substrate overlap and associated noise without sacrificing resonance performance.
3Ease of manufacture
If package structure is defined with fixed sound hole and accommodation space, then manufacturing is simplified, but resonance frequency cannot be improved without compromising other parameters
Solution Approach 1:
The patent applies segmentation by dividing the membrane support function into distinct support portions that are separately provided on the membrane. This segmentation allows independent optimization of the support structure without requiring changes to the overall package structure, sound hole, or accommodation space, thereby maintaining manufacturing simplicity while achieving enhanced resonance frequency through the added support portions.
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
This design effectively improves resonance frequency and maintains high signal noise ratio while preventing noise increase, ensuring reliable and crack-resistant membrane 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
the capacitance system includes a membrane and a back plate arranged at an interval
Data Source
AI summary
The present disclosure discloses a MEMS chip which includes a substrate, a back plate fixed on the substrate, and a membrane fixed on the substrate and located above the back plate. A sealed space is formed between the membrane and the back plate. A support pillar is received in the sealed space. Two ends of the support pillar along a vibration direction of the membrane are separately fixed on the membrane and the back plate. As a result, when decreasing the volume of the back cavity, the resonance frequency of the MEMS chip has been effectively improved and the SNR is simultaneously high. Furthermore, the support pillar can effectively improve the reliability and crack resistance of the membrane.